fpga286r2

80286 Retro computer board with FPGA

Tested software

• MSDOS 3.3 / 4.0 / 6.22
• Windows 2.0 in CGA mode

Some tested games

• Some old CGA games
• Prince of Persia (CGA and VGA mode)

New USB host controller is almost done!

Currently only keyboards are supported, only 1 button press at a time is possible. This is enough for work with some apps, but not enough for games.

I tried to keep the design as simple as possible - only 2 files (about 300 lines each) with 2 FSMs, total about 420 LEs. These FSMs make it easy to add new USB commands or to work with additional device's endpoints.

To test it:

• Connect your keyboard to an upper USB (only low-speed and no hubs/radio, sorry!).
• Start the DOS or 16-bit Minix and try some commands like "cd" or "dir" ("ls").
• Connect headphones to audio jack.
• Every time you push buttons on a keyboard you'll hear bleeps - thus the controller lets you know that a device's report has been received. Each key will have unique sound frequency which depends on a key's scancode.

"ACK" response on "GET DESCRIPTOR" command:

BIOS

Please use this compact BIOS:

https://github.com/b-dmitry1/BIOS

PCB

P-CAD 2006, Sprint Layout 6, and prepared for manufacturing Gerber files could be found in a "pcb" directory.

Technology:

• 4-layer PCB.
• 100x100 mm size.
• 0.2 mm min hole.
• 0.46 mm min via diameter.
• 0.127 mm min track.

I have paid only $7 for 5 PCBs on jlcpcb.com. It is safe to increase hole size to 0.3 mm, via to 0.63mm, and track width to 0.15 mm.

All the electronic components including FPGA (EP4CE15F23C8N) and CPU (80c286) could be found on AliExpress.

Top view:

Bottom view:

Simplified schematic diagram:

Compiling on Windows

Please use Altera Quartus II 13.0sp1 to compile the project.

Using disk images

Please use disk images from my e86r project:

https://github.com/b-dmitry1/e86r

Just write a FreeDos or an empty image to a SD card, mount it and add your files using File Explorer.

Docs and manuals

• Please check the "doc" directory.

Disclaimer

The project is provided "as is" without any warranty. Use at your own risk.

Due to lack of time, I made the PCB without any schematic diagrams, sorry. If you really need schematic diagram - contact me and I'll create it.