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Ecco come l’uomo è arrivato sulla luna grazie all’informatica

agosto 27, 2012 10:55 am
Techweaver
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Da pochi giorni è morto Neil Armstrong, il primo uomo che a bordo dell’Apollo 11, sbarcò sulla luna il 20 luglio del 69. E per onorare meglio questo evento ho pensato di rispolverare un vecchio link finito nella mia interminabile lista dei preferiti: si tratta dei codici “informatici” (equazioni), che sono serviti per far atterrare il modulo lunare sul satellite, ed anche se non ci capite granchè credo che sia comunque una bella sensazione possedere un “documento” del genere seppur in forma virtuale. Sono più di 1400 righe di codici, perciò vi allego il link azichè riportare tutto qui. Codici atterraggio lunare.

Aggiornamento: visto che la pagina web in futuro potrebbe essere eliminata riporto qui il codice integrale al fine di preservarlo nel tempo (scusate la lunghezza immensa )

# Copyright:	Public domain.
# Filename:	LUNAR_LANDING_GUIDANCE_EQUATIONS.s
# Purpose: 	Part of the source code for Luminary 1A build 099.
#		It is part of the source code for the Lunar Module's (LM)
#		Apollo Guidance Computer (AGC), for Apollo 11.
# Assembler:	yaYUL
# Contact:	HARTMUTH GUTSCHE <hgutsche@xplornet.com>.
# Website:	www.ibiblio.org/apollo.
# Pages:	798-828
# Mod history:	2009-05-23 HG	Transcribed from page images.
#		2009-06-05 RSB	Fixed a goofy thing that was apparently
#				legal in GAP but not in yaYUL.  Eliminated
#				a couple of lines of code that shouldn't 
#				have survived from Luminary 131 to here.
#		2009-06-07 RSB	Fixed a typo.
#
# This source code has been transcribed or otherwise adapted from
# digitized images of a hardcopy from the MIT Museum.  The digitization
# was performed by Paul Fjeld, and arranged for by Deborah Douglas of
# the Museum.  Many thanks to both.  The images (with suitable reduction
# in storage size and consequent reduction in image quality as well) are
# available online at www.ibiblio.org/apollo.  If for some reason you
# find that the images are illegible, contact me at info@sandroid.org
# about getting access to the (much) higher-quality images which Paul
# actually created.
#
# Notations on the hardcopy document read, in part:
#
#	Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
#	16:27 JULY 14, 1969 

# Page 798
		EBANK=	E2DPS
		COUNT*	$$/F2DPS

# ********************************************************
# LUNAR LANDING FLIGHT SEQUENCE TABLES
# ********************************************************

# FLIGHT SEQUENCE TABLES ARE ARRANGED BY FUNCTION.  THEY ARE REFERENCED USING AS AN INDEX THE REGISTER WCHPHASE:
#	WCHPHASE = -1 ---> IGNALG
#	WCHPHASE =  0 ---> BRAKQUAD
#	WCHPHASE =  1 ---> APPRQUAD
#	WCHPHASE =  2 ---> VERTICAL

