Summary

It adds an unpopular Japanese EGA (JEGA) video card emulation.

I wanted to make it generic, but the only available ROM is dumped from a laptop computer, Oki if386AX. The card initialization depends on the CMOS data of that machine, so I had to patch some part of the ROM. The original 16x16 font was not available from the contributor. I added Shinonome 16-dot font that is available in free, but it doesn't have NEC's special characters. These ROMs might be replaced in the future.

I tested it with the Shuttle 386SX machine.

To contributors, thank you for providing ROMs and testing.

Checklist

• Closes #xxx
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/

References

• https://en.wikipedia.org/wiki/AX_architecture
• Chips and Technologies 82C435 datasheet
• JEGA internal registers and I/O ports https://radioc.web.fc2.com/column/ax/jega_regs.htm

It seems there was an official English version of AX Technical Reference Guide, but it's not available in public.

Screenshots