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SBC: 6502 (65816) + SID 6581 + VDP TMS9918A

Well... It's that time of the year, when it's cold outside and it's time to find a little project to do.

I'd like to build a Single Board Computer based on 6502 (or 65816) that would have Commodore's SID 6581 as a sound chip, and TMS9918A as a video display processor (VDP). A couple years ago, I have successfully built a SBC with 6502 and 6581 along with some other ICs. It was a simple design, and since almost everything was clocked at 1 MHz - it was quite easy to interface the CPU to the SID. However, this time I'd like the CPU to be clocked much faster, at 8 to 14 MHz, use the VDP which uses/requires a 10.7+ MHz crystal, and the SID which must be clocked at around 1 MHz.

How do I interface these three chips that basically cannot be driven directly by the phi2 clock of my CPU? I'd like to use discrete logic for the entire project. I think interfacing VDP to the CPU should not be a problem, because VDP can work asynchronously (right?). How about the SID?

Please feel free to elaborate on the subject in any way possible. All your input would be highly appreciated as always. If you could reference part numbers I might need or should do research on I would appreciate it even more.

Thanks! Krystian

Reply to
ksergiejew
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Wow there's a blast from the past. You can indeed easily interface the

9918 onto the cpu bus, I cant quite remember if it needs 1 or 2 bytes of address space. You may have trouble getting the dram for it since they have been obsolete, as is the 9918, for at least a decade. I may even have a drawing somewhere.
Reply to
cbarn24050

I can get the parts - that's not the problem :) Just recently I bought two "new" TMS9918A ICs from a guy in Hong Kong on eBay.com. I also have all the technical documentation for the chips, which nowadays is easily obtainable from the Internet. The problem is that I am a newbie in EE and I don't know much about asynchronous bus designs. This is where I need the most help.

Perhaps somebody built something similar to what I intend and could elaborate. I'd like to hear about a way SID 6581 could be interfaced to a faster CPU on a faster bus... Would I need latches? Clock dividers? Anyone?

Reply to
Krystian Sergiejew

Check out 6502.org for lots of info on 6502/65816 based projects.

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The discussion forum there is also a great resource.

Reply to
Brian Lyons

If you're interested, I've got an old TMS99189 "University Board" SBC as well as a TMS99000 board. Was thinking about putting them on ebay, but I'm too lazy. Both (actually 3 boards as I have a cache board for the 99000) have copious documentation.

Reply to
Dan Major

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