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"