### FILE="Main.annotation"
## Copyright:   Public domain.
## Filename:	SERVICER207.agc
## Purpose:     Part of the source code for Colossus build 237.
##              This is for the Command Module's (CM) Apollo Guidance
##              Computer (AGC), for Apollo 8.
## Assembler:   yaYUL
## Contact:     Jim Lawton <jim DOT lawton AT gmail DOT com>
## Website:     www.ibiblio.org/apollo/index.html
## Page Scans:  www.ibiblio.org/apollo/ScansForConversion/Colossus237/
## Mod history: 2011-02-28 JL	Adapted from corresponding Colossus 249 file.
##		2017-01-01 RSB	Proofed comment text using octopus/ProoferComments,
##				and fixed errors found.
##		2017-01-18 RSB	Fixed comment-text errors noted while diff'ing
##				vs Colossus 249.

## Page 770
# PROGRAM NAME - PREREAD, READACCS, SERVICER, AVERAGE G.


# MOD NO.  00   BY M.HAMILTON   DEC.12, 1966


# FUNCTIONAL DESCRIPTION

# THE ROUTINES DESCRIBED BELOW ARE USED TO CALCULATE VALUES OF RN, VN, AND GDT/2 DURING ACCELERATED FLIGHT.
# THE SEVERAL ROUTINES COMPRISE A PACKAGE AND ARE NOT MEANT TO BE USED AS SEPARATE SUBROUTINES.

# GENERAL REFERENCES TO  SERVICER  OR  AVERAGE G  ARE UNDERSTOOD TO REFER TO THE ENTIRE SET OF ROUTINES INCLUDING
# READACCS, SERVICER, AVERAGE G, INTEREAD, SMOOTHER, AND ANY ADDITIONAL ROUTINES ATTACHED AT AVGEXIT (SEE BELOW).

# PROGRAMS INITIATING SERVICER ARE REQUIRED TO MAKE A WAITLIST CALL FOR PREREAD (OR, IF LIFTOFF, FOR BIBIBIAS)
# AT 2 SECONDS BEFORE THE FIRST AVERAGE G UPDATE IN ORDER TO INITIALIZE THE SEQUENCE, WHICH WILL RECUR EVERY
# 2 SECONDS FROM THAT TIME ON AS LONG AS AVEGFLAG REMAINS SET.

# THE USE OF ERASABLE AVGEXIT ALLOWS VARIOUS ROUTINES TO BE PERFORMED AS PART OF THE NORMAL CYCLE (SEE
# EXPLANATION OF AVGEXIT BELOW).

# DESCRIPTIONS OF INDIVIDUAL ROUTINES FOLLOW.


#    PREREAD

#          PREVIOUSLY EXTRAPOLATED VALUES COPIED FROM RN1, VN1, AND PIPTIME1 INTO RN, VN, AND PIPTIME.
#          LASTBIAS JOB SCHEDULED.
#          PIPS READ AND CLEARED VIA PIPASR SUBROUTINE.
#          AVERAGE G FLAG SET ON.
#          DRIFT FLAG SET OFF.
#          V37 FLAG SET ON.
#          INITIALIZATION OF   1) THRUST MONITOR (DVMON) - DVCNTR SET TO ONE.
#                              2) TOTAL ACCUMULATED DELV VALUE (DVTOTAL) - SET TO ZERO.
#                              3) AXIS VECTOR (AXIS) - SET TO (.5,0,0).
#          NORMLIZE JOB SCHEDULED.
#          READACCS TASK CALLED IN 2 SECONDS.


#    NORMLIZE

#          GDT/2 INITIALIZED VIA CALCGRAV SUBROUTINE.


#    READACCS

#          IF ONMON FLAG SET QUIKREAD ROUTINE IS PERFORMED BEFORE PIPASR ZEROS THE PIPA REGISTERS, AND THE 1/2 SEC
#          ONMONITOR LOOP IS INITIATED TO PROVIDE DOWNLINK INFORMATION DURING ENTRY.
#          PIPS READ AND CLEARED BY PIPASR SUBROUTINE.
#          IF CM/DSTBY IS ON, ENTRY VARIABLES INITIALIZED AND SETJTAG TASK CALLED.
## Page 771
#          IF AVERAGEG FLAG ON    READACCS CALLED TO RECYCLE IN 2 SECONDS.
#          IF AVERAGEG FLAG OFF   AVERAGE G EXIT (AVGEXIT) SET TO 2CADR AVGEND FOR FINAL PASS.
#          SERVICER JOB SCHEDULED.


