SEARCH HDRFIL
COMPIL(CHN,<GETCHN,NOTOPN,GETCHAN>,<GOGTAB>,<GETCHN, NOTOPN, GETCHAN>)
GETCHN:
	HRLI	A,(<PUUO 3,0>)	;PREPARE FOR ERR MESS
	TRZE	CHNL,777760	;CHECK FOR VALID CHANNEL NO
	 JRST	 NOTVALID	;INVALID CHANNEL NUMBER
	SKIPE	CDB,@CDBLOC(USER) ;IS CHANNEL OPEN? (CDBLOC SET BY ALLOC)
	POPJ	P,
NOTOPN:	
	XCT	A		;PRINT ROUTINE NAME
	ERR	<: CHANNEL OR FILE NOT OPEN>
NOTVALID:
	XCT	A		;ROUTINE NAME
	ERR	<: CHANNEL NUMBER INVALID>
HERE (GETCHAN)
	MOVE	USER,GOGTAB
	ADD	USER,[XWD A,CHANS]	;MAKE @ WORD
	MOVEI	A,1			;START AT CHANNEL 1
CHLUP:	SKIPN	@USER			;IF CHANNEL IS FREE,
	POPJ	P,			; RETURN
	CAIGE	A,17			;CYCLE TO 0?
	AOJA	A,CHLUP			;NO, TRY NEXT
	MOVEI	A,0			;TRY 0
	SKIPE	@USER			;FREE?
	HRROI	A,-1			;NOPE
	POPJ	P,			;DONE
ENDCOM(CHN)
END