#*********************************************************

# ROUTINES FOR STARTING NEW GUIDANCE PHASES:

		TCF	TTFINCR		# IGNALG
NEWPHASE	TCF	TTFINCR		# BRAKQUAD
		TCF	STARTP64	# APPRQUAD
		TCF	P65START	# VERTICAL

# PRE-GUIDANCE COMPUTATIONS:

		TCF	CALCRGVG	# IGNALG
PREGUIDE	TCF	RGVGCALC	# BRAKQUAD
		TCF	REDESIG		# APPRQUAD
		TCF	RGVGCALC	# VERTICAL

# GUIDANCE EQUATIONS:

		TCF	TTF/8CL		# IGNALG
WHATGUID	TCF	TTF/8CL		# BRAKQUAD
		TCF	TTF/8CL		# APPRQUAD
		TCF	VERTGUID	# VERTICAL

# POST GUIDANCE EQUATION COMPUTATIONS:

		TCF	CGCALC		# IGNALG
AFTRGUID	TCF	CGCALC		# BRAKQUAD
		TCF	CGCALC		# APPRQUAD
		TCF	STEER?		# VERTICAL

# Page 799
# WINDOW VECTOR COMPUTATIONS:

		TCF	EXGSUB		# IGNALG
WHATEXIT	TCF	EXBRAK		# BRAKQUAD
		TCF	EXNORM		# APPRQUAD

# DISPLAY ROUTINES:

WHATDISP	TCF	P63DISPS	# BRAKQUAD
		TCF	P64DISPS	# APPRQUAD
		TCF	VERTDISP	# VERTICAL

# ALARM ROUTINE FOR TTF COMPUTATION:

		TCF	1406P00		# IGNALG
WHATALM		TCF	1406ALM		# BRAKQUAD
		TCF	1406ALM		# APPRQUAD

# INDICES FOR REFERENCING TARGET PARAMETERS

		OCT	0		# IGNALG
TARGTDEX	OCT	0		# BRAKQUAD
		OCT	34		# APPRQUAD

#************************************************************************
# ENTRY POINTS:  ?GUIDSUB FOR THE IGNITION ALGORITHM, LUNLAND FOR SERVOUT
#************************************************************************

# IGNITION ALGORITHM ENTRY:  DELIVERS N PASSES OF QUADRATIC GUIDANCE

?GUIDSUB	EXIT
		CAF	TWO		# N = 3
		TS	NGUIDSUB
		TCF	GUILDRET +2

GUIDSUB		TS	NGUIDSUB	# ON SUCCEEDING PASSES SKIP TTFINCR
		TCF	CALCRGVG

# NORMAL ENTRY:  CONTROL COMES HERE FROM SERVOUT

LUNLAND		TC	PHASCHNG
		OCT	00035		# GROUP 5:  RETAIN ONLY PIPA TASK
		TC	PHASCHNG
		OCT	05023		# GROUP 3:  PROTECT GUIDANCE WITH PRIO 21  
		OCT	21000		#	JUST HIGHER THAN SERVICER'S PRIORITY

# Page 800
#*******************************************************************
# GUILDENSTERN:  AUTO-MODES MONITOR (R13)
#*******************************************************************

		COUNT*	$$/R13

# HERE IS THE PHILOSOPHY OF GUILDENSTERN:	ON EVERY APPEARANCE OR DISAPPEARANCE OF THE MANUAL THROTTLE
# DISCRETE TO SELECT P67 OR P66 RESPECTIVELY:   ON EVERY APPEARANCE OF THE ATTITUDE-HOLD DISCRETE TO SELECT P66
# UNLESS THE CURRENT PROGRAM IS P67 IN WHICH CASE THERE IS NO CHANGE

GUILDEN		EXTEND			# IS UN-AUTO-THROTTLE DISCRETE PRESENT?
# STERN					# RSB 2009: Not originally a comment.
  		READ CHAN30
		MASK	BIT5
  		CCS	A
  		TCF	STARTP67	# YES
P67NOW?		TC	CHECKMM		# NO:  ARE WE IN P67 NOW?
		DEC	67
		TCF	STABL?		# NO
STARTP66	TC	FASTCHNG	# YES
		TC	NEWMODEX
DEC66		DEC	66
		EXTEND
		DCA	HDOTDISP	# SET DESIRED ALTITUDE RATE = CURRENT
		DXCH	VDGVERT		# 	ALTITUDE RATE.
STRTP66A	TC	INTPRET
		SLOAD	PUSH
			PBIASZ
		SLOAD	PUSH
			PBIASY
		SLOAD	VDEF
			PBIASX
		VXSC	SET
			BIASFACT
			RODFLAG
		STOVL	VBIAS
			TEMX
		VCOMP
		STOVL	OLDPIPAX
			ZEROVECS
		STODL	DELVROD
			RODSCALE
		STODL	RODSCAL1
			PIPTIME
		STORE	LASTTPIP
		EXIT
		CAF	ZERO
		TS	FCOLD
		TS	FWEIGHT
		TS	FWEIGHT +1
VRTSTART	TS	WCHVERT
# Page 801
		CAF	TWO		# WCHPHASE = 2 ---> VERTICAL: P65,P66,P67
		TS	WCHPHOLD
		TS	WCHPHASE
		TC	BANKCALL	# TEMPORARY, I HOPE HOPE HOPE
		CADR	STOPRATE	# TEMPORARY, I HOPE HOPE HOPE
		TC	DOWNFLAG	# PERMIT X-AXIS OVERRIDE
		ADRES	XOVINFLG
		TC	DOWNFLAG
		ADRES	REDFLAG
		TCF	VERTGUID

