Connecting an 8086 or 8088 processor to a Raspberry Pi

Connecting an 8086 or 8088 processor to a Raspberry Pi(homebrew8088.com)

68 points by tadbit 3 years ago | 19 comments

trollied 3 years ago |

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...

LeoPanthera 3 years ago | |

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.

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 | |

This seems worthy of its own HN submission, so I did it:

https://news.ycombinator.com/item?id=31449828

reaperducer 3 years ago | |

Lots of interesting drop-in chip replacements in the retro computing world these days.

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.

Terry_Roll 3 years ago | | |

I wonder if we might see drop in replacements used in other tech from the past that might be end of life or near to, especially space satellites where power supplies permit.

phaedrus 3 years ago |

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.

Dangerous Prototypes wrote up a pretty good post about it: http://dangerousprototypes.com/blog/2012/02/22/prop-6502-pro...

redundantly 3 years ago | |

The Parallax page they link to is gone, archive.org doesn't have any of the pictures/videos of it.

Do you happen to still have this information somewhere?

phaedrus 3 years ago | | |

There's more pictures and info on my old blog:

http://dennisferron.blogspot.com/2008/12/prop6502-laptop-pro...

Looks like Parallax still has a link to their old site, but I couldn't find the contest pages there, either.

https://www1.parallax.com/

I'm pretty sure the code I wrote for it ended up on the Propeller object exchange, but that site also is gone... It probably lives on in the migration to a github repo, but it isn't so easy to search by author AFAICT.

http://obex.parallax.com/

My picture (along with the other design contest winners and honorable mentions) was on the back of the May 2009 Nuts and Volts magazine, but I just checked my copy and there's no article inside, just the blurb on the back cover.

tpmx 3 years ago |

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.

jesuslop 3 years ago | |

The idea is fantastic. It would make a great computer architecture lab asignment.

tpmx 3 years ago | | |

Yeah, you get a way of easily doing a GUI via HDMI or X over IP or whatever, much easier development for most people and lose some performance you don't really care about anyway in that situation.

wila 3 years ago |

Had to search for the PCB. Looks like this is the one:

https://www.ebay.com/sch/emil6190/m.html

tadbit 3 years ago | |

Correct! I recently ordered the 8086 version (the first CPU I used as a child) so I could play around with it.

dboreham 3 years ago |

Confused as to why this is a useful exercise vs emulating the 8086 on the Pi?

VLM 3 years ago | |

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.

synu 3 years ago | |

Perhaps it’s more to see if they can, or for fun, than strictly for some useful purpose.

morpheos137 3 years ago |

shouldn't this be trivially simple with an rs232 to usb adapter?