SUBROUTINE LPON
C************************************************************
C
C  THIS ROUTINE IS USED TO ENABLE THE LIGHT PEN.
C
C  POSSIBLE ERRORS:
C	?INVALID REPLY TO LPON COMMAND
C
C  ROUTINES CALLED:
C	SEND   - SENDS A COMMAND TO THE GT40
C	GET    - RECEIVES A STATUS TRANSMISSION FROM THE GT40
C	ERROR  - ERROR LOGGING ROUTINE
C
C************************************************************
	IMPLICIT INTEGER (A - Z)

100	CALL SEND(7, 0, 0, 0)
	CALL GET(STATUS, X, Y, DNUM)
	IF(STATUS .EQ. "66) GO TO 100
	IF(STATUS .EQ. 0) RETURN

	CALL ERROR('?INVALID REPLAY TO LPON, STATUS =',STATUS)
	RETURN
	END