Usagi ElectricWe’re back into the 5221A Frequency Counter! We finish recapping the rest of the black beauty capacitors with some nice new axial ones, and then we start troubleshooting, trying to get it to behave properly. We get it pretty close in this one!
Ben, if you see this, thank you so much for the years and years of excellent music! You’re one of my personal music heroes and to have some of your music in one of my tiny little videos is absolutely mega. Thank you so much!
Chapters 0:00 Intro 1:08 What capacitors still need replacing? 2:55 Recap time 3:43 Let’s give it a test 5:05 We made it worse? 8:00 C204 the coupling capacitor 11:24 Our problems lie here 12:43 More repair 13:25 Testing again 16:18 Outro 16:39 Deers?!
Restoring an HP 521A Frequency Counter: Part 2Usagi Electric2022-03-28 | We’re back into the 5221A Frequency Counter! We finish recapping the rest of the black beauty capacitors with some nice new axial ones, and then we start troubleshooting, trying to get it to behave properly. We get it pretty close in this one!
Ben, if you see this, thank you so much for the years and years of excellent music! You’re one of my personal music heroes and to have some of your music in one of my tiny little videos is absolutely mega. Thank you so much!
Chapters 0:00 Intro 1:08 What capacitors still need replacing? 2:55 Recap time 3:43 Let’s give it a test 5:05 We made it worse? 8:00 C204 the coupling capacitor 11:24 Our problems lie here 12:43 More repair 13:25 Testing again 16:18 Outro 16:39 Deers?!Emulating the Vacuum Tube Computer on the Centurion MinicomputerUsagi Electric2023-02-05 | Ren14500 has been an absolute legend in working on the Centurion, but Ren actually first reached out to me because he had written an emulator for the vacuum tube computer. It was an epic emulator, but he wrote it such that it could be run on an 80x24 display – which for the keen out there, is the same resolution as the Centurion ADDS terminals. Now that we’re into the OS and experimenting with programming, Ren actually ported his emulator over to Centurion Programming Language and we now have it on the Centurion!
Chapters 0:00 Introduction 2:58 CED and copying code 7:06 Compiling the emulator 10:48 First test drive 13:41 Putting the two side by side 15:20 Tubes vs CPL 19:35 Interesting discovery 22:33 Bunny!How Many PDP-11s? All the PDP-11s!Usagi Electric2023-01-30 | Ooooh boy, this one is exciting! Not because we dive into the PDP-11 we picked up in the previous episode (well, that’s pretty exciting too), but because a kind viewer reached out and hooked me up with a ton of QBUS PDP-11 stuff. The collection is absolutely staggering, and in this episode, we take an in-depth look at each card I received. Next, we need to think about what kind of system we want to build, because with all the new cards, we have some options. So check out the list of cards and let me know how you would build up your ultimate PDP-11!
Chapters 0:00 Introduction 2:11 Removing and cleaning the cards and chassis 4:13 But wait, there’s more! 7:48 H9275/H9278 Backplanes 9:01 M9407 Grant Continuity and M9405/05 Extender 10:13 M3107 8-Line Async MUX 11:17 M7555 RQDX3 HDD/FDD Controller 12:31 M7513 RQDXE Extender 13:32 SRQD11-B HDD Controller 15:15 M7546 TK50 Tape Controller 16:10 Mystery Floppy Controllers 17:50 Bomem DEB1800L 18:51 Matrox QRGD-G and Bomem DEB4100L 21:21 M8637, DMA5400 and Q-RAM 44B Memory 22:52 M8190 and M8192 QBUS CPU 24:25 A mystery memory card 25:40 What am I going to do with 6 CPUs? 26:07 A portable PDP-11 27:10 A mega PDP-11 29:37 Bunny!The Mini-Centurion Works!Usagi Electric2023-01-22 | In this episode, we finish off our mini-minicomputer build and get the Mini-Centurion fully working! The main drive behind this build is to have something to bring to the local retrocomputing meetup in just about one week now, and I think it delivers in spades. It wasn’t an easy journey though. We hade a ton of work left to do just to get it wired up and powered on, and we still need to figure out something for the OS. So tag along as we push through to finish the build in time!
Chapters 0:00 Introduction 2:09 Building the Power Supply Board 5:12 PSU Timing Problems 6:56 Finishing the Power Supply Board 7:53 Smoke Test Time! 10:28 Cooling and Cabling 12:37 Attempting to Repair the Memory Card 15:33 First Boot! 17:20 First Boot (Part 2) 18:57 Setting up the OS 26:43 Final Assembly 28:28 It Works! 31:46 Kitties!Building a “Miniature” Centurion Minicomputer (Part 1)Usagi Electric2023-01-15 | I’m in a bit of a pickle. The local retrocomputing group is having a meetup in just about two weeks and they asked me if I wouldn’t mind giving a short talk on something. I said sure, I’d love to talk about the Centurion! Only after did I realize, the Centurion is far too heavy and fragile to actually take with me. Without any visual material, I’m in a bind. What to do? Build a smaller Centurion of course!
