Ziatech Corporation ZT 8808A, Operating Manual

Page: 110 / 412

Application Examples
;***********************************************************
;* *
;* TEST CODE *
;* *
;***********************************************************
;
; INITIALIZE SEGMENT REGISTER AND STACK POINTER.
;
START:
MOV AX,SEG DATA
MOV DS,AX
MOV AX,SEG STACK
MOV SS,AX
MOV SP,OFFSET STACK_TOP
;
; INITIALIZE INTERRUPT VECTORS
;
PUSH DS
MOV AX,0
MOV DS,AX
MOV DI,OFFSET TYPE_248
MOV CX,1 ; 1 VECTOR TO BE INITIALIZED
VECT:
MOV WORD PTR [DI],OFFSET SERIAL_8250
ADD DI,2
MOV [DI],CS
ADD DI,2
LOOP VECT
POP DS
;
; INITIALIZE THE VARIABLE TO INDICATE NO INTERRUPT AT PRESENT
;
MOV INT_FLAG,0FFH
;
; INITIALIZE THE SERIAL PORT 0 AND THE 8259A INTERRUPT CONTROLLER
; ON THE ZT 8840 QUAD UART BOARD.
;
CALL INIT_UART
CALL INIT_PIC_8840
;
; INITIALIZE ZT 8809A 8259A INTERRUPT CONTROLLER.
;
CALL INIT_PIC_8809A
;
; AT THIS POINT, ALL THAT IS NEEDED IS TO ENABLE THE INTERRUPTS
; AT THE UART AND THE PROCESSOR, AND TO GENERATE AN
; INTERRUPT. AS SOON AS THE INTERRUPT IS ENABLED AT THE UART,
; THERE WILL BE AN INTERRUPT REQUEST TO THE 8259A. UPON RECEIPT
; OF THE INTERRUPT, THE PROGRAM WILL CAUSE THE LED TO STROBE ON
; AND OFF ONE TIME, AND TERMINATE.
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