Hello from the SFBA Delta!
Currently I don't have much in the way of vintage hardware, I used to have a decent m68k Apple collection but I had to get rid of a lot of it about a decade ago when my living circumstances changed.
I still have a non-working Mac Plus (v3 ROM, someone may want that, and a superdrive that at least was working before the tube went out years ago), an original Mac II (no video card though), and a good condition motherboard from a Mac SE.
Now though my interests are turning to vintage x86, or more specifically, last month I had this crazy idea to try and design and build a ATX form factor 486DX2/66 motherboard with minimal integrated chips (e.g. serial ports, parallel port, SATA, floppy controller as SEPARATE chips so that future repair is easier).
A 486DX2/66 was my "dream machine" back in the day when Computer Shopper was full of advertisements for them, but I never had one. I was stuck using the PS/2 Model 25 in the campus computer lab.
I've been spending the last week and half diving into data sheets and other resources and decided that before I try to design a i486 system, it would be better to try something simpler as a learning experience.
So...I'm now looking into designing an ATX form factor motherboard for an 8MHz i286. ATX so it can use modern cases with modern PSU (yes, I know ATX PSUs don't have -5V rail, that can be worked around if needed).
Still doing a lot of research but I did eBay some NOS N82077AA floppy controllers and what is allegedly an NOS N80286-10 processor (I'm always skeptical about NOS claims on processors) even though I'm nowhere near ready to use them. I don't think there should be any issues running a 10MHz CPU at 8MHz given PCs use to have a turbo button to underclock them.
I may even choose to run it at 8.33 MHz as 8.33 MHz seems to be the "unofficial" standard for 16-bit ISA on i486 boards, so that's probably a safe speed with a basic design that couples ISA bus speed to processor speed.
I don't want to just slap parts together onto a PCB, I want to try and program my own PS/2 keyboard interface in an 8-bit MCU and I want to try to write my own memory controller in an FPGA so that hopefully I can use a single memory slot that takes a more modern 4MiB stick. Both of those will be a fun challenge and the latter, I may fail.
There's a decent chance I'll never finish but it looks like many other people have done similar projects so I suspect if I get stuck, with enough searching, I can find how someone else solved the problem.
If I stumble upon an IBM XT or AT that needs restoring, I'll grab it (not interested in clones except my own) but mostly, I'm looking to build something old from new and used parts on a new PCB design if that makes sense.
I've got a lot of reading to do, I've learned more about hardware (especially the ISA bus) this last week than I've learned in a long time, so even if I don't get a working homemade 80286 PC/AT clone it isn't a loss.
---
Other stuff about me: I foster cats and I've been using GNU/Linux as my primary OS since 1998.
Glad to be here!
Currently I don't have much in the way of vintage hardware, I used to have a decent m68k Apple collection but I had to get rid of a lot of it about a decade ago when my living circumstances changed.
I still have a non-working Mac Plus (v3 ROM, someone may want that, and a superdrive that at least was working before the tube went out years ago), an original Mac II (no video card though), and a good condition motherboard from a Mac SE.
Now though my interests are turning to vintage x86, or more specifically, last month I had this crazy idea to try and design and build a ATX form factor 486DX2/66 motherboard with minimal integrated chips (e.g. serial ports, parallel port, SATA, floppy controller as SEPARATE chips so that future repair is easier).
A 486DX2/66 was my "dream machine" back in the day when Computer Shopper was full of advertisements for them, but I never had one. I was stuck using the PS/2 Model 25 in the campus computer lab.
I've been spending the last week and half diving into data sheets and other resources and decided that before I try to design a i486 system, it would be better to try something simpler as a learning experience.
So...I'm now looking into designing an ATX form factor motherboard for an 8MHz i286. ATX so it can use modern cases with modern PSU (yes, I know ATX PSUs don't have -5V rail, that can be worked around if needed).
Still doing a lot of research but I did eBay some NOS N82077AA floppy controllers and what is allegedly an NOS N80286-10 processor (I'm always skeptical about NOS claims on processors) even though I'm nowhere near ready to use them. I don't think there should be any issues running a 10MHz CPU at 8MHz given PCs use to have a turbo button to underclock them.
I may even choose to run it at 8.33 MHz as 8.33 MHz seems to be the "unofficial" standard for 16-bit ISA on i486 boards, so that's probably a safe speed with a basic design that couples ISA bus speed to processor speed.
I don't want to just slap parts together onto a PCB, I want to try and program my own PS/2 keyboard interface in an 8-bit MCU and I want to try to write my own memory controller in an FPGA so that hopefully I can use a single memory slot that takes a more modern 4MiB stick. Both of those will be a fun challenge and the latter, I may fail.
There's a decent chance I'll never finish but it looks like many other people have done similar projects so I suspect if I get stuck, with enough searching, I can find how someone else solved the problem.
If I stumble upon an IBM XT or AT that needs restoring, I'll grab it (not interested in clones except my own) but mostly, I'm looking to build something old from new and used parts on a new PCB design if that makes sense.
I've got a lot of reading to do, I've learned more about hardware (especially the ISA bus) this last week than I've learned in a long time, so even if I don't get a working homemade 80286 PC/AT clone it isn't a loss.
---
Other stuff about me: I foster cats and I've been using GNU/Linux as my primary OS since 1998.
Glad to be here!