Chapters 0:00 Introduction 1:02 I have a problem (understatement of the year) 3:34 Build montage baby! 11:57 That turned out really well 12:39 What went wrong? 13:41 Looks familiar 14:44 What’s left to do? 16:24 Bunny!Vacuum Tube Computer P.30 – Connecting 2-bytes of Tube RAM to the ProcessorUsagi Electric2023-01-09 | Welcome back to the tube computer! In this episode we try to get some usable memory hooked up to the processor. Of course it doesn’t go smoothly, we have all sorts of problems crop up, but nothing too serious (no magic smoke at least). In the end we got there and it’s really coming along!
Chapters 0:00 Introduction 0:50 For the uninitiated 3:35 What are we missing for addressing control? 4:50 Let’s make some PCBs! 6:16 First power on test 7:50 First data storage test 11:23 Second data storage test 14:47 What’s next? 16:00 Kitties!Coding on a 1980s Business Minicomputer!Usagi Electric2023-01-01 | NOTE: My understanding of Modulo was incorrect here. The actual remainder stored in "OPA" will be different than what I show in the video. In the examples, 28/3, the remainder will actually be 1 (9:3=27;28-27=1). For 37/5, the remainder will be 2 (5*7=35, 37-35=2).
Happy holidays y’all! There are many different facets to the Centurion project that we’ve been working hard on, and one of those is cracking the code for… code. And, I think we’ve got it! Tag along as I walk through writing a program in CPL, Centurion Programming Language, and have all sorts of trouble with the built-in editor, compile errors, coding mistakes, etc. You know, the usual fair when programming anything!
Chapters 0:00 Introduction 1:00 What is a Centurion? 5:08 Now a look at the software side 7:27 What kind of code are we going to write today? 8:33 Let’s spin the big boy up 10:24 Time to start coding 12:14 Necessary house keeping at beginning of code 13:47 Setting formats and declaring variables 15:38 Writing the entry into the program 16:28 Printing text on the CRT 17:28 Our main program loop 22:59 Printing the answer 24:06 Closing down the program and handing back control 25:18 Compile attempt #1 29:00 Compile attempt #2 30:10 Compile attempt #3 32:00 Compile attempt #4 (nailed it) 33:10 Why was it so slow? 33:56 What if you want to program something? 35:50 Bunny!I Bought a PDP-11/83!Usagi Electric2022-12-25 | Merry Christmas y'all!
The Centurion has a new Minicomputer friend in the house – a PDP-11/83! This was a sweet deal I was put on to by a Patreon member, Jon, and it took a little doing to get it home, but it’s here and it’s awesome. Well, it would be awesome if it wasn’t so filthy, so let’s get to cleaning!
Absolutely check out my brother's shop, Lovett Sundries! lovettsundries.com
Chapters 0:00 Introduction 0:39 How did I get this thing? 4:34 What have we got here? 5:29 The front and storage 6:53 The back, power and RS-232 9:05 Disassembly 12:23 Cleaning 13:59 Chassis reassembly 15:00 Power distribution 17:16 Cracking the box open 18:42 What's up Lukas! 20:51 Testing the power distribution box 24:14 What’s next? 25:35 Merry Bunmas!Welcome to the New Office!Usagi Electric2022-12-18 | This is a little something I’ve been working on behind the scenes for a few months now, and it’s finally here! The room I usually film in is actually the guest bedroom, and it was time to return it to that duty, but that meant that the Centurion (and all my other projects) didn’t have a good place to live. Well, after a little work on the office that was already in the garage, we’ve now got that space. So, step into my office, let me give you the tour!
Chapters 0:00 Welcome to an empty room 2:20 Let’s get building 5:01 Step into my office 6:03 The Centurion 8:19 The TI-99 10:00 The NEC PC-8001 12:22 The HP VTVMs 13:51 The tube computer 15:10 The pinball machines 16:15 The ADM-3A 16:37 The counterfeit Centurion 17:42 Moo!Minicomputer Part 24: Disaster with the Finch!Usagi Electric2022-12-11 | Usually, when I make these episodes, I plan everything out so there’s a narrative in my head that I can follow along with when filming. Usually, this requires double or sometimes triple checking that things are working (or not working) as expected before even turning the camera on. Then, sometimes, the old computer throws a curve ball that catches you totally off-guard. This was one of those times. The old Finch drive gave me a solid run for my sanity!
Chapters 0:00 Introduction 0:59 Hawk drive recap 1:35 Floppy drive recap 2:28 The Phoenix and Finch 4:12 Let’s test out the Finch (Disaster!) 5:22 Alright, what happened? 8:30 Let’s check the motor first 10:44 Let’s take another listen… 12:18 Okay, I think we gotta open it up 15:45 It’s better? 18:46 Will it crash? 19:25 Did we just dodge a bullet? 22:25 Kitty! (Our boy named Sue)The World’s Largest 555 Timer… Again!Usagi Electric2022-12-05 | PCBWay is having a great Winter sale now, check it out here: pcbway.com
We’re going back to an old one - the venerable vacuum tube 555 timer. This was a really fun project we took on a while back to try to make a 555 timer out of just vacuum tubes, and while the prototype made at home on the mill was excellent in every sense of the word, we were struggling coming up with a more professional looking version. Well, fear not, our sponsor PCBWay is here! PCBWay hooked me up with some pretty righteous PCBs, so let’s take a look at what they sent and see if we can get the new and improved 555 going.
If you need tubes, I strongly suggest either 6AU6 or the 6CB6, both work brilliantly. Just search eBay or your local auction site for “6AU6 lot” or “6CB6 lot.”
