simon wrote:The autorouting has been finished. Anyone interested in a PCB? I need three others at least to order a batch.
I'm interested.
Impressive work, indeed! Please, be undeterred - this (momentary) small interest comes from the fact, that you have
no advertisement at all. I'm interested in such projects since almost two years, and only yesterday - by accident - found your site. Have you considered adding your pages at least to Google and Bing, using a few significant keywords?
Regarding the proposals for improvements:
If I was going to enhance this design, I would replace the 68008 with a full 68000
Have you considered ARM CPU? It won't make your design that less "retro", since Archimedes was using one of the first ARMs - but it could make it much more powerful. I've got no idea, however, how much complication could it add to the electronics.
Oh, and one more: if this is more about "retro-computing" - maybe 65C816S could be a considerable option as well? It has 24-bit address bus, and AFAIK can be clocked up to 14 MHz.
I would also replace the almost-impossible-to-get SID chips with something easier to get. Maybe you could use a Yamaha YM family sound synthesis chip and some sort of raw DAC chip to handle sound effects and percussion and the things that the YM cant really do.
Such a combo has been seen on all kinds of consoles and arcade boards and I bet the YM chips are easier to get than SIDs.
For sound... There is the SwinSID which claims to be a drop-in replacement for the SID. My actual design went with the SID as I prefer it's sound over OPL chips (I have a YM262 OPL-3 laying around)
And I wasn't thinking OPL for the sound, I was thinking of a sound system more like that used in many arcade games that used a YM2151 FM synthesis chip and another chip to handle raw sound samples (used in the arcade games for sound effects and percussive samples that the 2151 couldn't do)
Being very fond of SID-tunes (my first computer was Commodore VC-20, bought in August 1984, several months later followed by C-64) I would to second the idea of replacing non-reachable anymore original soundchip with something more available.
And, actually, why not OPL-3? From what I see, it still could be ordered at far-Eastern distributors. It has nice capabilities, it gives pleasant FM-sound - and it could be completed with the mentioned chip "to handle raw sound samples".
If possible, of course it would be valuable to have VGA-connector - but not at a cost of disposing of any available presently video modes. Anyway, we can use PAL-VGA converters, available on the market for a few dollars (using such small box with my C-64/128).
Definitely it's interesting idea to be able to use ISA-cards. And having slots would mean, that your design would be expandable.
I would to add one thing, not mentioned: maybe could be possible to replace simplistic Atari-style sockets for game-controllers with the ones for NES game controllers? Having fond memories of C-64 gaming I have to admit, that it was always somewhat troublesome to use keyboard in case you only needed one more "fire button"... NES controller is the simplest one, that just "could do" offering two independent buttons, and two additional selection buttons. And it's available for peanuts. Yes, SNES controllers are even more extended, but I'm not sure, wouldn't it mean too much complication for the design. IMHO the older NES ones would be OK.