COMMENT ⊗   VALID 00017 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00003 00002	.SBTTL	RP04 CONSOLE SELECTION, 5-AUG-75
C00004 00003	RP04 ERROR REPORTER
C00005 00004	RP04 ERROR MESSAGES
C00006 00005	.SBTTL	RP04 FILE RENAME
C00008 00006	.SBTTL	ASCR50	ASCII TO RAD50 CONVERSION ROUTINE
C00010 00007	.SBTTL	RPLOAD	RP04 LOAD PACK (READ HOME BLOCK) ROUTINE
C00012 00008	.SBTTL	RPFIND	FIND FILE IN RP04 DIRECTORY
C00014 00009	2$:	CMP	(R2),(R4)	COMPARE DIRECTORY ENTRY
C00015 00010	.SBTTL	RPLKUP	RP04 FILE DIRECTORY LOOKUP ROUTINE
C00017 00011	.SBTTL	RPRDFL	READ A FILE (ON THE RP04)
C00019 00012		NEG	R3
C00020 00013	.SBTTL	RPWRFL	WRITE A FILE (ON THE RP04)
C00022 00014		ADD	R3,↑D17*2(R2)	COMPUTE NEW CURRENT POSITION
C00024 00015	.SBTTL	RPINIT	STORES UNIT NUMBER & TRIES TO SET VOLUME VALID
C00026 00016	.SBTTL	RPREAD & RPWRIT, RP04 READ & WRITE I/O ROUTINES
C00028 00017	.SBTTL	RPADDR	ADDS OFFSET TO AN RP04 PHYSICAL ADDRESS
C00029 ENDMK
C⊗;
.SBTTL	RP04 CONSOLE SELECTION, 5-AUG-75

$RP:	TTISDO			;GET RP04 SELECTION DIGIT
	CMP	R0,#7		;MUST BE 0 TO 7
	BLE	1$
	JMP	$CMDE

1$:	MOV	R0,RPUNIT	;SAVE
	MOV	#1,DEVTYP	;SET RP04 MODE

	RPLOAD			;INIT & LOAD PACK
	BCS	$RPERR

2$:	JMP	$KONSL

.SBTTL	RP04 FILE DIRECTORY LOOKUP

RPFIL:	RPFILE
	BCS	1$
	JMP	DTRPLD
1$:	JMP	$NONXF

$RPFILE:CLR	RPEOF		;CLEAR END-OF-FILE
	ASCR50			;CONVERT FILE.EXT TO RAD50
	  NAMBF
	  NAMRAD
	BCC	1$
	$PMSG			;NAME.EXT ERR
	  $$NAM
	BR	$RPERX

1$:	MOV	#NAMRAD,R0
	MOV	#FILDSB,R1
	RPLKUP			;LOOK UP FILE IN DIRECTORY
	BCC	3$

	CMP	#-24,R0
	BNE	$RPERR
	EXITERR

3$:	EXIT
;RP04 ERROR REPORTER

$RPERR:	PUSH	R0
	PMSG	<?RP04 ERROR >
	POP	R0
	NEG	R0
	MOV	R0,R1
	PNTOCS			;PRINT ERROR STATUS WORD
	PNTCI
	", 
	DEC	R1
	SL	R1,1
	MOV	RPERTB(R1),R0
	PNTAL			;PRINT ERROR REASON
$RPERX:	JMP	$CNTLC

RPERTB:	RPER1
	RPER2
	RPER3
	RPER4
	RPER5
	RPER6
	RPER7
	RPER10
	RPER11
	RPER12
	RPER13
	RPER14
	RPER15
	RPER16
	RPER17
	RPER20
	RPER21
	RPER22
	RPER23
	RPER24
	RPER25
;RP04 ERROR MESSAGES

