Int 57  C - Ti Professional Pc - Crt Mapping Hook                          [b]

   AX/BX/CX/DX/BP/SI/DI same as on entry to CRT subroutine (e.g. INT 49)
   DS = BIOS 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 which bypass INT 49

Note:  by default, this vector points at an IRET instruction

See Also: INT 49/AH=01h"TI",INT 50"TI Professional"