Summary

8514/A changes:

1. Correct interlaced display resolution.
2. Added a limit to cursor coordinates.
3. Test/WIP features of the add-on Mach8 side (ATI 8514/A Ultra) such as configurable BIOS.
4. Made the CMD 5 of the acceleration (Polygon Boundary) more accurate per manual (as much as I could regarding the clipping).

Cirrus related:

1. Added SUBSYS PCI vendor/device ID of the 5480 (per manual).

IBM VGA:

1. Built-in/option rom-less VGA don't need the "available" flag.

ATI Mach8/32:

1. As with 8514/A, corrected interlaced display.

XGA-1/-2:

1. Moved the XGA R/W memory size tests out of the SVGA R/W routines to reflect the per card basis, although anything that uses its own SVGA mapping would call the tests there (such as Cirrus, Headland and ATI) when not accessing the LFB. This finally puts an end to the XGA MCA mapping enabling bugs.
2. Re-organized the ISA standalone and non-standalone (INMOS) sides of the chips so that they work properly and remove the FILE rom loading hack from init.
3. The Memory Mapped R/W sides now account for instance in their address range.
4. INMOS only: prevent any ROM address access to anything lower than 0xc8000 to not conflict with the main BIOS rom loading.
5. Fixed native pitch by using the correct register, this fixes non 1024x768 resolutions under NT.
6. More logs when enabled to see any future bugs.

Checklist

• Closes IBM XGA-2 BIOS is not properly mapped during POST #4869 and INMOS XGA emulation is broken #4870
• 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

VESA XGA specification
INMOS G201 MCA/ISA
8514/A/Mach8/32 (for CMD 5)