;Bit Toggling of P2.7 on MDE 8051 Trainer
;Tested by Mazidi 
;Modified from Example 4-2 of 8051 Microcontroller book by Mazidis & McKinlay 
;Connect the P2.7 to an LED to see the toggling. 			
 			ORG	 0
 			CLR	P2.7		;P2.7 as output
BACK: 			CPL	P2.7
 			ACALL	 SDELAY	;one sec delay	
			SJMP	 BACK
;-------------------------
;One sec. delay for DS89C4x0 with MDE8051 Trainer
;XTAL=11.0592 MHz on MDE8051
;45 x 255 x 243 x 4 x 90 ns = 999.7 msec
;Notice DS89C4x0 uses 4 clocks for Machine Cycle. 
   			
SDELAY:
		MOV	 R5, #45
H3:		MOV	 R4, #242    
H2:  		MOV	 R3, #255    
H1:	 	DJNZ	 R3, H1 		
    		DJNZ	 R4, H2  
    		DJNZ	 R5, H3  
   		RET             
		   END