RPER1:	.ASCIZ	%UNIT #%
RPER2:	.ASCIZ	%UNAVAIL%
RPER4:
RPER5:
RPER3:	.ASCIZ	%DRV INIT%
RPER6:	.ASCIZ	%HOME BLK RD%
RPER7:	.ASCIZ	%NO HOME BLK%
RPER10:	.ASCIZ	%FILE SYS NAME%
RPER11:	.ASCIZ	%NO INDEX%
RPER12:	.ASCIZ	%NO DIR FILE%
RPER13:	.ASCIZ	%PAST EOF%
RPER20:
RPER14:	.ASCIZ	%POS%
RPER15:	.ASCIZ	%READ ERR%
RPER16:	.ASCIZ	%ALLOC CNG%
RPER17:	.ASCIZ	%BUFSIZ%
RPER21:	.ASCIZ	%INSUFF ALLOC%
RPER22:	.ASCIZ	%DIR REWRT%
RPER23:	.ASCIZ	%DATA WRT%
RPER24:	.ASCIZ	%EOF%
RPER25:	.ASCIZ	%RAD50%
.EVEN
.SBTTL	RP04 FILE RENAME

;COMMAND IS:
;	RENM:FILE.EXT FILE1.EXT

$RE:	TTICHR
	CMPB	#'N,R0
	BNE	1$
	TTICHR
	CMPB	#'M,R0
	BEQ	2$
1$:	JMP	$CMDER

2$:	TTITRM
	NAMEXT			;SETUP CURRENT FILE NAME.EXT

	RPFILE			;FIND AND SETUP FILE
	BCC	4$
	JMP	$NONXF

4$:	NAMEXT			;SETUP NEW FILE NAME.EXT

	ASCR50			;CONVERT NEW FILE.EXT TO RAD50
	  NAMBF
	  NAMRAD
	 BCS	1$		;NAME.EXT ERROR

	MOV	#WRTBAK,R5	;POINTER TO WRITE-BACK INFO TO R5

	MOV	(R5)+,R4	;GET CORE ADDRESS OF FILE DESCRIPTOR
	MOV	#NAMRAD,R3
	MOV	(R3)+,(R4)+	;TRANSFER NEW RAD50 FILE NAME.EXT
	MOV	(R3)+,(R4)+	;TO CURRENT FILE DESCRIPTOR BLOCK
	MOV	(R3),(R4)

	MOV	(R5)+,CYLNDR
	MOV	(R5)+,TRKSCT

	RPWRIT			;REWRITE DIRECTORY BLOCK
	 BCC	3$
	MOV	#-22,R0
	RPERROR

3$:	JMP	$CONSL
.SBTTL	ASCR50	ASCII TO RAD50 CONVERSION ROUTINE

;CALL:
;	ASCR50
;	  ASCII ADDRESS
;	  RAD50 ADDRESS
;NINE BYTES OF ASCII INPUT
;THREE WORDS OF RAD50 OUTPUT

$ASCR50:ADD	#4,12(SP)	;RETURN OVER TRAILING PARAMETERS
	PUSH	R0
	MOV	$EMADR,R5
	MOV	(R5)+,R1	;SETUP ASCII ADDRESS
	MOV	(R5),R4		;SETUP RAD50 STORAGE ADDRESS
	MOV	#066600,R3
1$:	CLR	(R4)		;RESULT WORD
2$:	MOV	#30$,R0		;SETUP SCAN TABLE
3$:	MOVB	(R0)+,R2	;PUT CONVERSION IN R2
	BEQ	20$		;IF END OF TABLE, ERROR
	CMPB	(R1),(R0)+	;COMPARE ASCII CHAR
	BLO	20$		;IF LESS THAN TABLE ENTRY, ERROR
	CMPB	(R1),(R0)+
	BHI	3$		;LOOP, HAVEN'T FOUND YET
	MOVB	(R1)+,R0	;FOUND, ASCII CHAR TO R0
	ADD	R2,R0		;CONVERT
	ASL	(R4)
	ASL	(R4)
	ASL	(R4)
	ADD	(R4),R0
	ASL	(R4)
	ASL	(R4)
	ADD	R0,(R4)
	ASL	R3		;SHIFT RAD50 WORD COUNTER
	BMI	2$		;NOT DONE WITH THIS RAD50 YET
	BEQ	10$		;IF 0, ALL DONE
	TST	(R4)+		;STEP TO NEXT RAD50 WORD
	BR	1$		;GO DO NEXT
10$:	POP	R0
	EXIT
20$:	POP	R0
	EXITERR

