Ampro Corporation 486E manual Parallel Port Interrupt

Product Reference

;----------------------------------------------------------

; 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 standard parallel port interrupts are IRQ7 for the primary port and IRQ5 for the secondary port. The IRQ channel assignments are standard and cannot be changed. A bit in the parallel port's command registers enables or disables the port’s connection to its interrupt line.

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