That's pretty cool. I see he has a DIY Jupiter Ace clone too, if one felt like having a self-hosting FORTH system instead of BASIC or CP/M.
Originally I had looked at dual ported RAMs with the intention of using them with some sort of external video generator, but they seem uncommon and the ones I could find (on Digikey) were way too expensive to even consider.
There are cheap ones on ebay if you only need a handful.
a 500k Xilinx Spartan-3E board, so I'm going to see if I can put some sort of soft core on there.
Pardon me for not remembering or googling for names, but there are some CPU softcores out there which, rather than being direct copies of known hard-CPUs, are original designs optimized for synthesis on FGPAs in the least gate-space. Poking around opencores.org should turn them up.
Still, there should be plenty of space on a 3E for a core or two of some description.
Note that in most computers that *don't* use the 6502 and have to use bus arbitration for DMA video it's generally transparent to the programmer as well, it just has some side effects with regard to instruction timings. Broadly speaking the system is going to run slightly slower than its clock speed would indicate compared to a system that doesn't share RAM with video.
The ZX-81 had a "fast" mode where it would stop updating the screen to run a chunk of code at double speed.
a parallel channel for "tinkering" / it looks like some of the "Stellaris" ARM Cortex CPUs do essentially that, offering a glob of GPIO pins that can be configured to run as a bus called "EPI".
Interesting, I'll have to check them out.
what I want is a small physical computing device that is entirely self hosting, and it should be able to reasonably utilize standard keyboards, mice, and displays.
Pardon me again for dropping bare unexplained searchterms, but ...
(propterm, playpower,
http://www.8052.com/, http://www.6502.org)
