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: …
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Cloning 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. …
Read MoreTandy 1000 Upgrades / PS2-Tandy Keyboard Adapter
In this video, I spiff up a Tandy 1000 that I bought on ebay: Purpose: A Tandy 1000 was the second computer that I owned, the first was a Tandy CoCo. Note that I keep a slightly different mental “computers that I owned” list and “computers that I used list”. There are a few computer …
Read MoreRestoring a Convergent Technologies NGEN PC/Workstation (Burroughs B25 / Unisys)
In this set of videos, I work on getting a used Convergent Technologies NGEN computer up and working: In the second video, I figure out the pinout for the 25-pin connector, and I get the keyboard working and the video displayed on an MCE2VGA. In the third video of the series, I design and build …
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