#          TEST CONNECTOR OUTBIT TURNED ON.


# ONMNITOR

#          A SEQUENCE OF THREE PASSES THROUGH QUICKREAD FOLLOWING A CALL TO READACCS WITH ONMONFLG SET AT 1/2 
#          SEC INTERVALS. INTERVALS ARE COUNTED OUT BY PIPCTR, INITIALISED AT 3 BY READACCS

#    QUIKREAD

#        READS CURRENT PIPS INTO X,Y,ZPIPBUF. READS OLD X,Y,ZPIPBUF INTO X,Y,ZOLDBUF. VALUES ARE SENT TO
#          DOWNLIST DURING ENTRY.
#    SERVICER
#          DELV VALUES CHECKED TO DETECT RUNAWAY PIP -
#                 IF BAD PIP   1) ALARM SENT.
#                              2) COMPENSATION, DVTOTAL ACCUMULATION, AND DVMON BYPASSED.  CONTROL
#                                 TRANSFERRED TO AVERAGE G.
#          PIPS COMPENSATED VIA 1/PIPA SUBROUTINE.
#          DVTOTAL INCREMENTED BY ABSOLUTE VALUE OF DELV.
#          THRUST MONITOR (DVMON) PERFORMED UNLESS IDLE FLAG IS ON.
#          CONTROL TRANSFERRED TO AVERAGE G.


#          DVMON

#             THRESHOLD VALUE (PLACED IN DVTHRUSH BY USER) CHECKED AGAINST ABSOLUTE VALUE OF DELV TO CHECK
#             THRUST LEVEL.
#                 IF THRUST    1) ULLAGE OFF ROUTINE PERFORMED.
#                              2) STEERING FLAG TURNED ON AT FIRST DETECTION OF THRUST.
#                              3) CONTROL TRANSFERRED TO AVERAGE G.
#                 IF NO THRUST 1) ON FIRST PASS THROUGH MONITOR, CONTROL TRANSFERRED TO AVERAGE G.
#                              2) ON SUBSEQUENT PASSES, CONTROL TRANSFERRED TO ENGINE FAIL ROUTINE IF THRUST
#                                 HAS FAILED FOR 3 CONSECUTIVE PASSES.


#		ENGINE FAIL

#                  ENGFAIL1 TASK CALLED IN 2.5 SECONDS.  THIS WILL RETURN CONTROL TO TIG-5 SO THAT THE IGNITION
#                      SEQUENCE MAY BE REPEATED.
#                  ENGINOF3 PERFORMED.
#                  DAP SET UP FOR RCS.


#    AVERAGE G

## Page 772
#          RN1, VN1, GDT1/2 CALCULATED VIA CALCRVG ROUTINE BY UPDATING RN, VN WITH DELV AND AN AVERAGED VALUE
#          OF GDT/2.
#          RN1, VN1, GDT1/2, PIPTIME1 COPIED INTO RN, VN, GDT/2, PIPTIME FOR RESTART PROTECTION.
#          CONTROL TRANSFERRED TO ADDRESS SPECIFIED BY USER (OR BY READACCS FOR LAST PASS) IN AVGEXIT.
#          LAST PASS (AVGEND)  1) FREE FALL GYRO COMPENSATION SET UP.
#                              2) DRIFT FLAG TURNED ON.
#                              3) STATE VECTOR TRANSFERRED VIA AVETOMID ROUTINE.
#                              4) ONMONITOR FLAG RESET.
#                              5) V37 FLAG RESET.
#                              6) TEST CONNECTOR OUTBIT RESET.
#                              7) CONTROL TRANSFERRED TO CANV37 TO CONTINUE MM CHANGE ROUTINE (R00).


