8-5-3.asm

书籍8051入门篇

;8-5-3.ASM
;2 BYTE DATA  SUBSTRACT
$MOD51
	ORG	0000H
	MOV	R0,#20H
	MOV	R1,#30H
	CLR	CY
	MOV	A,@R0		;A=(20H)
	SUBB	A,@R1		;A=(20H)-(30H)		
	MOV	@R1,A		;(30H)=(20H)-(30H)
	INC	R0		;R0=21H
	INC	R1		;R1=31H
	MOV	A,@R0		;A=(21H)
	SUBB	A,@R1		;A=(21H)-(31H)-CY
	MOV	@R1,A		;(31H)=(21H)-(31H)-CY
	END