STARTP67	TC	NEWMODEX	# NO HARM IN "STARTING" P67 OVER AND OVER
		DEC	67		# SO NO NEED FOR A FASTCHNG AND NO NEED
		CAF	ZERO		# TO SEE IF ALREADY IN P67.
		TS	RODCOUNT
		CAF	TEN
		TCF	VRTSTART

STABL?		CAF	BIT13		# IS UN-ATTITUDE-HOLD DISCRETE PRESENT?
		EXTEND
		RAND	CHAN31
		CCS	A
		TCF	GUILDRET	# YES ALL'S WELL

P66NOW?		CS	MODREG
		AD	DEC66
		EXTEND
		BZF	RESTART?

		CA	RODCOUNT	# NO. HAS THE ROD SWITCH BEEN "CLICKED"?
		EXTEND
		BZF	GUILDRET	# NO. CONTINUE WITH AUTOMATIC LANDING
		TCF	STARTP66	# YES. SWITCH INTO THE ROD MODE.

RESTART?	CA	FLAGWRD1	# HAS THERE BEEN A RESTART?
		MASK	RODFLBIT
		EXTEND
		BZF	STRTP66A	# YES.  REINITIALIZE BUT LEAVE VDGVERT AS
					#	IS.

		TCF	VERTGUID	# NO: CONTINUE WITH R.O.D.

# *******************************************************************************
# INITIALIZATION FOR THIS PASS
# *******************************************************************************

		COUNT*	$$/F2DPS

GUILDRET	CAF	ZERO
		TS	RODCOUNT

# Page 802
 +2		EXTEND
 		DCA	TPIP
		DXCH	TPIPOLD

		TC	FASTCHNG

		EXTEND
		DCA	PIPTIME1
		DXCH	TPIP

		EXTEND
		DCA	TTF/8
		DXCH	TTF/8TMP

		CCS	FLPASS0
		TCF	TTFINCR

BRSPOT1		INDEX	WCHPHASE
		TCF	NEWPHASE

# ******************************************************************
# ROUTINES TO START NEW PHASES
# ******************************************************************

P65START	TC	NEWMODEX
		DEC	65
		CS	TWO
		TS	WCHVERT
		TC	DOWNFLAG	# PERMIT X-AXIS OVERRIDE
		ADRES	XOVINFLG
		TCF	TTFINCR

STARTP64	TC	NEWMODEX
		DEC	64
		CA	DELTTFAP	# AUGMENT TTF/8
		ADS	TTF/8TMP
		CA	BIT12		# ENABLE RUPT10
		EXTEND
		WOR	CHAN13
		TC	DOWNFLAG	# INITIALIZE REDESIGNATION FLAG
		ADRES	REDFLAG

#		(CONTINUE TO TTFINCR)

# *********************************************************************************
# INCREMENT TTF/8, UPDATE LAND FOR LUNAR ROTATION, DO OTHER USEFUL THINGS
# *********************************************************************************
#
#	TTFINCR COMPUTATIONS ARE AS FOLLOWS --
# Page 803
#		TTF/8 UPDATED FOR TIME SINCE LAST PASS:
#			TTF/8 = TTF/8 + (TPIP - TPIPOLD)/8
#		LANDING SITE VECTOR UPDATED FOR LUNAR ROTATION:
#			____               ____   ____                   __
#			LAND = /LAND/ UNIT(LAND - LAND(TPIP - TPIPOLD) * WM)
#		SLANT RANGE TO LANDING SITE, FOR DISPLAY:
#			                 ____   _
#			RANGEDSP = ABVAL(LAND - R)

TTFINCR		TC	INTPRET
		DLOAD	DSU
			TPIP
			TPIPOLD
		SLR	PUSH		# SHIFT SCALES DELTA TIME TO 2(17) CSECS
			11D
		VXSC	VXV
			LAND
			WM
		BVSU	RTB
			LAND
			NORMUNIT
		VXSC	VSL1
			/LAND/
		STODL	LANDTEMP
		EXIT

		DXCH	MPAC
		DAS	TTF/8TMP	# NOW HAVE INCREMENTED TTF/8 IN TTF/8TMP

		TC	FASTCHNG

		EXTEND
		DCA	TTF/8TMP
		DXCH	TTF/8

		EXTEND
		DCA	LANDTEMP
		DXCH	LAND
		EXTEND
		DCA	LANDTEMP +2
		DXCH	LAND     +2
		EXTEND
		DCA	LANDTEMP +4
		DXCH	LAND	 +4