# CALLING SEQUENCE

#          PREREAD ENTERED DIRECTLY FROM TIG-30 VIA POSTJUMP.
#          READACCS CALLED AS WAITLIST TASK.				.


# SUBROUTINES CALLED

#          UTILITY ROUTINES - PHASCHNG FLAGUP FLAGDOWN NOVAC FINDVAC WAITLIST ALARM NEWPHASE 2PHSCHNG

#          OTHER - PIPASR  1/PIPA  CALCGRAV  CALCRVG  AVETOMID


# NORMAL EXIT MODES

#          ENDOFJOB  TASKOVER  CANV37

#          AVGEXIT - THIS IS A DOUBLE PRECISION ERASABLE LOCATION BY WHICH CONTROL IS TRANSFERRED AT THE END
#                    OF EACH CYCLE OF AVERAGE G.
#                    THE 2CADR OF A ROUTINE TO BE PERFORMED AT THAT TIME (E.G., STEERING EQUATIONS TO BE PERFORMED
#                    AT 2 SECOND INTERVALS) MAY BE SET BY THE USER INTO AVGEXIT.
#                    ALL SUCH ROUTINES SHOULD RETURN TO SERVEXIT, WHICH IS THE NORMAL EXIT FROM AVERAGE G.

#          SERVEXIT - DOES A PHASE CHANGE FOR RESTART PROTECTION AND GOES TO ENDOFJOB.
#                    THE 2CADR OF SERVEXIT IS SET INTO AVGEXIT BY THE USER IF NO OTHER ROUTINE (SEE ABOVE).

#          AVGEND - LAST PASS OF AVERAGE G EXITS HERE, BYPASSING SPECIAL ROUTINE (SEE ABOVE UNDER READACCS).
#                    FINAL EXIT IS TO CANV37.                             F AVERAGE G).


# OUTPUT

#    DVTOTAL(2)  PIPTIME(2)  XPIPBUF(2)  YPIPBUF(2)  ZPIPBUF(2)
#    RN(6)        REFERENCE COORD.   SCALED AT 2(+29)M/CS
#    VN(6)        REFERENCE COORD.   SCALED AT 2(+7)M/CS
#    GDT/2(6)     REFERENCE COORD.   SCALED AT 2(+7)M/CS
#    DELV(6)      STABLE MEMB. COORD.SCALED AT 2(+14)*5.85*10(-4)M/CS (KPIP1 USED TO GET DV/2 AT 2(+7))
## Page 773
#    DELVREF(6)   REFERENCE COORD.   SCALED AT 2(+7)M/CS

# INITIALIZATION

#          ONMONITOR FLAG SET BY ENTRY TO SHOW PIPBUF VALUES REQUIRED.
#          IDLE FLAG ON IF DVMON TO BE BYPASSED.
#          DVTHRUSH SET TO APPROPRIATE VALUE FOR DVMON.
#          AVGEXIT SET TO 2CADR OF ROUTINE, IF ANY, TO BE PERFORMED AFTER EACH CYCLE OF AVERAGE G.  IF NO ROUTINE
#                 TO BE DONE, AVGEXIT SET TO SERVEXIT.
#          VALUES NEEDED
#                 REFSMMAT
#                 UNITW - FULL UNIT VECTOR, IN REFERENCE COORD., OF EARTH S ROTATIONAL VECTOR
#                 RN1, VN1, PIPTIME1 - IN REFERENCE COORD., CONSISTENT WITH TIME OF EXECUTION OF PREREAD


# DEBRIS

#    CENTRALS     A, L, Q
#    OTHER        INTERNAL - DVCNTR(1)  PIPAGE(1)  PIPCTR(1)  AVGEXIT(2)
#                 EXTERNAL - ITEMP1(1)  ITEMP2(1)  RUPTREG1(1)  TEMX(1)  TEMY(1)  TEMZ(1)
#                 USEFUL DEBRIS
#                    RN1(6)  VN1(6)  GDT1/2  PIPTIME1(2)
#                        THESE LOCATIONS USED AS BUFFER STORAGE FOR NEWLY CALCULATED VALUES OF RN, VN, GDT/2,
#                        AND PIPTIME DURING PERFORMANCE OF SERVICER ROUTINES.
#                    UNITR - HALF UNIT VECTOR OF RN, REFERENCE COORD.
#                    RMAG SCALED AT 2(+58) IN 36D.
#                    RMAGSQ SCALED AT 2(+58) IN 34D.
#                    (RE/RMAG)SQ IN 32D.


