Summary

Fix two issues with the SBPro side of the Yamaha YMF-7xx cards:

• Lower the default auto-init DMA length, fixes an "SB Check failed" message in SETUPSA after rebooting into MS-DOS mode from Win9x
• Change the power-on default value of the Interrupt Channel Configuration register on YMF-71x cards to put all devices on IRQ-A, fixes multiple sound issues in Duke Nukem 3D and Ultimate Doom under Windows 9x. The datasheet specifies a default value that puts the SBPro and MPU-401 onto a second IRQ but neither standalone card nor the AN430TX PnP resource data supports a second IRQ.

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.