# Page 804
		TC	TDISPSET
		TC	FASTCHNG	# SINCE REDESIG MAY CHANGE LANDTEMP

BRSPOT2		INDEX	WCHPHASE
		TCF	PREGUIDE

# *********************************************************************
# LANDING SITE PERTURBATION EQUATIONS
# *********************************************************************

REDESIG		CA	FLAGWRD6	# IS REDFLAG SET?
		MASK	REDFLBIT
		EXTEND
		BZF	RGVGCALC	# NO:  SKIP REDESIGNATION LOGIC

		CA	TREDES		# YES:  HAS TREDES REACHED ZERO?
		EXTEND
		BZF	RGVGCALC	# YES:  SKIP REDESIGNATION LOGIC

		INHINT
		CA	ELINCR1
		TS	ELINCR
		CA	AZINCR1
		TS	AZINCR
		TC	FASTCHNG

		CA	ZERO
		TS	ELINCR1
		TS	AZINCR1
		TS	ELINCR	+1
		TS	AZINCR  +1

		CA	FIXLOC		# SET PD TO 0
		TS	PUSHLOC

		TC	INTPRET
		VLOAD	VSU
			LAND
			R		#                 ____   _
		RTB	PUSH		# PUSH DOWN UNIT (LAND - R)
			NORMUNIT
		VXV	VSL1
			YNBPIP		#                    ___        ____   _
		VXSC	PDDL		# PUSH DOWN - ELINCR(YNB * UNIT(LAND - R))
			ELINCR
			AZINCR
		VXSC	VSU
			YNBPIP
		VAD	PUSH		# RESULTING VECTOR IS 1/2 REAL SIZE

# Page 805

		DLOAD	DSU		# MAKE SURE REDESIGNATION IS NOT
			0		# 	TOO CLOSE TO THE HORIZON.
			DEPRCRIT
		BMN	DLOAD
			REDES1
			DEPRCRIT
		STORE	0
REDES1		DLOAD	DSU
			LAND
			R
		DDV	VXSC
			0
		VAD	UNIT
			R
		VXSC	VSL1
			/LAND/
		STORE	LANDTEMP
		EXIT			# LOOKANGL WILL BE COMPUTED AT RGVGCALC

		TC	FASTCHNG

		EXTEND
		DCA	LANDTEMP
		DXCH	LAND
		EXTEND
		DCA	LANDTEMP +2
		DXCH	LAND +2
		EXTEND
		DCA	LANDTEMP +4
		DXCH	LAND +4

		TCF	RGVGCALC

# *********************************************************************
# COMPUTE STATE IN GUIDANCE COORDINATES
# *********************************************************************
#
#	RGVGCALC COMPUTATIONS ARE AS FOLLOWS:--
#	VELOCITY RELATIVE TO THE SURFACE
#		_______   _   _   __
#		ANGTERM = V + R * WM
#	STATE IN GUIDANCE COORDINTES:
#		___   *   _   ____
#		RGU = CG (R - LAND)
#		___   *   _   __   _
#		VGU = CG (V - WM * R)
# Page 806 actually starts one line earlier but that would separate the markers from their variables
#
#	HORIZONTAL VELOCITY FOR DISPLAY
#
#		VHORIZ = 8 ABVAL (0, VG , VG )
#		                       2    1
# 	DEPRESSION ANGLE FOR DISPLAY:
#		                       _   ____  ______
#		LOOKANGL = ARCSIN(UNIT(R - LAND).XMBPIP)

CALCRGVG	TC	INTPRET		# IN IGNALG, COMPUTE V FROM INTEGRATION
		VLOAD	MXV		#	OUTPUT AND TRIM CORRECTION TERM
			VATT1		#	COMPUTED LAST PASS AND LEFT IN UNFC/2
			REFSMMAT
		VSR1	VAD
			UNFC/2
		STORE	V
		EXIT

