🇩🇪 Nixdorf LK-3000 Personal Computer: Part 3 (HELLO WORLD!) [TCE #0646] The Clueless Engineer 2025-10-07 | Thanks to #PCBWay for their ongoing support! pcbway.comLet's see if we can get HELLO WORLD! working on this little machine ... the first new software written for it in several decades? We'll use an Arduino Uno due to its simplicity and its size ... it should be small enough to implement a barebones Arduino on a self-contained cartridge.There's two aspects we need to take care of: reading the keyboard and writing characters to the display. As they are "smart" display modules we don't need to refresh them at all once the data has been written. Nice.The biggest hurdle to my understanding was how the 7-bit ASCII (0x20 to 0x5F) codes were loaded into the displays via the cartridge interface which only has a 6-bit data bus.It turns out that in the 0x20 to 0x5F range the value of D5 and D6 are ALWAYS opposite ... so if we set D5 then D6 is also known, and this behaviour is handled by the CD4503 buffer chip. How very clever.We have four address bits available ... two to address the four characters in each module and two to address the modules themselves, 16 characters in total. Each character can be addressed individually.For now we will just concentrate on getting the display working. When my development keyboard arrives we'll look at the keyboard scanning side of things.00:00 ... Intro00:50 ... Breakout cartridges02:50 ... Quick schematic overview05:15 ... Seven bits from six07:05 ... Development using an Arduino08:00 ... First test (almost OK)10:25 ... Second test (OK!)11:48 ... Third test (scrolling!)12:10 ... Fourth test (better scrolling!)13:35 ... Replacement module (NOK)15:00 ... Channel thanks & outro--------------------------------From Part 2:Let's see if we can put this machine to some use in 2025. I was initially just going to re-use the HPDL-1414 display modules but then thought it might be more interesting to use the whole machine as is ... it supplies a keyboard & display ... we just need to supply the CPU and firmware!As the machine is quite simple I drew up a schematic on how I think it works, including the keyboard matrix ... we either check the data bus for a key being pressed (keyboard strobe), or we put an ASCII character onto the bus and get it displayed (display strobe). So simple that I almost understand it.I designed some simple cartridge PCBs for initial development & testing - one cartridge with a prototyping area and one with a breakout header to allow development externally (i.e. wired up to an Arduino).I captured some signalling on the cartridge interface (Saleae Logic 2) to get an idea how we should talk to it ... whilst the development cartridges are being fabricated, I can whip up some Arduino code to check the keyboard and print to the display.All the details are on my Github for this machine which will be updated as I progress:github.com/0ddjob/Nixdorf-LK-3000Some discussion of possible uses here:forum.vcfed.org/index.php?threads/need-some-ideas-for-repurposing-a-nixdorf-lk-3000.1254359--------------------------------From Part 1:Let's take a look at this interesting "personal computer" from 1979. It's essentially a language translator using cartridges but has a few other tricks: it can be used as a calculator, an electronic notepad, a filing system and also a remote computer terminal (via an acoustic coupler).The machine has a very nice 16 character display (four DL1414 modules) and runs on four NiCd rechargeable cells. It also comes with a 6VDC power adaptor that can be switched between 120VAC and 220VAC.There is very little inside the machine itself - a few logic chips, the display and the battery. All of the intelligence is contained within the cartridges: usually a ROM and a CPU-type device. --------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 6 (Universal BackPack Drive) [TCE #0645] The Clueless Engineer 2025-10-03 | Thanks to #PCBWay for their ongoing support! pcbway.comNow that we've replaced the keyboard, let's try the UBPD again on the Z88. I'm using my Z88 DE9-to-DB25 serial port converter to connect the device and have XOB Disc Manager on a ROM cartridge.Well, it works! I'm a bit limited as to what I can do as I'm still running OZ 3.0 ... with OZ 4.6.2 I can load "RAM Applications" (such as Jet Set Willy and Manic Miner). For now I can load BBC Basic programs into my 512KB of RAM (tried Z88 Transworld Golf). I could probably also load ROM images and write them to a blank EPROM cartridge (will try that next).And, of course, I can no doubt transfer documents.00:00 ... Intro01:40 ... Checking free RAM02:15 ... Universal BackPack Drive and FTDI VDrive306:00 ... Configuring the Z88 & UBPD09:40 ... Loading XOB Disc Manager13:00 ... Types of applications on the Z8814:15 ... Loading Z88 Transworld Golf (a BBC Basic program)19:30 ... Filename limitations of the UBPD (8.3 vs 12.3)23:49 ... Channel thanks & outro--------------------------------From Part 5:Okay, let's finally upgrade the stock 32KB of XRAM (what NEC called their Pseudo-static RAM, a cross between DRAM and SRAM) to 512KB (4Mb) of SRAM (B=byte, b=bit). This should also reduce power drain. The upgraded RAM seems to be available even with the original OZ 3.0 firmware, showing over 500KiB free in the Diary application (♢EMF command).I'm using an Alliance AS6C4008 chip as they can still be bought new in PDIP-32 form for AU$11 each (Oct 2025 ... greetings if you're watching this in 2035 ... be sure to say "hi" in the comments!).Next job will be upgrading the stock 28-pin ROM (OZ 3.0?) to a 32-pin 512KB flash ROM with OZ 4.7.1. I've designed a small daughterboard to help with that:github.com/0ddjob/Sinclair/tree/main/Z88_Flash_ROM--------------------------------From Part 2:The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?--------------------------------From Part 1:What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.WoS info:worldofspectrum.org/z88forever/index.htmlZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 5 (512KB RAM Upgrade) [TCE #0644] The Clueless Engineer 2025-10-01 | Okay, let's finally upgrade the stock 32KB of XRAM (what NEC called their Pseudo-static RAM, a cross between DRAM and SRAM) to 512KB (4Mb) of SRAM (B=byte, b=bit). This should also reduce power drain. The upgraded RAM seems to be available even with the original OZ 3.0 firmware, showing over 500KiB free in the Diary application (♢EMF command).I'm using an Alliance AS6C4008 chip as they can still be bought new in PDIP-32 form for AU$11 each (Oct 2025 ... greetings if you're watching this in 2035 ... be sure to say "hi" in the comments!).Installation is pretty simple:[1] De-solder the 28-pin 32KB chip[2] Clean up the additional four unused pins[3] Cut pin 1 track to disconnect it from the POE signal[4] Cut pin 30 track to disconnect it from 5V[5] Solder in the new 32-pin 512KB chip[6] Connect pin 1 to A18[7] Connect pin 30 to A17[8] Go to Diary and check free memory (♢EMF)We can pick up A17 and A18 from one of the cartridge ports.Alternatively, if you don't want to cut tracks, you can lift pins 1 & 30 od the SRAM chip and wire them to A17/A18. I don't see any point in downgrading to 32KB so I'm happy to cut tracks.Next job will be upgrading the stock 28-pin ROM (OZ 3.0?) to a 32-pin 512KB flash ROM with OZ 4.7.1. I've designed a small daughterboard to help with that:github.com/0ddjob/Sinclair/tree/main/Z88_Flash_ROM00:00 ... Intro02:17 ... The plan03:20 ... That's why you can't fit an IC socket04:08 ... 323KB removed05:23 ... 512KB installed06:00 ... Testing (OK!)08:30 ... ROM upgrade plan09:57 ... Channel thanks & outroUseful upgrade posts:[1] christopherrivett.co.uk/2023/07/21/cambridge-z88-ram-and-rom-upgrade[2] https://privat.bahnhof.se/wb782177/z88/motherboard.htm[3] sinclairzxworld.com/viewtopic.php?p=43036#p43036--------------------------------From Part 3:The rubber mat on my Z88 doesn't work very well so let's try replacing it with a mechanical keyboard.I've designed this keyboard to use Gateron KS-33 low profile switches and, after a lot of searching, settled on a set of MA profile key caps that included an ISO ENTER key:Aliexpress store name: Skyloong Guangming StoreAliexpress store ID: 910796037aliexpress.com/item/1005004649108572.htmlI still need to find a few more spare key caps for the special keys.MA profile are taller than XDA or DSA profile ... DSA profile might be the best but it's just a matter of trying to find a complete set in black ... The keyboard is working fine from my initial testing. I didn't allow for a few millimetres of overhang by the LCD bezel, so I need to shave this off the top of my PCB to allow everything to fit back together nicely ... that'll be REV. B.My Github repository:github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_Keyboard--------------------------------From Part 2:The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?--------------------------------From Part 1:What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.WoS info:worldofspectrum.org/z88forever/index.htmlZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇲🇩 Вектор 06Ц (Vector 06C): Quick Update [TCE #0643] The Clueless Engineer 2025-09-29 | I'm hoping that a small modification to the video output stage will fix the sync issues of this interesting Moldovan computer. I designed a simple PCB that implements the changes, requiring only some wiring from the PCB and a few cut tracks.Details are in my repository on Github:github.com/0ddjob/Vector-06C00:00 ... Intro01:00 ... Oscilloscope ... C.SYNC02:45 ... Oscilloscope ... H.SYNC (ССИ)04:00 ... Oscilloscope ... V.SYNC (КСИ)05:20 ... Redrawn KiCad schematics08:10 ... Possible solution10:39 ... Channel thanks & Outro--------------------------------From Part 3:The Vector is known to have issues with modern displays because of its sloppy sync timing. I'm not really sure the best way to fix it ... I've scrolled through over 50 pages of Russian language forum posts where 15 different solutions were proposed, but no-one seems to have a definitive answer for the 02 model ... well, definitive enough for this lazy non-Russian speaker to just pick up and use.The pinout for the 7-pin video is:Pin 1 = sound (звук) Pin 2 = video (видео, i.e. composite sync) Pin 3 = blue Pin 4 = greenPin 5 = red Pin 6 = ground Pin 7 = +12v (упров/control)--------------------------------From Part 2:Let's try powering this interesting Moldovan machine on. As it uses an 8080-compatible CPU it requires three voltages: ±5VDC and +12VDC. I normally use a Mean Well GP25A13A-R1B with a 5-pin DIN plug for this. Comparing the 7-pin DIN socket on the Vector it's a very close match to the pinout on the Mean Well ... pin 2 on the Mean Well is 0V/GND but is -5VDC on the Vector. Easiest solution ... I'm not in the mood to make cables ... is to de-solder the 7-pin socket on the Vector and cut the track connecting pins 2 & 4 (-5V) so that pin 2 is not used. This will mean I can plug my Mean Well PSU directly into the Vector. Simples!Revised pinout for my Vector's 7-pin power socket to match the Mean Well's 5-pin plug:Pin 1 = groundPin 2 = not connected (ground on Mean Well)Pin 3 = +5VPin 4 = -5VPin 5 = +12VPin 6 = not connected (ground on Vector)Pin 7 = not connected (+5V on Vector)Next, checking the CPU and video output with the oscilloscope definitely shows activity! The keyboard doesn't seem to trigger anything ... no key press beep, no change in РУС/ЛАТ LED.Also ... the RGBS output on my Vector is 7-pin DIN and not 5-pin like on the schematic I'm referring to ... most likely because I've got a 06Ц.02 model and the schematic is for the original.When in doubt, guess!And ... it does seem there is a video signal ... it appears to be the tape loading screen, with ВЕКТОР 06Ц written up the top! But, as @night_gryphon warned in the Part 1 comments, the video output is a bit weird ... so some massaging to get it to work with modern equipment, in Australia, will be required:"The other catch is the non standard video output with non standard sync and inverted RGB levels. It was designed to cheat the CRT TV but most likely will confuse most of scan doublers etc."But, I'm happy that the machine appears to be functional!--------------------------------From Part 1:Let's have a look at a unique 8080-based (КР580ВМ80А) machine that was designed in the Moldovan SSR and released in 1987. This is the 2nd version of the machine, the Вектор 06Ц.02. The original had a 512 byte ROM that was enough to bootstrap loading from tape but this machine has a 2KByte ROM (556РТ7А, similar to a Philips 82S191) that has more functionality.The machine was apparently well regarded for its excellent graphics capabilities.As it's an 8080 machine it requires ±5V and +12V DC via a 7-pin DIN. I'll need to make up a 5-pin to 7-pin converter so I can use my Mean Well power supply with it.It has 64KBytes of DRAM in 32 x КР565РУ6 (similar to Intel 2118) ... yay! Lots of chips where something could go wrong!More information can be found here:github.com/alemorf/retro_computers--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Simple KiCad For Simple Vintage Computer Hobbyists: Part 9 (Mostek MK36000 Converter) [TCE #0642] The Clueless Engineer 2025-09-27 | Thanks to #PCBWay for their ongoing support! pcbway.comLet's design a simple ROM converter board so we can dump the contents of a Mostek MK36000 64kbit ROM using a modern EPROM programmer. This board will make the MK36000 look like a 2764-type EPROM. These ROMs from the 1970s are used in the cartridges for the Nixdorf LK-3000.We'll need to do a few things:[1] Create a new schematic symbol for the MK36000[2] Create a new footprint for the 2764 converter[3] Create a (simple) 3D model for the 2764 converter by reusing an existing model[4] Upload to PCBWAY for fabrication using their plug-inDesign can be found here:github.com/0ddjob/Conversion_Boards/tree/main/2764-to-MK36000Disclaimer: I'm not a KiCad super-user, I'm not a circuit design guru, I'm just a simple vintage computer hobbyist who needs simple PCBs from time to time. And yes, this sort of thing has probably been designed a dozen times before, but there's no harm in trying to learn how it's done is there?I'm using KiCad 9.0.4 on a 2022 MacBook Air (M2 with 24GB RAM) running macOS 15.6.1.Application: KiCad arm64 on arm64Version: 9.0.4, release buildPlatform: macOS Sequoia Version 15.6.1 (Build 24G90), 64 bit, Little endian, wxMac00:00 ... Intro03:30 ... Creating the MK36000 symbol08:55 ... Creating the 2764 footprint12:40 ... Creating the 3D model 15:00 ... Designing the schematic22:45 ... Creating the PCB28:30 ... Adding ground plane32:40 ... Uploading fabrication files to PCBWAY34:50 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇩🇪 Nixdorf LK-3000 Personal Computer: Part 2 (Lets Start Hacking It) [TCE #0641] The Clueless Engineer 2025-09-23 | Let's see if we can put this machine to some use in 2025. I was initially just going to re-use the HPDL-1414 display modules but then thought it might be more interesting to use the whole machine as is ... it supplies a keyboard & display ... we just need to supply the CPU and firmware!As the machine is quite simple I drew up a schematic on how I think it works, including the keyboard matrix ... we either check the data bus for a key being pressed (keyboard strobe), or we put an ASCII character onto the bus and get it displayed (display strobe). So simple that