Summary

Add ASUS TX97-XV (HP OEM) board.

Also add ATi Mach64 VT3 emulation. Fix color keying of video overlays on Mach64 VT and later.

Drive-by: Fix memory offsets in S3 Trio64+/ViRGE colorkey emulation.

Checklist

• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - Add ASUS TX97-XV (HP OEM) BIOS ROM roms#442
• This pull request requires changes to the asset set
  • I have opened an assets pull request - https://github.com/86Box/assets/pull/changeme/

References

None.