Click above to get retro games delivered to your door ever month!

  Service 1CH (decimal 28) is provided by the ROM BIOS only in the PS/2
  models 50, 60, and 80, and with VGA adapters. (In other words, where you
  find a VGA you also find service 1CH.) This BIOS service lets you preserve
  all information that describes the state of the video BIOS and hardware.
  The ROM BIOS can preserve three types of information: the video DAC state,
  the BIOS data area in RAM, and the current values in all video control
  registers.

  You can select three different subservices with the value you pass in
  register AL: subservices 00H, 01H, and 02H.

  Subservice 00H (decimal 0) is designed to be called before subservices 01H
  or 02H. Subservice 00H requires you to specify which of the three types of
  information you want to preserve, by setting one or more of the three
  low-order bits of the value in CX. When this service returns, BX contains
  the size of the buffer you will need to store the information.

  Subservice 01H (decimal 1) saves the current video state information in
  the buffer whose address you pass in ES:BX. Then you can change video
  modes, reprogram the palette, or otherwise program the ROM BIOS or video
  hardware.

  Subservice 02H (decimal 2) lets you restore the previous video state.