I almost understand it.I designed some simple cartridge PCBs for initial development & testing - one cartridge with a prototyping area and one with a breakout header to allow development externally (i.e. wired up to an Arduino).I captured some signalling on the cartridge interface (Saleae Logic 2) to get an idea how we should talk to it ... whilst the development cartridges are being fabricated, I can whip up some Arduino code to check the keyboard and print to the display.All the details are on my Github for this machine which will be updated as I progress:github.com/0ddjob/Nixdorf-LK-3000Some discussion of possible uses here:forum.vcfed.org/index.php?threads/need-some-ideas-for-repurposing-a-nixdorf-lk-3000.125435900:00 ... Intro02:42 ... The DL-1414 display module03:35 ... Showing a cartridge in action10:15 ... Another inside peek12:00 ... Preparing to capture cartridge signalling13:00 ... How it kinda works15:45 ... Logic analyser (Saleae)17:57 ... Final thoughts18:40 ... Channel thanks & outro--------------------------------From Part 1:Let's take a look at this interesting "personal computer" from 1979. It's essentially a language translator using cartridges but has a few other tricks: it can be used as a calculator, an electronic notepad, a filing system and also a remote computer terminal (via an acoustic coupler).The machine has a very nice 16 character display (four DL1414 modules) and runs on four NiCd rechargeable cells. It also comes with a 6VDC power adaptor that can be switched between 120VAC and 220VAC.There is very little inside the machine itself - a few logic chips, the display and the battery. All of the intelligence is contained within the cartridges: usually a ROM and a CPU-type device. I couldn't find any information on the CPU-type chip - I'm assuming it's some sort of custom/cut-down Motorola 6800 with some internal program ROM and RAM ... ? Each chip is customised for the cartridge, bearing the cartridge's ID.For example, the chip in the LK-3050 Spanish language cartridge is labelled:LK3051M7914 (datecode)SC80230PAnd in the electronic notepad:SC80293P8006LK3500MThese are the cartridges I'm aware of:LK-0280: Winter Olympics - Lake PlacidLK-0680: Summer Olympics - MoscowLK-1001: Filing SystemLK-3050: English-SpanishLK-3060: English-FrenchLK-3070: English-ItalianLK-3080: English-GermanLK-3090: English-SwedishLK-3100: English-PolishLK-3110: English-PortugueseLK-3120: English-RussianLK-3130: English-GreekLK-3140: English-Arabic (also LK-3145?)LK-3150: English-HebrewLK-3160: English-JapaneseLK-3170: English-ChineseLK-3200: English-Spanish-French-German-Italian-GreekLK-3500: Electronic NotepadLK-3900: Calculator--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Amstrad ACL-386SX: Part 5 (Compact Flash Storage) [TCE #0640] The Clueless Engineer 2025-09-19 | Let's replace the 541MB (only 270MB usable) "spinning rust" drive with a modern Compact Flash drive. It won't make the same comforting noise anymore but it'll be a lot easier to copy files onto it and I won't need to worry about it failing.As this machine already has an IDE interface all I need to do is introduce the XTIDE Universal BIOS (XUB) as an Option ROM to take over the fixed storage duties from the machine's quite limited BIOS.It seems one of the easiest ways to do this is via a Network Interface Card (NIC) that has an Option ROM socket - I ended up with a 16-bit Networth UTP-16A. There were a few choices available -- I chose this one as it had (documented) jumpers that could configure the ROM.I configured the XUB ROM image (IDE_386L) on the machine itself and then programmed a 16KByte 27128 ROM with the resulting file. After a little bit of fiddling of the NIC's configuration headers, I finally got it to work and I could boot off the Conner hard drive. At this point the original Conner drive was now fully usable - the full 541MB capacity. However that wasn't our end goal.With some more fiddling I could introduce the CF card as a 2nd hard drive to which I could backup all the files from the Conner hard drive.As a final test I confirmed that I could boot off just the CF card itself. It'll require some additional bodgework before its properly installed (new power wiring required), but another modernisation task ticked off the list.00:00 ... Intro08:00 ... Configuring the XTIDE Universal BIOS13:50 ... First attempt at installing the NIC (NOK)18:00 ... Second attempt at installing the NIC (OK)21:00 ... Testing the XUB with original Conner CFS541A drive25:00 ... Testing the XUB with additional CF card (NOK)32:00 ... Testing with CF (primary) and Conner (secondary) (OK)34:00 ... Copying original files to CF using XCOPY (Soldering Tunes)37:00 ... Copying finished successfully!40:00 ... Booting off just the CF (OK)44:05 ... Channel thanks & outro--------------------------------From Part 4:The internal drive is a Citizen U1DA-71A with 1.44MB capacity and 26-pin connector - this cut-down connector also includes +5VDC power. It has two known issues:[1] it uses a rubber belt that degrades,[2] it uses surface mount electrolytic capacitors that will leak.This machine uses a 36-way Centronics type connector with pinout almost identical to the now-standard 34-way IDC connector. I've designed a converter board that can plug in and offers both 3½" and 5¼" compatible connectors:github.com/0ddjob/Amstrad-PC/tree/main/Amstrad_ACL386_FloppyIn the meantime I created a simple crimped cable - just use a 34-way cable, ensure floppy-end odd pins connect to Centronics pins 1 to 17 (ground), and pin 1 connects to pin 1. No connection needed on Centronics pins 18 & 36. See the schematic in my Github for more info.--------------------------------From Part 1:A big thank you to Steve at the base of the Blue Mountains, west of Sydney, for sending me this weighty (8.15kg!) Amstrad ACL-386SX120 laptop from 1991! Really appreciate it!Unfortunately it doesn't seem to work - the Rubycon RPS-1205 power supply spins up the fan but doesn't seem to output anything over 1VDC to the motherboard (yes, even "under load" when connected to the motherboard). So some work is required.There is some excellent documentation here, including stripping the power supply - maybe that's what I need to do:forum.vcfed.org/index.php?threads/amstrad-acl-386sx-laptop-computer.1244823This machine has the following features:- 80386SX at 20MHz- 80387 co-processor installed- DOS 5.0 and Windows 3.0 (on ten disks originally)- max. 20MB of RAM installed (4MB of built-in RAM plus 16MB expansion)- 120MB swappable hard drive- 3½" floppy drive with 36-pin Centronics for external drive- colour, backlit TFT LCD screen- built-in VGA/EGA/CGA/MDA/Hercules support & DE15 for external monitor- 5-pin DIN socket for external keyboard- built-in trackball & buttons- serial (DE9) and parallel (DB25) ports- one AT expansion slotThe 386SX has a 24 bit address bus and is thus apparently limited to being able to address up to 16MB ... but the manual definitely says that up to 20MB can be installed and configured ... let's see ...--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇩🇪 Nixdorf LK-3000 Personal Computer: Part 1 (First Look) [TCE #0639] The Clueless Engineer 2025-09-16 | Let's take a look at this interesting "personal computer" from 1979. It's essentially a language translator using cartridges but has a few other tricks: it can be used as a calculator, an electronic notepad, a filing system and also a remote computer terminal (via an acoustic coupler).The machine has a very nice 16 character display (four DL1414 modules) and runs on four NiCd rechargeable cells. It also comes with a 6VDC power adaptor that can be switched between 120VAC and 220VAC.There is very little inside the machine itself - a few logic chips, the display and the battery. All of the intelligence is contained within the cartridges: usually a ROM and a CPU-type device. I couldn't find any information on the CPU-type chip - I'm assuming it's some sort of custom/cut-down Motorola 6800 with some internal program ROM and RAM ... ? Each chip is customised for the cartridge, bearing the cartridge's ID.For example, the chip in the LK-3050 Spanish language cartridge is labelled:LK3051M7914 (datecode)SC80230PAnd in the electronic notepad:SC80293P8006LK3500MThese are the cartridges I'm aware of:LK-0280: Winter Olympics - Lake PlacidLK-0680: Summer Olympics - MoscowLK-1001: Filing SystemLK-3050: English-SpanishLK-3060: English-FrenchLK-3070: English-ItalianLK-3080: English-GermanLK-3090: English-SwedishLK-3100: English-PolishLK-3110: English-PortugueseLK-3120: English-RussianLK-3130: English-GreekLK-3140: English-Arabic (also LK-3145?)LK-3150: English-HebrewLK-3160: English-JapaneseLK-3170: English-ChineseLK-3200: English-Spanish-French-German-Italian-GreekLK-3500: Electronic NotepadLK-3900: Calculator00:00 ... Intro03:30 ... A Triumph of West German Technology05:00 ... Disassembling the device12:00 ... Powering on14:10 ... Disassembling a language cartridge16:25 ... Disassembling the electronic notepad cartridge20:15 ... Channel thanks & outroMy Github for this machine:github.com/0ddjob/Nixdorf-LK-3000--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Amstrad ACL-386SX: Part 4 (Floppy Drives) [TCE #0638] The Clueless Engineer 2025-09-12 | Let's find out what's wrong with the internal 3½" floppy drive and see if we can connect an external drive.The internal drive is a Citizen U1DA-71A with 1.44MB capacity and 26-pin connector - this cut-down connector also includes +5VDC power. It has two known issues:[1] it uses a rubber belt that degrades,[2] it uses surface mount electrolytic capacitors that will leak.In my case I have both problems so I'll need to source a replacement belt and capacitors which will take time.So let's try an external floppy drive. This machine uses a 36-way Centronics type connector with pinout almost identical to the now-standard 34-way IDC connector. I've designed a converter board that can plug in and offers both 3½" and 5¼" compatible connectors:github.com/0ddjob/Amstrad-PC/tree/main/Amstrad_ACL386_FloppyIn the meantime I created a simple crimped cable - just use a 34-way cable, ensure floppy-end odd pins connect to Centronics pins 1 to 17 (ground), and pin 1 connects to pin 1. No connection needed on Centronics pins 18 & 36. See the schematic in my Github for more info.00:00 ... Intro00:50 ... Internal 3.6V NiCd battery removal02:10 ... Listening to internal floppy drive noise03:00 ... Removing the internal floppy drive07:30 ... Dismantling the floppy drive23:40 ... Testing an Amstrad 3" floppy drive belt (NOK)26:00 ... Figuring out the external floppy pinout28:30 ... Making the cable30:32 ... Testing with a Sony MPF920-E 1.44MM 3½" floppy drive 33:30 ... Loading "The Ancient Art of War" from floppy36:30 ... Future plans39:05 ... Channel thanks & outro--------------------------------From Part 3:Let's get the power supply repaired & working again and try booting. The stock machine came with a 120MB hard drive (type 40) but this one has been upgraded with a 541MB Connor MFS541A. This drive isn't fully compatible with the BIOS, which supports a maximum of 504MB only.The geometry of this drive is:Cylinders = 523Heads = 32Sectors = 63After some fiddling I discovered the correct BIOS settings for the drive to work:Cylinders = 523Heads = 16 (BIOS max.)Sectors = 63The next issue seems to be the floppy drive - I'll get that out next and see if I can repair it. I would also like to switch to a CF drive but I'm not sure how to do it on a 80386 machine ... I've only ever installed one with an XT-IDE interface on 8086 machines ... ?--------------------------------From Part 2:Let's strip down the Rubycon RPS-1205 power supply and check for leaks ... oh, there's actually quite a few failed electrolytic capacitors! I'm guessing it was powered on to test after a few decades which triggered the capacitors to fail.I'll have to order replacements - I want to make sure I get good quality ones with the right pin pitch. I'll also clean and reapply fresh thermal paste to all the transistors with heat sinks.--------------------------------From Part 1:A big thank you to Steve at the base of the Blue Mountains, west of Sydney, for sending me this weighty (8.15kg!) Amstrad ACL-386SX120 laptop from 1991! Really appreciate it!Unfortunately it doesn't seem to work - the Rubycon RPS-1205 power supply spins up the fan but doesn't seem to output anything over 1VDC to the motherboard (yes, even "under load" when connected to the motherboard). So some work is required.There is some excellent documentation here, including stripping the power supply - maybe that's what I need to do:forum.vcfed.org/index.php?threads/amstrad-acl-386sx-laptop-computer.1244823This machine has the following features:- 80386SX at 20MHz- 80387 co-processor installed- DOS 5.0 and Windows 3.0 (on ten disks originally)- max. 20MB of RAM installed (4MB of built-in RAM plus 16MB expansion)- 120MB swappable hard drive- 3½" floppy drive with 36-pin Centronics for external drive- colour, backlit TFT LCD screen- built-in VGA/EGA/CGA/MDA/Hercules support & DE15 for external monitor- 5-pin DIN socket for external keyboard- built-in trackball & buttons- serial (DE9) and parallel (DB25) ports- one AT expansion slotThe 386SX has a 24 bit address bus and is thus apparently limited to being able to address up to 16MB ... but the manual definitely says that up to 20MB can be installed and configured ... let's see ...--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Amstrad ACL-386SX: Part 3 (PSU Repair & Booting) [TCE #0637] The Clueless Engineer 2025-08-31 | Let's get the power supply repaired & working again and try booting. The stock machine came with a 120MB hard drive (type 40) but this one has been upgraded with a 541MB Connor MFS541A. This drive isn't fully compatible with the BIOS, which supports a maximum of 504MB only.The geometry of this drive is:Cylinders = 523Heads = 32Sectors = 63After some fiddling I discovered the correct BIOS settings for the drive to work:Cylinders = 523Heads = 16 (BIOS max.)Sectors = 63The next issue seems to be the floppy drive - I'll get that out next and see if I can repair it. I would also like to switch to a CF drive but I'm not sure how to do it on a 80386 machine ... I've only ever installed one with an XT-IDE interface on 8086 machines ... ?00:00 ... Intro00:50 ... Soldering Tunes02:42 ... Let's test the PSU (OK!)04:00 ... Powering on the machine08:10 ... Checking the boot-up (video capture)18:53 ... Removing the hard drive22:40 ... Successful boot/exploring the hard drive28:55 ... Memory module connector 30:10 ... Channel thanks & outro--------------------------------From Part 2:Let's strip down the Rubycon RPS-1205 power supply and check for leaks ... oh, there's actually quite a few failed electrolytic capacitors! I'm guessing it was powered on to test after a few decades which triggered the capacitors to fail.I'll have to order replacements - I want to make sure I get good quality ones with the right pin pitch. I'll also clean and reapply fresh thermal paste to all the transistors with heat sinks.