30$:	.BYTE	-40,' ,' 	;SPACE
	.BYTE	-11,'$,'$	;DOLLAR SIGN
	.BYTE	-22,'.,'.	;PERIOD
	.BYTE	-22,'0,'9	;DIGITS
	.BYTE	-100,'A,'Z	;UPPER CASE LETTERS
	.ENABL	LC
	.BYTE	-140,'a,'z	;LOWER CASE LETTERS
	.BYTE	0		;INDICATE THE END OF THE TABLE
	.EVEN
.SBTTL	RPLOAD	RP04 LOAD PACK (READ HOME BLOCK) ROUTINE

$RPLOAD:RPINIT			;INITIALIZE RP04
	BCS	10$

	MOV	#-6,R5
	CLR	CYLNDR
	MOV	#1,TRKSCT
	MOV	#DVBUF,BUFADR
	MOV	#BLKSIZ,BUFSIZ
	MOV	#-BLKSIZ,WRDCNT
	RPREAD			;READ HOME BLOCK
	BCS	9$		;-6 ERROR
	DEC	R5

;SAVE INFORMATION ABOUT THE INDEX FILE & FILE DIRECTORY

	MOV	#DVBUF+<↑D105*2>,R1
	MOV	#RPIXCY,R2
1$:	MOV	(R1)+,(R2)+
	CMP	R1,#DVBUF+<↑D111*2>
	BLO	1$

;CHECK THAT THIS IS REALLY THE HOME BLOCK

	CMP	DVBUF,#105755	;LAST 16 BITS OF "HOM" IN SIXBIT
	BNE	9$		;-7, BRANCH IF NOT HOM BLOCK
	DEC	R5

;CHECK THAT THIS PACK CONTAINS OUR FILE SYSTEM (KLFEDDCS)

	MOV	#DVBUF+<↑D98*2>,R1
	MOV	#FSNAME,R2
2$:	CMP	(R1)+,(R2)+
	BNE	9$		;-10, BRANCH IF FILE SYSTEM NAME IS INCORRECT
	CMP	R1,#DVBUF+<↑D104*2>
	BLO	2$
	DEC	R5
	TST	RPIXCY		;DOES INDEX FILE EXIST?
	BLE	9$		;-11, BRANCH IF INDEX FILE DOES NOT EXIST
	DEC	R5
	TST	RPFDCY		;DOES FILE DIRECTORY EXIST?
	BLE	9$		;-12, BRANCH IF FILE DIRECTORY DOES NOT EXIST
	EXIT			;INDICATE SUCCESS

9$:	MOV	R5,R0		;PUT ERROR CODE IN R0
10$:	SETFLG			;INDICATE FAILURE
	  RPUNIT
11$:	EXITERR

FSNAME:	.ASCII	/KLFEDDCS    /	;FILE SYSTEM NAME
.SBTTL	RPFIND	FIND FILE IN RP04 DIRECTORY

;R0 = POINTER TO FILE NAME IN RAD50
;R1 = POINTER TO RETURN STORE BLOCK
;	CORE ADR OF FILE DESCRIPTOR BLOCK
;	CYLINDER NUMBER
;	TRACK/SECTOR NUMBER

$RPFIND:MOV	R0,R4		;SAVE FILE NAME POINTER
	MOV	R1,R5		;SAVE RETURN POINTER
	MOV	#DVBUF,BUFADR
	MOV	#-BLKSIZ,WRDCNT
	MOV	#BLKSIZ,BUFSIZ
	MOV	#FILDSB,R3	;SETUP FILE DESCRIPTOR POINTER
	MOV	#RPFDCY,R2	;SETUP DIRECTORY START

	MOV	(R2)+,4*2(R3)
	MOV	(R2)+,5*2(R3)
	MOV	(R2),R0		;CHANGE DIR BLOCK COUNT TO
	SHIFTL			;WORD COUNT
	  8.
	MOV	R0,9.*2(R3)
	CLR	8.*2(R3)

