C	PROGRAM MAGTAP.FT
C	-----------------
C
C
C
C	MAGTAP - A TC58 MAGTAPE HANDLER FOR OS/8 FORTRAN II.
C	---------------------------------------------------
C
C
C
	SUBROUTINE MAGTAP(NUMB,ADDR,ICMD,MTRS,IBYTE,IUNIT)
C
C
C	PETER LEMKIN
C	IPU, DBCD
C	NATIONAL CANCER INSTITUTE
C	NATIONAL INSTITUTES OF HEALTH
C	BETHESDA, MD. 20014
C
C	AUG 12 1976 - ADDED XTENDED GAP
C	AUG 11, 1976 - WORKS
C	AUG 8, 1976 - REVISED FROM OLD GLASS&LEMKIN ROUTINE.
C
C
C	ABSTRACT
C	------------
C	"MAGTAP" IS AN OS/8  FORTRAN II SUBROUTINE WHICH
C	ENABLES THE USER TO CONTROL EITHER A TU10
C	OR A TU20 9 TRACK MAGTAPE DRIVE UTILIZING
C	THE TC58 CONTROLLER. THIS MAGTAPE DEVICE HANDLER
C	ALLOWS THE USER TO READ, WRITE, READ-COMPARE,
C	SPACE BACKWARDS, SPACE FORWARD, WRITE END OF FILE,
C	CHECK FOR BEGINING OR END OF TAPE, CHECK
C	FOR END OF FILE MARK, AND REWIND THE TAPE. MAGTAP RUNS
C	WITH INTERRUPTS OFF.
C
C
C
C	ARGUMENT LIST
C	-------------
C
C	NUMB	/THE NUMBER OF WORDS TO BE TRANSFERED
C		/TO OR FROM THE MAGTAP. 4096
C		/WORDS OR BYTES, IS THE MAXIMUM SIZE
C		/FOR THE ARGUMENT 'NUMB'.
C
C	ADDR	/THE FORTRAN VARIABLE ARRAY USED TO
C		/SPECIFY WHERE DATA IS READ OR WRITTEN.
C
C	ICMD	/THIS COMMAND RANGES OVER 0 TO 13.
C		/AND DISPATCHES THE FUNCTION SPECIFIED
C		/IN THE ICMD TABLE, (SECTION IV).
C
C	MTRS / RESULTS OF MTRS TC58 STATUS REGISTER AFTER COMMAND.
C
C	IBYTE / 0 IS BYTE MODE, +1 IS CORE DUMP MODE
C		ADD +2 FOR WRITING EXTENDED GAP FOR WRITE AND EOF
C
C	IUNIT /THE UNIT NUMBER OF THE MAGTAPE DRIVE
C		/MUST BE FROM 0 TO 7.
C
C
C
C
C	DEFINITION OF BYTE MODE:
C	------------------------
C	A BYTE (THE RIGHT 8 BITS OF A PDP8 WORD WHERE)
C	BITS 0-3 ARE NOT USED.) IS TRANSFERED TO THE 9 TRACK
C	MAGTAPE AS A ONE TAPE FRAME. THIS IS CONSTRUCTED
C	IN THE FOLLOWING MANNER: BITS 1 TO 8 ARE
C	AN 8-BIT BYTE WORD, AND BIT 9 IS THE PARITY BIT.
C	THIS MEANS THAT PDP8 BITS 4-11 ARE NOW MAGTAPE
C	BITS 1 TO 8.
C
C
C
C	CORE DUMP MODE
C	--------------
C	A PDP8 12-BIT WORD IS TRANSFERED TO THE 9
C	TRACK MAGTAPE AS TWO CONSECUTIVE 6-BIT BYTES. EACH
C	TAPE WORD IS CONSTRUCTED AS FOLLOWS:
C	BIT 9 IS USED AS A PARITY BIT, BITS 1 AND
C	2 ARE NOT USED, BITS 3 TO 6 ARE THE 6 BIT BYTE,
C	IE:THE FIRST PART OF THE 12 BIT PDP8 WORD
C	IS BITS 0-5. THE SECOND PART OF THE 12 BIT WORD
C	IS BITS 6-11.