		BANK	27
		SETLOC	SERVICES
		BANK

		EBANK=	DVCNTR
# *************************************   PREREAD   **************************************************************
#

		COUNT	37/SERV

PREREAD		CA	OCT31		# 5.31 PROTECTS REDO5.31 AS IMMEDIATE TASK
		TS	L
		COM
		DXCH	-PHASE5

		CAF	PRIO21
		TC	NOVAC
		EBANK=	NBDX
		2CADR	LASTBIAS	# DO LAST GYRO COMPENSATION IN FREE FALL
## Page 774
REDO5.31	TC	PREREAD1

		CAF	PRIO32
		TC	FINDVAC		# SET UP NORMLIZE JOB REQUIRED PRIOR TO
		EBANK=	DVCNTR		# FIRST AVERAGE G PASS
		2CADR	NORMLIZE
		CAF	2SECS
		TC	WAITLIST
		EBANK=	AOG
		2CADR	READACCS
		CS	TWO
		TC	NEWPHASE
		OCT	5

		TCF	TASKOVER


PREREAD1	EXTEND
		QXCH	RUPTREG1

		TC	PIPASR		# CLEAR + READ PIPS LAST TIME IN FREE FALL

		CAF	ONE		# SET UP PIPAGE FOR REREADAC IN CASE A
		TS	PIPAGE		#      RESTART OCCURS BEFORE READACCS

		CS	FLAGWRD1	# SET AVEG FLAG
		MASK	BIT1
		ADS	FLAGWRD1

		CA	POSMAX
		MASK	FLAGWRD2
		TS	FLAGWRD2	# KNOCK DOWN DRIFT FLAG

		CS	FLAGWRD7	# SET V37 FLAG
		MASK	BIT6
		ADS	FLAGWRD7

		CAF	ZERO
		TS	DVTOTAL		# CLEAR DVTOTAL
		TS	DVTOTAL +1

		TC	RUPTREG1

## Page 775
# *************************************   READACCS   *************************************************************
		EBANK=	AOG
READACCS	TC	PIPASR

PIPSDONE	CAF	FIVE
		TS	L
		COM
		DXCH	-PHASE5

REDO5.5		CAF	ONE		# SHOW PIPS HAVE BEEN READ
		TS	PIPAGE

		CA	TWO		# SET PIPCTR FOR ONMINTOR
		TS	PIPCTR		# AFTER ABOVE PHASCHNG

		CS	CM/FLAGS
		MASK	BIT2		# CM/DSTBY
		CCS	A
		TC	CHEKAVEG

		CS	PIPTIME1 +1
		TS	TBASE6		# FOR RESTARTS
		EXTEND			# CONTINUE FOR ENTRY DAP
		DCA	AOG
		DXCH	AOG/PIP
		CA	AMG
		XCH	AMG/PIP
		EXTEND
		DCA	ROLL/180
		DXCH	ROLL/PIP
		CA	BETA/180
		XCH	BETA/PIP
		CA	CM/FLAGS
		MASK	BIT12		# CM/DAPARM  93D  BIT12
		EXTEND			# DURING ENTRY, WHEN RCS DAP IS INACTIVE,
		BZF	NOSAVPIP	# SAVE PIPAS EACH 0.5 SEC FOR TM.

		CA	0.5SEC
		TC	WAITLIST
		EBANK=	XPIPBUF
		2CADR	QUIKREAD
#					  NO NEED TO RESTART PROTECT THIS.
		CA	DELVX		# SAVE PIPAS AS READ (BUT NOT COMPENSATED)
		XCH	XPIPBUF
		TS	XOLDBUF

