Reminds me of the project that used a Raspberry Pi running a software emulator as an Amiga CPU - Pi plugged into the CPU socket via an adapter board. Probably the most impressive project I've ever seen. https://www.hackster.io/news/hands-on-with-the-pistorm-the-u...
There's a similar project for the Acorn BBC Micro called PiTubeDirect, which allows the Pi to emulate several different CPUs, while connected to the BBC Micro's "tube" second processor slot.
(The BBC Micro itself was quite remarkable for supporting multiple processors, which did not have to be the same architecture as the host 6502. Amazing for 1981.)
I did a similar thing with a 6502 and the Propeller microcontroller. I always meant to make an 8086 or 8088 version, but moved on to other things before ever doing so.
Love the simple/elegant/powerful idea of driving the CPU clock from code running on RPI/Linux. It sidesteps the difficulty of efficiently doing bitbanging on RPI/Linux in a neat way.
This is a sort-deep link to one page of the site and the main page of the site explains the overall project to design and build one's own XT-clone. Kind of ambitious.
So start with a Pi running around 1/30th normal speed, then get the memory card working and remove that from the pi, then get the video and BIOS support working and remove that from the pi, eventually remove the last thing from the pi and crank the speed up about 30-times faster and you've got a gradually bootstrapped fully operational XT-clone.
Its an interesting project plan, usually people bring up a system by having just CPU and memory at least partially working, then add peripherals like disk, display, rs232, GPIO, etc. But this way you can bring it all up, at least enough to run CP/M (err, ms-dos I guess?), admittedly glacially slowly and mostly emulated, and then upgrade the parts to hardware as see fit.
Could probably do something with a FPGA that would be much more difficult but could at least run full speed (or maybe faster?). Of course in early 2022 what's more unobtanium, RasPis or FPGAs? If you can't buy either I guess it doesn't matter.
trollied|3 years ago
LeoPanthera|3 years ago
https://github.com/hoglet67/PiTubeDirect
(The BBC Micro itself was quite remarkable for supporting multiple processors, which did not have to be the same architecture as the host 6502. Amazing for 1981.)
metadat|3 years ago
https://news.ycombinator.com/item?id=31449828
reaperducer|3 years ago
Two I can think of off the top of my head:
- FPGA 6581 to replace a Commodore 64 SID chip.
- There's a drop-in sorta Z-80 so you can run CP/M on the TRS-80 Model 100.
phaedrus|3 years ago
Dangerous Prototypes wrote up a pretty good post about it: http://dangerousprototypes.com/blog/2012/02/22/prop-6502-pro...
redundantly|3 years ago
Do you happen to still have this information somewhere?
tpmx|3 years ago
jesuslop|3 years ago
wila|3 years ago
https://www.ebay.com/sch/emil6190/m.html
tadbit|3 years ago
dboreham|3 years ago
VLM|3 years ago
So start with a Pi running around 1/30th normal speed, then get the memory card working and remove that from the pi, then get the video and BIOS support working and remove that from the pi, eventually remove the last thing from the pi and crank the speed up about 30-times faster and you've got a gradually bootstrapped fully operational XT-clone.
Its an interesting project plan, usually people bring up a system by having just CPU and memory at least partially working, then add peripherals like disk, display, rs232, GPIO, etc. But this way you can bring it all up, at least enough to run CP/M (err, ms-dos I guess?), admittedly glacially slowly and mostly emulated, and then upgrade the parts to hardware as see fit.
Could probably do something with a FPGA that would be much more difficult but could at least run full speed (or maybe faster?). Of course in early 2022 what's more unobtanium, RasPis or FPGAs? If you can't buy either I guess it doesn't matter.
synu|3 years ago
unknown|3 years ago
[deleted]
morpheos137|3 years ago