RGVGCALC	TC	INTPRET		# ENTER HERE TO RECOMPUTE RG AND VG
		VLOAD	VXV
			R
			WM
		VAD	VSR2		# RESCALE TO UNITS OF 2(9) M/CS
			V
		STORE	ANGTERM
		MXV
			CG		# NO SHIFT SINCE ANGTERM IS DOUBLE SIZED
		STORE	VGU
		PDDL	VDEF		# FORM (0,VG ,VG ) IN UNITS OF 2(10) M/CS
			ZEROVECS	#           2   1
		ABVAL	SL3
		STOVL	VHORIZ		# VHORIZ FOR DISPLAY DURING P65.
			R		#           _   ____
		VSU	PUSH		# PUSH DOWN R - LAND
			LAND
		MXV	VSL1
			CG
		STORE	RGU
		ABVAL
		STOVL	RANGEDSP
		RTB	DOT		# NOW IN MPAC IS SINE(LOOKANGL)/4
			NORMUNIT
			XNBPIP
		EXIT

		CA	FIXLOC		# RESET PUSH DOWN POINTER
		TS	PUSHLOC

# Page 807 
		CA	MPAC		# COMPUTE LOOKANGLE ITSELF
		DOUBLE
		TC	BANKCALL
		CADR	SPARCSIN -1
		AD	1/2DEG
		EXTEND
		MP	180DEGS
		TS	LOOKANGL	# LOOKANGL FOR DISPLAY DURING P64

BRSPOT3		INDEX	WCHPHASE
		TCF	WHATGUID

# **************************************************************************
# TTF/8 COMPUTATION
# **************************************************************************

TTF/8CL		TC	INTPRETX
		DLOAD*
			JDG2TTF,1
		STODL*	TABLTTF +6	# A(3) = 8 JDG  TO TABLTTF
			ADG2TTF,1	#             2
		STODL	TABLTTF +4	# A(2) = 6 ADG  TO TABLTTF
			VGU 	+4	#             2
		DMP	DAD*
			3/4DP
			VDG2TTF,1
		STODL*	TABLTTF +2	# A(1) = (6 VGU  + 18 VDG )/8 TO TABLTTF
			RDG +4,1	#              2         2
		DSU	DMP
			RGU +4
			3/8DP
		STORE	TABLTTF		# A(0) = -24 (RGU  - RDG )/64 TO TABLTTF
		EXIT			#                2      2

		CA	BIT8
		TS	TABLTTF +10	# FRACTIONAL PRECISION FOR TTF TO TABLE

		EXTEND
		DCA	TTF/8
		DXCH	MPAC		# LOADS TTF/8 (INITIAL GUESS) INTO MPAC
		CAF	TWO		# DEGREE - ONE
		TS	L
		CAF	TABLTTFL
		TC	ROOTPSRS	# YIELDS TTF/8 IN MPAC
		INDEX	WCHPHASE
		TCF	WHATALM

		EXTEND			# GOOD RETURN
		DCA	MPAC		# FETCH TTF/8 KEEPING IT IN MPAC
		DXCH	TTF/8		# CORRECTED TTF/8

# Page 808
		TC	TDISPSET

# 		(CONTINUE TO QUADGUID)

# *********************************************************************************
# MAIN GUIDANCE EQUATION
# *********************************************************************************
#
#	AS PUBLISHED --
#		              ___   __       ___   __
#		___   ___   6(VDG + VG)   12(RDG - RG)
#		ACG = ADG + ----------- + ------------
#		                TTF        (TTF)(TTF)
#	AS HERE PROGRAMMED --
#		             ___   __
#		      3 (1/4(RDG - RG)   ___   __)
#		      - (------------- + VDG + VG)
#		___   4 (    TTF/8               )   ___
#		ACG = ---------------------------- + ADG
#		                  TTF/8

QUADGUID	CS	TTF/8
		AD	LEADTIME	# LEADTIME IS A NEGATIVE NUMBER
		AD	POSMAX		# SAFEGUARD THE COMPUTATIONS THAT FOLLOW
		TS	L		#	BY FORCING -TTF*LEADTIME > OR = ZERO
		CS	L
		AD	L
		ZL
		EXTEND
		DV	TTF/8
		TS	BUF		# - RATIO OF LAG-DIMINISHED TTF TO TTF
		EXTEND
		SQUARE
		TS	BUF +1
		AD	BUF
		XCH	BUF +1		# RATIO SQUARED - RATIO
		AD	BUF +1
		TS	MPAC		# COEFFICIENT FOR VGU TERM
		AD	BUF +1
		INDEX	FIXLOC
		TS	26D		# COEFFICIENT FOR RDG-RGU TERM
		AD	BUF +1
		INDEX	FIXLOC
		TS	28D		# COEFFICIENT FOR VDG TERM
		AD	BUF
		AD	POSMAX
# Page 809
		AD	BUF +1
		AD	BUF +1
		INDEX	FIXLOC
		TS	30D		# COEFFICIENT FOR ADG TERM