--------------------------------From Part 1:A big thank you to Steve at the base of the Blue Mountains, west of Sydney, for sending me this weighty (8.15kg!) Amstrad ACL-386SX120 laptop from 1991! Really appreciate it!Unfortunately it doesn't seem to work - the Rubycon RPS-1205 power supply spins up the fan but doesn't seem to output anything over 1VDC to the motherboard (yes, even "under load" when connected to the motherboard). So some work is required.There is some excellent documentation here, including stripping the power supply - maybe that's what I need to do:forum.vcfed.org/index.php?threads/amstrad-acl-386sx-laptop-computer.1244823This machine has the following features:- 80386SX at 20MHz- 80387 co-processor installed- DOS 5.0 and Windows 3.0 (on ten disks originally)- max. 20MB of RAM installed (4MB of built-in RAM plus 16MB expansion)- 120MB swappable hard drive- 3½" floppy drive with 36-pin Centronics for external drive- colour, backlit TFT LCD screen- built-in VGA/EGA/CGA/MDA/Hercules support & DE15 for external monitor- 5-pin DIN socket for external keyboard- built-in trackball & buttons- serial (DE9) and parallel (DB25) ports- one AT expansion slotThe 386SX has a 24 bit address bus and is thus apparently limited to being able to address up to 16MB ... but the manual definitely says that up to 20MB can be installed and configured ... let's see ...--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Soviet Computers on ebay (Patreon Exclusive 2) [TCE #0631] The Clueless Engineer 2025-08-26 | {This was a Patreon exclusive video - thanks for your support!} I thought it might be interesting to have a browse of the Soviet/post-Soviet (and their associates) computers on ebay. Maybe it's interesting or useful.My main guy is "dragonberseker" in Slovakia ... you can't beat his range!https://www.ebay.com.au/str/dragonbersekerNormally I would prefer the US store front ... ebay.com ... over the AU one as it didn't always show everything he listed ... if he forgot to include shipping to Australia then the AU usually didn't show it. But at the moment (5-Aug-2025) there are 783 items listed on the AU storefront vs 731 on the US one ... hmmm ... ?There are other sellers but they don't have the range that dragonberseker does ... you can browse his listings, get some ideas of computer names then search elsewhere if someone else is selling them (usually seen Ukraine or Moldova).--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 4 (Revised Mechanical Keyboard) [TCE #0636] The Clueless Engineer 2025-08-16 | Thanks to #PCBWay for their ongoing support! pcbway.comMy initial design had some fitment issues because of the LCD bezel's overhang so I made some small adjustments and got it almost right. I've made a few more adjustments so it should now be just about perfect.00:00 ... Intro05:03 ... Soldering tunes07:35 ... Rev. B built09:40 ... Drilling attachment holes (3mm)14:30 ... Need to shave a few millimetres off still16:35 ... Fitting keyboard to Z8818:00 ... Testing (OK!)19:45 ... Final result22:59 ... Channel thanks & outro--------------------------------From Part 3:The rubber mat on my Z88 doesn't work very well so let's try replacing it with a mechanical keyboard.I've designed this keyboard to use Gateron KS-33 low profile switches and, after a lot of searching, settled on a set of MA profile key caps that included an ISO ENTER key:Aliexpress store name: Skyloong Guangming StoreAliexpress store ID: 910796037aliexpress.com/item/1005004649108572.htmlI still need to find a few more spare key caps for the special keys.MA profile are taller than XDA or DSA profile ... DSA profile might be the best but it's just a matter of trying to find a complete set in black ... The keyboard is working fine from my initial testing. I didn't allow for a few millimetres of overhang by the LCD bezel, so I need to shave this off the top of my PCB to allow everything to fit back together nicely ... that'll be REV. B.My Github repository:github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_Keyboard--------------------------------From Part 2:The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?--------------------------------From Part 1:What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.WoS info:worldofspectrum.org/z88forever/index.htmlZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Amstrad ACL-386SX: Part 2 (PSU Stripdown) [TCE #0635] The Clueless Engineer 2025-08-12 | Let's strip down the Rubycon RPS-1205 power supply and check for leaks ... oh, there's actually quite a few failed electrolytic capacitors! I'm guessing it was powered on to test after a few decades which triggered the capacitors to fail.I'll have to order replacements - I want to make sure I get good quality ones with the right pin pitch. I'll also clean and reapply fresh thermal paste to all the transistors with heat sinks.00:00 ... Intro02:09 ... De-soldering tunes part 103:16 ... Dodgy capacitor05:10 ... De-soldering tunes part 205:54 ... Final count of dodgy capacitors08:15 ... Channel thanks & outro--------------------------------From Part 1:A big thank you to Steve at the base of the Blue Mountains, west of Sydney, for sending me this weighty (8.15kg!) Amstrad ACL-386SX120 laptop from 1991! Really appreciate it!Unfortunately it doesn't seem to work - the Rubycon RPS-1205 power supply spins up the fan but doesn't seem to output anything over 1VDC to the motherboard (yes, even "under load" when connected to the motherboard). So some work is required.There is some excellent documentation here, including stripping the power supply - maybe that's what I need to do:forum.vcfed.org/index.php?threads/amstrad-acl-386sx-laptop-computer.1244823This machine has the following features:- 80386SX at 20MHz- 80387 co-processor installed- DOS 5.0 and Windows 3.0 (on ten disks originally)- max. 20MB of RAM installed (4MB of built-in RAM plus 16MB expansion)- 120MB swappable hard drive- 3½" floppy drive with 36-pin Centronics for external drive- colour, backlit TFT LCD screen- built-in VGA/EGA/CGA/MDA/Hercules support & DE15 for external monitor- 5-pin DIN socket for external keyboard- built-in trackball & buttons- serial (DE9) and parallel (DB25) ports- one AT expansion slotThe 386SX has a 24 bit address bus and is thus apparently limited to being able to address up to 16MB ... but the manual definitely says that up to 20MB can be installed and configured ... let's see ...--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Amstrad ACL-386SX: Part 1 (First Look - NOK - PSU Issues) [TCE #0634] The Clueless Engineer 2025-08-11 | A big thank you to Steve at the base of the Blue Mountains, west of Sydney, for sending me this weighty (8.15kg!) Amstrad ACL-386SX120 laptop from 1991! Really appreciate it!Unfortunately it doesn't seem to work - the Rubycon RPS-1205 power supply spins up the fan but doesn't seem to output anything over 1VDC to the motherboard (yes, even "under load" when connected to the motherboard). So some work is required.There is some excellent documentation here, including stripping the power supply - maybe that's what I need to do:forum.vcfed.org/index.php?threads/amstrad-acl-386sx-laptop-computer.1244823This machine has the following features:- 80386SX at 20MHz- 80387 co-processor installed- DOS 5.0 and Windows 3.0 (on ten disks originally)- max. 20MB of RAM installed (4MB of built-in RAM plus 16MB expansion)- 120MB swappable hard drive- 3½" floppy drive with 36-pin Centronics for external drive- colour, backlit TFT LCD screen- built-in VGA/EGA/CGA/MDA/Hercules support & DE15 for external monitor- 5-pin DIN socket for external keyboard- built-in trackball & buttons- serial (DE9) and parallel (DB25) ports- one AT expansion slotThe 386SX has a 24 bit address bus and is thus apparently limited to being able to address up to 16MB ... but the manual definitely says that up to 20MB can be installed and configured ... let's see ...00:00 ... Intro08:30 ... Power on test (NOK)10:30 ... Checking optional expansions under keyboard13:40 ... Screen hinge problem16:00 ... Disassembly begins20:00 ... Top case removal25:30 ... Power on test again27:40 ... Carefully checking voltages29:00 ... Power supply closeup33:00 ... Discovering the battery pack37:20 ... Trying with 12VDC power42:20 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇺🇸 Hewlett Packard HP 95LX Palmtop PC: Part 2 (Repair & File Transfer) [TCE #0633] The Clueless Engineer 2025-08-08 | I "Hallenised" the RS232 serial port ... modified it from 1x4 at 2mm pitch to 1x3 at 2.54mm pitch ... now I can create a serial cable and transfer files. I also re-wired the speaker so it'll work now.Hallenisation: making a modification to an otherwise perfectly functioning piece of equipment for reasons that are obvious to me but appear ridiculous to a normal person.I don't recommend changing the serial port pins ... a bit of a hassle. Getting transfers to work ... via null-modem cable ... was a little flaky at first but I got it working and transferred some HP 95LX specific software over. Needed to wire the 1x3-to-DE9 cable as a null-modem cable, not straight through serial.I'll need to get myself some additional PCMCIA-based storage ... up to 32MB I've read ... which will act as an A: drive.00:15 ... Hallenising the serial port09:20 ... Re-wiring the speaker12:50 ... Reassembly15:40 ... Does it still work?16:30 ... Testing serial communication (send OK, receive NOK)23:50 ... Working both ways!25:10 ... Transferring PACMAN via XMODEM29:30 ... Trying OTHELLO31:30 ... Trying HP DUNGEON36:35 ... Running diagnostics37:43 ... Channel outro & thanks--------------------------------From Part 1:Let's take a look at HP's first MS-DOS "palmtop" PC, the 95LX from 1991. This is quite a light little machine with 1MB of RAM, running MS-DOS (ROM) 3.22 on an NEC V20 CPU. It has a four-pin serial port, infrared and PCMCIA.It runs on two AA batteries and has a CR2032 for backup. It came with a US 10VAC power adaptor but seemed to be quite happy on 10VDC. It kept complaining that the battery was low despite fresh batteries ... hmmm.It has Lotus 1-2-3 built-in which seems to be quite usable on the "quarter-CGA" resolution ... 40x16 characters or 240x128 pixels.It also has a game called TigerFox (rev 3.3) by HP designed just for the machine.It does have a large piezo speaker but mine was disconnected ... the case has very obviously been opened before and they have perhaps cut the speaker wires, so I'll need to repair that.I don't have a plug that will suit the 2mm-pitch serial port pins so will replace them with 2.54mm pitch (next video) ... the two outside pins are essentially ground so only one is needed ... three 2.54mm-pitch pins will just fit.Overall it's a really neat little computer. I still want something that I can play "The Ancient Art of War" and PAC-GIRL on, so will look at getting a 200LX at some stage.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇺🇸 Hewlett Packard HP 95LX Palmtop PC: Part 1 (Boot & Disassembly) [TCE #0632] The Clueless Engineer 2025-08-07 | Let's take a look at HP's first MS-DOS "palmtop" PC, the 95LX from 1991. This is quite a light little machine with 1MB of RAM, running MS-DOS (ROM) 3.22 on an NEC V20 CPU. It has a four-pin serial port, infrared and PCMCIA.It runs on two AA batteries and has a CR2032 for backup. It came with a US 10VAC power adaptor but seemed to be quite happy on 10VDC. It kept complaining that the battery was low despite fresh batteries ... hmmm.It has Lotus 1-2-3 built-in which seems to be quite usable on the "quarter-CGA" resolution ... 40x16 characters or 240x128 pixels.It also has a game called TigerFox (rev 3.3) by HP designed just for the machine.It does have a large piezo speaker but mine was disconnected ... the case has very obviously been opened before and they have perhaps cut the speaker wires, so I'll need to repair that.I don't have a plug that will suit the 2mm-pitch serial port pins so will replace them with 2.54mm pitch (next video) ... the two outside pins are essentially ground so only one is needed ... three 2.54mm-pitch pins will just fit.Overall it's a really neat little computer. I still want something that I can play "The Ancient Art of War" and PAC-GIRL on, so will look at getting a 200LX at some stage.00:15 ... Intro05:50 ... Powering on11:00 ... Lotus 1-2-316:05 ... TigerFox20:00 ... Serial port23:30 ... Boot-up sequence24:55 ... Setup options28:30 ... Calculator32:30 ... TigerFox again33:45 ... Browsing DOS36:40 ... Time to disassemble43:20 ... It's apart finally!47:35 ... Main board is free49:00 ... "Hallenising" the serial port51:40 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Микроша (Mikrosha): Part 5 (Improved Video Output!) [TCE #0630] The Clueless Engineer 2025-08-04 | Thanks to @0toleranz, @ВасилийМельников-з8м and @do1kv for noticing the lack of decoupling capacitors - completely missed that.Adding 100nF across the power pins of the CRT controller (8275 or КР580ВГ75) and the hex inverter (74LS04 or К555ЛН1) greatly improved the video stability. I then also added them to the CPU (8080A or КР580ВМ80А) and DMA controller (8257 or КР580ВТ57) for good measure.As I plan to continue using the original power supply I'll also look at replacing its electrolytics.The machine booted with no problems this morning (maybe after adding some insulation to a capacitor on the underside).Now I just need to figure out what I'm going to do with the key switches. I think I will proceed to replace the rest of the keyboard with my replacement, and also start learning OpenSCAD so I can design my own custom 17mm square key caps (smaller than the 18mm square standard today) using the KeyV2 library:github.com/rsheldiii/KeyV2I would need to design my own anyway as it's impossible to get JCUKEN layout.00:20 ... Jayne Mansfield01:25 ... Decoupling capacitors (doh!)04:55 ... Video output comparison05:30 ... Motherboard changes06:50 ... Keyboard plans10:55 ... What to do with the bodges?12:00 ... Channel thanks & outro--------------------------------From Part 4:I got the video output working! It was staring at me ... and I was commenting on it ... the whole time! Like any 86RK-based machine, it does take a while to warm up and actually start working - pretty much all of them require the [RESET] button to be pressed several times before it becomes stable.In addition, this machine actually seems to need to warm up ... first thing in the morning it will refuse to work, but after being powered for a few minutes (and, indeed, being powered off/on a few times too), it'll eventually boot and then work more reliably.The video output issue was due to the missing 10µF electrolytic and shorted 22nF ceramic capacitors which meant that the DC component of the signal wasn't being blocked. Once I added these back into the circuit, the video output started working (once the computer was working, of course).--------------------------------From Part 3:This is a two part video: first we look at the daughterboard I designed to possibly replace the original key switches, and then we continue fiddling to see if the machine is working.The key switch daughterboard design was covered in TCE #0625:youtu.be/o9SSxjUYZY4The design can be found on my Github - obviously some further work is required:github.com/0ddjob/Conversion_Boards/tree/main/Soviet-Keyswitch-ReplacementA common issue with the Radio 86RK design is that they never seem to boot "first time" ... it usually takes a few presses of the [RESET] button to jolt them into life. This one is no different.After a LOT of coaxing, the machine does in fact seem to be working ... I'm getting key press sounds! ... but the my LCD (and composite-to-HDMI converter) can't lock onto the video signal.So that's the next hurdle to sort out.