C
C
C
C
C
C
C
C	MTRS (OCTAL) STATUS BIT PATTERNS FOR VARIOUS CONDITIONS
C	-------------------------------------------------------
C	1616 - READ/WRITE ERROR
C	1636 - READ/COMPARE ERROR
C	0100 - EOF DETECTED
C	1000 - BOT DETECTED
C	0040 - EOT DETECTED
C
C	MTRS BITS
C	---------
C	4000 - ERROR FLAG
C	2000 - TAPE REWINDING
C	1000 - BOT
C	0400 - ILLEGAL COMMAND
C	0200 - PARITY ERROR (LAT OR LONG)
C	0100 - EOF
C	0040 - EOT
C	0020 - READ/COMPARE ERROR
C	0010 - RECORD LENGTH (WC=0 LONG, WC NEQ 0 SHORT)
C	0004 - DATA REQUEST LATE
C	0002 - BAD TAPE
C	0001 - MTF OR JOB DONE
C
C	IV. ICMD COMMAND TABLE ASSIGNMENTS.
C	------------------------------
C	ICMD	FUNCTION
C	----	--------
C	0	NO OPERATION (NOP )
C
C	NUMB:-
C	ADDR:-
C	ICMD:=0
C	MTRS: MTRS STATUS
C	IBYTE:-
C	IUNIT:-
C
C
C	1	REWIND THE TAPE
C
C	NUMB:-
C	ADDR:-
C	ICMD:=1
C	MTRS: MTRS STATUS
C	IBYTE:-
C	IUNIT:UNIT #
C
C
C	2	READ 1 RECORD FROM THE TAPE.
C	A RECORD MAY BE ANY NUMBER OF
C	WORDS,DEPENDING ON THE SIZE OF
C	"NUMB".
C
C	NUMB: # OF PDP8E WORDS TO TRANSFER
C	ADDR: TC58/PDP8 I/O BUFFER
C	ICMD:=2
C	MTRS: MTRS STATUS .
C	IBYTE: BYTE(0)/CORE DUMP(1)
C	IUNIT:UNIT #
C
C
C	3	READ/COMPARE 1 RECORD FROM THE TAPE.
C
C	NUMB: # OF PDP8E WORDS TO TRANSFER
C	ADDR: TC58/PDP8 I/O BUFFER
C	ICMD:=3
C	MTRS: MTRS STATUS
C	IBYTE: BYTE(0)/CORE DUMP(1)
C	IUNIT:UNIT #
C
C	4	WRITE 1	RECORD ONTO THE TAPE.
C
C	NUMB: # OF PDP8E WORDS TO TRANSFER
C	ADDR: TC58/PDP8 I/O BUFFER
C	ICMD:=4
C	MTRS: MTRS STATUS .
C	IBYTE: BYTE(0)/CORE DUMP(1)
C	IUNIT:UNIT #
C
C
C	5	WRITE END OF FILE
C
C	NUMB:-
C	ADDR:-
C	ICMD:=5
C	MTRS: MTRS STATUS
C	IBYTE: BYTE(0)/CORE DUMP(1)
C	IUNIT:UNIT #
C
C
C	6	SPACE FORWARD 1 RECORD.
C
C	NUMB: # OF RECORDS TO  FORWARD.
C	ADDR:-
C	ICMD:=6
C	MTRS: MTRS STATUS
C	IBYTE: BYTE(0)/CORE DUMP(1)  
C	IUNIT:UNIT #
C
C
C	7	SPACE REVERSE 1 RECORD.
C
C	NUMB: # OF RECORDS TO  REVERSE.