		CAF	ZERO
		TS	MODE

		TC	INTPRETX
		VXSC	PDDL
			VGU
			28D
		VXSC*	PDVL*
			VDG,1
			RDG,1
		VSU	V/SC
			RGU
			TTF/8
		VSR2	VXSC
			26D
		VAD	VAD
		V/SC	VXSC
			TTF/8
			3/4DP
		PDDL	VXSC*
			30D
			ADG,1
		VAD
AFCCALC1	VXM	VSL1		# VERGUID COMES HERE
			CG
		PDVL	V/SC
			GDT/2
			GSCALE
		BVSU	STADR
		STORE	UNFC/2		# UNFC/2 NEED NOT BE UNITIZED
		ABVAL
AFCCALC2	STODL	/AFC/		# MAGNITUDE OF AFC FOR THROTTLE
			UNFC/2		# VERTICAL COMPONENT
		DSQ	PDDL
			UNFC/2 +2	# OUT-OF-PLANE
		DSQ	PDDL
			HIGHESTF
		DDV	DSQ
			MASS		#                        2    2    2
		DSU	DSU		# AMAXHORIZ = SQRT(ATOTAL - A  - A  )
		BPL	DLOAD		#                            1    0
			AFCCALC3
			ZEROVECS
AFCCALC3	SQRT	DAD
			UNFC/2 +4
# Page 810
		BPL	BDSU
			AFCCLEND
			UNFC/2 +4
		STORE	UNFC/2 +4
AFCCLEND	EXIT
		TC	FASTCHNG

		CA	WCHPHASE	# PREPARE FOR PHASE SWITCHING LOGIC
		TS	WCHPHOLD
		INCR	FLPASS0		# INCREMENT PASS COUNTER

BRSPOT4		INDEX	WCHPHASE
		TCF	AFTRGUID

# ***********************************************************************
# ERECT GUIDANCE-STABLE MEMBER TRANSFORMATION MATRIX
# ***********************************************************************

CGCALC		CAF	EBANK5
		TS	EBANK
		EBANK=	TCGIBRAK
		EXTEND
		INDEX	WCHPHASE
		INDEX	TARGTDEX
		DCA	TCGFBRAK
		INCR	BBANK
		INCR	BBANK
		EBANK=	TTF/8
		AD	TTF/8
		XCH	L
		AD	TTF/8
		CCS	A
		CCS	L
		TCF	EXTLOGIC
		TCF	EXTLOGIC
		NOOP

		TC	INTPRETX
		VLOAD	UNIT
			LAND
		STODL	CG
			TTF/8
		DMP*	VXSC
			GAINBRAK,1	# NUMERO MYSTERIOSO
			ANGTERM
		VAD
			LAND
		VSU	RTB
			R
			NORMUNIT
# Page 811
		VXV	RTB
			LAND
			NORMUNIT
		STOVL	CG +6		# SECOND ROW
			CG
		VXV	VSL1
			CG +6
		STORE	CG +14
		EXIT

#		(CONTINUE TO EXTLOGIC)
#
# ***********************************************************************
# PREPARE TO EXIT
# ***********************************************************************
#
# DECIDE (1) HOW TO EXIT, AND (2) WHETHER TO SWITCH PHASES
#
EXTLOGIC	INDEX	WCHPHASE	# WCHPHASE = 1   APPRQUAD
		CA	TENDBRAK	# WCHPHASE = 0   BRAKQUAD
		AD	TTF/8

EXSPOT1		EXTEND
		INDEX	WCHPHASE
		BZMF	WHATEXIT

		TC	FASTCHNG

		CA	WCHPHOLD
		AD	ONE
		TS	WCHPHASE
		CA	ZERO
		TS	FLPASS0		# RESET FLPASS0

		INDEX	WCHPHOLD
		TCF	WHATEXIT		

# ***********************************************************************
# ROUTINES FOR EXITING FROM LANDING GUIDANCE
# ***********************************************************************
#
# 1.	EXGSUB IS THE RETURN WHEN GUIDSUB IS CALLED BY THE IGNITION ALGORITHM.
# 2.	EXBRAK IN THE EXIT USED DURING THE BRAKING PHASE.  IN THIS CASE UNIT(R) IS THE WINDOW POINTING VECTOR.
# 3.	EXNORM IS THE EXIT USED AT OTHER TIMES DURING THE BURN.
# (EXOVFLOW IS A SUBROUTINE OF EXBRAK AND EXNORM CALLED WHEN OVERFLOW OCCURRED ANYWHERE IN GUIDANCE.)