The 7-pin sockets can be found on most online retailers like Amazon or AliExpress. Just search for “7 pin tube socket” and look for the ones that are PCB mount.
Chapters 0:00 A look back at the OG 555 1:28 The new hotness 2:30 A close look at the new PCBs 5:14 Let’s build it 7:50 A close look at the datasheet 9:10 Tuning the OpAmps 13:01 Testing: Schmitt Trigger 14:24 Testing: Astable oscillator 16:46 How do you get one? 18:53 What’s next? (The CSS555!) 21:49 Bunny!How to Write a Movie Script in 1981 on a Wangwriter!Usagi Electric2022-11-28 | We found it y’all, we found the system disk, and it’s glorious! Seriously though, Wang’s word processing software for this Wangwriter is brilliant. But, what are we going to write with it? What better than a Christopher Walken speech! So come on along as we type up a script as if though we were living in 1981.
Chapters 0:00 Story time 3:49 Let’s see that OS! 5:12 Getting the Archive Disk ready 8:04 Let’s start writing our script 17:08 Time to fix that printer 19:30 Let’s print out our script 22:23 I adore this machine! 24:00 The Lion Speech 25:39 Bunny!Wangwriter Pt.3 – It Runs Zork!Usagi Electric2022-11-20 | This is bananas, I thought it would be months before we had something usable happening with the Wangwriter, but 256byteram is an absolute legend and got some really special stuff cooked up for us in this episode! But, there’s a few things we gotta fix first, so let’s hop into and get this machine doing computery stuff!
Chapters 0:00 Introduction 2:22 Figuring out output and input 5:00 Checking the keyboard scancodes 6:29 Repairing the foam and foil keyboard 8:50 A closer look at the keyboard PCB 10:07 Checking the keyboard scancodes… again 11:28 Getting 256byteram’s program onto a floppy 14:41 CP what?! 16:03 Zork works! Job done, right? Right? 17:12 47k aint enough… 20:20 What’s the endgame here? 21:18 Bunny!Minicomputer Part 23: The CDC Floppy Drive Finally Works!Usagi Electric2022-11-07 | Boom shaka laka! It works baby! It was a ridiculous journey, and it wasn’t a clean win, but a win’s a win. But first, let’s answer a couple questions, notably, why am I spending so much time on this floppy in the first place. And then, let’s dive into the microcode and see what it took to get that updated, and finally, let’s play around with the working floppy and see what kind of neat stuff we can do with it.
Chapters 0:00 Introduction 1:00 Centurion Roadmap 4:14 Understanding the FFC microcode 6:20 What did we need to update? 9:15 Where is that one byte located at? 10:14 That fixed it, right? Right? 11:50 Let’s exercise that floppy! 14:26 Let’s properly format this disk for the Centurion! 16:26 A slight detour to understand Centurion “tracks” 17:58 Can we get the OS onto a floppy? 20:24 Let’s boot from the floppy! 21:47 Hooray! A largely useless OS! 24:03 Where is this really going to shine? 26:04 Bird?!What is this Mystery Wang PCB?Usagi Electric2022-10-31 | Sometimes life comes at you fast and you paddle as hard as you can just to try to keep your head above water. That’s what this week has been like for me! So, today, we’re going to do something a little more chill. I recently bought this mystery Wang PCB off eBay and I genuinely have no clue what it is or what it’s a part of. So, let’s take a quick look at the construction and the ICs in use, and maybe throw guesses out there as to what it might be!
Chapters 0:00 Introduction 2:34 Let’s waddle over to the bench 3:21 You dolt, it’s written right there! 4:07 Let’s look at the ICs anyways 7:26 It feels like so much more 8:59 If you know let me know! 10:18 Bunny!Minicomputer Part 22: Working on the FFC and CDC Floppy DriveUsagi Electric2022-10-24 | PCBWay hooked me up with some awesome PCBs, check them out here! pcbway.com
Man oh man, this floppy drive. This floppy drive is kicking my butt six ways to Sunday! But, we aint no quitters and I’m gonna keep wading into battle with this thing until it submits. No matter how tough it gets, I just gotta channel my inner John Connor – we can’t let the machines win. In this episode we take another crack at diagnosing the FFC and the Floppy drive, and while we don’t emerge victorious just yet, we have made some pretty good progress!
Chapters 0:00 Introduction 2:07 Where were we? 3:46 Some new tools! 7:53 Hooking the riser card up 10:02 Testing out the riser card 11:29 More new tools!! 12:45 Hooking up and using the Logic Analyzer 14:18 What is Microcode? 17:48 More probing o the FFC 18:45 Maybe the floppy is still giving us guff? 19:58 After three days of battle… 21:21 A new problem 25:05 Kitties!Wangwriter Pt.2 – It’s Alive!Usagi Electric2022-10-17 | This Wang never ceases to be utterly awesome! We’re still shy a system disk, but that isn’t stopping us from doing some really tricky stuff with the system. In this episode, we fix the problems we discovered in the last episode (it really just needed a quick clean is all), and then we start on the journey of convincing this machine to do what we want it to do. Any day that the electrons do what you’re expecting is a good day, and this was a good day!
