Uploaded June 2025 | Updated September 2026, 3 weeks ago
In this video, I restore a Prompt 80 trainer that I bought on eBay. The trainer came with no CPU board, so I had to acquire one myself. This uses a multibus board like an 80/10, 80/10A, or 80/10B. Typically shipped with 3 KB of ROM and 1 KB of RAM, two 8255s for parallel IO, and a serial port. The front panel exposes a number of functions from the built-in monitor software letting you examine memory, enter bytes, run programs, single step, and examine all the registers. It's nice that it include two sets of 7segment displays -- one for the main display and a secondary display that continually displays register contents. I built a variant of fig-forth and put it in the remaining ROM space. Then I installed a SP0256A-AL2 speech synthethis multimodule and made the thing talk. For more vintage computer projects, see smbaker.com
In this video, I restore a Prompt 80 trainer that I bought on eBay. The trainer came with no CPU board, so I had to acquire one myself. This uses a multibus board like an 80/10, 80/10A, or 80/10B. Typically shipped with 3 KB of ROM and 1 KB of RAM, two 8255s for parallel IO, and a serial port. The front panel exposes a number of functions from the built-in monitor software letting you examine memory, enter bytes, run programs, single step, and examine all the registers. It's nice that it include two sets of 7segment displays -- one for the main display and a secondary display that continually displays register contents. I built a variant of fig-forth and put it in the remaining ROM space. Then I installed a SP0256A-AL2 speech synthethis multimodule and made the thing talk. For more vintage computer projects, see smbaker.com
![Raspberry Pi 4 Thermal Investigation [Part 2] Frequency cap, Throttling, & Real-world test](https://i.ytimg.com/vi/D5YuP0IDFKU/mqdefault.jpg "Raspberry Pi 4 Thermal Investigation [Part 2] Frequency cap, Throttling, & Real-world test
In this video I continue taking a look at the thermal properties of the raspberry pi 4. I spend some time looking into frequency capping in detail. I even take a heat gun to the pi to make it cap and throttle all the way down to 300 Mhz. Then I do some real world tests to see how much heat comes from youtube streaming to an HDMI monitor, copying data to/from the USB3 port, and compiling software in the background. Then I throw the same delta fan on it that I showed in the previous video and demonstrate that performance returns back to normal.")
