.NLIST	TTM 
	.TITLE	HIZERO 
	.IDENT	/RICE04/
;
;	CALL	ZHIST(NO.)
;	NO.  = HIST NO.  IF  ZERO  THEN ZERO ALL ***
; 
HIZERO::
ZHIST::	MOV	#1,R0		;ONLY 1 PARAM 
	JSR	PC,R5CHEK	;CHECK INPUT PARAM
	MOV	#1,R1
	MOV	@(R5)+,R0	;NO OF HIST TO ZERO 
	MOV	R0,R4
	BNE	ZIP
	MOV	#7777,R1	;NUMBER OF HISTS TO DO
ZIP:	MOV	R4,R0		;HIST TO CLEAR
	BEQ	10$		; Skip hist #0
	JSR	PC,SWC		;GET ADDRESS OF HEADER
	BCS	RETURN		;LAST ONE OR NONE EXISTS
	MOVB	(R0),R3 	; Get 2 dim size
	BIC	#177400,R3	; STRIP OFF EXTRA
	BNE	1$		; If zero is 1 dim.
	MOV	#1,R3		; ASSUME 1 DIMENSION
1$:	MUL	4(R0),R3  	;SIZE OF ARRAY 
	BLE	10$		;INCORRECT
	CMPB	1(R0),#1	;CHECK TYPE
	BLT	10$		; None
	BEQ	4$		;SINGLE WORD
	ASL	R3		;DOUBLE WORD
4$:
	ADD	2(R0),R0	;POINTS TO DATA
5$:	CLR	(R0)+		;CLEAR 1 MEM LOCATION
	SOB	R3,5$ 
10$:	INC	R4		;NEXT HIST TO CLEAR
	SOB	R1,ZIP		;END OF NEXT HIST LOOP
RETURN:	RETURN
	.END