Chapters 0:00 Introduction 1:57 Where did we leave off? 03:49 A sign of life! 05:15 Time to read the manual 08:23 Booting with an Archive Disk 10:45 Now what? 13:34 I want to see that print code 14:46 Setting up and using the GreaseWeazle 19:41 What did we find? 22:10 Hellorld! 25:14 Usagi!Vacuum Tube Computer P.29 – Addressing and Fanout ProblemsUsagi Electric2022-10-10 | It has been a hot minute since the last episode in this little series, and when I say “hot” I mean it quite literally! Texas went through a brutal heat wave this summer, so I gave the old CNC mill a much needed break until it cooled back down. But, now it’s much nicer outside, so let’s get to cutting. Today, we take a look at solving our memory addressing issues and tackle the always present problem of fanout. What’s fanout you ask? Well, give it a watch to see!
Chapters 0:00 Introduction 3:09 A refresher on our memory 4:13 How are we addressing one bit? 6:18 How are we addressing all bits? 7:34 Fanout rears its ugly head 10:06 A practical example 12:00 A wild cathode follower has appeared! 14:54 What can the 6CG7 do? 16:56 Time to build it! 18:23 Let’s give it a test 21:07 Super easy, barely an inconvenience 22:38 Lazy kitty!Minicomputer Part 21: Prepping the OS for the Floppy and FinchUsagi Electric2022-10-03 | This is a weird one, because we’re still working towards repairing the FFC and getting the Floppies as well as the Finch to work on the system, but in order to do that, we gotta spin up the Hawk drive and do some pretty hairy stuff. First of all, there’s some great diagnostics on the Hawk, but it’s terrifying using them with our only physical copy of the OS. So, let’s get that copy of the OS onto another platter, but nothing ever goes smoothly, does it?
Chapters 0:00 Introduction 2:32 Where were we? 4:30 Let’s spin up that Hawk! 6:05 New diagnostics on Hawk 9:02 How can we protect the Hawk? 12:44 That should not have happened… 13:40 What went wrong? 16:00 Let’s copy that not so floppy! 19:00 That’s an interesting new error… 22:16 Editing the system configuration file 27:25 Outroduction 28:11 Fluffy boy!Say Hello to my New Wangwriter 5503!Usagi Electric2022-09-26 | Sometimes, lady luck shifts the winds in your favor and a chance encounter can end up with some of the coolest stuff coming home with you, and this Wangwriter is exactly that! Colin is an absolute legend and we met through vacuum tubes actually, but it turns out his mother bought this Wangwriter back in 1981 new and has been keeping it in storage ever since the late 80s when it got supplanted by a more modern PC. It’s in staggering good shape for being 41 years old, so join us as we take a deep dive into the Wangwriter!
Chapters 0:00 Introduction 2:15 So what did Colin have hiding out? 3:10 The worst Wang pun 4:52 A box of goodies 9:55 The monitor and keyboard 12:28 The printer and computer 17:45 The computer boards 22:15 The power supply 24:07 Let’s throw some electrons at it 28:03 Bunny!Minicomputer Part 20: Connecting the CDC 8” Floppy Drives to the CenturionUsagi Electric2022-09-19 | In the previous episode we got the floppy drives almost working, but there was one wild problem we were still butting our heads against – a jittery nightmare of a head seek. I asked the community and y’all came out swinging with some amazing suggestions! In this episode, we get the drives fully working and plug them in to the Centurion to see if we can get any life at all out of the FFC card!
Chapters 0:00 Introduction 1:01 Was it the power supply? 2:12 A few people nailed it 3:32 It works properly now 5:45 Where did I get it wrong? 7:47 Tidy up 9:42 Plugged in to the Centurion 13:52 Working on Drive B 16:18 What was wrong with Drive B? 20:46 Plugging Drive B into the Centurion 23:23 Kitty!Playing with Neons (NE2 and MTX90)Usagi Electric2022-09-12 | This is an episode I’ve been wanting to do for a while, because I absolutely love neons! Sure they’re gorgeous to look at and a modern LED can only dream of putting out such a good looking glow, but they’re also have some incredibly unique characteristics that we can exploit to build some really, really cool stuff. So tag along as we learn how neons work and what makes them special, as well as builing some circuits to test them out.
Chapters 0:00 Introduction 1:13 Size comparison 3:10 What is a neon lamp? 5:03 How do they work? 6:52 But what makes them really special? 8:33 Some applications for neons 9:27 A few examples to play with 12:54 Scoping the astable multivibrator 14:52 Enter the MTX90 15:58 What’s going on here? 18:50 It’s a thyratron! 19:45 Can the MTX90 multivibrate? 20:38 Scoping the oscillator 22:46 Bunny!Minicomputer Part 19: Troubleshooting the CDC 8” Floppy Drives (it did NOT go well)Usagi Electric2022-09-05 | In the previous episode we got the floppy drives nice and clean, but we didn’t check them electrically beyond just checking that the AC motors worked. In this episode, we want to make sure the floppies are working in tip top shape before we get too deep into FFC troubleshooting. Unfortunately, things didn’t go as planned and it’s been a whirlwind of work trying to get these old floppies up. Ultimately, we’re left with a mysterious fault that I still don’t know the answer to!
