BIOS status

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These are the BIOS interrupts that need to be implemented in order to make FreeDOS boot. The last number is the number of ocurrences of this call.

System Timer ISR Entry Point

  • int 08h AH=00 9
  • int 08h AH=02 1
  • int 08h AH=13 1

Screen I/O VGA BIOS

  • int 10h AH=01 1
  • int 10h AH=03 4
  • int 10h AH=08 1
  • int 10h AH=0e 607
  • int 10h AH=0f 2
  • int 10h AH=12 3

The crtc_addr in text mode is 0x3d4 for the address register and 0x3d5 for the value.

Equipment List Service Entry Point

  • int 11h AH=00 1
  • int 11h AH=10 1
  • int 11h AH=bb 1

Memory Size Service Entry Point

  • int 12h AH=00 1
  • int 12h AH=0f 1

Fixed Disk Services Entry Point

  • int 13h AH=00 2
  • int 13h AH=02 20
  • int 13h AH=08 6
  • int 13h AH=15 3
  • int 13h AH=41 167
  • int 13h AH=42 167
  • int 13h AH=48 3

Other

  • Serial Communications Service Entry Point: int 14h AH=00 1
  • Keyboard Service Entry Point: int 16h AH=11 961
  • Printer Service Entry Point: int 17h AH=01 1