		CA	DELVY
		XCH	YPIPBUF
		TS	YOLDBUF
## Page 776
		CA	DELVZ
		XCH	ZPIPBUF
		TS	ZOLDBUF

NOSAVPIP	CA	FIVE
		TS	CM/GYMDT

		CA	JTAGTIME	# ACTIVATE CM/RCS AFTER PIPUP TO GO
#					  IN JTAGTIME +5 CS.
		TC	WAITLIST
		EBANK=	AOG
		2CADR	SETJTAG

		CS	THREE		# 1.3SPOT FOR SETJTAG
		TC	NEWPHASE
		OCT	1

		CAF	OCT37
		TS	L
		COM
		DXCH	-PHASE5

CHEKAVEG	CS	FLAGWRD1
		MASK	BIT1
		CCS	A		# IF AVEG FLAG DOWN SET FINAL EXIT AVEG
		TC	AVEGOUT

		CAF	2SECS
		TC	WAITLIST
		EBANK=	AOG
		2CADR	READACCS

MAKESERV	CAF	PRIO20		# ESTABLISH SERVICER ROUTINE
		TC	FINDVAC
		EBANK=	DVCNTR
		2CADR	SERVICER

		CS	FOUR		# RESTART SERVICER AND READACCS
		TC	NEWPHASE
		OCT	5

		CAF	BIT9
		EXTEND
		WOR	DSALMOUT	# TURN TEST CONNECTOR OUTBIT ON

		TCF	TASKOVER	# END PREVIOUS READACCS WAITLIST TASK

## Page 777
AVEGOUT		EXTEND
		DCA	AVOUTCAD
		DXCH	AVGEXIT
		TCF	MAKESERV

		EBANK=	DVCNTR
AVOUTCAD	2CADR	AVGEND

## Page 778
# ROUTINE NAME:	ONMNITOR
# MOD 04 BY BAIRNSFATHER  30 APR 1968                     REDO ONMNITOR TO SAVE PIPS EACH 0.5 SEC FOR TM,ENTRY.
# MOD 03 BY FISHER DECEMBER 1967
# MOD 02 BY RYE SEPT 1967
# MOD 01 BY KOSMALA 23 MAR 1967
# MOD 00 BY KOSMALA 27 FEB 1967

# FUNCTIONAL DESCRIPTION

#          THE PURPOSE OF ONMONITOR IS TO PROVIDE 1/2 SEC.READING OF PIPAS FOR DOWNLIST DURING ENTRY.
#          X,Y,ZPIPBUF CONTAIN PRESENT VALUES X,Y,ZOLDBUF CONTAIN VALUES FROM PREVIOUS READING.

# CALLING SEQUENCE

#          CALL AS WAITLIST TASK. TERMINATES ITSELF IN TASKOVER

# INITIALISATION

#          PIPCTR = 2 (FOR DT = 0.5 SEC)
#          X,Y,ZPIPBUF SET TO PREVIOUS PIPAX,Y,Z

# OUTPUT

#          X,Y,ZPIPBUF, X,Y,ZOLDBUF
# DEBRIS

#          X,Y,ZPIPBUF CONTAIN LAST PIPAX,Y,Z VALUES
#                 X,Y,ZOLDBUF CONTAIN LAST-BUT-ONE PIPAX,Y,Z VALUES
#          RUPTREG1
#          PIPCTR

ONMNITOR	TS	PIPCTR

		TC	FIXDELAY	# WAIT
0.5SEC		DEC	50

QUIKREAD	CAF	TWO
		TS	RUPTREG1
		INDEX	A
		CA	PIPAX		# SAVE ACTUAL PIPAS FOR TM.
		INDEX	RUPTREG1
		XCH	XPIPBUF		# UPDATE X,Y,ZPIPBUF
		INDEX	RUPTREG1
		TS	XOLDBUF		# AND X,Y,ZOLDBUF
CHKCTR		CCS	RUPTREG1
		TCF	QUIKREAD +1	# LOOP AGAIN
		CCS	PIPCTR
		TCF	ONMNITOR
		TC	TASKOVER

## Page 779
# *************************************   SERVICER   *************************************************************
#

		EBANK=	DVCNTR

SERVICER	CAF	TWO
		INHINT
PIPCHECK	TS	RUPTREG1

		DOUBLE
		INDEX	A
		CCS	DELVX
		TC	+2
		TC	PIPLOOP

		AD	-MAXDELV	# DO PIPA-SATURATION TEST BEFORE
		EXTEND
		BZMF	PIPLOOP		# COMPENSATION.