	MOV	R3,R2
	ADD	#FDESIZ*2,R2
	CLR	(R2)+		;CLEAR CURRENT POSITION
	CLR	(R2)

1$:	MOV	R3,R0
	RPRDFL			;READ DIRECTORY DATA BLOCK
	 BCS	4$		;ERROR

	MOV	(R0)+,R2	;DATA BUFFER POSITION
	MOV	(R0),R1		;BYTE COUNT
2$:	CMP	(R2),(R4)	;COMPARE DIRECTORY ENTRY
	BNE	3$		;AND REQUESTED FILE
	CMP	1*2(R2),1*2(R4)
	BNE	3$
	CMP	2*2(R2),2*2(R4)
	BNE	3$		;NOT THIS ENTRY

	MOV	R2,(R5)+	;RETURN CORE ADDRESS OF DESCRIPTOR BLOCK
	MOV	CYLNDR,(R5)+	;RETURN CYLINDER NUMBER
	MOV	TRKSCT,(R5)+	;RETURN TRACK/SECTOR NUMBERS
	EXIT			;"SUCCESS" RETURN

3$:	ADD	#FDESIZ*2,R2	;FINISHED THIS DIRECTORY BLOCK ?
	SUB	#FDESIZ*2,R1
	BHI	2$		;NO
	BR	1$		;YES, GO READ NEXT

4$:	CMP	#1,R0		;EOF ?
	BNE	5$		;NO, RETURN ERROR CODE
	MOV	#-24,R0		;YES, RETURN EOF CODE
5$:	EXITERR
.SBTTL	RPLKUP	RP04 FILE DIRECTORY LOOKUP ROUTINE

;R0/ POINTER TO FILENAME IN RAD50
;R1/ STORE ADDRESS FOR FILE DESCRIPTOR

;FILE DESCRIPTOR BLOCK
;	 0/ FILENAME
;	 1/   "
;	 2/ FILE EXT
;	 3/ CREATION DATE
;	 4/ PHYSICAL BLOCK NUMBER
;	 5/   "
;	 6/ NUMBER OF WORDS ALLOCATED
;	 7/  "
;	 8/ NUMBER OF WORDS WRITTEN
;	 9/  "
;	10/ PDP-11 LOAD ADDRESS
;	11/ PDP-11 START ADDRESS
;	12/ FILE TYPE & FILE STATUS
;	13/ CHECKSUM
;	14/ 0
;	15/ 0
;	16/ CURRENT POSITION
;	17/  "

$RPLKUP:MOV	R1,R5		;SAVE FILE DESCRIPTOR POINTER
	MOV	#WRTBAK,R1

	RPFIND			;FIND FILE
	BCS	2$		;NOT THERE

	MOV	#FDESIZ,R2	;TRANSFER FILE INFO
	MOV	(R1),R1
1$:	MOV	(R1)+,(R5)+	;TO FILE DESCRIPTOR BLOCK
	DEC	R2
	BNE	1$

	CLR	(R5)+		;SET CURRENT POSITION AT ZERO
	CLR	(R5)+
	EXIT

2$:	EXITERR
.SBTTL	RPRDFL	READ A FILE (ON THE RP04)

;R0 = POINTER TO FILE DESCRIPTOR

$RPRDFL:MOV	R0,R2		;SETUP FILE DESCRIPTOR POINTER
	MOV	R2,R4
	ADD	#↑D16*2,R4	;R4 POINTS TO CURRENT POSITION BLOCK
	MOV	BUFSIZ,R3	;BUFFER SIZE TO R3

	MOV	↑D8*2(R2),R0	;R0 = M.S. NUMBER OF WORDS WRITTEN
	MOV	↑D9*2(R2),R1	;R1 = L.S. NUMBER OF WORDS WRITTEN
	SUB	2(R4),R1	;R1 = L.S. NUMBER OF WORDS REMAINING
	SBC	R0		;PROPAGATE THE "BORROW"
	SUB	(R4),R0		;R0 = M.S. NUMBER OF WORDS REMAINING
	BLT	40$		;BRANCH IF PAST EOF (ERROR)

