printbyte.asm

.data zp
.space _na 1	; a的临时存放处
.text
printbyte:
	php
	pha
	sta _na
	txa
	pha
	ldx #8		; 打印8bit
*	lda #$30	; a = '0'
	asl _na		; 左移一位，溢出到c
	adc #0		; a = a + c + 0
	jsr chrout	; putchar(a)
	dex			; x--
	bne -		; if(x != 0) goto 上个星号
	lda #$20
	jsr chrout
	pla
	tax
	pla
	plp
	rts