		TC	ALARM
		OCT	00205		# SATURATED-PIPA ALARM  ***CHANGE LATER
		TC	AVERAGEG

PIPLOOP		CCS	RUPTREG1
		TCF	PIPCHECK

		TC	PHASCHNG	# RESTART REREADAC + SERVICER
		OCT	16035
		OCT	20000
		EBANK=	DVCNTR
		2CADR	DVTOTUP

		TC	BANKCALL	# PIPA COMPENSATION CALL
		CADR	1/PIPA

DVTOTUP		TC	INTPRET
		VLOAD	ABVAL		# GET ABS VALUE OF DELV
			DELV
		DMP	EXIT
			KPIP1		# SCALE AT 2(+7)
	
		EXTEND
		DCA	MPAC
		DAS	DVTOTAL		# ACCUMULATE DVTOTAL
AVERAGEG	TC	PHASCHNG
		OCT	10035

		TC	INTPRET
		CALL
## Page 780
			CALCRVG
		EXIT

		TC	PHASCHNG
		OCT	10035

		CAF	OCT31		# COPY RN1,VN1,GOT102,GOBL1/2,PIPTIME1
		TC	GENTRAN		# INTO RN ,VN ,GDT/12 ,GOBL/2 ,PIPTIME
		ADRES	RN1
		ADRES	RN
		RELINT			# GENTRAN DOES AN INHINT
		TC	PHASCHNG
		OCT	10035

		EXTEND
		DCA	AVGEXIT
		DXCH	Z		# AVERAGEG EXIT

AVGEND		CA	PIPTIME +1	# FINAL AVERAGE G EXIT
		TS	OLDBT1		# SET UP FREE FALL GYRO COMPENSATION

		TC	UPFLAG		# SET DRIFTFLG
		ADRES	DRIFTFLG	# BIT 15  FLAG 2
		TC	2PHSCHNG
		OCT	5		# GROUP 5 OFF
		OCT	05022		# GROUP 2 ON FOR AVETOMID
		OCT	20000

		TC	INTPRET
		CALL
			AVETOMID	# CONVERT STATE VECTOR TO REFERENCE SCALE.
		EXIT

		CAF	ZERO		# ZERO MARK COUNTERS.
		TS	VHFCNT
		TS	TRKMKCNT

		TC	BANKCALL
		CADR	PIPFREE

		CS	BIT9
		TS	MRKBUF2		# INVALIDATE MARK BUFFER
		EXTEND
		WAND	DSALMOUT

		TC	DOWNFLAG
		ADRES	CM/DSTBY

		TC	DOWNFLAG
		ADRES	V37FLAG
## Page 781
		CAF	BIT7		# RESTORE GROUP 1 + 2 IF P20 IS RUNNING.
		MASK	FLAGWRD0
		EXTEND
		BZF	+4

		TC	2PHSCHNG
		OCT	111		# 1.11SPOT
		OCT	132		# 2.13SPOT

		TC	POSTJUMP
		CADR	CANV37

SERVEXIT	TC	PHASCHNG
		OCT	00035		# A, 5.3 = REREADAC  (ONLY)

		TCF	ENDOFJOB

DVTHRUSH	EQUALS	ELEVEN		# 15 PERCENT OF 2SEC PIPA ACCUMULATION,
#					       FOR 503-FULL CSM/LEM....DELV SC.AT
#					       5.85 CM/SEC.

-MAXDELV	DEC	-6398		# 3200 PPS FOR 2 SEC  CCS TAKES 1


JTAGTIME	DEC	120		# = 1 SEC + T CDU, T CDU = .1 SEC

2.5SEC		DEC	250
MDOTFAIL	DEC	144.0 B-16	# 5 SEC MASS LOSS AT 28.8 KG/SEC
#					  SHOULD BE 2-4 SECS FOR NO START
#					            6-8 SECS FOR FAILURE

## Page 782
#    NORMLIZE PERFORMS THE INITIALIZATION REQUIRED PRIOR TO THE FIRST ENTRY TO AVERAGEG, AND SCALES RN SO THAT IT
# HAS 1 LEADING BINARY ZERO. IN MOST MISSIONS, RN WILL BE SCALED AT 2(+29), BUT IN THE 206 MISSION, RN WILL BE
# SCALED AT 2(+24)M.