--------------------------------From Part 2:Sorry, a bit of a long-winded one with no payoff at the end - the machine isn't working at the moment.I removed all the key caps and gave them a wash. The underlying key switches look a bit dodgy ... might look at creating some sort of converter boards so I can use Cherry MX key switches.The power supply seems to be working okay - I had to replace the fuse holder as the original Soviet 500mA slow blow fuse is smaller (15x4mm) than the M205 (20x5mm) fuses I can source. But that was pretty simple and the power supply seemed to be working quite fine.The Микроша itself seems to be quite dead - there was a clock signal being generated by the 8224 (КР580ГФ24) but I didn't see any activity on the 8080 (КР580ВМ80А) or the DRAMs (КР565РУ6). No chips looked particularly hot so no obvious shorted-IC that could be causing the problem.There's a lot of bodge work ... cut tracks, bodge wires, re-soldering work ... so no idea what has been done nor why - it's one of the bodgiest 86RK clones I've come across. Could the issue be as simple as a shorted address or data line ... ?github.com/alemorf/retro_computers/tree/master/Microsha--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Микроша (Mikrosha): Part 4 (Video Output Fixed!) [TCE #0629] The Clueless Engineer 2025-08-03 | I got the video output working! It was staring at me ... and I was commenting on it ... the whole time! Like any 86RK-based machine, it does take a while to warm up and actually start working - pretty much all of them require the [RESET] button to be pressed several times before it becomes stable.In addition, this machine actually seems to need to warm up ... first thing in the morning it will refuse to work, but after being powered for a few minutes (and, indeed, being powered off/on a few times too), it'll eventually boot and then work more reliably.The video output issue was due to the missing 10µF electrolytic and shorted 22nF ceramic capacitors which meant that the DC component of the signal wasn't being blocked. Once I added these back into the circuit, the video output started working (once the computer was working, of course).So, the next issue is sorting out what I'm going to do with the keyboard. I don't know how much longer the original Soviet-era key switch mechanisms will work.00:15 ... Checking the schematic03:30 ... Checking the motherboard05:30 ... Replacing the capacitors07:00 ... Testing, testing09:30 ... SUCCESS!13:20 ... Checking signal on oscilloscope with 51Ω resistor17:00 ... Checking with 75Ω resistor19:55 ... Checking video signal components26:55 ... Channel thanks & outro--------------------------------From Part 3:This is a two part video: first we look at the daughterboard I designed to possibly replace the original key switches, and then we continue fiddling to see if the machine is working.The key switch daughterboard design was covered in TCE #0625:youtu.be/o9SSxjUYZY4The design can be found on my Github - obviously some further work is required:github.com/0ddjob/Conversion_Boards/tree/main/Soviet-Keyswitch-ReplacementA common issue with the Radio 86RK design is that they never seem to boot "first time" ... it usually takes a few presses of the [RESET] button to jolt them into life. This one is no different.After a LOT of coaxing, the machine does in fact seem to be working ... I'm getting key press sounds! ... but the my LCD (and composite-to-HDMI converter) can't lock onto the video signal.So that's the next hurdle to sort out.--------------------------------From Part 2:Sorry, a bit of a long-winded one with no payoff at the end - the machine isn't working at the moment.I removed all the key caps and gave them a wash. The underlying key switches look a bit dodgy ... might look at creating some sort of converter boards so I can use Cherry MX key switches.The power supply seems to be working okay - I had to replace the fuse holder as the original Soviet 500mA slow blow fuse is smaller (15x4mm) than the M205 (20x5mm) fuses I can source. But that was pretty simple and the power supply seemed to be working quite fine.The Микроша itself seems to be quite dead - there was a clock signal being generated by the 8224 (КР580ГФ24) but I didn't see any activity on the 8080 (КР580ВМ80А) or the DRAMs (КР565РУ6). No chips looked particularly hot so no obvious shorted-IC that could be causing the problem.There's a lot of bodge work ... cut tracks, bodge wires, re-soldering work ... so no idea what has been done nor why - it's one of the bodgiest 86RK clones I've come across. Could the issue be as simple as a shorted address or data line ... ?github.com/alemorf/retro_computers/tree/master/Microsha--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Микроша (Mikrosha): Part 3 (Its Working But ...) [TCE #0628] The Clueless Engineer 2025-08-02 | Thanks to #PCBWay for their ongoing support! pcbway.comThis is a two part video: first we look at the daughterboard I designed to possibly replace the original key switches, and then we continue fiddling to see if the machine is working.The key switch daughterboard design was covered in TCE #0625:youtu.be/o9SSxjUYZY4The design can be found on my Github - obviously some further work is required:github.com/0ddjob/Conversion_Boards/tree/main/Soviet-Keyswitch-ReplacementA common issue with the Radio 86RK design is that they never seem to boot "first time" ... it usually takes a few presses of the [RESET] button to jolt them into life. This one is no different.After a LOT of coaxing, the machine does in fact seem to be working ... I'm getting key press sounds! ... but the my LCD (and composite-to-HDMI converter) can't lock onto the video signal.So that's the next hurdle to sort out.00:00 ... Intro02:50 ... Panelisation by PCBWAY06:25 ... The daughterboard07:30 ... Preparing the daughterboard11:30 ... Installing the new key switches13:00 ... Testing fit with key caps (NOK)16:50 ... Initial motherboard checks21:30 ... Oscilloscope check on CPU, CRT controller & КР565РУ6 DRAM27:00 ... Checking video signal 28:45 ... Checking video output (LCD)34:20 ... Final motherboard look (key beeps!)35:10 ... Channel thanks & outro--------------------------------From Part 2:Sorry, a bit of a long-winded one with no payoff at the end - the machine isn't working at the moment.I removed all the key caps and gave them a wash. The underlying key switches look a bit dodgy ... might look at creating some sort of converter boards so I can use Cherry MX key switches.The power supply seems to be working okay - I had to replace the fuse holder as the original Soviet 500mA slow blow fuse is smaller (15x4mm) than the M205 (20x5mm) fuses I can source. But that was pretty simple and the power supply seemed to be working quite fine.The Микроша itself seems to be quite dead - there was a clock signal being generated by the 8224 (КР580ГФ24) but I didn't see any activity on the 8080 (КР580ВМ80А) or the DRAMs (КР565РУ6). No chips looked particularly hot so no obvious shorted-IC that could be causing the problem.There's a lot of bodge work ... cut tracks, bodge wires, re-soldering work ... so no idea what has been done nor why - it's one of the bodgiest 86RK clones I've come across. Could the issue be as simple as a shorted address or data line ... ?--------------------------------From Part 1:This just arrived from Belarus today - this Микроша (Mikrosha) was based on the home brew Радио-86РК (Radio-86RK) design and built in the Russian SFSR. This particular example was built in 1988 and cost (цена) 500 Soviet Roubles ... about US$120 (1988). This might seem cheap but consider that this equated to about two months salary.As it's based on the 86RK it uses the Intel 8080 family of chips (well, the Soviet equivalents). This means that it also requires a tri-voltage power supply: ±5VDC and +12VDC. It does have one but the fuse has blown so I'll need to replace it before attempting to power on the power supply.It apparently has some differences to the pure 86RK ... for example, the 8253 PIT used for sound. One other major difference to the other 86RKs I've worked on ... this appears to have baseband video output, rather than RF modulated ... yay!Once I get a replacement fuse and check the pin out of everything from the documentation, I'll be able to try powering it up.github.com/alemorf/retro_computers/tree/master/Microsha--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇺🇸 Micro Palm Computers PC/4000 & PC/5000: Part 5 (DD50 Breakout Board) [TCE #0627] The Clueless Engineer 2025-07-29 | Thanks to #PCBWay for their ongoing support! pcbway.comI finally designed a breakout board for the DD50 connector on the PC/4000 and PC/5000, the idea being to try to figure out the pinout so I can finally get a machine to boot properly into MS-DOS 2.25! Even though it has DOS in ROM it still needs some files transferred across to actually boot ... I've still not been able to find much solid, useful information about the company or their computers. I did stumble across the name of the founder ... Velton "Vel" Casler ... who sadly passed away in 2023:lindquistmortuary.com/obituaries/velton-caslerLooks like they were used by the US Army Corps of Engineers at one stage:ia600803.us.archive.org/35/items/DTIC_ADA299981/DTIC_ADA299981.pdfOne other scrap of info ... in June 1991 MPC were apparently paying Microsoft $22k/year for "ROM DOS 2.25 & 3.22" licences:web.archive.org/web/20070211123428/http://www.iowaconsumercase.org:80/011607/0000/PX00784.pdfWith the breakout board I was able to figure out a few more pins, including eight pins connected to one side of an octal bus transceiver (74HCT245) that connects to a rather large chip by "PPS, Inc.". The chip is labelled "L1A2710 GA00001" and I assume it's a custom chip that crams in a lot of an IBM PC's functionality ... so I have no idea what the purpose of that interface is ... a parallel port?I will update my Github with the little bit of extra information I've gleaned. I'll try to connect to the serial ports via an Arduino next and see if I can get some communication going.00:14 ... New project: reference book04:55 ... DD50 breakout board07:06 ... Soldering Tunes08:36 ... Construction complete09:20 ... The PC/4000 and PC/5000 beasts12:00 ... The pinout so far16:49 ... Mysterious 8-bit port19:07 ... Channel thanks & outro--------------------------------From previous videos:The PC/5000 is the big brother to MPC's PC/4000 - handheld IBM PC compatible machines running MS-DOS. Both machines run on the same hardware (an 80C88) and have 256KB of system RAM. The PC/4000 has two built-in 256KB storage modules whereas the PC/5000 has a built-in 1024KB storage module and space for a second module that can be added without opening the machine - mine has a second 1024KB storage module.The PC/4000 is a 1988 manufacture and this PC/5000 appears to be a 1991 manufacture.This particular machine came with a GE "Type SC-2 Smartcoupler" attached to the DD50 port. I have no information about this attachment apart from it having a catalogue number of "9937450G3". It may have had a barcode wand attached to it - it has a cable that has been cut ... ? It has an 8-bit microcontroller on board (a Motorola MC68HC70508CFN).I have updated the pinout document on my Github with the Smartcoupler details:github.com/0ddjob/MicroPalm-PC-4000--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 3 (Mechanical Keyboard Test) [TCE #0626] The Clueless Engineer 2025-07-25 | Thanks to #PCBWay for their ongoing support! pcbway.comThe rubber mat on my Z88 doesn't work very well so let's try replacing it with a mechanical keyboard.I've designed this keyboard to use Gateron KS-33 low profile switches and, after a lot of searching, settled on a set of MA profile key caps that included an ISO ENTER key:Aliexpress store name: Skyloong Guangming StoreAliexpress store ID: 910796037aliexpress.com/item/1005004649108572.htmlI still need to find a few more spare key caps for the special keys.MA profile are taller than XDA or DSA profile ... DSA profile might be the best but it's just a matter of trying to find a complete set in black ... The keyboard is working fine from my initial testing. I didn't allow for a few millimetres of overhang by the LCD bezel, so I need to shave this off the top of my PCB to allow everything to fit back together nicely ... that'll be REV. B.My Github repository:github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_Keyboard00:00 ... Intro03:15 ... The PCB05:50 ... Soldering Tunes06:45 ... Testing the first row12:07 ... Full keyboard ready for testing13:59 ... Comparison with original rubber mat15:13 ... Testing with BASIC18:49 ... Adjustments required 21:12 ... Channel thanks & outro--------------------------------From Part 2:The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?--------------------------------From Part 1:What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.WoS info:worldofspectrum.org/z88forever/index.htmlZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Simple KiCad For Simple Vintage Computer Hobbyists: Part 8a (Soviet Key Switch 1) [TCE #0625] The Clueless Engineer 2025-07-16 | Thanks to #PCBWay for their ongoing support! pcbway.comLet's see if we can design a carrier board for Cherry MX-style key switches to replace old, Soviet-era key switches (possibly called «ВМ16») in a Микроша (Mikrosha) computer. These key switches are used in various computers, calculators (like the Электроника МК44) and in telephones.The ВМ16 (VM16) key switches come in blocks of different sizes which can be cut to purpose - in the Микроша they are mainly 1x4 with some cut-down 1x2 blocks used. The cursor/function key cluster is one 3x4 block.As we'll need a few of these boards to replace all the original key switches, lets try panelisation this time. We can either panellise the design ourselves or ask PCBWay to do it. For simplicity, let's see the result when PCBWay do it ... we'll request a panel of five PCBs, with five panels ordered, meaning we'll have replacements for up to 100 key switches.0:00:00 ... Intro0:05:35 ... Removing the key switch block0:10:55 ... Taking measurements0:15:45 ... The schematic0:18:40 ... Creating a footprint for Soviet key switch0:22:45 ... Let's try that again0:29:00 ... PCB layout & design0:48:00 ... Panelisation info0:52:14 ... Test fit of design0:56:38 ... Panel by PCBWay configuration1:03:00 ... Channel outro & thanksThe design can be found here:github.com/0ddjob/Soviet-Keyswitch-ReplacementDisclaimer: I'm not a KiCad super-user, I'm not a circuit design guru, I'm just a simple vintage computer hobbyist who needs simple PCBs from time to time. And yes, this sort of thing has probably been designed a dozen times before, but there's no harm in trying to learn how it's done is there?I'm using KiCad 9.0.3 on a 2022 MacBook Air (M2 with 24GB RAM) running macOS 15.5.Application: KiCad arm64 on arm64Version: 9.0.3, release buildPlatform: macOS Sequoia Version 15.5 (Build 24F74)--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇦🇺 The TEC-1G: Part 4 (Quick Update) [TCE #0624] The Clueless Engineer 2025-07-13 | In the last video I had an issue with the power LED and keypad not working - let's fix those thanks to some fresh parts from Mark.Running the diagnostics for the GLCD results in a garbled screen so I'll need to look into that further. There is also some text corruption on the 20x4 LCD ... is that expected?In addition