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back2root:ibm-pc-ms-dos:interrupts:int_11:start

Int 11h - BIOS Equipment Determination / BIOS Equipment Flags

Request/Call:

no input data

Return:

reg descr
AX contains followings bit flags

Values code:

bit description specific PS/2
0 IPL diskette installed
1 math coprocessor
2 old PC system board RAM < 256K pointing device installed (PS/2)
3 not used
4-5 initial video mode
6-7 # of diskette drives, less 1
8 0 if DMA installed
9-11 number of serial ports
12 game adapter installed
13 unused internal modem (PS/2)
14-15 number of printer ports

bits 3 & 2, system board RAM if less than 256K motherboard

  • 00 - 16K
  • 01 - 32K
  • 10 - 16K
  • 11 - 64K (normal)

bits 5 & 4, initial video mode

  • 00 - unused
  • 01 - 40×25 color
  • 10 - 80×25 color
  • 11 - 80×25 monochrome

bits 7 & 6, number of disk drives attached, when bit 0=1

  • 00 - 1 drive
  • 01 - 2 drives
  • 10 - 3 drive
  • 11 - 4 drives

Notes & Comments

  • returns data stored at BIOS Data Area location 40:10
  • some flags are not guaranteed to be correct on all machines
  • bit 13 is used on the PCjr to indicate serial printer

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back2root/ibm-pc-ms-dos/interrupts/int_11/start.txt · Dernière modification : 2024/08/13 08:12 de frater