*1400
/
/
/NON-RESIDENT TAPE HANDLER MODULE. PERFORMS ALL LINC
/TAPE I/O. DECODES MTP INSTRUCTION AND EXECUTES SAME.
/
/
	-TAPEM		/INDICATOR THAT THIS IS TAPE MOD
	JMS	GETP1	/PUT SECOND INSTR WD IN SBN
	TAD	TIFLG	/TAPE COMMAND INTERRUPTED?
	SZA CLA
	JMP	MTPC	/YES, CONTINUE
/
/WE WERE NOT INTERRUPTED, MUST SET EVERYTHING UP
/
	TAD	LINS
	DCA	MTPINS	/PUT LINC INSTR IN MTPINS
	JMS	RS20	/DO THINGS IF THIS IS BY DO SW
	CLC
	DCA	WCGF
MTP0,	TAD	SBN	/GET SECOND WORD OF INSTR
	AND	(777	/GET BLOCK NUMBER
	DCA	BN	/AND SAVE
/
/SEE IF WE ARE DOING A GROUP COMMAND
/
	TAD	LINS	/GET TAPE INSTR
	RTR
	SPA CLA
	SZL
	JMP	MTP1	/NOT A GROUP COMMAND
	JMS	SETG	/A GROUP COMMAND - SET UP FOR
	JMP	MTPI
/
/NOT A GROUP COMMAND - SET UP FOR
/
MTP1,	TAD	SBN	/GET SECOND WORD OF INSTR
	RTL
	RTL
	AND	C7	/GET QUARTER NUMBER
	DCA	QN	/AND SAVE
	CLC
	DCA	QCT	/ONLY 1 QTR ALLOWED
	DCA	WCGF	/CLEAR WRT GRP CNT FLG
MTPC,	DCA	TIFLG	/CLEAR TAPE INTERRUPT FLAG
/
/DECODE THE MAG TAPE INSTRUCTION
/
MTPI,	TAD	MTPINS	/GET FIRST WORD OF INSTR
	AND	C7
	TAD	(JMP I MTPJ
	DCA	.+1
	0
MTPJ,	RDC		/READ AND CHECK BLOCK
	RDC		/READ AND CHECK GROUP
	RDE		/READ, NO CHECK
	MTB		/MOVE TOWARD BLOCK
	WRC		/WRITE AND CHECK BLOCK
	WCG		/WRITE AND CHECK GROUP
	WRI		/WRITE, NO CHECK
	CHK		/CHECK ONLY
 
/
/SEARCH TAPE FOR RIGHT BLOCK NUMBER
/
SEARCH, 0
	TAD	(SKP CLA
	DCA	MCDF	/NO STORAGE DURING CHK
	JMS	STMEM
	DCA	WCDF
	TAD	WCDF
	ISZ	CHKS	/CHK?
	DCA	MCDF	/NO - SKIP IF YES
	CLA		/CLEAR AC ANYWAY
	TAD	MTPINS	/GET FIRST INSTR WORD
	RTR		/PUT UNIT BIT IN LINK
	RTR
	AND	(4	/WE WANT TO END UP WITH X002
	RAR		/MOVE UNIT BIT TO AC 0
	DCA	UNIT
	ICA
UNIT,	0		/SELECT UNIT
/
/SET TAPE UP TO BE MOVING FORWARD
/
	TAD	INTSAV
	RTR
	SPA CLA		/SKIP IF MOTION BIT = 0
	JMP	.+3
	TAD	(4001
	JMP	.+4
	SZL
	ICON
	IAC
	ICON		/MAKES GO FORWARD
	CLC
	DCA	LNCA	/SET UP FOR CHECKSUM
	TAD	(-401
	DCA	WCNT	/SET UP TO COUNT WORDS
CSRCH,	JMS	TPWAIT	/WAIT FOR NEXT BL NO.