	BGT	10$		;BRANCH IF MORE THAN 2**16 WORDS REMAIN

	TST	R1		;NOW LOOK AT L.S. # OF WORDS REMAINING
	BEQ	60$		;BRANCH IF AT EOF

	CMP	R1,R3		;COMPARE REMAINING WORDS WITH "BUFSIZ"
	BHI	10$		;BRANCH IF REMAINING WORDS IS LARGER

	MOV	R1,R3		;REMAINING WORDS IS SMALLER (OR EQUAL)
	BR	15$		;AVIOD TRUNCATING THE BUFFER SIZE

10$:	BIC	#BLKSIZ-1,R3	;TRUNCATE TO A MULTIPLE OF THE BLOCK SIZE

15$:	BIT	#BLKSIZ-1,2(R4)	;IS CURRENT POSITION A MULTIPLE OF BLOCK SIZE?
	BNE	50$		;BRANCH IF NOT A MULTIPLE OF BLOCK SIZE

	MOV	4*2(R2),CYLNDR	;CYLINDER NUMBER OF START OF FILE
	MOV	5*2(R2),TRKSCT	;TRACK,SECTOR OF START OF FILE
	MOV	(R4),R2		;R2 = M.S. CURRENT POSITION
	SWAB	R2
	BISB	3(R4),R2
	MOV	R2,OFFSET

	RPADDR			;COMPUTE BLOCK # TO BE READ
	NEG	R3
	MOV	R3,WRDCNT	;SETUP WORD COUNT
	NEG	R3

	RPREAD			;READ FILE DATA BLOCK
	BCS	70$		;READ ERROR

	ADD	R3,2(R4)	;UPDATE L.S. CURRENT POSITION
	ADC	(R4)		;PROPAGATE CARRY INTO M.S. CURRENT POSITION
	ASL	R3		;CONVERT WORDS READ TO BYTES
75$:	MOV	R3,$RPINFO+2	;AND STORE AS BYTE COUNT ARGUMENT
	MOV	BUFADR,$RPINFO	;STORE BUFFER ADDRESS
	MOV	#$RPINFO,R0
	EXIT

40$:	MOV	#-13,R0		;WE SEEM TO BE PAST THE EOF
	BR	30$
50$:	MOV	#-14,R0		;WE WERE POSITIONED AT A NON-MULTIPLE OF BLKSIZ
	BR	30$
60$:	MOV	#1,R0		;WE WERE ALREADY AT EOF
	BR	30$
70$:	MOV	#-15,R0		;INDICATE THAT NO DATA WAS READ
30$:	EXITERR
.SBTTL	RPWRFL	WRITE A FILE (ON THE RP04)

;R0 = POINTER TO FILE DESCRIPTOR
;BUFADR = ADDRESS OF BUFFER
;BUFSIZ = NUMBER OF WORDS TO BE WRITTEN
;RPEOF = BIT15=0, DON'T WRITE EOF; BIT15=1, WRITE EOF

$RPWRFL:MOV	R0,R2
	MOV	↑D16*2(R2),R0	;R0 = M.S. CURRENT POSITION
	MOV	↑D17*2(R2),R1	;R1 = L.S. CURRENT POSITION
	MOV	BUFSIZ,R3
	BEQ	70$		;BRANCH IF THE WORD COUNT IS ZERO

	TST	RPEOF		;WRITING AN EOF ?
	BMI	1$		;YES

	BIT	#BLKSIZ-1,R3	;IS BUFSIZ A MULTIPLE OF BLKSIZ?
	BNE	RPWER1		;BRANCH IF IT IS NOT A MULTIPLE

1$:	BIT	#BLKSIZ-1,R1	;IS THE CURRENT POSITION A MULTIPLE?
	BNE	RPWER2		;BRANCH IF IT IS NOT A MULTIPLE

	MOV	R0,R4		;R4 = M.S. CURRENT POSITION
	ADD	R3,R1		;R1 = L.S. NEW POSITION
	ADC	R0		;R0 = M.S. NEW POSITION
	CMP	↑D6*2(R2),R0	;COMPARE WITH WORDS ALLOCATED
	BGT	5$		;BRANCH IF MORE WORDS ALLOCATED

