Teardown and reverse engineering of the HP 27201A speech output module, which uses the TMS5220 speech processor IC and was designed to be used with the HP 1000 and HP 3000 series minicomputers.
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The VTEK Small Talk Plus Epson HX-20, World First Laptop — Talking!
In this video, I tear down and repair a unique variant of the Epson HX-20 Laptop, the VTEK Small Talk Plus What might it be, and where did it come from? I’ve been looking for an HX-20 for a while to add to my Vintage collection, and one day I came across a listing for …
Read MoreThis is Digitalker! … and Jameco JE520 too. Vintage Speech Synthesis.
In this post, I create a board for the Digitalker speech synthesizer chipset Background The digitalker chipset by national semiconductor was popular during the 80s as a way to add speech capability to products and projects. The chipset was sold by Jameco and other electronics parts resellers. Here’s an excerpt from a typical Jameco catalog: …
Read MoreCloning the ET-3404 6809 adapter for the Heathkit ET-3400
In this video, I make a clone of the ET-3404 6809 adapter: Purpose I’ve become somewhat of a Heathkit ET-3400 enthusiast lately, after building my ETA-3400 memory/io clone. I decided to also clone the ET-3404, which is a 6809 adapter board for the ET-3400. Why? Simply for completeness sake. The official “experiments” for the ET-3404 …
Read MoreDesigning a Memory/IO (ETA-3400) addon for the ET-3400 Trainer
In this video, I build a memory/IO expansion for the vintage Heathkit ET-3400 trainer: Purpose I’ve always wanted one of these Heathkit microprocessor trainers, and finally one caught my eye on eBay and I pulled the trigger. The basic interaction with the trainer is through the onboard keypad and LED displays, but Heathkit also made …
Read MoreOverclocking the pi4 with the Blink Blink ICE Tower CPU Cooling Fan
In this video, I evaluate a tower heatsink and combo provided to be my Seeed Studio: Background I’ve already done a blog post on Raspberry Pi4 cooling where I tried a Raspberry Pi 4, both with and without a fan. I investigated whether you really needed a fan (my conclusion generally being “it depends”) and …
Read MoreSupercapacitor Uninterruptable Power Supply (UPS) for Raspberry Pi
In this post, I build a couple supercapacitor UPS boards for my raspberry pi projects. Motivation For my Convergent restoration, I decided to build an RASCSI to replace some failing SCSI hard drives. The RASCSI is a SCSI emulator built using a raspberry pi. Problem with these types of emulators is that if you carelessly …
Read MoreThe Hayes Chronograph, a Remake for 2020
I couldn’t find myself a Hayes Chronograph, so in this video I just went off and built one… Purpose I always wanted a Hayes Chronograph, but I seem to miss the opportunity to acquire one, every time the opportunity presents itself. So I decided that in 2020 I would just have one … or else. …
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