I have blogged about the HPD–12, my PDP–8 Clone Project. I have had a bunch of thoughts about other retro and homebrew computers. An incomplete list off the top of my head include:
- Jupiter ACE clone. I always wanted one back in the day.
- One of Grant Searles’ minimal 8-bit systems.
- A CP/M system.
- An “Atari 816XLD” – this would be an 65816 system with improved graphics and sound using the Amiga chipset.
- An MSX system, probably MSX 2.
- Something built around the old TI TMS9900 chip.
- An RCA1802 system such as the COSMAC Elf or the Olduino.
- An odd dual processor laptop with a Z80 CP/M system that can open terminal into an onboard 6120 system.
I did some serious work on gathering information on a CP/M machine in the late 80s and the 90s.
I have also acquired the first edition Amiga chipset for the pseudo-Atari. In many ways that is the project, I am most interested in. My first computer was an Atari 800XL. Atari originally sponsored the Amiga chipset development which was headed by the man behind the sound and graphics chipset used in the original Atari 8-bit machines. Atari even announced the 1850XLD using the Amiga chipset. Atari also sampled the 65816 which Apple used in the Apple IIgs. My homebrew idea would be my imagined version of what an Atari machine using those two objects would have been.
Yet, despite having been interested in, and reading about, doing this for thirty years it was only in 2018 I took real steps. The above mentioned HPD–12 project is the first, and I will have a post on my first steps next week. Last month I ordered some new old stock of the 1802 used in the Elf because it was designed for a beginner to take his first steps into homebrew computers all the way back in the 70s. It also uses a toggle switch front panel for programming.
I also saw a new old supply of the TMS9900 and ordered three due to a series of YouTube videos. He has since abandoned the project, but the videos are fun and useful. He is also implementing a RISC-V out of components which has been fascinating.
The real question is why bother doing this?
Nothing on that list is modern. The highest end machine would be a rough parallel to the Apple IIgs, which was state of the art when it came out in 1986 (and outsold the Mac for a while). While some work could make it compatible with the old Atari 8-bit line, probably by including the older chipset, what would that give me beyond my old 800XL? The expanded features would only work with material I wrote.
The CP/M machine, the MSX machine, the Jupiter Ace, and the COSMAC Elf would allow me to use software written by other people, with varying sizes of libraries, most of that software is well behind what the laptop I am using to write this provides. Except as terminals to Unix systems none of my day job as a programmer or night job as an author. Yes, I could do some fiction writing in an old CP/M, but I would still wind up importing it into Scrivener running on Windows.
What any of those machines would provide is a huge amount of DIY work. That is their value. I have been reading 70s issues of BYTE, Kilobaud, and Dr. Dobbs Journal of Computer Calisthenics & Orthodontia. Yes, that last is the original title of what in the 90s I read as a professional magazine. The subtitle was “Running Light without Overbyte.” Reading these old magazines has been an education on a lot of things. It isn’t just how to write tight basic programs, but all kinds of hardware. One of my favorites is an article on adding a hardware stack to an 8008 system which might find its way onto a breadboard next to 1802.
In the end, to answer my title question, hobbyist computing is the thrill of building it yourself. It is the computer parallel to making your own furniture even if an Ikea flat pack would be just as good and easier to obtain. Hobbyist computing is a working computer system as a journey, not an end.
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