INT 10H 12H BL=32H: Enable/Disable Video RAM & I/O Ports
Expects: AH 12H
AL setting: 00H enable access
01H disable access
Returns: AH 12H if a valid value was passed in AL
Info: You can use this to suppress CPU access to video RAM and I/O
ports on VGA-compatible displays. It updates bit 0 of the
VgaFlagsRec (at 0040:0089).
Notes: You can disable an EGA card via bit 1 of port 3c2H.
See Also: INT 10H 12H (EGA/VGA Special Functions/Alternate Select)
INT 10H: Video Services
EGA/VGA Data Areas