ch18_计算2kb程序空间的校验和值（checksum）.asm

51单片机基础篇 对于有一定基础的人看看 包含书中所以的源代码

     ;FUNCTION NAME: CALCULATE 2KB PROGRAM MEMORY CHECKSUM
     ;FUNCTION: CHECKSUM(05)(04)=(DPTR+2048)+... +(DPTR)
     ;
     CHECKSUM
           	MOV  	R4,#00H
           	MOV  	R5,#00H
           	MOV  	R2,#08H
     $1 	MOV  	R1,#00H
     $2 	MOVC 	A,@A+DPTR		;READ PROGRAM DATA
           	ADD  	A,04H
           	MOV  	04H,A
           	CLR  	A
           	ADDC  	A,05H
           	MOV   	05H,A
           	INC  	DPTR
           	DJNZ 	R1,$2
           	DJNZ 	R2,$1
           	RET  				;RESULT IN(05)(04)
     ;