prog5.asm

主要是8051源代码

;  PROG5 - Jumping Around
;
;  This Program demonstrates how jumping is done in the 8051.  
;
;  This program will run in the UMPS simulator for a DS80C320.
;
;  Myke Predko
;  98.02.03
;
;  Hardware Notes:
;   This program is only meant to run on the Simulator

;  Variable Declarations
;   No Registers of Variables are required

;  Mainline
 org 0				;  Execution Starts Here

  sjmp	 Short_Label		;  Jump to a Short Label

 org 10

Back_Label:

  ajmp	 Valid_Label		;  Jump within the Page

 org 20

Short_Label:			;  Showing how to Jump to Different Locations - Short Jump
				;   Back a Bit
  sjmp	 Back_Label

 org 30

Valid_Label:			;  "ajmp Valid_Label" will Come Here

;  ajmp	 Invalid_Label          ;  Invalid Jump to Next Page
  db     021h, 000h             ;  Make My own "ajmp" to 0900h 

  ljmp   Invalid_Label          ;  Valid Jump to Next Page


 org 0100h

;  #### - End up here, wrong address for "ajmp", should have used "ljmp"

Bad_Loop:			;  In the wrong Section of Code
  ajmp	 Bad_Loop		;   Have to Look at your "jmp" Statement Again


 org 0900h                      ;  In the Next Code Page (Over 2048)			

Invalid_Label:			;  This is only accessible via "ljmp"

Loop:				;  Loop Here Forever when Finished
  ljmp	 Loop