Requesting the EXEC Function

To load and execute a child program, the parent must execute an Int 21H with the registers set up as follows:

AH = 4BH

AL = 00H (subfunction to load child program)

DS:DX = segment:offset of pathname for child program

ES:BX = segment:offset of parameter block

The parameter block, in turn, contains addresses of other information needed by the EXEC function.