Chapters 0:00 Introduction 1:41 Plugging it into the FFC 5:05 Testing with the FFC 6:28 Figuring out the pinout 10:00 Testing without the FFC 13:23 And it starts to go down hill 14:54 Testing the stepper and Drive B 18:14 And it all went wrong 19:09 Power reduction option 23:03 St-st-st-stutter 24:49 So what’s wrong? 28:22 Possible fixes? 30:11 Almost there 31:40 Wild bunny!Minicomputer Part 18: Restoring CDC 8” Floppy DrivesUsagi Electric2022-08-28 | It’s time for the next step in the Centurion project! But, with so much already accomplished, where do we go from here? Well, we still have the Finch drive to explore! However, the controller card for the Finch seems to have a fault, and its dangerous business to use the Finch to troubleshoot the FFC card. So, today, we’re restoring a pair of CDC made 8” floppy drives to use for FFC troubleshooting (and potential future builds). I’m pretty sure these were underwater at some point, so it’s going to take some heavy duty cleaning to get them back to looking good.
Chapters 0:00 Introduction 1:22 What’s up with the Finch? 5:12 The floppies 7:55 Removing the drives 8:19 A closer look at the drives 10:00 Let’s clean these things up 12:54 The differences between them 15:41 New power supplies 19:43 Let’s flip the switch 21:38 A floppy drive needs floppies 22:38 That’s all folks 23:44 Bunny!Restoring an HP 521A Frequency Counter: Part 3 – Victory!Usagi Electric2022-08-22 | After a 5-month long hiatus, we’re finally back into the 5221A Frequency Counter! I have a pretty good excuse for the hiatus though, which the thumbnail should spoil pretty well. They’re adorable aren’t they! Sue is the light brown one, Ten is the Calico, and Jun is the Tabby. Jun is actually from a different litter, but all three were barn rescues, so they’re all family as far as we’re concerned. Alright, enough about the kitties, the 521A is so close to working perfectly, so let’s get to work and get it across the finish line in this one!
Chapters 0:00 Intro with kitties! 2:40 Where are we at? 5:30 Let’s get it fixed 8:27 Making sure all the neons illuminate 10:42 But, we’re out of adjustment 11:35 PSU adjustment 12:46 Phantastron frequency divider adjustment 14:20 Amplitude discriminator confirmation 16:16 Crystal time base adjustment 22:45 The trifecta of HP 25:43 Kitties!A Look at Mercury and Xenon RectifiersUsagi Electric2022-08-15 | Today we’re doing something a little different – we’re taking a look at some unique tubes I have in the collection. Notably, we’ll be looking at a Mercury Vapor Rectifier as well as a Xenon Gas Rectifier. These both operate in nearly the same way, but they both have very different visual results. In this short episode we take a look at just how a gas rectifier works, then power them to see the glow and even take a look on the scope at them doing some rectification!
Chapters 0:00 Introduction 2:13 What is a rectifier? 4:10 What is a mercury vapor rectifier? 5:53 Let’s put some power into these things 10:26 Can we see the rectification? 13:00 Outro 13:45 Bunny!The TI-99 x Centurion Minicomputer Crossover EpisodeUsagi Electric2022-08-07 | This is one of those projects that really has no practical use, but it just sounded like a fun time! We pull the TI-99 out again and firstly swap in a black keyboard from a TI-99 that was donated by Rinoa from Rinoa’s Auspicious Travails (link below). Then, we pull out the RS-232 sidecar and try to get it set up to work as a remote data terminal for the Centurion minicomputer. I never would have imagined that there was an intersection between these two machines, but we made it work and it’s real cool to see Centurion data on the TI-99!
Chapters 0:00 Introduction 2:10 Checking the TI-99s 3:39 Disassembly and troubleshooting 6:34 Cleaning and testing the new keyboard 9:24 Comparing the TI-99 against the Centurion 16:30 How are we going to test the RS232 sidecar? 18:20 Setting up the TI-99 19:42 Setting up the Centurion 22:01 Will it work? 23:50 What it took to make it work 26:10 Outro 26:52 Bunny!Centurion Minicomputer: Trash to TreasureUsagi Electric2022-07-30 | The Centurion story has been a long one full of wonderful twists and turns, but if you find yourself with just about 5 minutes and curious how it started and how we got here, this one is for you!
As a side note, I've been a little under the weather lately, so this week's video is a little shorter than normal. Hoping to back into it full fledged by next week!
Chapters 0:00 Teardown 1:51 Rebuild 4:40 The Reveal 5:36 Bunny!Minicomputer Part 17: Welcome to the OS!Usagi Electric2022-07-18 | We did it y’all, we got into the OS! It put up a fight every step of the way, but we emerged victorious and have now found ourselves in the middle of an OS we have no clue how to use. It’s absolutely glorious!
Chapters 0:00 Introduction 1:09 Solving ATTN PRINT 4:08 The Fix 6:47 Parity Circuitry Inoperative 8:42 Show me that OS! 11:15 DIR 12:33 KOMPOZ 14:26 S_CRT 15:40 JCL 17:00 TESTS 18:05 TOS6 21:08 Getting back to the OS 22:24 What next? 22:57 Bunny!Minicomputer Part 16: Aligning the Heads on the CDC Hawk DriveUsagi Electric2022-07-11 | We are so close – we have an OS on a removable platter and it absolutely should be bootable, but it doesn’t. The heads of the Hawk drive have actually been knocked out of alignment due to some rubber bump stops deteriorating over the last 40 years. Hop on along as we go through repairing and aligning our Hawk drive to get it back to perfect working condition!
