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MPM OPERATING SYSTEMS/MPM II/MPM II SOURCE 2/Control_2/treadles.lib

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+;	MACRO LIBRARY FOR STREET TREADLES
+;
+TRINP	EQU	01H	;TREADLE INPUT PORT
+TROUT	EQU	01H	;TREADLE OUTPUT PORT
+;
+TREAD?	MACRO	TR,IFTRUE
+;;	"TREAD?" IS INVOKED TO CHECK IF
+;;	TREADLE GIVEN BY TR HAS BEEN SENSED.
+;;	IF SO, THE LATCH IS CLEARED AND CONTROL
+;;	TRANSFERS TO THE LABEL "IFTRUE"
+	LOCAL	IFFALSE		;;IN CASE NOT SET
+;;
+	IN	TRINP	;;READ TREADLE SWITCHES
+	ANI	1 SHL TR	;;MASK PROPER BIT
+	JZ	IFFALSE		;;SKIP RESET IF 0
+	MVI	A,1 SHL TR	;;TO RESET THE BIT
+	OUT	TROUT		;;CLEAR IT
+	JMP	IFTRUE		;;GO TO TRUE LABEL
+IFFALSE:
+	ENDM
+