Table des matières
INT 0x10 - 0x04 - Read Light Pen Position
Not available on VGA
Request/Call:
reg | value | descr |
---|---|---|
AH | 0x04 |
Return:
reg | descr |
---|---|
AH | 0 : light pen switch not triggered 1 : light pen triggered |
BX | pixel column (0-319 or 0-639, mode dependent) |
CH | raster line (0-199) (CGA and EGA modes 4, 5 and 6) |
CX | raster line (EGA modes except 4, 5 and 6) |
DH | row (0-24) |
DL | column (0-79 or 0-79 mode dependent) |
Notes & Comments
- data returned as a byte coordinate, leaving horizontal accuracy to within 2 pixels (320) or 4 pixels (640)
- on a CGA, returned column numbers are always multiples of 2 (320-column modes) or 4 (640-column modes)
- vertical accuracy within 2 lines
- PS/2's don't support the light pen interface