Chapters 0:00 Introduction 3:20 Repairing the Hawk Drive 6:20 Still not working, huh? 7:28 Using TOS to discover the heads are misaligned 13:34 DIY head alignment 16:52 Let’s try to boot it! 19:01 Alright, it didn’t boot, but we’re close 20:52 Bunny!Minicomputer Part 15: We Found the Holy Grail!Usagi Electric2022-07-04 | Oh man, what a journey to get here. There were ups and downs and at several points, all hope seemed lost. But we’ve done it, we found some long lost software on a removable platter and we got it fully backed up and saved in multiple locations around the world! Now, it doesn’t quite boot just yet, but regardless, we have it backed up and saved and that was the big one!
Chapters 0:00 Introduction 2:49 What is CCDP? 6:07 How will CCDP back data up? 8:27 Let’s copy that floppy! 12:34 What did we find? 15:46 The holy grail! 17:26 Let’s boot it! Or not? 20:01 Kitties!Vacuum Tube Computer P.28 – Exploring an Emulator of the UE14500!Usagi Electric2022-06-27 | This one is so exciting! A fellow enthusiast, Ren, has built an emulator for the UE14500, and it’s every bit as epic as it sounds. Ren did an absolutely phenomenal job coding the emulator and the assembler up, and the result is fantastic. So, hop along with us as we pit the emulator vs. the real hardware!
For more detailed information on the Tube Computer and for the emulator itself, check out the wiki: github.com/Nakazoto/UEVTC/wiki
Chapters 0:00 Intro 1:52 The Emulator 7:07 Pitting the Emulator against the real hardware 13:47 The Assembler 17:20 The Wiki 18:37 Bunny!Vacuum Tube Computer P.27 – Trying to Build a Mount for the ComputerUsagi Electric2022-06-20 | This is one I’ve been agonizing over for a while now – we need to build some kind of mount or rack that can hold our tube computer boards. But, with boards so ridiculously large, what’s the best design? Well, we build version 1 and I don’t think it’s going to be the best design, it does lead us into thinking about other potential designs. Do you have an idea on a good design? Let me know below!
Chapters 0:00 What’s in a name? 2:22 What’re we building today? 3:26 Less talky, more buildy 5:56 Okay, that’s a little… big 8:46 Potential future designs 14:30 What do you think? 16:23 Kittens!Reverse Engineering Bendix G-20 Mainframe CardsUsagi Electric2022-06-13 | This one is really interesting! A very gracious viewer let me borrow some vintage Bendix G-20 Mainframe cards to hopefully reverse engineer. And while we may have managed to get schematics out of most of them, there’s still a whole lot of mystery floating around these gorgeous pieces of computing history. If you have any additional insight, check out the wiki below to add what you know!
Chapters 0:00 Introduction 2:34 A little background 4:42 AND gate + OR gate 7:21 Emitter follower 8:42 Quad inverting amplifier 10:30 Flip flop 11:56 Full adder 16:10 Help, I need somebody, help, not just anybody 16:57 Gated CPA and DLO amplifier 17:42 Outro 18:15 Bunny!Minicomputer Part 14: Spinning up the 1970’s 10MB Hard Drive!Usagi Electric2022-06-05 | We’re back out in the garage, oop, that’s not right… We’re inside with the Centurion enjoying the nice air conditioning and working on the drives! First, an update on the Finch drive, because we may have left it on a bit of a cliffhanger in the last episode. Then, we fire up the big one – the Hawk drive! This thing sounds like a jet engine and shakes the whole table every time it seeks the heads, but it’s worth it because it’s just the coolest thing around!
Chapters 0:00 Introduction 3:02 What did we get wrong on the Finch? 5:26 What is still wrong on the Finch? 8:00 The next steps with the Finch 9:36 A wild Hawk appeared! 12:28 Jean-Luc Picard’s wisdom 13:12 We’re no quitters though 16:36 Let’s fire this puppy up! 23:15 What’s up with the WIPL? 26:46 One final test of the WIPL 28:10 Where do we go from here? 30:48 Bunny!Minicomputer Part 13: Working on the Finch DriveUsagi Electric2022-05-30 | We’re back out in the garage, working on the Centurion again, and this time, we’re going to try to get the Finch drive spun up! Although, the key word here is “try.” We aren’t exactly successful, but, well, you’ll have to watch to find out exactly what’s going on with it. Also, don’t forget to check out the Wiki linked below for a ton of excellent information on the Centurion!
Chapters 0:00 A Short Film 1:43 Addressing the previous video 5:31 The FFC Board 8:56 Baseline Testing 10:47 Testing the FFC Board 14:12 Sorting out the Finch 17:29 Genuine First Test 20:04 Welp, that didn’t work 23:54 Kitten!Vacuum Tube Computer P.26 – Memory Map and 4-Bits of RAMUsagi Electric2022-05-22 | Time to build our first proper PCB that will go on the final memory board, and it’s a doozy! Easily the longest board I’ve ever cut and certainly one of the most involved to solder up and test, this board of *just* 4-bits of RAM was a journey to build. And this is just the beginning, I have 11 more of these to build. But, the real question is, why is it built the way it is? Well, let’s take a deep dive into the memory map, look at how the memory will be laid out, and then finally, let’s give this 4-bits of memory a test!