C	ADDR:-
C	ICMD:=7
C	MTRS: MTRS STATUS
C	IBYTE: BYTE(0)/CORE DUMP(1)  
C	IUNIT:UNIT #
C
C
C
C	V. COMPILING AND LOADING
C	------------------------
C	. R FORT
C	*MAGTAP.RL,MAGTAP.LS<--MAGTAP.FT
C	.R LOADER
C	*MAIN AND ANY SUBROUTINES...
C       *MAGTAP.RL
C	* ETC...
C	*LIB8/L$
C	.SAVE SYS:MAIN ETC...
C
C
C
C	VI. ADDITIONAL INFORMATION
C	----------------------
C	FOR A COMPLETE DESCRIPTION OF WHICH
C	MAGTAPE COMMANDS MUST BE USED AND WHICH
C	COMMANDS MAY BE IGNORED FOR ANY CALL
C	TO THIS SUBROUTINE SEE: INSTRUCTION MANUAL
C	------------------
C	MAGNETIC TAPE CONTROL-TC58, SECTION 2.6
C	---------------------------------------
C	OF DEC-08-I4AA-D , MARCH 1968.
C	-------------------------------
C
C
C
C	NEW SABR OPERATORS
C	--------------------
S	OPDEF MTAF 6712	/CLEAR THE STATUS AND COMMAND REGISTOR
S	OPDEF MTLC 6716	/LOAD THE CONTENTS OF AC0-11 INTO
C	/THE COMMAND REGISTOR
S	OPDEF MTGO 6722	/EXECUTE THE COMMAND IN THE COMMAND
C	/REGISTOR
S	OPDEF MTRS 6706	/READ CONTENSE OF STATUS REGISTOR
S	OPDEF MTRC 6724 /OR THE COMMAND REGISTER INTO THE AC.
S	SKPDF MTCR 6711	/SKIP ON TAPE CONTROLL READY
S	SKPDF MTSF 6701	/SKIP ON ERROR FLAG OR MAGTAP FLAG
S	SKPDF MTTR 6721	/SKIP ON TAPE TRANSPORT READY
C
C	[0.0] POINTERS
	GOTO 123
C	****POINTERS*****
S	DUMMY WC7752
S	DUMMY CA7753
S	CPAGE 2
S WC7752,	6201
S	7752
S	CPAGE 2
S CA7753,	6201
S	7753
C
S COMMAND,	0 /COMMAND FORMED FROM ICMD & COMMAND MASK.
S BFIELD,	0 /DATA BUFFER FIELD FROM ADDR.
C
C
C
C	[1.0] CALL BY VALUE, AND INITIALIZE.
123	KBYTE=0
C	INIT OUTPUT ERROR DEVICE
	IDEV=1

C
C	TEST IBYTE .AND. '0002 FOR EXTENEDED GAP
	IXTDGAP=0
S	TAD I \IBYTE /LOOK AT BIT 10 FOR EXTENDED GAP
S	AND (0002
S	SZA CLA
S	TAD (100 /EXTENDED 3 INCH GAP
S	DCA \IXTDGAP
C
C
C	[2] TEST IF LEGAL COMMAND. IF SO THEN PUT INTO
C	COMMAND REGISTER WORD BITS 6:8.
C	IS COMMAND MINUS < 0?
	IF(ICMD)2,3,3
2	WRITE(IDEV,902)ICMD
	RETURN
902	FORMAT(' BAD MAGTAP COMMAND. ICMD=',I5)
C
C
C
C	[2.1] TEST IF A MAGTAPE COMMAND  .LE. 7.
3	IF(ICMD-7)4,4,2
S\4,	TAD I \ICMD
S	RTL;RAL
S	AND (0070 /00 TO 70
S	DCA \ICMD
C
C	[3] TEST IF BYTE(0) OR CORE DUMP(1) MODE.
