.s
d_state 100
dg1	101
dg2	102
dg3	103
dg4	104
row	0
col	1
.a 0
.c
	lda d_state
	xor #0
	jz ds0
	lda d_state
	xor #1
	jz ds1
	lda d_state
	xor #2
	jz ds2
	lda d_state
	xor #3
	jz ds3
:ds0	lda #1
	out row
	lda dg1
	out col
	jmp cont
:ds1	lda #2
	out row
	lda dg2
	out col
	jmp cont
:ds2	lda #4
	out row
	lda dg3
	out col
	jmp cont
:ds3	lda #8
	out row
	lda dg4
	out col
	jmp cont
:cont	lda d_state
	add #1
	xor #4
	jz ds5
	lda d_state
	add #1
	sta d_state
	jmp exit
:ds5	sta d_state
:exit	rts
.e

