INT 57 C - TI Professional PCIBM PC - CRT MAPPING HOOK AX/BX/CX/DX/BP/SI/DI same as on entry to CRT subroutine (e.g. INT 49) DS = BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. system segment ES = DE00h Return: DF/IF flags must be preserved ES,DS,BP preserved AX,BX,CX,DX,SI,DI may be changed as necessary to modify the original call Desc: hooking this vector permits programs to intercept or modify all screen output, including both application calls to INT 49 and calls generated internally by the BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. which bypass INT 49 Note: by default, this vector points at an IRET instruction SeeAlso: INT 49/AH=01h"TI",INT 50"TI Professional"