ece362/5_1_1b.txt

	XDEF	Entry
	XREF	__SEG_END_SSTACK

Variables:		Section
VAR_1       dc.b	   $EC

Constants:	     Section
DDR_S	    equ	  	$24A
DDR_T	    equ   	$242
PORT_T      equ     $240
PORT_S      equ     $248

Code:			Section
Entry:
			BSET		DDR_S,#$FF	;set all bits of DDR_S (output)
			BSET		DDR_T,#$00	;clear all bits of DDR_T (input)

			LDAA		#$00		;all 0's (off)
			STAA		PORT_S		;turn off all LED's

			LDAA		VAR_1		;read VAR_1 into acc. A
			ANDA		#%11011111	;clear bit 6
			ORAA		#%00001000	;set bit 4
			STAA		VAR_1		;store again into VAR_1

CheckOff:
			LDAB		PORT_T		;read the DIP switches into acc. B
			ANDB		#%00000010	;mask all but switch bit 1
			BEQ			CheckOff    ;check switch bit 1 in a loop (exit this loop if switch 1 is unset)

CheckOn:
			LDAB		PORT_T		;read the DIP switches into acc. B
			ANDB		#%00000010	;mask all but switch bit 1
			BNE			CheckOn     ;check switch bit 1 in a loop (exit this loop if switch 1 is set)

			LDAB		PORT_T
			BITB		#%00000010
			BVS		    OffLoop