ca65 V2.17 - Git 582aa41
Main file   : counter_keyboard.ca65
Current file: counter_keyboard.ca65

000000r 1               ;
000000r 1               ; ACORN System 1 Applications: Counter Keyboard
000000r 1               ;
000000r 1               ; From the Acorn System 1 User's Manual
000000r 1               ;
000000r 1               ; (Chris Oddy January 2022)
000000r 1               ;
000000r 1               ; entry point $0200
000000r 1               ;
000000r 1               		.setcpu			"6502"
000000r 1               		.listbytes		unlimited
000000r 1               ;
000000r 1               COUNT	:=		$19
000000r 1               DISPLAY	:=		$FE0C		; scan the display
000000r 1               QHEXTD1	:=		$FE64		; quad hex to display 1
000000r 1               ;
000000r 1               		.org			$0200
000200  1               ;
000200  1  20 0C FE     DISP:	jsr		DISPLAY		; look for key
000203  1  90 0A        		bcc		CHANGE		; check if control key carry set if so
000205  1  C9 17        		cmp		#$17
000207  1  F0 1F        		beq		DOWN
000209  1  C9 16        		cmp		#$16
00020B  1  F0 11        		beq		UP
00020D  1  D0 F1        		bne		DISP
00020F  1  C9 00        CHANGE:	cmp		#$00
000211  1  85 79        		sta		$79
000213  1  F0 EB        MORE:	beq		DISP		; increment No. of times of TEY
000215  1  20 43 02     		jsr		INCR
000218  1  C6 79        		dec		$79
00021A  1  10 F7        		bpl		MORE
00021C  1  30 E2        		bmi		DISP
00021E  1  20 43 02     UP:		jsr		INCR		; rapid increment
000221  1  20 32 02     		jsr		ZOOM
000224  1  D0 DA        		bne		DISP
000226  1  F0 F6        		beq		UP
000228  1  20 4C 02     DOWN:	jsr		DECR		; rapid decrement
00022B  1  20 32 02     		jsr		ZOOM
00022E  1  D0 D0        		bne		DISP
000230  1  F0 F6        		beq		DOWN
000232  1  A9 1F        ZOOM:	lda		#$1F
000234  1  85 0E        		sta		$0E			; set for one scan only
000236  1  20 0C FE     		jsr		DISPLAY
000239  1  90 03        		bcc		STOP		; check if key depressed claer if one is
00023B  1  A9 00        		lda		#$00
00023D  1  60           		rts
00023E  1  A9 FF        STOP:	lda		#$FF		; reset so that jsr DISPLAY waits for input
000240  1  85 0E        		sta		$0E
000242  1  60           		rts
000243  1               ;
000243  1               ;	Counter Keyboard Subroutine
000243  1               ;
000243  1               CNTL	:=		$1A
000243  1               CNTH	:=		$1B
000243  1               ;
000243  1  E6 7A        INCR:	inc		$7A
000245  1  D0 0D        		bne		UPDATE
000247  1  E6 7B        		inc		$7B
000249  1  38           		sec
00024A  1  B0 08        		bcs		UPDATE
00024C  1  A5 7A        DECR:	lda		$7A
00024E  1  D0 02        		bne		NOT
000250  1  C6 7B        		dec		$7B
000252  1  C6 7A        NOT:	dec		$7A
000254  1  A2 7A        UPDATE:	ldx		#$7A
000256  1  20 64 FE     		jsr		QHEXTD1
000259  1  60           		rts
000259  1