If you're going to the trouble of using an FPGA, you may as well do everything on it as Rob already suggested. But I prefer to limit myself to older technology for this particular project.


Thanks.

Unless you know of some tricks I don't know of, I don't see how this would be possible. First of all, the '612 is a 40-pin device and the 22V10 is a 24-pin PDIP. Second of all, as far as I know, the 22V10 only has 10 flip flops on it which is not nearly enough state. You'd probably need something like 64 macrocells just to implement the simple MMU I describe at the top of this thread -- 32 for the memory alone.


No disagreement here. I'll pick up a couple to try, but I would like to experiment more with the idea I've presented as well as I think it may even be fast enough for a 14 MHz system.

I'm consciously limiting myself to parts available in DIP format, or at least easily converted to DIP format.


There are quite a few projects out there (MiniMig, etc.) where people reverse engineer a complete system from the 1980's and then implement part or all of the system using an FPGA. I admire the skill involved, but don't feel moved to go in this direction myself at the moment. BTW, have you seen this thread: http://forum.6502.org/viewtopic.php?f=4&t=3500?

It's great to hear that I'm not the only 6809 fan here. It shares significant lineage with the 6502, too.

If you're programming the x86 in 16-bit real mode, the code density is very high -- much more so than even a 65c816. By way of example, have a look at this 125-byte long program to calculate the first 9304 digits of Pi: http://www.boo.net/~jasonp/pi_com.uu. If there's interest, we could start another thread in the Programming section to follow up on this.

In the hands of a master like dclxvi, the NMOS 6502 can do something similar in about 130 bytes, but I agree that 8086 code is impressively dense. [double entendre, anyone? ]

Mike B.

... and Bruce didn't have the advantage of MUL or DIV instructions!

That is an impressive bit of 6502 code! It would be interesting to see how many bytes an x86 "master" could translate it into. I guess it would vary inversely with his personal density.

Out of curiousity, I did a little searching and found this: http://www.boo.net/~jasonp/bf3pi.zip which does it in 40% the size of the 6502 code (52 bytes)!

Back on topic: I'm going to complete the design for the MMU presented at the top of this thread by defining the logic equations for the GAL. Then it'll just be a matter of building up a new system on breadboard for testing as my previous 65c02 system (http://forum.6502.org/viewtopic.php?f=4&t=3476) has already grown too large to fit this onto. Given the lack of availability of sufficiently large breadboards, I may have to build one up myself similar to what Brad has done for his Vulcan74 project (http://forum.6502.org/viewtopic.php?f=4&t=3329).