Specifications

Application Examples
;***********************************************************
;* *
;* INTERRUPT HANDLERS *
;* *
;***********************************************************
;
; ONLY ONE SERIAL INTERRUPT HANDLER IS ILLUSTRATED. OTHER
; HANDLERS CAN BE ADDED HERE AS NEEDED.
;
CODE SEGMENT PARA
;
ASSUME CS:CODE,SS:STACK,DS:DATA,ES:NOTHING
;
SERIAL_8250 PROC
; THIS PROCEDURE HANDLES INTERRUPTS GENERATED BY THE
; 8259A PIC ON THE ZT 8840. THE INT_FLAG LOCATION
; WILL RECORD THAT THE INTERRUPT WAS RECEIVED WITH
; A ZERO VALUE. IT IS ASSUMED THE FLAG IS INITIALLY 0FFH.
;
; INPUTS: NONE
; OUTPUTS: INT_FLAG - 0H
; CALLS: NONE
; DESTROYS: NONE
;
PUSH AX
PUSH DX
MOV INT_FLAG,0 ; RECORD THAT THE INT WAS RECV’D
MOV AL,0
PUT UART1+PORT_INTEN ; DISABLE FURTHER INTERRUPTS
MOV AL,OCW2_8809A ; SEND EOI’S
PUT PORT_A_8809A
MOV AL,OCW2_8840
MOV DX,PORT_A_8840
OUT DX,AL
POP DX
POP AX
IRET
SERIAL_8250 ENDP
;
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