	BLT	RPWER3		;BRANCH IF NOT ENOUGH WORDS ALLOCATED

	CMP	↑D7*2(R2),R1	;ITS CLOSE, LOOK FURTHER
	BLO	RPWER3		;BRANCH IF NOT ENOUGH WORDS ALLOCATED

5$:	SWAB	R4
	BISB	<↑D17*2>+1(R2),R4
	MOV	R4,OFFSET
	MOV	↑D4*2(R2),CYLNDR ;CYLINDER NUMBER
	MOV	↑D5*2(R2),TRKSCT ;TRACK/SECTOR NUMBERS
	RPADDR
	NEG	R3
	MOV	R3,WRDCNT
	NEG	R3

	RPWRIT			;WRITE DATA BLOCK
	BCS	RPWER5
	ADD	R3,↑D17*2(R2)	;COMPUTE NEW CURRENT POSITION
	ADC	↑D16*2(R2)	;PROPAGATE CARRY
	MOV	↑D17*2(R2),↑D9*2(R2) ;SET EOF AT CURRENT POSITION
	MOV	↑D16*2(R2),↑D8*2(R2) ;(M.S. ALSO)

70$:	TST	RPEOF		;ARE WE WRITING AN EOF
	BPL	RPWEX		;NO
	MOV	R2,R0
	MOV	#WRTBAK,R1

	MOV	#DVBUF,BUFADR
	MOV	#-BLKSIZ,WRDCNT
	MOV	#BLKSIZ,BUFSIZ

	MOV	2(R1),CYLNDR	;SETUP SAME DIRECTORY BLOCK
	MOV	4(R1),TRKSCT

	RPREAD			;READ CURRENT FILE DIRECTORY BLOCK
	BCS	RPWER4

	MOV	(R1)+,R3
	CMP	↑D6*2(R2),↑D6*2(R3)
	BNE	RPWER0		;BRANCH IF ALLOCATION IS DIFFERENT
	CMP	↑D7*2(R2),↑D7*2(R3)
	BNE	RPWER0		;BRANCH IF ALLOCATION IS DIFFERENT

	MOV	#FDESIZ,R4
71$:	MOV	(R2)+,(R3)+
	DEC	R4
	BNE	71$

	MOV	(R1)+,CYLNDR
	MOV	(R1)+,TRKSCT

	RPWRIT			;REWRITE DIRECTORY
	BCS	RPWER4

RPWEX:	EXIT			;SUCCESSFUL COMPLETION WITH NO EOF

RPWER0:	MOV	#-16,R0		;ATTEMPT TO CHANGE FILE'S ALLOCATION
	BR	RPWERX
RPWER1:	MOV	#-17,R0		;BUFSIZ IS NOT A MULTIPLE OF BLOCK SIZE
	BR	RPWERX
RPWER2:	MOV	#-20,R0		;CURRENT POS. IS NOT A MULTIPLE OF BLOCK SIZE
	BR	RPWERX
RPWER3:	MOV	#-21,R0		;INSUFFICIENT ALLOCATION TO COMPLETE THIS WRITE
	BR	RPWERX
RPWER4:	MOV	#-22,R0		;DIRECTORY REWRITE FAILURE
	BR	RPWERX
RPWER5:	MOV	#-23,R0		;DATA BLOCK WRITE FAILURE

RPWERX:	EXITERR
.SBTTL	RPINIT	STORES UNIT NUMBER & TRIES TO SET VOLUME VALID

$RPINIT:MOV	#-1,R0
	MOV	RPUNIT,R2	;CHECK RP04 UNIT #
	BIT	#↑C7,R2
	BNE	2$		;-1 ERROR, BAD

	DEC	R0
	MOV	RPRH11,R1
	MOV	#RPCLR,RPCS2(R1) ;CLEAR RP04
	MOV	R2,RPCS2(R1)	;SELECT
	BIT	#RPDVA,(R1)	;IS DRIVE AVAILABLE ?
	BEQ	2$		;-2 ERROR, NO