to figuring out those issues, I will build and try out the 8x8 RGB display thanks to the board that Brian sent me.00:00 ... Intro01:57 ... Power LED replacement04:54 ... Keypad encoder replacement06:20 ... First DIAG test - NOK08:00 ... Second DAIG test - OK!10:25 ... GLCD test - NOK11:30 ... Running other tests12:55 ... MON3 test - not sure ... (need to RTFM!)14:00 ... MON-1B test16:05 ... RGB LED 8x8 display17:57 ... Channel thanks & outro--------------------------------From Part 3:The TEC-1 (Talking Electronics Computer) is an Aussie Z80 based single board computer (SBC) first released in 1983 by Colin Mitchell's "Talking Electronics" magazine:talkingelectronics.comUnfortunately I couldn't afford the kit back in the 80s, but always wanted to get one. There's always a lot of appreciation when someone brings out their TEC-1B that they built with their dad 40 years ago ... and still in perfect working order.I won't rehash the history - check here for more info ... and most importantly ... the correct attributions of who did what:en.wikipedia.org/wiki/TEC-1The TEC-1D boards were reproduced in 2018 and I managed to grab some. I did almost finish building it (surprise) but got distracted onto other things - one small difficulty for me was just trying to keep track off what add-ons I would need ... so many different boards were designed!In 2023 @MarkovAllTrades brought the machine up-to-date for its 40th anniversary with the TEC-1G revision. Mark popped in last week and he showed me his state-of-the-art TEC-1G. Very cool. He kindly sent me another board to build ... the Signature Edition version this time ... and I was determined to get it working ... I'm quite a bit more experienced now. I will definitely re-visit the Beta board Mark originally sent me ... one major issue why it didn't work was my mixing 74HC with 74HCT/74LS logic ... duh.I did get this one built & booting. But the keypad is unresponsive ... the 74C923 is suspect. I will investigate further - definitely going to look at making a proper keyboard for it.Unicorn Electronics in the US is a reputable supplier (if you don't want to gamble on Aliexpress) and they do appear to have stock (but you'd need to check):unicornelectronics.com/IC/Tele.htmlYou can find all the information on the TEC at Mark's Github:github.com/MarkJelic/TEC-1GTindie store for simple everything-included options:tindie.com/stores/tec1Also check out the Facebook group, if that's your thing:facebook.com/groups/tec1z80And, of course, Mark's YouTube channel:youtube.com/@TEC-1G--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Микроша (Mikrosha): Part 2 (Power On - NOK) [TCE #0623] The Clueless Engineer 2025-07-12 | Sorry, a bit of a long-winded one with no payoff at the end - the machine isn't working at the moment.I removed all the key caps and gave them a wash. The underlying key switches look a bit dodgy ... might look at creating some sort of converter boards so I can use Cherry MX key switches.The power supply seems to be working okay - I had to replace the fuse holder as the original Soviet 500mA slow blow fuse is smaller (15x4mm) than the M205 (20x5mm) fuses I can source. But that was pretty simple and the power supply seemed to be working quite fine.The Микроша itself seems to be quite dead - there was a clock signal being generated by the 8224 (КР580ГФ24) but I didn't see any activity on the 8080 (КР580ВМ80А) or the DRAMs (КР565РУ6). No chips looked particularly hot so no obvious shorted-IC that could be causing the problem.There's a lot of bodge work ... cut tracks, bodge wires, re-soldering work ... so no idea what has been done nor why - it's one of the bodgiest 86RK clones I've come across. Could the issue be as simple as a shorted address or data line ... ?00:00 ... Intro05:45 ... Keyboard & motherboard close up06:59 ... Key switches (replacement?)11:40 ... First peek underneath the motherboard (yikes!)16:40 ... Replacement fuse20:10 ... Replacement fuse holder26:33 ... Power supply test - OK!30:55 ... Video pinout32:02 ... Making the video cable36:00 ... Power on test - NOK39:51 ... Checking 8224 clock generator on oscilloscope - OK43:18 ... Discussing next steps47:30 ... Channel outro & thanks--------------------------------From Part 1:This just arrived from Belarus today - this Микроша (Mikrosha) was based on the home brew Радио-86РК (Radio-86RK) design and built in the Russian SFSR. This particular example was built in 1988 and cost (цена) 500 Soviet Roubles ... about US$120 (1988). This might seem cheap but consider that this equated to about two months salary.As it's based on the 86RK it uses the Intel 8080 family of chips (well, the Soviet equivalents). This means that it also requires a tri-voltage power supply: ±5VDC and +12VDC. It does have one but the fuse has blown so I'll need to replace it before attempting to power on the power supply.It apparently has some differences to the pure 86RK ... for example, the 8253 PIT used for sound. One other major difference to the other 86RKs I've worked on ... this appears to have baseband video output, rather than RF modulated ... yay!Once I get a replacement fuse and check the pin out of everything from the documentation, I'll be able to try powering it up.github.com/alemorf/retro_computers/tree/master/Microsha--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Simple KiCad For Simple Vintage Computer Hobbyists: Part 7b (Keyboard Design 2) [TCE #0622] The Clueless Engineer 2025-07-06 | Thanks to #PCBWAY for their ongoing support! pcbway.comLet's finish off the keyboard for the Cambridge Computer Z88 by deciding on how big the PCB will be and where we'll position the mounting holes and connectors. We also modify the layout so that we have a proper inverted-T cursor arrangement (thanks for the idea @alexquant1335!)And, of course, routing all the tracks and generating the fabrication (Gerber) files.The design can be found on my Github:github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_KeyboardThe fabricated PCB & built keyboard can be seen in this video:youtu.be/vxIY81ir3Ao00:00 ... Intro06:20 ... PCB size07:05 ... Connectors & mounting holes10:30 ... Stabilisers (for 2u & 7u)23:40 ... 3D view of keyboard with stabilisers24:30 ... Auto-routing won't work26:35 ... Manual routing29:38 ... Inverted-T cursor layout!39:00 ... Using vias41:55 ... Routing is finished!43:40 ... Generating fabrication (Gerber) files44:50 ... Rounded corners! (I hate sharp PCB corners)45:38 ... Final layout check with paper PCB47:39 ... Channel thanks & outro--------------------------------From Part 1:Let's see if we can design a replacement mechanical keyboard for the 1987 Cambridge Computer Z88 using Gateron KS-33 low profile key switches. The rubber keyboard (Sir Clive special!) doesn't seem to work too well on my machine so maybe a mechanical one would be nice.Maybe ... maybe not, but let's give it a try and see how it turns out.This video covers how to use some tools to quickly layout a keyboard for a vintage computer. Relevant links:[1] Gateron KS-33 footprint for KiCad:github.com/siderakb/key-switches.pretty[2] Keyboard Layout Editorkeyboard-layout-editor.com[3] Plate Builderhttp://builder.swillkb.com[4] Thin film connectorTE Connectivity/AMP part 5-520314-8KiCad files from Mouser[5] Gateron 3D modelgateron.com/pages/3dDisclaimer: I'm not a Kicad super-user, I'm not a circuit design guru, I'm just a simple vintage computer hobbyist who needs simple PCBs from time to time. And yes, this sort of thing has probably been designed a dozen times before, but there's no harm in trying to learn how it's done is there?I'm using Kicad 9.0 on a 2022 MacBook Air (M2 with 24GB RAM) running macOS 15.5.Application: KiCad arm64 on arm64Version: 9.0.0, release buildPlatform: macOS Sequoia Version 15.5 (Build 24F74)--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Микроша (Mikrosha): Part 1 (First Look) [TCE #0621] The Clueless Engineer 2025-07-04 | This just arrived from Belarus today - this Микроша (Mikrosha) was based on the home brew Радио-86РК (Radio-86RK) design and built in the Russian SFSR. This particular example was built in 1988 and cost (цена) 500 Soviet Roubles ... about US$120 (1988). This might seem cheap but consider that this equated to about two months salary.As it's based on the 86RK it uses the Intel 8080 family of chips (well, the Soviet equivalents). This means that it also requires a tri-voltage power supply: ±5VDC and +12VDC. It does have one but the fuse has blown so I'll need to replace it before attempting to power on the power supply.It apparently has some differences to the pure 86RK ... for example, the 8253 PIT used for sound. One other major difference to the other 86RKs I've worked on ... this appears to have baseband video output, rather than RF modulated ... yay!Once I get a replacement fuse and check the pin out of everything from the documentation, I'll be able to try powering it up.github.com/alemorf/retro_computers/tree/master/Microsha--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Simple KiCad For Simple Vintage Computer Hobbyists: Part 7a (Keyboard Design 1) [TCE #0620] The Clueless Engineer 2025-07-02 | Let's see if we can design a replacement mechanical keyboard for the 1987 Cambridge Computer Z88 using Gateron KS-33 low profile key switches. The rubber keyboard (Sir Clive special!) doesn't seem to work too well on my machine so maybe a mechanical one would be nice.Maybe ... maybe not, but let's give it a try and see how it turns out.This video covers how to use some tools to quickly layout a keyboard for a vintage computer. We won't cover routing nor worry about the physical mounting aspects - we'll cover that in Part 7b:youtu.be/aaBBvU5d50oThe design can be found on my Github:github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_KeyboardRelevant links:[1] Gateron KS-33 footprint for KiCad:github.com/siderakb/key-switches.pretty[2] Keyboard Layout Editorkeyboard-layout-editor.com[3] Plate Builderhttp://builder.swillkb.com[4] Thin film connectorTE Connectivity/AMP part 5-520314-8KiCad files from Mouser[5] Gateron 3D modelgateron.com/pages/3dDisclaimer: I'm not a Kicad super-user, I'm not a circuit design guru, I'm just a simple vintage computer hobbyist who needs simple PCBs from time to time. And yes, this sort of thing has probably been designed a dozen times before, but there's no harm in trying to learn how it's done is there?I'm using Kicad 9.0 on a 2022 MacBook Air (M2 with 24GB RAM) running macOS 15.5.Application: KiCad arm64 on arm64Version: 9.0.0, release buildPlatform: macOS Sequoia Version 15.5 (Build 24F74)0:00:00 ... Intro0:04:45 ... Custom symbols, footprints, 3D models0:14:30 ... Schematic design0:26:56 ... Assign footprints0:28:00 ... Keyboard layout0:43:20 ... Generate key switch layout guide0:48:30 ... Key switch layout on PCB0:57:45 ... Physical PCB1:00:45 ... 3D view of our keyboard1:03:02 ... KBPLACER plugin1:05:30 ... Freerouting attempt1:06:03 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 2 (Backpack Drive - First Attempt) [TCE #0619] The Clueless Engineer 2025-06-30 | The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?00:00 ... Intro 04:10 ... DE9-to-DB25 converter built05:45 ... Configuring the uBPD09:00 ... Copying Disc Manager from ROM to RAM11:08 ... And I did something wrong (probably)13:25 ... Rant about keyboard16:08 ... Z88 upgrade plans (keyboard, ROM, RAM)20:37 ... Channel outro & thanks--------------------------------From Part 1:What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.WoS info:worldofspectrum.org/z88forever/index.htmlZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇧🇾 Астра (Astra) ZX Spectrum Clone: Part 2 (Power On - NOK) [TCE #0618] The Clueless Engineer 2025-06-29 | I was able to create an RGB cable for the РГ1Н-1 type port ... the plug was labelled «РШ2Н-1-17» (I think). Unfortunately the machine doesn't seem to work as powering on gives a garbled screen with some sync issues. It's been a while since I've had to troubleshoot a Speccy. I vaguely think that maybe it's a RAM issue, although an initial check of each DRAM chip seems to be okay.Manual & schematic can be found here (Russian):https://zxbyte.ru/astra.htmTrying with a diagnostics ROM ... or no ROM chips at all ... makes no difference.00:00 ... Intro01:50 ... Video cable08:20 ... Video pinout09:10 ... Power on - NOK11:35 ... Motherboard closeup13:25 ... Channel thanks & outro--------------------------------From Part 1:Let's have a quick look at this Soviet-era Sinclair ZX Spectrum clone from Minsk in the Byelorussian SSR ... it's called Универсальная Телеигровая Приставка Астра, or Universal Television Game Console Astra.It's an interesting machine as it looks to have less chips than a genuine Speccy but doesn't use a БМК (Basic Matrix Crystal, the Soviet version of a ULA or gate array). It does use some "mini ROMs" (similar to the Сантака 002) ... a pair of КР556РТ4А (KR556RT4A), labelled "К" and "С", which are 1024 bit (256x4) and one socketed К155РЕ3 (K155RE3), labelled "М" which is 256 bit (32x8).It uses a genuine Zilog Z80 but otherwise has Soviet parts ... notable are the aforementioned "mini-ROMs" and a pair of КС573РФ4Б (KS573RF4B) 64kbit EPROMs (i.e. 2764) that would have the 16KByte Speccy ROM (or some cloned variant).It also has it's "good" capacitors (the ones with palladium & silver) still intact!It has an interesting mix of exterior ports as well.We have the usual 5-pin DINs for cassette (МАГ) and +5VDC power (БП) but we also have some 2x4 РГ1Н-1 (RG1N-1) ports which use a 2.5mm pitch. The Western equivalent is probably the D-sub interfaces like DE9 and DB25.One is used for the "remote control" (ДУ = дистанционное управление) which is probably a joystick ... this is unusual as usually there would be a 5-pin DIN (they didn't use DE9 in the USSR).The other is for the RGB video output (ТВ). At first this seems weird as they could've used a 5-pin DIN like most other machines, but this machine doesn't have an internal speaker and thus includes audio with the RGB signal. Fair enough ... other machines of the era used a 7-pin DIN then.Perhaps these were not available, hence the use of the РГ1Н-1.Not sure what I'll do - not worried about the joystick port, but the video output ... ? I could replace it with a 6-pin DIN as there looks to be space, or I could try to source the equivalent plug from Ukraine ... let's see.