NORMLIZE	CAF	THIRTEEN	# SET UP TO COPY 14 REGS- RN1,VN1,PIPTIME1
		TC	GENTRAN		# INTO RN,VN, PIPTIME
		ADRES	RN1		# FROM HERE
		ADRES	RN		# TO HERE

		RELINT
		TC	INTPRET
		VLOAD	CALL		# LOAD RN FOR CALCGRAV
			RN
			CALCGRAV	# INITIALISE UNITR RMAG GDT1

		STOVL	GDT/2
			GOBL1/2
		STORE	GOBL/2
		EXIT
		TCF	ENDOFJOB

## Page 783
# *****  PIPA READER *****


#                 MOD NO. 00  BY D. LICKLY  DEC.9 1966


# FUNCTIONAL DESCRIPTION

#    SUBROUTINE TO READ PIPA COUNTERS, TRYING TO BE VERY CAREFUL SO THAT IT WILL BE RESTARTABLE.
#    PIPA READINGS ARE STORED IN THE VECTOR DELV. THE HIGH ORDER PART OF EACH COMPONENT CONTAINS THE PIPA READING,
#    RESTARTS BEGIN AT REREADAC.


#    AT THE END OF THE PIPA READER THE CDUS ARE READ AND STORED AS A
# VECTOR IN CDUTEMP.  THE HIGH ORDER PART OF EACH COMPONENT CONTAINS
# THE CDU READING IN 2S COMP IN THE ORDER CDUX,Y,Z.  THE THRUST
# VECTOR ESTIMATOR IN FINDCDUD REQUIRES THE CDUS BE READ AT PIPTIME.

# CALLING SEQUENCE AND EXIT

#    CALL VIA TC, ISWCALL, ETC.

#    EXIT IS VIA Q.


# INPUT

#    INPUT IS THROUGH THE COUNTERS PIPAX, PIPAY, PIPAZ, AND TIME2.


# OUTPUT

#    HIGH ORDER COMPONENTS OF THE VECTOR DELV CONTAIN THE PIPA READINGS.
#    PIPTIME CONTAINS TIME OF PIPA READING.


# DEBRIS (ERASABLE LOCATIONS DESTROYED BY PROGRAM)

#          LOW ORDER DELV'S ARE ZEROED FOR TM INDICATION.
#          TEMX   TEMY   TEMZ   PIPAGE


PIPASR		EXTEND
		DCA	TIME2
		DXCH	PIPTIME1	# CURRENT TIME	POSITIVE VALUE
		CS	ZERO		# INITIALIZE THESE AT NEG ZERO.
		TS	TEMX
		TS	TEMY
		TS	TEMZ
## Page 784
		CA	ZERO
		TS	DELVZ		# OTHER DELVS OK INCLUDING LOW ORDER
		TS	DELVY

		TS	DELVX +1	# LOW ORDER DELV'S ARE ZEROED FOR TM: THUS
		TS	DELVY +1	# IF DNLNK'D LOW ORDER DELVS ARE NZ, THEY
		TS	DELVZ +1	# CONTAIN PROPER COMPENSATION. IF=0, THEN
#					  THE TM VALUES ARE BEFORE COMPENSATION.

		TS	PIPAGE		# SHOW PIPA READING IN PROGRESS

REPIP1		EXTEND
		DCS	PIPAX		# X AND Y PIPS READ
		DXCH	TEMX
		DXCH	PIPAX		# PIPAS SET TO NEG ZERO AS READ.
		TS	DELVX
		LXCH	DELVY

REPIP3		CS	PIPAZ		# REPEAT PROCESS FOR Z PIP
		XCH	TEMZ
		XCH	PIPAZ
DODELVZ		TS	DELVZ

		TC	Q


		EBANK=	AOG

REREADAC	CCS	PHASE5		# LAST PASS CHECK
		TCF	+2
		TCF	TASKOVER

		CCS	PIPAGE
		TCF	READACCS	# PIP READING NOT STARTED. GO TO BEGINNING

		CAF	DONEADR		# SET UP RETURN FROM PIPASR
		TS	Q

		CCS	DELVZ
		TC	Q		# Z DONE, GO DO CDUS
		TCF	+3		# Z NOT DONE, CHECK Y.
		TC	Q
		TC	Q
		ZL
		CCS	DELVY
		TCF	+3
		TCF	CHKTEMX		# Y NOT DONE, CHECK X.
		TCF	+1
		LXCH	PIPAZ		# Y DONE, ZERO Z PIP.
## Page 785
		CCS	TEMZ
		CS	TEMZ		# TEMZ NOT = -0, CONTAINS -PIPAZ VALUE.
		TCF	DODELVZ
		TCF	-2
		LXCH	DELVZ		# TEMZ = -0, L HAS ZPIP VALUE.
		TC	Q

