SUBROUTINE CHANGE (BLK)
C
C	ROBERT WATSON
C	CISCO, INC.
C	(918)665-2110
C	4135 S. 100TH E. AVE.
C	TULSA OK 74145
C
C	THIS PROGRAM HAS BEEN DONATED TO THE PUBLIC DOMAIN
C	AND IS NOT TO BE COPYRIGHTED.
C
	INTEGER*4	IBEG,		PC,		IWD
	INTEGER*2	BLK(256),	Q,		IWDDUM(2),
	1		LOIWD,		HIIWD,		PCDUM(2),
	2		HIPC,		LOPC
	BYTE		IN,		Z,		LOC(6),
	1		MAC(6),		B,		F,
	2		BDUM(2),	RAD(3)
	EQUIVALENCE	(IWD,IWDDUM(1)),	(IWDDUM(1),LOIWD),
	1		(IWDDUM(2),HIIWD),	(PC,PCDUM(1)),
	2		(PCDUM(1),LOPC),	(PCDUM(2),HIPC),
	3		(IDUM,BDUM(1))
	Z = .TRUE.
100	IN = .FALSE.
	B = ' '
150	WRITE  (5,200)
200	FORMAT (/,' ENTER OCTAL ADDRESS OF WORD TO BE CHANGED',/,
	1	' OR RETURN TO CHANGE MODES ',$)
	READ   (5,250,END=800,ERR=100) Q, IBEG
250	FORMAT (Q,O6)
	IF (Q .LE. 0) GO TO 600
	IF ((IBEG.AND.1) .EQ. 0) GO TO 255
	WRITE  (5,256) 7
256	FORMAT (/,' WORD ADDRESS MUST BE EVEN',A1)
	GO TO 150
255	CALL INIT (BLK, ISUB, IBEG, IREC, PC)
	IN = .TRUE.
	PC = IBEG
260	WRITE  (5,300)
300	FORMAT (/,' RETURN TO VIEW NEXT WORD',/,
	1	' ENTER ''I'' TO INSERT NEW CONTENTS',/,
	2	' ENTER ''N'' TO GO TO NEW LOCATION',/,
	3	' ENTER ''X'' TO CHANGE MODES',/)
400	CALL OCTL (LOPC, LOC, Z)
	CALL OCTL (BLK(ISUB), MAC, Z)
490	WRITE  (5,500) LOC, MAC
500	FORMAT (X,6A1,2X,6A1,2X,$)
	READ   (5,501,ERR=260,END=800) Q, B
501	FORMAT (Q,A1)
	IF (Q .LE. 0) GO TO 560
	IF (B .EQ. 'N') GO TO 600
	IF (B .EQ. 'X') GO TO 600
	IF (B .EQ. 'I') GO TO 503
	WRITE  (5,502) 7
502	FORMAT (/,' ???',A1,/)
	GO TO 490
503	WRITE  (5,504)
504	FORMAT (/,' ENTER NEW CONTENTS AS ASCII, OCTAL WORD,',
	1	' OR RAD50',/,' (A, O, OR R)? ',$)
	READ   (5,505,END=800) F
505	FORMAT (A1)
	IF (F.NE.'A' .AND. F.NE.'O' .AND. F.NE.'R') GO TO 503
	IF (F .NE. 'A') GO TO 508
	WRITE  (5,506)
506	FORMAT (/,' ENTER TWO ASCII CHARACTERS: ',$)
	READ   (5,507,END=800) BDUM
507	FORMAT (2A1)
	BLK(ISUB) = IDUM
	GO TO 550
508	IF (F .EQ. 'R') GO TO 512
509	WRITE  (5,510)
510	FORMAT (/,' ENTER ONE TO SIX OCTAL DIGITS: ',$)
	READ   (5,511,ERR=509,END=800) IWD
511	FORMAT (O6)
	BLK(ISUB) = LOIWD
	GO TO 550
512	WRITE  (5,513)
513	FORMAT (/,' ENTER THREE RAD50 CHARACTERS: ',$)
	READ   (5,514,END=800) RAD
514	FORMAT (3A1)
	N = IRAD50 (3, RAD, LOIWD)
	IF (N .NE. 3) GO TO 512
	BLK(ISUB) = LOIWD
550	WRITE  (5,555)
555	FORMAT ('  ')
560	PC = PC + 2
	ISUB = ISUB + 1
	IF (ISUB .LE. 256) GO TO 400
	WRITE  (1'IREC) BLK
	IREC = IREC + 1
	CALL FILL (BLK, IREC, ISUB, PC)
	GO TO 400
600	IF (IN) WRITE (1'IREC) BLK
	IF (B .EQ. 'N') GO TO 100
700	RETURN
800	STOP
	END