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇦🇺 Gaming Keyboard for ZX80/ZX81/Minstrel/Jupiter Ace: Part 1 (Minstrel 2 Test) [TCE #0617] The Clueless Engineer 2025-06-26 | Thanks to #PCBWAY for their ongoing support! pcbway.comJust a bit of fun. Thought it might be interesting to design a "proper keyboard" for the Minstrel series of computers, which means it's also compatible with the Sinclair ZX80, ZX81 and the Jupiter Ace.One difficulty my brain found with playing games using the original ZX keyboard layout is the location of the cursor keys on the 5/6/7/8 keys. Thus I added a dedicated cursor cluster ... that's the main "highlight" of this board.I like it and enjoy using it, and I definitely think it makes playing KONG, or programming, a lot easier and a more pleasant experience.Unfortunately my attempt to add a dedicated [RUBOUT] key still didn't work, so something I'll need to figure out ... or I might just remove. Pressing [SHIFT] + [0] isn't terribly onerous ... I was just trying to be clever.It should also work with the Minstrel 4th, and I guess the Jupiter Ace, but I will confirm this in another video.More info on my Github:github.com/0ddjob/SinclairThe Minstrel 2 (ZX80), Minstrel 3 (ZX81) and Minstrel 4th/4D are computers designed by Dave at Tynemouth Software:tindie.com/stores/tynemouth00:00 ... Intro05:49 ... Building the keyboard08:16 ... Build finished10:07 ... Initial testing11:45 ... ZX80 KONG15:17 ... CHECKMEM16:15 ... ROCKET MAN20:25 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Cambridge Computer Z88: Part 1 (First Look & Power On) [TCE #0616] The Clueless Engineer 2025-06-26 | What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.00:00 ... Intro03:27 ... Keyboard close-up04:00 ... Universal Backpack Drive (UBPD)06:19 ... First power-on attempt - NOK07:50 ... Second power-on attempt - OK10:07 ... EPROMs & eraser11:40 ... Opening the case14:50 ... DE9 serial port16:20 ... Opening up the keyboard21:22 ... Keyboard repaired22:10 ... Motherboard close-up23:00 ... Testing29:32 ... Channel thanks & outroZ88 motherboard mods:https://privat.bahnhof.se/wb782177/z88/motherboard.htmZ88 Wiki:cambridgez88.jira.com/wikiROM replacement:github.com/bkw777/aDIPtersZ88 parts:http://www.rakewell.com/main/index.shtmlUniversal Backpack Drive:soigeneris.com/universal-backpack-drive--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇵🇱 Quick Update: 25-Jun-2025 (Package from Polska) [TCE #0615] The Clueless Engineer 2025-06-25 | A big thank you to Karol in Poland for sending me some spares for my Электроника ВЛ-100 (Elektronika VL-100) television as well as a Soviet model С1-112А Осциллограф (Oscillograph/Oscilloscope) to have a look at. He sent them via sea/surface ... took just over three months from Poland to Australia ... and arrived in perfect condition thanks to his excellent packaging.We'll have a quick look today, and more in-depth in a later video. Promise.00:00 ... Intro04:50 ... Электроника ВЛ-100 television parts06:15 ... Осциллограф С1-112А oscilloscope13:45 ... Sundry other parts15:33 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇦🇺 The TEC-1G: Part 3 (Build & Test) [TCE #0614] The Clueless Engineer 2025-06-23 | {Relevant links at the bottom}The TEC-1 (Talking Electronics Computer) is an Aussie Z80 based single board computer (SBC) first released in 1983 by Colin Mitchell's "Talking Electronics" magazine:talkingelectronics.comUnfortunately I couldn't afford the kit back in the 80s, but always wanted to get one. There's always a lot of appreciation when someone brings out their TEC-1B that they built with their dad 40 years ago ... and still in perfect working order.I won't rehash the history - check here for more info ... and most importantly ... the correct attributions of who did what:en.wikipedia.org/wiki/TEC-1The TEC-1D boards were reproduced in 2018 and I managed to grab some. I did almost finish building it (surprise) but got distracted onto other things - one small difficulty for me was just trying to keep track off what add-ons I would need ... so many different boards were designed!In 2023 @MarkovAllTrades brought the machine up-to-date for its 40th anniversary with the TEC-1G revision. Mark popped in last week and he showed me his state-of-the-art TEC-1G. Very cool. He kindly sent me another board to build ... the Signature Edition version this time ... and I was determined to get it working ... I'm quite a bit more experienced now. I will definitely re-visit the Beta board Mark originally sent me ... one major issue why it didn't work was my mixing 74HC with 74HCT/74LS logic ... duh.I did get this one built & booting. But the keypad is unresponsive ... the 74C923 is suspect. I will investigate further - definitely going to look at making a proper keyboard for it.Unicorn Electronics in the US is a reputable supplier (if you don't want to gamble on Aliexpress) and they do appear to have stock (but you'd need to check):unicornelectronics.com/IC/Tele.htmlYou can find all the information on the TEC at Mark's Github:github.com/MarkJelic/TEC-1GTindie store for simple everything-included options:tindie.com/stores/tec1Also check out the Facebook group, if that's your thing:facebook.com/groups/tec1z80And, of course, Mark's YouTube channel:youtube.com/@TEC-1G00:00 ... Intro05:05 ... Building starts11:00 ... Intermission15:17 ... Building resumes17:50 ... First power-on test21:30 ... Running diagnostics - OK!28:30 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇲🇩 Вектор 06Ц (Vector 06C): Part 3 (Video Troubleshooting Starts) [TCE #0614] The Clueless Engineer 2025-06-21 | The Vector is known to have issues with modern displays because of its sloppy sync timing. I'm not really sure the best way to fix it ... I've scrolled through over 50 pages of Russian language forum posts where 15 different solutions were proposed, but no-one seems to have a definitive answer for the 02 model ... well, definitive enough for this lazy non-Russian speaker to just pick up and use.The pinout for the 7-pin video is:Pin 1 = sound (звук) Pin 2 = video (видео, i.e. composite sync) Pin 3 = blue Pin 4 = greenPin 5 = red Pin 6 = ground Pin 7 = +12v (упров/control)There was also a lack of easy-to-find information on the 02 model, so I've created a new repository with what I've found:github.com/0ddjob/Vector-06C00:00 ... Intro04:50 ... Video test with cable & GBS Control05:18 ... Schematics08:44 ... Sync pulses on oscilloscope13:24 ... An almost stable image?15:30 ... Channel thanks & Outro--------------------------------From Part 2:Let's try powering this interesting Moldovan machine on. As it uses an 8080-compatible CPU it requires three voltages: ±5VDC and +12VDC. I normally use a Mean Well GP25A13A-R1B with a 5-pin DIN plug for this. Comparing the 7-pin DIN socket on the Vector it's a very close match to the pinout on the Mean Well ... pin 2 on the Mean Well is 0V/GND but is -5VDC on the Vector. Easiest solution ... I'm not in the mood to make cables ... is to de-solder the 7-pin socket on the Vector and cut the track connecting pins 2 & 4 (-5V) so that pin 2 is not used. This will mean I can plug my Mean Well PSU directly into the Vector. Simples!Revised pinout for my Vector's 7-pin power socket to match the Mean Well's 5-pin plug:Pin 1 = groundPin 2 = not connected (ground on Mean Well)Pin 3 = +5VPin 4 = -5VPin 5 = +12VPin 6 = not connected (ground on Vector)Pin 7 = not connected (+5V on Vector)Next, checking the CPU and video output with the oscilloscope definitely shows activity! The keyboard doesn't seem to trigger anything ... no key press beep, no change in РУС/ЛАТ LED.Also ... the RGBS output on my Vector is 7-pin DIN and not 5-pin like on the schematic I'm referring to ... most likely because I've got a 06Ц.02 model and the schematic is for the original.When in doubt, guess!And ... it does seem there is a video signal ... it appears to be the tape loading screen, with ВЕКТОР 06Ц written up the top! But, as @night_gryphon warned in the Part 1 comments, the video output is a bit weird ... so some massaging to get it to work with modern equipment, in Australia, will be required:"The other catch is the non standard video output with non standard sync and inverted RGB levels. It was designed to cheat the CRT TV but most likely will confuse most of scan doublers etc."But, I'm happy that the machine appears to be functional!--------------------------------From Part 1:Let's have a look at a unique 8080-based (КР580ВМ80А) machine that was designed in the Moldovan SSR and released in 1987. This is the 2nd version of the machine, the Вектор 06Ц.02. The original had a 512 byte ROM that was enough to bootstrap loading from tape but this machine has a 2KByte ROM (556РТ7А, similar to a Philips 82S191) that has more functionality.The machine was apparently well regarded for its excellent graphics capabilities.As it's an 8080 machine it requires ±5V and +12V DC via a 7-pin DIN. I'll need to make up a 5-pin to 7-pin converter so I can use my Mean Well power supply with it.It has 64KBytes of DRAM in 32 x КР565РУ6 (similar to Intel 2118) ... yay! Lots of chips where something could go wrong!More information can be found here:github.com/alemorf/retro_computers--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇲🇩 Вектор 06Ц (Vector 06C): Part 2 (Power On) [TCE #0613] The Clueless Engineer 2025-06-16 | Let's try powering this interesting Moldovan machine on. As it uses an 8080-compatible CPU it requires three voltages: ±5VDC and +12VDC. I normally use a Mean Well GP25A13A-R1B with a 5-pin DIN plug for this. Comparing the 7-pin DIN socket on the Vector it's a very close match to the pinout on the Mean Well ... pin 2 on the Mean Well is 0V/GND but is -5VDC on the Vector. Easiest solution ... I'm not in the mood to make cables ... is to de-solder the 7-pin socket on the Vector and cut the track connecting pins 2 & 4 (-5V) so that pin 2 is not used. This will mean I can plug my Mean Well PSU directly into the Vector. Simples!Revised pinout for my Vector's 7-pin power socket to match the Mean Well's 5-pin plug:Pin 1 = groundPin 2 = not connected (ground on Mean Well)Pin 3 = +5VPin 4 = -5VPin 5 = +12VPin 6 = not connected (ground on Vector)Pin 7 = not connected (+5V on Vector)Next, checking the CPU and video output with the oscilloscope definitely shows activity! The keyboard doesn't seem to trigger anything ... no key press beep, no change in РУС/ЛАТ LED.Also ... the RGBS output on my Vector is 7-pin DIN and not 5-pin like on the schematic I'm referring to ... most likely because I've got a 06Ц.02 model and the schematic is for the original.When in doubt, guess!And ... it does seem there is a video signal ... it appears to be the tape loading screen, with ВЕКТОР 06Ц written up the top! But, as @night_gryphon warned in the Part 1 comments, the video output is a bit weird ... so some massaging to get it to work with modern equipment, in Australia, will be required:"The other catch is the non standard video output with non standard sync and inverted RGB levels. It was designed to cheat the CRT TV but most likely will confuse most of scan doublers etc."But, I'm happy that the machine appears to be functional!00:00 ... Intro02:40 ... Power supply requirements10:41 ... Video output?14:01 ... Checking signals on the oscilloscope18:09 ... Testing video output pins19:52 ... Trying random pins for R/G/B/S22:25 ... Channel thanks & outro--------------------------------From Part 1:Let's have a look at a unique 8080-based (КР580ВМ80А) machine that was designed in the Moldovan SSR and released in 1987. This is the 2nd version of the machine, the Вектор 06Ц.02. The original had a 512 byte ROM that was enough to bootstrap loading from tape but this machine has a 2KByte ROM (556РТ7А, similar to a Philips 82S191) that has more functionality.The machine was apparently well regarded for its excellent graphics capabilities.As it's an 8080 machine it requires ±5V and +12V DC via a 7-pin DIN. I'll need to make up a 5-pin to 7-pin converter so I can use my Mean Well power supply with it.It has 64KBytes of DRAM in 32 x КР565РУ6 (similar to Intel 2118) ... yay! Lots of chips where something could go wrong!More information can be found here:github.com/alemorf/retro_computers--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Minstrel 2 (Sinclair ZX80 Clone): Part 3 (Gaming Keyboard) [TCE #0612] The Clueless Engineer 2025-06-14 | Let's make a "gaming keyboard" for the ZX80/ZX81/Minstrel to see if I really am bad at KONG or if the use of 5/6/7/8 as cursor keys just sucks. The main reason for the keyboard is to have a dedicated cursor cluster (i.e. 5/6/7/8 keys).The keyboard *mostly* works ... I've been doing manual track routing in KiCad lately and like a dumb-ass I messed up some of the tracks. But I figured out what I'd done and fixed it on the board so it's working.The design can be found on my Github - I have updated/corrected the design but not yet fabricated a test board to confirm (15-Jun-2025):github.com/0ddjob/SinclairIt certainly does make a big improvement, in my opinion, to gameplay and general typing ... but don't type too fast as the ZX80 can't keep up!00:00 ... Intro02:07 ... The Bytes Brothers03:48 ... Keyboard built05:19 ... Now with key caps09:46 ... First test - NOK12:48 ... Second test - OK14:25 ... Gameplay - KONG17:53 ... Gameplay - PACMAN19:40 ... Gameplay - MAZOGS28:03 ... Typing a short program30:14 ... Keyboard close-up30:50 ... Channel outro & Thanks--------------------------------From Part 2:Let's see if we can implement Dave's (Tynemouth Software) fix for the ZX80's pixel synchronisation issue on our Minstrel 2 v2.6 board. This issue wouldn't have been noticeable on a CRT back in the 1980s.This fix is implemented in the current v2.9 version of Dave's Minstrel 2 board, and he has an excellent writeup about the issue and how he fixed it on his blog - part 1 can be found here:http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.htmlI created a small daughterboard by comparing Dave's v2.6 and v2.9 video output stages (thanks for schematics Dave!). My implementation can be found on my Github here:github.com/0ddjob/SinclairHUOM!This is purely for the Minstrel 2 v2.6 board - I don't have an original ZX80 to compare or test with. The design & board works as it is, but I want to make some cosmetic changes (like reordering the bodge wires).