;----------------------------------------------------------------
; LD262.ASM  This program responds to the the external interrupt,
; ExtInt on the DECE-I microcomputer. Each interrupt branches
; control to an interrupt handler where a variable is incremented
; and displayed at port-3. C.P. Diduch, October 8, 2004.
;----------------------------------------------------------------
; MAIN PROGRAM			; void main(void) {
				;
.EQU	Tmp	R0		; #define Tmp R0
.EQU	N	R1		; #define N   R1
				;
	.ORG	0x8000		; main {
				;
	ADD	N, NULL, NULL	;    N = 0 ;
	ADD	R2, NULL, NULL	;    R2 = 0 ;
	ADD	R3, NULL, NULL	;    R3 = 0 ;
        ADDL    Tmp, NULL, IH  	;    "initialize interrupt vector"
        STOREM  0, Tmp          ;
        ADDL    Tmp, NULL, 0xF8	;    "write Interrupt Controller
	STOREP	0x001A, Tmp	;     Control Word to clear all
				;     Irq's and unmask ExtInt"
	ORL#	FL, FL, 0x0040	;    "set DECE IF"
                                ;    
M0:     JMP     M0              ; do {}
				; }
;----------------------------------------------------------------
; void interrupt IH(void)
;
; Each time the interrupt handler, IH, is invoked it 
; adds "1" to N and and writes the new value to port-3.
;
IH:                             ; void interrupt IH(void) {
				;
	ADDL	N,N, 1		;    N = N + 1;
        STOREP  0x0003, N	;    outport(3, N) ; 
				; 
        ADDL    Tmp, NULL, 0x88	;    "write Interrupt Controller
	STOREP	0x001A, Tmp	;     Control Word to clear 
				;     IrqExt at Interrupt Controller
				;     with IrqExt unmasked"
        RETI                    ; }
;----------------------------------------------------------------