- Joined
- Jan 28, 2018
I didn't do my research that deeply, looks like he got burned. Well that's more understandable then. I guess a computer like this does have it's commercial value, even if that value lies into selling it to retro hipsters. (Apparently though BASIC seems to show up in quite a bit of embedded programming too, a fact he mentioned in there, huh wouldn't have thought in this day and age) Guess you'd actually have to make that request to see what he's willing to share and under which conditions, then. Still doesn't sit entirely well with me.As for the CMM2's source, the dude that designed the Maximite series is quite critical about where open source is in the current year, which would explain why he insists that people contact him for a copy.
It looks that simple because it really kinda is. Lots of CPUs of that time basically just need an external clock and off they go looking for something to do as soon as power is applied. You can even visualize this with LEDs on the pins if you'd like to. Any connected ROM to CPUs like this you have to imagine as an .exe file in physical form the processor reads as soon as it starts/is reset. It doesn't have to be even that complicated though. You could easily set up a bunch of switches (yes physical switches you set in a specific order) and put in the opcodes of your program manually that way, one by one, if you want. I once did this with an 68k. You don't even need RAM. We used to program computers like that. It's of course not practical to use such a CPU that way but it can teach you some basics. The problems aren't often in the theory as the theory with hardware of this vintage is actually kinda straightforward, the devil is usually in the detail and actually putting that theory into the physical world. Things don't always work like you think they should or are supposed to, the analog world often manages to screw your digital plan up and that's where the problems that consume all your time usually lie.BTW it's funny you should mention bootstrapping a Z80 on a breadboard... this video came up in my feed yesterday. This guy makes it looks so simple that even I could probably manage it (eventually).
Usually where all these computer kits run into trouble is periphery and turning this simple system setup into a full blown, stand-alone computer with modern input and output. This is also coincidentally what made these old machines like the Amiga or C64 so special. Their CPUs weren't anything to write home about, even the 68k was on the cheap and lower end by 1987, it's all the custom circuity and software programming in the OS that made the magic happen and there's way too little focus in many of the projects on this, as this is actually the hard part. Input/An OS complicated enough to process the input and do something interesting with it/give Output in the form of at least VGA compatible graphics and optionally sound, that's what you want today. Then you optionally want your custom chips to be a bit clever and do some things on their own so your slow CPU doesn't get taxed so much. (Projects could take boring shortcuts here by turning the CPU into a performance monster, in a FPGA for example) Things start to grow complicated then by quite a bit. I've built a very simple Z180 (which is basically a Z80 SoC with many important parts already onboard+MMU+also a lot faster than your usual Z80) System on which I basically planned to use Forth as the OS and my biggest problem was to add an appropriate graphics controller which I also could connect to anything. I chose the TMS9918 because it was cheap to get and I could find a lot of documentation for it but I ran into a few snags and then saw somebody else solve it for the rc2014 platform which somehow put a damper on my own efforts although again, that's the wrong attitude to have. The output of that chip is very poor to begin with quality-wise. (just composite and not very clean, although using a Framemeister helped) I was also playing with the thought to use some graphics chip from one of the early VGA graphics cards I have lying around but that didn't feel right and also was more complicated than I wanted it to be. Then I got bored/distracted. An optimal solution would be something custom and CPLD/FPGA based but again, the complexity of it all. I want to make another attempt for my computerized writing machine, but maybe with more modern hardware. It's not that old hardware is impossible it's just all a bit tedious. There's also the possibility to hook it up to an actual computer and do VT100 style terminal emulation on the computer and get pixel-perfect HDMI output and there are even projects for things like the Pi Zero for that, but it feels weird to use a comparative super computer as a dumb terminal for something more primitive than the circuity in my optical mouse, makes the entire thing feel kinda pointless.
Anyways, all these projects don't pop up because they're so incredibly hard to do, they just need the effort and doing your own really is not that hard. That's also why so many of them go hopelessly overbroad and then somehow end up erroneously thinking they sit on the next computer revolution. Let's just say there's still quite a bit of way to go from an FPGA graphics chip for your pet 8/16-bit computer to a RTX 3060.
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