--------------------------------From Part 1:Let's build the Minstrel 2, a ZX80 compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 3 (ZX81), Minstrel 4th & 4D (Jupiter Ace) and MiniPET.It includes both 4K Integer BASIC and 8K Floating Point BASIC.I got the kit a few years ago - mine is v2.6, where as the latest available is v2.9 which has some improvements over this board, including the ZX80 pixel synchronisation problem (see below).Loading software via the tape interface was a bit tricky. Files are available in various formats such as .O, .P, and .P81. Using tools like mame-castool and another converter didn't really work. It was only when I found some already-generated WAV files that I could get it to work - these can be found here:http://qrp.gr/zx80/software.htmThere is a cut-down version of the ZXpand available which makes loading files a lot simpler.As I'm using an LCD display an artefact of the ZX80's original design becomes easily visible on the screen - Dave has a post about this on his blog and has fixed it in the current Minstrel 2 version:http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.htmlDave's Tindie store:tindie.com/stores/tynemouth--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇲🇩 Вектор 06Ц (Vector 06C): Part 1 (First Look) [TCE #0611] The Clueless Engineer 2025-06-13 | Let's have a look at a unique 8080-based (КР580ВМ80А) machine that was designed in the Moldovan SSR and released in 1987. This is the 2nd version of the machine, the Вектор 06Ц.02. The original had a 512 byte ROM that was enough to bootstrap loading from tape but this machine has a 2KByte ROM (556РТ7А, similar to a Philips 82S191) that has more functionality.The machine was apparently well regarded for its excellent graphics capabilities.As it's an 8080 machine it requires ±5V and +12V DC via a 7-pin DIN. I'll need to make up a 5-pin to 7-pin converter so I can use my Mean Well power supply with it.It has 64KBytes of DRAM in 32 x КР565РУ6 (similar to Intel 2118) ... yay! Lots of chips where something could go wrong!More information can be found here:github.com/alemorf/retro_computers00:00 ... Intro02:00 ... Checking the interface ports06:00 ... Keyboard close-up07:50 ... Opening the case10:45 ... Motherboard revealed14:45 ... Key switch close-up19:27 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇺🇦 ПК-01 Львов (PC-01 Lviv): Part 8 (Where Was I?) [TCE #0610] The Clueless Engineer 2025-05-25 | Sorry, this one is a bit long - I now have a fourth machine that looks in good shape (ahem) and as it's been a while since I worked on these machines, let's try to get back up to speed and get one working. After this video I might have an idea what might help, although one or more of the ROMs may also be suspect and require de-soldering and re-programming ... a hassle which is why I've not done it yet.Soundtrack: The Twilight Sadthetwilightsad.bandcamp.com00:00 ... Intro06:30 ... Opening machine no. 413:40 ... Examining the motherboard15:21 ... The Twilight Sad16:20 ... Damn capacitors23:40 ... Okay, this is the nicer looking machine (ceramic EPROMs, original KM capacitors)24:45 ... Power cable shibari27:30 ... Power on test - NOK29:05 ... Data bus contention?32:00 ... Final thoughts32:40 ... Channel thanks & OutroRepair notes:github.com/codepainters/lvov--------------------------------From Part 7:I got feedback on the Lviv forums that it could be a ROM issue, in that the BASIC wasn't booting.http://pc01.lviv.ua/forum/viewtopic.php?f=2&t=489Unfortunately only one of the machines has all the ROMs socketed, and this is the one that was stripped for a few roubles of previous metals. The other two machines only have the C000 ROM socketed (why?).Also, of the three machines, two uses plastic DIPs for the ROMs and one uses nice ceramic ones. The ROMs are КР573РФ5 (KR573RF5) types, equivalent to a Western 2716, holding 2Kbytes each for a total of 16Kbytes of ROM.Each ROM has address lines A0 to A10, with a КР1533ИД7 (74LS138 3-to-8 decoder) using A11 to A13 to select the eight ROMs.When I put the logic analyser (Saleae Logic Pro 16) on this chip (D9 on the schematic) it appeared the O5 was not working, remaining active low all the time. This is the enable line for ROM D15.I removed the suspect part and replaced it with a 74LS138 - no boot screen this time, just garbage. Checking the analyser again I could see O5 was now working, but it looked like the CPU was just stepping through addresses, like it can't find any executable code (just NOPs) in the ROMs to execute ... ?Quick summary: The PC-01 Lviv is a Soviet Ukrainian machine built around the КР580ВМ80А (KR580VM80A, the Soviet clone of the Intel 8080). There was also, briefly, the PC-02 Kyiv ... I have one sample that is under repair.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Minstrel 2 (Sinclair ZX80 Clone): Part 2 (Pixel Synch. Issue) [TCE #0609] The Clueless Engineer 2025-05-23 | Thanks to PCBWAY for again sponsoring my video! pcbway.comLet's see if we can implement Dave's (Tynemouth Software) fix for the ZX80's pixel synchronisation issue on our Minstrel 2 v2.6 board. This issue wouldn't have been noticeable on a CRT back in the 1980s.This fix is implemented in the current v2.9 version of Dave's Minstrel 2 board, and he has an excellent writeup about the issue and how he fixed it on his blog - part 1 can be found here:http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.htmlI created a small daughterboard by comparing Dave's v2.6 and v2.9 video output stages (thanks for schematics Dave!). My implementation can be found on my Github here:github.com/0ddjob/SinclairHUOM!This is purely for the Minstrel 2 v2.6 board - I don't have an original ZX80 to compare or test with. The design & board works as it is, but I want to make some cosmetic changes (like reordering the bodge wires).00:00 ... Intro04:40 ... Thanks to PCBWAY!05:23 ... Board is built07:05 ... Testing!09:20 ... Final thoughts10:07 ... Channel thanks & Outro--------------------------------From Part 1:Let's build the Minstrel 2, a ZX80 compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 3 (ZX81), Minstrel 4th & 4D (Jupiter Ace) and MiniPET.It includes both 4K Integer BASIC and 8K Floating Point BASIC.I got the kit a few years ago - mine is v2.6, where as the latest available is v2.9 which has some improvements over this board, including the ZX80 pixel synchronisation problem (see below).Loading software via the tape interface was a bit tricky. Files are available in various formats such as .O, .P, and .P81. Using tools like mame-castool and another converter didn't really work. It was only when I found some already-generated WAV files that I could get it to work - these can be found here:http://qrp.gr/zx80/software.htmThere is a cut-down version of the ZXpand available which makes loading files a lot simpler.As I'm using an LCD display an artefact of the ZX80's original design becomes easily visible on the screen - Dave has a post about this on his blog and has fixed it in the current Minstrel 2 version:http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.htmlDave's Tindie store:tindie.com/stores/tynemouth--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Сириус (Sirius) ZX Spectrum Clone: Part 3 (Smallest Speccy board?) [TCE #0608] The Clueless Engineer 2025-05-22 | Let's have a look at a 2nd example of the post-Soviet Сириус Sinclair ZX Spectrum clone from Russia. This one looks to be dated around 1994. What drew me to this example was the motherboard ... for me, at least, this is the smallest 1990-era implementation of a Speccy I've come across - essentially the size of a ZX81.Unfortunately all of the decoupling capacitors have been removed so they will need replacing before I have a hope of getting it to work.The machine, otherwise, seems to be in good shape. It has a T34 type БМК (ULA), also sometimes labelled as КА1515ХМ1-216. The Z80 is an Angstrem КР1858ВМ1 with associated T34-ish КР1013РЕ1-20 Spectrum masked ROM.00:00 ... Intro02:20 ... Internal power supply07:40 ... Interesting PCB attachment method09:00 ... Motherboard close-up11:10 ... Comparing with Issue 4S from Spectrum+12:30 ... Comparing with ZX81 case13:53 ... Channel thanks & outro--------------------------------From Part 2:A bit of a mixed bag - I managed to figure out the RGBS pinout, although I think the video appears a bit dark ... too many resistors? Most of the time I spent going around in circles trying to figure out the TAPE IN ... it looks like I did finally figure out where TAPE IN and TAPE OUT signals are on the board ... but the TAPE IN is a real mess (in my humblest of opinions) ... I can't see how it ever worked.I had another crack at it tonight and I finally made some progress - couldn't load anything, but at least the machine could see *something*.No luck with the speaker output either. Some further work required there.--------------------------------From Part 1:This machine was initially a bit of a mystery - well, obviously it's a Sinclair ZX Spectrum clone. It has all Soviet-era parts (dated mostly 1991 & 1992) including a beautiful, ceramic Т34ВМ1 CPU, a Т34РЕ1-020 ROM (containing the Czechoslovak "Didaktik Skalica" firmware) and absolutely no manufacture markings on the case or motherboard.Thanks to some sleuthing by Martin (via Patreon) who discovered that the machine (case at least) appears to be a "Sirius" from Russia (confirmed also with UCHC, Ukrainian Computing History Community, on Telegram):https://sblive.narod.ru/ZX-Spectrum/Sirius/Sirius.htmThanks to Eugene on UCHC for his insight:"Actually, this is one of numerous cheap clones that built around latest Soviet ULA replacement. This one, in particular, created by small garage company with a quite shitty soldering and assembling. And board itself seems to be assembled somewhere using automated production line, so seems they have ordered boards somewhere else and then assemble them in case. This can explain why boards in these instances are different."This Wiki page about the T34 series of chips seems to indicate the Sirius is from Ukraine, but maybe different "Sirius" ... or it's just wrong:- Sirius (Украина)ru.wikipedia.org/wiki/Т34ВМ1_и_Т34ВГ1It was initially AC powered with a very simple and unsafe looking transformer (assuming 220VAC-to-9VAC), a КЦ410Б bridge rectifier and a КРЕН5А 5V linear regulator. I will replace these with a simple 2.1mm DC socket for direct 5VDC input (i.e. USB charger). On booting it was drawing about 330mA at 5V.It utilises a Soviet equivalent to a Gate Array or ULA called a БМК (Базового Матричного Кристалла, or Basic Matrix Crystal) ... the КА1515ХМ1-216. I have had very little success with machines that use this chip actually working ... however it does greatly simplify the circuit design!The only other major chips are the Т34ВМ1 (Soviet Z80 clone, later called the КР1858ВМ1 or КМ1858ВМ1 depending on case type), a Т34РЕ1 (Spectrum ROM), 64KBytes of DRAM using КР565РУ5 and a few other support chips.The machine only has three ports: 5-pin DIN for joystick, 5-pin DIN for RGBS video & sound output and a 3-pin DIN for cassette input/output. It also has a reset button.The keyboard is okay ... but when you pull it apart it does appear to be quite cheaply made.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Minstrel 2 (Sinclair ZX80 Clone): Part 1 (Build & Testing) [TCE #0607] The Clueless Engineer 2025-05-21 | Let's build the Minstrel 2, a ZX80 compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 3 (ZX81), Minstrel 4th & 4D (Jupiter Ace) and MiniPET.It includes both 4K Integer BASIC and 8K Floating Point BASIC.I got the kit a few years ago - mine is v2.6, where as the latest available is v2.9 which has some improvements over this board, including the ZX80 pixel synchronisation problem (see below).Loading software via the tape interface was a bit tricky. Files are available in various formats such as .O, .P, and .P81. Using tools like mame-castool and another converter didn't really work. It was only when I found some already-generated WAV files that I could get it to work - these can be found here:http://qrp.gr/zx80/software.htmThere is a cut-down version of the ZXpand available which makes loading files a lot simpler.As I'm using an LCD display an artefact of the ZX80's original design becomes easily visible on the screen - Dave has a post about this on his blog and has fixed it in the current Minstrel 2 version:http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.htmlDave's Tindie store:tindie.com/stores/tynemouth00:00 ... Intro00:30 ... Troubleshooting05:40 ... Power on - OK!06:40 ... Trying to load - NOK07:55 ... New Minstrel boards to build08:50 ... The Culverdon watch11:55 ... Minstrel expansion boards13:45 ... Loading PACMAN (4K version)18:50 ... Loading ZX80-KONG (4K version)23:15 ... Final thoughts24:10 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 dktronics Keyboard for ZX Spectrum: Part 3 (Power On - OK!) [TCE #0606] The Clueless Engineer 2025-05-17 | Made some progress. First ... before I forget again ... I designed the missing MicroDrive port bridge PCB that was originally included to extend the Sinclair Interface 1 edge connector. Of course, I could've also just made a longer ribbon cable ...Anyway, I gutted the RF modulator can and just stuck a 100µF electrolytic in there, replacing the 470µF that was originally used for the composite mod. I thought 100µF was sufficient, but the picture looks a little noisier to me. Doesn't really matter as the vLA82 replacement ULA that I'm using has the option for RGB output, which I might as well use.I did find a short on the underside of the board - two capacitor legs were touching. Didn't solve the issue though.Without the vLA82 installed the Z80 still heated up very fast. I couldn't find any issue with the voltages - they all measured okay, and I couldn't find any shorts between them. So maybe the Z80 was just fscked.It's not socketed so never an easy thing to just replace to see if it fixes it. But I've been using the Japanese-made ENGINEER SS-03 solder sucker quite a lot the past few months and it worked really well to remove the Z80 in this case - came off very cleanly.I installed a socket and stuck a new (2021) Z80 in, still without the ULA. The current draw was immediately a lot lower and the Z80 remained quite cool. Sticking the vLA82 in and the Speccy booted!Unfortunately it seems the keyboard key switches are a little bit dodgy so might need cleaning, if that's possible with these types ...00:00 ... Intro03:10 ... Dodgy dodgy04:45 ... RF modulator can gutted05:15 ... Checking underside of board07:13 ... Z80 replaced08:10 ... Power on ...10:18 ... New keyboard connectors12:45 ... Interface 1 & Speccy installed 14:09 ... Keyboard test19:00 ... Channel thanks & outro--------------------------------From Part 2:Let's have a quick look at the Issue 4S board ZX Spectrum+ board that came with the keyboard. The ULA was missing as was one of the 4116 16kbit DRAM chips that make up the lower 16KB of RAM. I noticed that the composite video mod. had been done already. Looks like the board might've been used for spares so might not be in a good state.I used one of vRetroDesign Charlie's vLA82s to replace the missing ULA and substituted a 4164 temporarily in place of a 4116.vretrodesign.comLooks like some troubleshooting is required ...Dave of Tynemouth Software has an interesting blog post about repairing an Issue 4S board:http://blog.tynemouthsoftware.co.uk/2018/06/zx-spectrum-mystery-repair.html--------------------------------From Part 1:Let's have a look at this keyboard & case for the Sinclair ZX Spectrum from dk'tronics. As with the Fuller FDS keyboard & case, the Speccy must be denuded for it to fit. This case is designed to also accomodate the Spectrum's Interface 1 (also denuded) which adds MicroDrive, RS232 serial and network support to the Speccy, similar to the Fuller FDS.There's not much to it. The keyboard is okay, nothing spectacular. It has a lot of space inside which would allow your Speccy to breath a bit more, although you can also fit your power supply inside as well. It apparently came with a double-ended PCB that you could attach to the MicroDrive port on the Interface 1 to allow your MicroDrive cable to connect from outside.The Speccy that it came with is an Issue 4S and is missing its ULA (not a major issue). It also has a reset button attached (I assume), although it's floating free rather than affixed to the case.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 dktronics Keyboard for ZX Spectrum: Part 2 (Power On - NOK) [TCE #0605] The Clueless Engineer 2025-05-16 | Let's have a quick look at the Issue 4S board ZX Spectrum+ board that came with the keyboard. The ULA was missing as was one of the 4116 16kbit DRAM chips that make up the lower 16KB of RAM. I noticed that the composite video mod. had been done already. Looks like the board might've been used for spares so might not be in a good state.I used one of vRetroDesign Charlie's vLA82s to replace the missing ULA and substituted a 4164 temporarily in place of a 4116.vretrodesign.comLooks like some troubleshooting is required ...Dave of Tynemouth Software has an interesting blog post about repairing an Issue 4S board:http://blog.tynemouthsoftware.co.uk/2018/06/zx-spectrum-mystery-repair.html00:00 ... Intro05:34 ... Repairs done06:25 ... Power on - NOK07:10 ... Thermal imaging - CPU is hot!10:47 ... Channel thanks & outro--------------------------------From Part 1:Let's have a look at this keyboard & case for the Sinclair ZX Spectrum from dk'tronics. As with the Fuller FDS keyboard & case, the Speccy must be denuded for it to fit. This case is designed to also accomodate the Spectrum's Interface 1 (also denuded) which adds MicroDrive, RS232 serial and network support to the Speccy, similar to the Fuller FDS.There's not much to it. The keyboard is okay, nothing spectacular. It has a lot of space inside which would allow your Speccy to breath a bit more, although you can also fit your power supply inside as well. It apparently came with a double-ended PCB that you could attach to the MicroDrive port on the Interface 1 to allow your MicroDrive cable to connect from outside.The Speccy that it came with is an Issue 4S and is missing its ULA (not a major issue). It also has a reset button attached (I assume), although it's floating free rather than affixed to the case.--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 dktronics Keyboard for ZX Spectrum: Part 1 (First Look) [TCE #0604] The Clueless Engineer 2025-05-15 | Let's have a look at this keyboard & case for the Sinclair ZX Spectrum from dk'tronics. As with the Fuller FDS keyboard & case, the Speccy must be denuded for it to fit. This case is designed to also accomodate the Spectrum's Interface 1 (also denuded) which adds MicroDrive, RS232 serial and network support to the Speccy, similar to the Fuller FDS.There's not much to it. The keyboard is okay, nothing spectacular. It has a lot of space inside which would allow your Speccy to breath a bit more, although you can also fit your power supply inside as well. It apparently came with a double-ended PCB that you could attach to the MicroDrive port on the Interface 1 to allow your MicroDrive cable to connect from outside.The Speccy that it came with is an Issue 4S and is missing its ULA (not a major issue). It also has a reset button attached (I assume), although it's floating free rather than affixed to the case.00:00 ... Intro02:52 ... Close-up of keyboard04:17 ... Opening the case07:00 ... Interface 1 & MicroDrive cable09:00 ... Quick comparison with Fuller FDS keyboard10:55 ... Fitting the denuded Interface 1 & Speccy14:40 ... Fitting the Interface 2 externally15:06 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