S	TAD I \IBYTE
S	AND (0001 /ONLY LOOK AT THE MODE BIT
S	SZA CLA
S	JMP \41 /CORE DUMP
C
C
C
C	[3.1] BYTE MODE 0407 IS THE CONTROL WORD.
S\40,	TAD (0407
S	DCA \KBYTE
	GOTO 42
C
C
C
C
C
C	[3.2] DUMP MODE 0607-IS THE CONTROL WORD.
S\41,	TAD (0607
S	DCA \KBYTE
C
C
C
C	[4] SET UP THE WORD COUNT AND THE CURRENT ADDRESS
C	REGISTERS.
S \42,	CLA
S	TAD I \NUMB
S	CIA
S	DCA I WC7752 /WORD COUNT
C
S	TAD \ADDR /GET THE FIELD FROM THE DUMMY POINTER
S	AND (0070
S	DCA BFIELD /DATA FIELD
S	CLA CMA /LOAD -1
C
S	TAD \ADDR# /GET THE ADDRESS FROM THE DUMMY POINTER
S	DCA I CA7753 /CURRENT ADDRESS
C
C
C	[5] CHECK IF IUNIT IS LEGAL (0 TO 7)
	IF(IUNIT)64,66,66
66	IF(IUNIT-7)63,63,64
64	WRITE(IDEV,65)IUNIT
65	FORMAT(' IUNIT MUST BE FROM 0 TO 7 : ',I5)
	RETURN
C
C	[5.1] MOVE IUNIT INTO BITS 0 TO 2.
S\63,	CLA
S	TAD I \IUNIT
S	RTL;RTL;RTL /LEFT SHIFT 6 BITS
S	RTL;RAL /LEFT SHIFT ANOTHER 3
S	AND (7000	/MAKE SURE BITS 0 TO 2
S	DCA \IUNIT /SAVE FOR INSERTION INTO COMMAND WORD
C
C	[6] COMPUTE THE COMPLETE THE COMMAND
S	TAD \ICMD 	/00X0
S	TAD \IUNIT 	/X000
S	TAD \KBYTE	/0407 OR 0607
S	TAD \IXTDGAP	/0000 (NO GAP), 100 (3 INCH GAP)
S	DCA COMMAND
C
C
C
C	[7] CLEAR THE CONTROLLER AND WAIT FOR BOTH DRIVE
C	AND CONTROLLER  TO BECOME READY
S	MTAF	/CLEAR TAPE CONTROL REGISTERS.
C	WAIT FOR THE TAPE TO BECOME READY
S WAIT1C,	MTCR /CONTROLLER READY?
S	JMP WAIT1C /NO
C
S WAIT1T,	MTTR /TRANSPORT READY?
S	JMP WAIT1T /NO
C
C
C	[8] LOAD CMD REGISTER
S	TAD COMMAND
S	MTLC	/LOAD THE COMMAND.
S	CLA
C
C	[9] START THE OPR WITH BUFFER FIELD IN THE AC
S	TAD BFIELD	/GET THE BUFFER FIELD.
S	MTGO	/GO DO IT.
S	CLA
C
C	[10] WAIT FOR CONTROLLER TO BE READY
S WAIT2C,	MTCR /CONTOLLER READY?
S	JMP WAIT2C /NO
C
S WAIT2T,	MTTR /DRIVE READY
S	JMP WAIT2T /NO
C
C
C
C	[11] RETURN WITH TC58 STATUS IN MTRS.
S	MTRS /GET STATUS
S	DCA I \MTRS
C
C
C	[12] RETURN
	RETURN
	END
C	****POINTERS*****
S	DUMMY WC7752
S	DUMMY CA7753
S	CPAGE 2
S WC7752,	6201
S	7752
S	CPAGE 2
S CA7753,	6201
S	7753
C
S COMMAND,	0 /COMMAND FORMED FROM ICMD & COMMAND MASK.
S BFIELD,	0 /DATA BUFFER FIELD FROM ADDR.
C