Chapters 0:00 Intro 0:10 Unexpected ASMR 2:34 The real intro 4:15 The control word 5:23 Using a 6-bit address (with 2 bank bits) 7:00 The memory map 9:13 Actualizing it 13:22 Soldering it up 14:28 Testing all four bits 16:54 Outro 17:54 Bunny!Working on the TI-99Usagi Electric2022-05-09 | WARNING: There is a 15kHz whine from the CRT monitor in a few shots. Unfortunately, I have tinnitus and couldn’t hear it at all during filming, editing or even the final confirmation check. My normal lapel mic usually doesn’t pick it up, but in a few shots, I used a different mic, and it apparently picked it up very strongly. I apologize for this, I should have visually checked the audio waveform form before uploading. On the plus side, if you can hear, congratulations, you still have excellent hearing!
I found myself in an interesting situation where I needed to make a spreadsheet, so I pulled out the latest and greatest piece of spreadsheet software I had, Microsoft Multiplan, and got to work. Or, at least I tried to, but my TI-99 wasn’t having it, so before we can get to the spreadsheet, we gotta fix the old TI!
Disclaimer: I'm not very well versed in either the TI-99 or TI990, so everything mentioned here may be mildly or grossly incorrect!
Chapters 0:00 Not… That…? 2:30 Intro 3:55 Disassembly 5:15 A Little History 10:07 Troubleshooting 15:03 Reassembly and Testing 16:22 Victory! 18:26 Kittens!Minicomputer Part 12: I Bought a What?!Usagi Electric2022-05-02 | The number one question I get is some variation of asking if we can save the data on the crashed hard disk platter. Unfortunately, I don’t think that’s possible, at least not affordably. However, I can do one better, because I bought a compl… oops, almost spoiled it there! Come along as we dig even further down the rabbit hole!
Chapters 0:00 A Chance Encounter 4:47 Corporate Espionage 10:40 The Cards 11:51 CPU6 (and the Wiki) 13:19 MEM 14:14 MUX 14:55 DSK1+DSK2 16:15 FFC 17:27 Finch Floppy Controller 19:31 Where do we go from here? 24:46 Bunny!Vacuum Tube Computer P.25 – New VFDs for the ProcessorUsagi Electric2022-04-25 | On every big project, there's a point where you have to redo some work previously done, and that’s exactly what we’re doing in this episode. The IV-15 VFDs I used as indicators for the Processor just aren’t working right, so let’s take a look at what I did wrong, how we’re going to fix it, and then get to work cutting new boards and soldering them up!
Chapters 0:00 Intro 2:20 Firing the processor up again 4:23 The problem 5:22 IV-15 vs. 6977 7:03 What I got wrong (and how to fix it) 8:59 Testing on the breadboard 11:26 Making new boards 13:43 Giving the new VFDs a workout 15:10 Storing to our 1-bit memory module 17:09 Outro 18:20 Bunny!Minicomputer Part 11: Running Real Centurion Code off the DIAG Card!Usagi Electric2022-04-18 | This is a big one! We’ve got the machine booting, we’ve got the DIAG card sorted, it’s time to plug them together and see what happens. Given that the video is 24 minutes long, I think it’s safe for you to assume a lot happens, haha. We explore pretty much every facet of the DIAG card and learn some really, really cool things!
Dramatic Reenactment Music: Artist: Ben Prunty Title: The Train Robbery www.benpruntymusic.com
Thanks for watching!
Chapters 0:00 Intro 2:14 Plugging the DIAG board in 4:48 I’m in! – A short film 5:20 The tests 6:23 How to read the displays 7:12 Test 01 – 03 (DMA, MEM, Interrupt Tests) 8:24 Test 04 – 06 (MUX Tests) 9:34 Test 07 – 09 (Hawk Tests) 9:58 Test 0B – 0C (Bootstrap and Self-Test) 10:40 Test 0D (Auxiliary Tests) 12:24 That’s as far as we can go, right? 13:47 Test 0A (Test Operating System TOS) 17:33 Hellorld! – A short film 18:32 Where do we go from here? 21:01 Custom TOS/Assembly only board 22:12 Custom floppy interface board 22:51 Getting online 23:35 Outro 24:12 Bunny!Minicomputer Part 10: Will it Boot?Usagi Electric2022-04-11 | We’re back with the Centurion again and we have one singular goal: get this thing to boot! We’re about 90% of the way there, but we still have a few little problems that we have to tackle. Most notably, we gotta figure out what’s up with the terminal. I’m feeling quite good about this one, so join us as we get the old girl up and running again!
All information on the Centurion can be found here (DANGER, WILL ROBINSON, there be a lot of SPOILERS on that github!): github.com/Nakazoto/CenturionComputer
Chapters 0:00 Intro and Thanks 1:10 The game plan 3:38 Getting the backplane out 6:24 Troubleshooting the terminal 10:36 Testing the terminal 12:14 Will it boot? 13:18 Nope, let’s look at the cable 18:54 Will it boot? (Round 2) 20:35 The bootstrap code 22:51 Outro 23:49 Bunny!Minicomputer Part 9: Reverse Engineering the Diagnostic BoardUsagi Electric2022-04-03 | We’re back into the Centurion today, and boy howdy, things have been crazy the past two weeks! The story is an epic one, and it all starts with the Diagnostic Board and the code squirreled away in the little EPROMs on there. Today, we take a look at what that code is as well as the hardware on the Diagnostic board itself, and start to get an idea of just how cool this little board is.
