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INT 0x10 - 0x05 - Select Active Display Page


reg value descr
AH 0x05
AL parm new page number (see Video Pages)

:!: for PCjr only:

reg value descr
AL 0x80 read CRT/CPU page registers
0x81 set CPU page register
BL: CPU page register
0x82 set CRT page register
BH: CRT page register
0x83 set bot CRT and CPU page register
BL: CPU page register
BH: CRT page register
  • the CPU page determines which 16K block of the first 128K of physical memory will be mapped at B800h by the hardware
  • the CRT page determines the start address of the memory used by the video controller

Return (valid only for PCJr)

reg descr
BH CRT page register
BL CPU page register

Notes & Comments

  • returns data from BIOS DATA AREA locations 40:50, 40:60 and 40:61
  • the 6845 can also be used to read the cursor position
  • the return data can be circumvented by direct port I/O to the 6845 CRT Controller since this function returns the data found in the BIOS Data Area without actually checking the controller
  • to determine whether the requested page actually exists, use AH=0Fh to query the current page after making this call


back2root/ibm-pc-ms-dos/interrupts/int_10/int_10_05.txt · Dernière modification : 2023/01/19 21:19 de frater