	DEC	R0
	MOV	RPDS(R1),R2	;READ STATUS
	COM	R2
	BIC	#↑C<RPMOL!RPDPR!RPDRY>,R2
	BNE	2$		;-3 ERROR, DRIVE ERROR

	DEC	R0
	MOV	#RPPRST,(R1)	;SET READ-IN PRESET
1$:	TSTB	(R1)		;WAIT FOR CONTROLLER READY
	BPL	1$

	BIT	#<RPTRE!RPMCPE>,(R1)
	BNE	2$		;-4 ERROR, DRIVE ERROR

	DEC	R0
	BIT	#<RPATA!RPERR>,RPDS(R1)
	BNE	2$		;-5 ERROR, DRIVE ERROR

3$:	EXIT

2$:	BIS	#100000,RPUNIT	;ERROR, FORCE RESELECT
	EXITERR

.SBTTL	RPBASE	RETURN RP04 PARAMETER BLOCK BASE ADDRESS

$RPBASE:MOV	#FILDSB,R0
	EXIT
.SBTTL	RPREAD & RPWRIT, RP04 READ & WRITE I/O ROUTINES

$RPWRIT:MOV	#RPWTFN,R5	;SETUP WRITE FUNCTION
	CLR	R4
	BR	RPFUNC

$RPREAD:MOV	#RPRDFN,R5	;SETUP READ FUNCTION
	MOV	#10.,R4		;10 RETRIES

RPFUNC:	JSR	PC,$PTTYC
	TST	RPUNIT		;VALID UNIT ?
	BMI	2$		;NO

	MOV	RPRH11,R1
5$:	MOV	RPUNIT,RPCS2(R1) ;SELECT DRIVE
	BIT	#RPDVA,(R1)	;IS DRIVE AVAILABLE ?
	BEQ	2$		;NO

	MOV	RPDS(R1),R2	;CHECK DRIVE STATUS
	COM	R2
	BIC	#↑C<RPMOL!RPDPR!RPDRY!RPVV>,R2
	BNE	2$		;ERROR

	MOV	CYLNDR,RPDC(R1)	;START DRIVE OPERATION
	MOV	TRKSCT,RPDA(R1)
	MOV	BUFADR,RPBA(R1)
	MOV	WRDCNT,RPWC(R1)
	MOV	R5,(R1)

1$:	BIT	#<RPTRE!RPMCPE!RPRDY>,(R1)
	BEQ	1$		;WAIT FOR COMPLETION OR ERROR

	BIT	#<RPTRE!RPMCPE>,(R1)
	BNE	2$		;ERROR

	BIT	#<RPATA!RPERR>,RPCS2(R1)
	BNE	4$		;ERROR

3$:	EXIT			;COMPLETED

2$:	EXITERR

4$:	DEC	R4		;RETRY READ ERRORS, 10 TIMES
	BLE	2$		;HARD ERROR
	MOV	#RPCLR,RPCS2(R1) ;CLEAR RP04
	BR	5$		;TRY AGAIN
.SBTTL	RPADDR	ADDS OFFSET TO AN RP04 PHYSICAL ADDRESS

$RPADDR:MOV	CYLNDR,R0	;SETUP INITIAL VALUES
	MOV	TRKSCT,R1
	MOV	OFFSET,R2

	MOVB	R1,R3		;COMPUTE NEW POSITION
	CLRB	R1
	SWAB	R1
	ADD	R3,R2
1$:	BPL	2$
	DEC	R0
	ADD	#↑D19*↑D20,R2
	BR	1$
2$:	SUB	#↑D19*↑D20,R2
	BLT	3$
	INC	R0
	BR	2$
3$:	ADD	#↑D19*↑D20,R2
4$:	SUB	#↑D20,R2
	BLT	5$
	INC	R1
	BR	4$
5$:	ADD	#↑D20,R2
6$:	SUB	#↑D19,R1
	BLT	7$
	INC	R0
	BR	6$
7$:	ADD	#↑D19,R1
	SWAB	R1
	BISB	R2,R1

	MOV	R0,CYLNDR	;RETURN NEW POSITION
	MOV	R1,TRKSCT
	EXIT