Returns the number of the active alternate register set or, if no alternate set is active, saves the state of the mapping registers into a buffer and returns its address.
Call with:
AH = 5BH
AL = 00H
Returns:
If function successful and alternate map register set active
AH = 00H
BL = current active alternate map register set
If function successful and alternate map register set not active
AH = 00H
BL = 00H
ES:DI = segment:offset of alternate map register save area
(if BL = 0)
If function unsuccessful
AH = error code
Notes:
The address of the save area must have been specified in a previous call to Int 67H Function 5BH Subfunction 01H, and the save area must have been initialized by a previous call to Int 67H Function 4EH Subfunction 00H. If there was no previous call to Int 67H Function 5BH Subfunction 01H, the address returned is zero, and the registers are not saved.
This function is intended for use by operating systems only and can be disabled by the operating system at any time.