Ampro Corporation 486E Parallel Port Interrupt

Product Reference
2–23
;----------------------------------------------------------
; Code to change the parallel port direction to input
;----------------------------------------------------------
MOV DX,37Ah
IN AL,DX
OR AL,20h ;set bit 5
OUT DX,AL
;
;----------------------------------------------------------
; Code to change the parallel port direction to output
;----------------------------------------------------------
MOV DX,37Ah
IN AL,DX
AND AL,0DFh ;clear bit 5
OUT DX,AL
Parallel Port Interrupt
The parallel port can be configured to generate an interrupt request upon a variety of conditions. In
most applications, the interrupt is not used. The stand ard par alle l port interru pts are IRQ7 fo r the
primary port and IRQ5 for the secondary port. The IRQ chan nel a ssignme nts are stand ard and
cannot be changed. A bit in the parallel port's command registers enables or disables the port’s
connection to its interrupt line.