Summary

Improve the Cirrus VBIOS loading behavior for several machines by making the following changes:

• Give the Commodore SL386SX/25 its own CL-GD5402 device and make the normal onboard one not load its own VBIOS allowing the Tandy 1000 RSX to load the correct VBIOS from system ROM
• Give both the ISA and VLB CL-GD5428s the onboard flag in .local
• Cirrus: Add code to load the 5428 VBIOSes from system ROM specifically for the following machines: Acer A1G, HP Vectra 486VL, Siemens-Nixdorf D824
• OPTi 499: The ROMCS# Enable bits in register 2Dh override the ROMCS# disable behavior of 22h bit 5, this allows the Alaris Cobalt LPX to properly load its VBIOS from system ROM
• Intel Monsoon: Give the machine its own version of the Phoenix jumper device, this allows the machine to correctly load its VBIOS from system ROM

Checklist

• Closes #xxx
• 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 - https://github.com/86Box/roms/pull/changeme/
• This pull request requires changes to the asset set
  • I have opened an assets pull request - https://github.com/86Box/assets/pull/changeme/

References

Provide links to datasheets or other documentation that helped you implement this pull request.

• OPTi 82c499 datasheet: https://www.datasheets360.com/part/detail/82c499/812351419068118665/