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

• Full-speed (12 Mbit/s) device support for fast gaming keyboards and mouses.
• Composite device support (Radio keyboard+mouse, 2-in-1 devices).
• USB PHYs are now controlled by RISC-V I/O processor. Firmware was written in C and can be easily improved.
• Virtual COM-port emulation for serial mouse drivers.
• Some cheap joysticks are supported too, they will work in a keyboard mode. Key mappings could be defined in a RISC-V program.

If you need mouse please use ctmouse.exe driver from FreeDOS - it works perfectly on COM1 (virtual USB-RS232).

The RISC-V core will print USB device information on a DEBUG port. If you need the DEBUG port to be controlled by main processor comment "txd" line on a RISC-V UART and uncomment "txd" line of a CPU's UART.

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.

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.

FPGA pin test is included. Check the fpga_pin_test project.

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

• Electrical schematic diagram is in "sch" directory.
• Please check the "doc" directory.

Disclaimer

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