CHKTEMX		CCS	TEMX		# HAS THIS CHANGED
		CS	TEMX		# YES
		TCF	+3		# YES
		TCF	-2		# YES
		TCF	REPIP1		# NO
		TS	DELVX

		CS	TEMY
		TS	DELVY

		CS	ZERO		# ZERO X AND Y PIPS
		DXCH	PIPAX		# L STILL ZERO FROM ABOVE

		TCF	REPIP3

DONEADR		GENADR	PIPSDONE

## Page 786
# *************************************************************************************************************

#          ROUTINE CALCRVG INTEGRATES THE EQUATIONS OF MOTION BY AVERAGING THE THRUST AND GRAVITATIONAL
# ACCELERATIONS OVER A TIME INTERVAL OF 2 SECONDS.

#          FOR THE EARTH-CENTERED GRAVITATIONAL FIELD, THE PERTURBATION DUE TO OBLATENESS IS COMPUTED TO THE FIRST
# HARMONIC COEFFICIENT J.

#          ROUTINE CALCRVG REQUIRES...
#                 1) THRUST ACCELERATION INCREMENTS IN DELV SCALED SAME AS PIPAX,Y,Z IN STABLE MEMBER COORDS.
#                 2) VN SCALED 2(+7)M/CS IN REFERENCE COORDS.
#                 3) RN SCALED AT 2(+29) METERS IN REFERENCE COORDS.
#                 4) UNITW THE EARTH S UNIT ROTATIONAL VECTOR (SCALED AS A FULL UNIT VECTOR) IN REFERENCE COORDS.

# IT LEAVES RN1 UPDATED (SCALED AT 2(+29)M, VN1 (SCALED AT 2(+7)M/CS), AND GDT1/2 (SCALED AT 2(+7)M/CS). ALSO HALF
# UNIT VECTOR UNITR, RMAG IN 36D SCALED AT 2(+29)M, R MAG SQ. IN 34D SCALED AT 2(+58) M SQ.
#

CALCGRAV	UNIT	PUSH		# ENTER WITH RN IN MPAC
		STORE 	UNITR
		LXC,1	SLOAD
			RTX2
			X1
		BMN	VLOAD
			ITISMOON
		DOT	PUSH
			UNITW
		DSQ	BDSU
			DP1/20
		PDDL	DDV
			RESQ
			34D		# (RN)SQ
		STORE	32D		# TEMP FOR (RE/RN)SQ
		DMP	DMP
			20J
		VXSC	PDDL
			UNITR
		DMP	DMP
			2J
			32D
		VXSC	VAD
			UNITW
		STADR
		STORE	GOBL1/2
		VAD	PUSH
			UNITR
ITISMOON	DLOAD	NORM
			34D
			X2
		BDDV*	SLR*
## Page 787
			-MUDT(E),1
			0 -21D,2
		VXSC	STADR
		STORE	GDT1/2		# SCALED AT 2(+7) M/CS
		RVQ

CALCRVG		VLOAD	VXSC
			DELV
			KPIP1
		VXM	VSL1
			REFSMMAT
		STORE	DELVREF		# DELV IN REF COORDS AT 2(+7)
		VSR1	PUSH
		VAD	PUSH		# (DV-OLDGDT)/2 TO PD SCALED AT 2(+7)M/CS
			GDT/2
		VAD	VXSC
			VN
			2SEC(22)
		VAD	STQ
			RN
			31D
		STCALL	RN1		# TEMP STORAGE OF RN SCALED 2(+29)M
			CALCGRAV

		VAD	VAD
		VAD
			VN
		STCALL	VN1		# TEMP STORAGE OF VN SCALED 2(+7)M/CS
			31D

KPIP		2DEC	.1024		# SCALES DELV TO 2(+4)
KPIP1		2DEC	0.074880	# 207 DELV SCALING. 1 PULSE = 5.85 CM/SEC.
-MUDT(E)	2DEC*	-7.9720645 E+12 B-44*
-MUDT(M)	2DEC*	-9.805556 E+10 B-44*
2SEC(22)	2DEC	200 B-22

DP1/20		2DEC	0.05
RESQ		2DEC*	40.6809913 E12 B-59*
20J		2DEC*	3.24692010 E-2 B1*
2J		2DEC*	3.24692010 E-3 B1*