Chapters 0:00 Intro 2:05 Why are the ROMs important? 2:58 Let’s pull the data off them! 4:55 How do we know it’s good data though? 6:47 Tackling the problem from two directions 8:02 Sure wish I had a schematic… 10:53 Now, on to the software! 13:20 The MMIO 15:30 Outro 16:28 Bunny!Reverse Engineering a Knight Photo-Electric Relay SystemUsagi Electric2022-03-21 | We’re taking a short detour today to take a look at a really interesting little device I picked up on my last trip to Computer Reset. The Knight Photo-Electric Relay System is a simple little device that lets you turn a full mains powered system on or off depending on whether the beam of light being shone into the lens is interrupted or not. Inside there’s an interesting little PCB with some clever design on the relay to get some cool functionality with a bare minimum of parts!
Chapters 0:00 How do we start this video? 2:18 What is this thing? 3:18 But what does it do? 6:09 Ok, how does it do that? 7:26 Do you have the schematic? 14:33 Nice, but it’s lunch time, can you wrap it up? 15:08 What if I only clicked for the bunny?Minicomputer Part 8: Status Update and Unfortunate NewsUsagi Electric2022-03-13 | It has been a hot minute since the last Centurion video, but we’re back on it with some interesting developments! In this episode we take a look at the computer itself, the terminals and the drives and take stock of everything that still needs a lot of work before we can get there. And, when looking at the drives, we come to some troubling conclusions. But, all hope is not lost yet!
Chapters 0:00 Intro 0:55 Recap 2:50 Mr. Romaine to the rescue! 4:17 The Computer 8:54 The Terminal 11:29 The Hawk Drive 13:15 The Phoenix Drive 16:07 The unfortunate end… 17:17 … or is it? 22:22 Bird!Vacuum Tube Computer P.24 – Building SR Flip Flops with Trial and ErrorUsagi Electric2022-03-07 | Now that we’re getting closer to the design for the RAM on the vacuum tube computer, let’s take a quick look at some of the different types of memory I tried to implement. It was a long journey with a lot of trial and error, but I think there were some genuinely good ideas in here that could have been expanded out in other circumstances!
Chapters 0:00 Intro 0:58 Delay Line memory 2:17 Neon bulb fangirling 4:12 What are we doing today again? 5:08 VFD RAM 9:43 Thyratron Memory 14:49 Multivibrator Memory 18:56 6AU6 / 6977 Memory 22:52 The design to use 24:01 Bunny!Restoring an HP 521A Frequency Counter: Part 1Usagi Electric2022-02-28 | We’re back into vintage HP stuff baby! In the previous HP video I asked y’all what piece you wanted to see next, and the while the voting was tight, the 521A Frequency Counter won out in the end. Honestly, I’m quite happy it won because it was the one I was most excited about! There’s all sorts of digital and analog magic going on inside of the purely tube instrument, so let’s dig in deep and see if we can’t figure out what’s going on inside!
Ben, if you see this, thank you so much for the years and years of excellent music! You’re one of my personal music heroes and to have some of your music in one of my tiny little videos is absolutely mega. Thank you so much!
Chapters 0:00 Intro 1:57 Cleaning, painting and recapping 4:27 What I didn’t replace yet 5:43 Theory of operation 8:20 Amplitude discriminator 10:23 Crystal controlled time-base 12:16 AC-4A decade counters 17:55 First start 19:31 There’s going to be a part 2 isn’t there? 21:05 Outro 21:58 Bunny!Vacuum Tube Computer P.23 – Electrostatic, Rotating Drum and Core MemoryUsagi Electric2022-02-21 | We’re back baby! It’s time to get right into building the tube computer again! Although, before we start building anything, we’re going to take a quick little aside and have a closer look at some different types of memory that were used on vacuum tube computers back in the day and look at why they weren’t necessarily going to be the best option for us. So, come join us as we try to figure out just how exactly all the weird memories used to work!
Chapters 0:00 Intro 0:55 Refresher 2:53 Memory intro 4:14 Disclaimer (I’m making this stuff up as I go) 5:29 Williams Tube (Electrostatic) Memory 8:43 Rotating Drum Memory 11:48 Core Memory 18:23 Primary limitation 19:41 Outro 20:33 Bunnies!A Low Voltage Vacuum Tube OTL Audio AmplifierUsagi Electric2022-02-14 | In this episode, we revisit the low voltage audio amplifier that we built many, many moons ago. This time though, we’re making one critical change – we’re eliminating the output transformers! That’s right, OTL amplifiers usually use hundreds of volts, but we’re going to attempt to build one at just 48V, and the results are surprisingly good!
Chapters 0:00 Intro 2:22 OG amplifier baseline 3:23 What we’re going to change 6:08 Did this fool really say “one two B four A”? 9:20 Breadboard testing 11:30 The new hotness! 14:01 Let’s give it a listen 17:00 How does it compare to the OG? 18:12 Outro 19:20 Bunny!Break Time with the Isuzu Bellett 1800 GTUsagi Electric2022-02-07 | In this episode, we take a break! It’s a pretty big departure from our usual affair, but sometimes it’s good to set things down and do something completely different for a day!