Int 67H [EMS 4.0] Function 5BH (91) Subfunction 01H Set alternate map registers

Selects an alternate map register set or (if alternate sets are not supported) restores the mapping context from the specified buffer.

Call with:

AH = 5BH

AL = 01H

BL = alternate register set number or 00H

ES:DI = segment:offset of map register context restore area

(if BL = 0)

Returns:

If function successful

AH = 00H

If function unsuccessful

AH = error code

Notes:

The buffer address specified in this call is returned by subsequent calls to Int 67H Function 5BH Subfunction 00H with BL = 00H.

The save area must have been initialized by a previous call to Int 67H Function 4EH Subfunction 00H.

This function is intended for use by operating systems only and can be disabled by the operating system at any time.