Easy Add-on Projects for Amstrad CPC & MSX Computers - Picture Digitiser: Part 1 [TCE #0595] The Clueless Engineer 2025-05-14 | Thanks to #PCBWAY for their ongoing support! pcbway.com(This was my first Patreon-exclusive video)I was rifling through my book collection looking for a Timex Sinclair TS1500 manual and came across this book by Owen Bishop, published in 1986.Thankfully a good quality scanned copy is available online here:archive.org/details/easy-add-on-projects-for-amstrad-cpc-464-664-6128-and-msx-computers-owen-bishopacmeLet's try to build Project 2, a picture digitiser. On the Amstrad it uses Mode 1 text screen allowing a picture of 23 rows by 40 columns ... at 5mm per "screen pixel" this allows a picture 200 x 115mm to be scanned into Mode 1 text chunkiness. It also uses just four levels of grey.Project files can be found here:github.com/0ddjob/Easy-Add-on-Projects-for-Amstrad-CPCI had a thought ... "back in the day" one way to get a colour image if you only had a B&W digitiser was to take the scan three times, once each with a red, green, then blue filter attached. Recombine the images to get a colour image.So instead of using just a plain white LED, itself a modern improvement, perhaps use an RGB LED ... ?Anyway, let's see if we can get this one working first. In this first part let's design the PCB that will digitise the image for us. In the next part we will try to 3D design & print the hardware required.00:00 ... Intro06:14 ... The Gold Coast06:45 ... Schematic & PCB design13:09 ... Design Summary18:15 ... Channel thanks & outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇦🇺 Commodore VIC-20 Internal RAM Replacement: Part 1 (First Test of 8KB) [TCE #0603] The Clueless Engineer 2025-05-11 | Thanks to PCBWAY for sponsoring this video! pcbway.comI've long wondered about replacing the internal 5KB of RAM in the original VIC-20 (not the CR!) in case it becomes faulty and/or to reduce power consumption. At the same time, I've wondered if it would be possible to fill in that 3KB hole in BLK0 internally. I'm just interested in the BLK0 chunk of RAM - the additional RAM upgrades get more complicated, especially if you want them to be switchable on/off without opening the VIC up ... just use a modern cartridge for those. So far, the answer seems to be yes! It requires a bit of work removing chips ... but it reduces power draw by just over 200mA which is pretty good ... almost 20%.My design is switchable so you can easily switch between the base 5KB or the expanded 8KB via an external switch.I designed this board in a previous video:youtu.be/WQpgBGNAkP0The Github for this design can be found here - in the process of being updated (12-May-2025):github.com/0ddjob/Commodore_VIC20/tree/main/Internal_8KB The method at the moment is the following:[1] Remove the ten 2114 RAM chips from the board (UD2-UD6, UE2-UE6 on my board) ... carefully. Don't touch the single 2114 (UE1) used for the colour RAM! [2] Remove the 74LS138 (UC4) just above the RAM chips, the RAM decoder. This will be replaced by the logic in the PLD.[3] Install three IC sockets (turned pin preferably) in the UC4, UD4, UE4 locations: 2x18 pin and 1x16 pin.[4] Program the PLD.[5] Build my board and install.[6] Install the wiring.Done!00:00 ... Intro04:46 ... Old RAM removed06:04 ... First test - YIKES!07:58 ... Got it working with explanation13:05 ... Close-up of final installation14:05 ... Both RAM configs are working!17:50 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Minstrel 4th (Jupiter Ace Clone): Part 2 (SD Card Interface) [TCE #0602] The Clueless Engineer 2025-05-08 | Let's build the Jester Ace, an SD card interface for the Minstrel 4th, designed by Ian Johnson. It will allow us to load TAP files (see note below) from an SD card rather than having to convert them to WAV and load them like a cassette.I got it a few years ago - mine is a v1.1 board with v2.2.4 firmware.They were available from Ian's Tindie store but are unfortunately out of stock at the moment (8-May-2025):tindie.com/products/dr_ian_johnson/jester-aceIt was pretty easy to build and worked without hassle - once I'd inserted a micro SD card ... won't do nuthin' if one isn't inserted. As my Minstrel 4th has stand-offs, the Jester Ace felt a bit wobbly - I solved this by drilling a 3.5mm hole in a track-free part of the board and installing its own stand-off. Now nice and stable.It requires the TAP files to have a v2 header that is 27 bytes in length - this includes an additional "program type" byte that 26-byte TAP file headers don't include. If the TAP file has a 26 byte header you'll get an "error 10" when trying to load, even though the TAPLS.PY script doesn't flag a problem.This meant that programs I got from George's repository (link below) like Tut-Tut, Valkyr and 3D Monster Maze wouldn't work initially.I solved the issue by using some of Ian's Python scripts on his Github to convert the TAP file to TZX format, and then back to TAP format ... now with a 27 byte header.Ian also has a Github repository related to the Jester Ace:github.com/ianjohnson/jesterace00:00 ... Intro02:35 ... Board is built05:20 ... Adding extra stand-off06:38 ... First test14:45 ... TAP file header problem17:45 ... Loading Valkyr24:54 ... Loading 3D Monster Maze30:20 ... Changing directory on the SD card33:35 ... Loading Tut-Tut38:36 ... Channel thanks & Outro--------------------------------From Part 1:The Minstrel 4th is a Jupiter Ace compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 2 (ZX80), Minstrel 3 (ZX81) and MiniPET.As it's a Jupiter Ace it runs Forth natively, something that has always intrigued me. It also has an RC2014 interface which gives it a lot of expandability.Dave co-incidentally re-launched this machine today - check out all the details on his blog post:http://blog.tynemouthsoftware.co.uk/2025/05/minstrel-4th-returns.htmlI got the kit a few years ago - mine is v4.28.It only took a few hours to build and worked straight away. The power connection is a little flaky but that's my fault - rather than using the dependable 2.1mm DC jack that Dave included in the kit I decided to use a fancy one with built-in ON/OFF switch. I shall be switching to the simpler jack.Loading software via the tape interface wasn't too difficult but required a few tweaks for it to work for me using my 2012-era Mac mini server as the "cassette player":[1] Use the mame-castool with "jupiter" format to convert TAP files to WAV, and then, using Audacity,[2] Apply an 8kHz LPF to the audio, and[3] Bump the volume up by +10dBNot surprisingly, there is a post on Dave's blog about this:http://blog.tynemouthsoftware.co.uk/2020/05/loading-programs-on-minstrel-4th-or-jupiter-ace.htmlDave's Tindie store:tindie.com/stores/tynemouthGeorge's Jupiter Ace repository:github.com/markgbeckett/jupiter_aceNew software on tape for the Ace/Minstrel 4th from Cronosoft - 3DMM (3D Monster Maze) and Tut-Tut:cronosoft.fwscart.com--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇬🇧 Minstrel 4th (Jupiter Ace Clone): Part 1 (Build & Testing) [TCE #0601] The Clueless Engineer 2025-05-04 | Let's build the Minstrel 4th, a Jupiter Ace compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 2 (ZX80), Minstrel 3 (ZX81) and MiniPET.As it's a Jupiter Ace it runs Forth natively, something that has always intrigued me. It also has an RC2014 interface which gives it a lot of expandability.Dave co-incidentally re-launched this machine today - check out all the details on his blog post:http://blog.tynemouthsoftware.co.uk/2025/05/minstrel-4th-returns.htmlI got the kit a few years ago - mine is v4.28.It only took a few hours to build and worked straight away. The power connection is a little flaky (05:40) but that's my fault - rather than using the dependable 2.1mm DC jack that Dave included in the kit I decided to use a fancy one with built-in ON/OFF switch. I shall be switching to the simpler jack.Loading software via the tape interface wasn't too difficult but required a few tweaks for it to work for me using my 2012-era Mac mini server as the "cassette player":[1] Use the mame-castool with "jupiter" format to convert TAP files to WAV, and then, using Audacity,[2] Apply an 8kHz LPF to the audio, and[3] Bump the volume up by +10dBNot surprisingly, there is a post on Dave's blog about this:http://blog.tynemouthsoftware.co.uk/2020/05/loading-programs-on-minstrel-4th-or-jupiter-ace.htmlI'll be building the Jester Ace next which adds SD card support to the machine via the RC0214 interface.Dave's Tindie store:tindie.com/stores/tynemouthGeorge's Jupiter Ace repository:github.com/markgbeckett/jupiter_aceNew software on tape for the Ace/Minstrel 4th from Cronosoft - 3DMM (3D Monster Maze) and Tut-Tut:cronosoft.fwscart.com00:00 ... Intro01:45 ... The Minstrel 4th03:40 ... Power-on test04:24 ... Finished05:55 ... First command test09:20 ... Loading Gobble(de)Gook (PacMan clone)17:00 ... Loading TUT-TUT26:30 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇧🇾 Астра (Astra) ZX Spectrum Clone: Part 1 (First Look) [TCE #0600] The Clueless Engineer 2025-04-30 | Let's have a quick look at this Soviet-era Sinclair ZX Spectrum clone from Minsk in the Byelorussian SSR ... it's called Универсальная Телеигровая Приставка Астра, or Universal Television Game Console Astra.It's an interesting machine as it looks to have less chips than a genuine Speccy but doesn't use a БМК (Basic Matrix Crystal, the Soviet version of a ULA or gate array). It does use some "mini ROMs" (similar to the Сантака 002) ... a pair of КР556РТ4А (KR556RT4A), labelled "К" and "С", which are 1024 bit (256x4) and one socketed К155РЕ3 (K155RE3), labelled "М" which is 256 bit (32x8).It uses a genuine Zilog Z80 but otherwise has Soviet parts ... notable are the aforementioned "mini-ROMs" and a pair of КС573РФ4Б (KS573RF4B) 64kbit EPROMs (i.e. 2764) that would have the 16KByte Speccy ROM (or some cloned variant).It also has it's "good" capacitors (the ones with palladium & silver) still intact!It has an interesting mix of exterior ports as well.We have the usual 5-pin DINs for cassette (МАГ) and +5VDC power (БП) but we also have some 2x4 РГ1Н-1 (RG1N-1) ports which use a 2.5mm pitch. The Western equivalent is probably the D-sub interfaces like DE9 and DB25.One is used for the "remote control" (ДУ = дистанционное управление) which is probably a joystick ... this is unusual as usually there would be a 5-pin DIN (they didn't use DE9 in the USSR).The other is for the RGB video output (ТВ). At first this seems weird as they could've used a 5-pin DIN like most other machines, but this machine doesn't have an internal speaker and thus includes audio with the RGB signal. Fair enough ... other machines of the era used a 7-pin DIN then.Perhaps these were not available, hence the use of the РГ1Н-1.Not sure what I'll do - not worried about the joystick port, but the video output ... ? I could replace it with a 6-pin DIN as there looks to be space, or I could try to source the equivalent plug from Ukraine ... let's see.00:00 ... Intro03:10 ... Interface ports on back06:30 ... Opening the case07:55 ... Motherboard close-up09:37 ... Video output discussion 11:13 ... Mini-ROMs12:39 ... Channel thanks & Outro--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
🇷🇺 Пентагон 128 2+ (Pentagon) ZX Spectrum Clone: Part 1 (First Look) [TCE #0599] The Clueless Engineer 2025-04-29 | So, I *think* this might be a Пентагон derivative from 1993-1994, in this case a clone of the Sinclair (Amstrad-era) Spectrum 128 ... let's have a quick look. Some work is required before I can try powering it on ... It was possibly built by a Moscow company called Солон (Solon) ... please do let me know if you do actually recognise the board layout/design!https://w.wiki/DwZUspeccy.info/Pentagonspeccy.info/СолонIt's mostly Soviet-era parts (some manufactured post-Soviet) but it does have a genuine Zilog Z80, Yamaha YM2149F (a modified AY-3-8910) on a daughterboard and a Texas Instruments TMS27C512 64KByte EPROM. All the other parts are Soviet-era designs including the КР1818ВГ93 (KR1818VG93) floppy disc controller (FDC), a clone of the Western Digital FD1793. There is an additional 8KByte EPROM (a Soviet-era КС573РФ2 or KS573RF2) that I assume contains the DOS (TR-DOS?).They must've originally used the "good" capacitors containing previous metals as ALL the decoupling capacitors have been removed 🤯 ... decoupling capacitors really DO make a difference to the stability of a machine so I'll need to replace them before attempting to power it on.00:00 ... Intro01:10 ... Interface ports02:55 ... Motherboard06:00 ... Close-up of motherboard09:30 ... Keyboard15:17 ... Channel thanks & OutroSome confirmation thanks to @RandomBlankUsername - this is likely a Pentagon 128 2+ ...https://users.atw.hu/zxspectrum/index.htmlspeccy4ever.speccy.org/doc/Pentagon.pdf--------------------------------Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!patreon.com/TheCluelessEngineer--------------------------------Music by Karl Casey @ White Bat Audio karlcasey.bandcamp.comyoutube.com/@WhiteBatAudio
![🇨🇳 M5Stack Cardputer [#TCE0509]](https://i.ytimg.com/vi/98RpTlwTXIo/hqdefault.jpg)