	TAD	INTSAV
	RAR		/MOTION INTO LINK 1=BKWDS
	CLA
	IAAC
	TAD	BN
	IAC		/DIF: +=GO FWD, -=GO BKWD
	IACA		/DISPLAY DIFFERENCE
	SZA		/IS THIS THE BLOCK
	JMP	MTPS1	/NO
	SNL		/YES, FWD (L=1 FWD IF AC=0)
	JMP	TURN
/
/CORRECT BLOCK HAS BEEN FOUND
/
	ICA		/BLOCK MODE
	3
	ISZ	SEARCH
	JMP I	SEARCH	/EXIT FROM SUBROUTINE
/
/WE MUST GO THE OTHER WAY
/
TURN,	JMS	TPWAIT	/WAIT FOR NEXT BLOCK
	CLA CLL		/BEFORE TURNING AROUND
MTPS1,	SZL		/NOT THE BLOCK - CHG DIRECTION
	JMP	SX	/NO - EXIT
	CMA RAL		/YES
	CLA RAR
	ICON		/CLEAR MOTION
	IAC	
	ICON		/SET MOTION
SX,	CLA
	TAD	BN
	IACB		/DISPLAY BLOCK WANTED
	CLA
	JMP I	SEARCH	/AND EXIT
/
/SET UP TO WAIT FOR TAPE INTERRUPT
/
TPWAIT,	0		/SUBROUTINE ENTRANCE
	CLA
	TAD	TPWAIT	/GET EXIT ADDRESS
	DCA	TAPE	/SET UP TO RETURN THERE
	TAD	(TPW	/6
	DCA	JOBS	/INDICATE TAPE OPR IN PROGRESS
	ION		/ENABLE INTERRUPTS
	JMP	TIMER	/AND WAIT
/
/END OF PAGE SIX OF NON-RESIDENT TAPE HANDLER MODULE
/
	*1600
/
/MOVE TOWARD BLOCK
/
MTB,	JMS	SEARCH
	NOP
	IAAC	
	TAD	BN
	IACA
	DCA	LNCA	/SET TO RET DIFF IN LINC A
	ICA
C4,	4
	JMP	RDX
/
/CHECK BLOCK
/
CHK,	CLC
	DCA	CHKS	/SET CHK SW - NO DATA STORING
	SKP CLA
/
/READ AND CHECK
/
RDC,	CLC		/SET FOR CHECK
/
/READ BLOCK
/
RDE,	DCA	CHECK	/SET CHK SW - 0=NO CHK
	JMS	SEARCH
	JMP	CSRCH
	JMS	TPINT	/WAIT FOR CHECK MARK TO PASS
/
/READ LOOP
/
RDL,	JMS	TPINT	/WAIT FOR FIRST WORD
	IAAC
	TAD	LNCA
	DCA	LNCA	/FORM CHECKSUM
	ISZ	WCNT	/DONE YET?
	JMP	RWORD	/NOSSIR!!
	ICA
	6		/SHUT TAPE DOWN
	ISZ	CHECK	/CHECK WANTED?
	JMP	RDX	/NOPE
	IAC
	TAD	LNCA	/TEST CHECKSUM
	SZA CLA
	JMP	CKFAIL
	ISZ	BN
	ISZ	QN
	ISZ	QCT	/CHECH MAKES, MORE BLOCKS TO DO?
	JMP	MTPI
/
/TAPE READ EXIT
/
RDX,	TAD	MTPINS
	AND	C20
	SZA CLA		/LEAVE TAPE IN MOTION?
	JMP	DOGO	/YES, EXIT FROM INSTRUCTION
	ICA		/NO, STOP TAPE
	1
	ICA
	4001		/TURN AROUND MODE
	JMP	DOGO
/
/STORE THE WORD READ
/
RWORD,	IAAC		/GET WORD AGAIN
MCDF,	0		/PROPER CDF WILL BE HERE
	DCA I	MEMT
	CDF
	JMP	RDL
/
/WRITE AND CHECK GROUP
/
WCG,	TAD	WCGF
	SZA CLA
	JMP	WRC
WCHK,	CLC
	DCA	CHKS	/NO STORAGE DURING CHECK
	JMP	RDC
/
/A CHECK HAS FAILED DURING READ OR WRITE
/
CKFAIL, TAD	MTPINS	/GET TAPE INSTR
	AND	C4	/LOOK AT WRITE BIT
	SNA CLA		/IS IT SET
	JMP	RDC	/NO, READ AGAIN
/
/WRITE AND CHECK BLOCK
/
WRC,	CLC
/
/WRITE WITH NO CHECK
/
WRI,	DCA	CHECK
	JMS	SEARCH
	JMP	CSRCH
	ICA
	5
	ISZ	WCNT	/COUNT IS ONE HIGH FOR WRITE
/
/WRITE LOOP
/
WCDF,	0		/BECOMES RIGHT CDF
	TAD I	MEMT
	CDF
	IACB
	TAD	LNCA
	DCA	LNCA
	JMS	TPINT	/WAIT FOR WORD TO BE WRITTEN
	ISZ	WCNT
	JMP	WCDF
	TAD	LNCA
	CMA
	IACB
/
/WRITE CHECKSUM
/
	JMS	TPINT	/WRITE NEXT TO LAST WORD
	JMS	TPINT	/WRITE LAST WORD
	ICA
	6
	TAD	WCGF
	SZA CLA
	JMP	WGP
	ISZ	CHECK
	JMP	RDX
	JMP	WCHK
WGP,	ISZ	BN
	ISZ	QN
	ISZ	QCT
	JMP	MTPI
	DCA	WCGF
	JMP	MTP0
/
/TAPE WAIT ROUTINE, FOR READING OR WRITING INDIVIDUAL
/WORDS IN A BLOCK WITH THE INTERRUPT OFF.
/
TPINT,	0		/SUBROUTINE ENTRANCE
	CLA
	INTS		/GET LINC INTERRUPT STATUS
	SMA CLA		/IS TAPE INTERRUPT SET
	JMP	.-2	/NO
	ICA		/YES, CLEAR INTERRUPTS
	7
	JMP I	TPINT	/AND RETURN
/
/FLAGS AND COUNTS
/
CHECK,	0		/CHECK WANTED - 0=NO
WCNT,	0		/WORD COUNT
CHKS,	0		/CHECK SWITCH - 0=CHECK
/
/END OF NON-RESIDENT TAPE HANDLER MODULE
/
/END OF PROGRAM.