EXGSUB		TC	INTPRET		# COMPUTE TRIM VELOCITY CORRECTION TERM.
# Page 812
		VLOAD	RTB
			UNFC/2
			NORMUNIT
		VXSC	VXSC
			ZOOMTIME
			TRIMACCL
		STORE	UNFC/2
		EXIT

		CCS	NGUIDSUB
		TCF	GUIDSUB
		CCS	NIGNLOOP
		TCF	+3
		TC	ALARM
		OCT	01412

 +3		TC	POSTJUMP
 		CADR	DDUMCALC

EXBRAK		TC	INTPRET
		VLOAD
			UNIT/R/
		STORE	UNWC/2
		EXIT
		TCF	STEER?

EXNORM		TC	INTPRET
		VLOAD	VSU
			LAND
			R
		RTB
			NORMUNIT
		STORE	UNWC/2		# UNIT(LAND - R) IS TENTATIVE CHOICE
		VXV	DOT
			XNBPIP
			CG +6
		EXIT			# WITH PROJ IN MPAC 1/8 REAL SIZE

		CS	MPAC		# GET COEFFICIENT FOR CG +14
		AD	PROJMAX
		AD	POSMAX
		TS	BUF
		CS	BUF
		ADS	BUF		# RESULT IS 0 IF PROJMAX - PROJ NEGATIVE

		CS	PROJMIN		# GET COEFFICIENT FOR UNIT(LAND - R)
		AD	MPAC
		AD	POSMAX
		TS	BUF +1
		CS	BUF +1
# Page 813
		ADS	BUF +1		# RESULT IS 0 IF PROJ - PROJMIN NEGATIVE

		CAF	FOUR
UNWCLOOP	MASK	SIX
		TS	Q
		CA	EBANK5
		TS	EBANK
		EBANK=	CG
		CA	BUF
		EXTEND
		INDEX	Q
		MP	CG +14
		INCR	BBANK
		EBANK=	UNWC/2
		INDEX	Q
		DXCH	UNWC/2
		EXTEND
		MP	BUF +1
		INDEX	Q
		DAS	UNWC/2
		CCS	Q
		TCF	UNWCLOOP

		INCR	BBANK
		EBANK=	PIF

STEER?		CA	FLAGWRD2	# IF STEERSW DOWN NO OUTPUTS
		MASK	STEERBIT
		EXTEND
		BZF	RATESTOP

EXVERT		CA	OVFIND		# IF OVERFLOW ANYWHERE IN GUIDANCE
		EXTEND			#	DON'T CALL THROTTLE OR FINDCDUW
		BZF	+13

EXOVFLOW	TC	ALARM		# SOUND THE ALARM NON-ABORTIVELY
		OCT	01410

RATESTOP	CAF	BIT13		# ARE WE IN ATTITUDE-HOLD?
		EXTEND
		RAND	CHAN31
		EXTEND
		BZF	DISPEXIT	# YES

		TC	BANKCALL	# NO:  DO A STOPRATE
		CADR	STOPRATE

		TCF	DISPEXIT

GDUMP1		TC	THROTTLE
# Page 814
		TC	INTPRET
		CALL
			FINDCDUW -2
		EXIT

# 		(CONTINUE TO DISPEXIT)

# ***********************************************************************
# GUIDANCE LOOP DISPLAYS
# ***********************************************************************

DISPEXIT	EXTEND			# KILL GROUP 3:  DISPLAYS WILL BE
		DCA	NEG0		#	RESTORED BY NEXT GUIDANCE CYCLE.
		DXCH	-PHASE3

 +3		CS	FLAGWRD8	# IF FLUNDISP IS SET, NO DISPLAY THIS PASS
 		MASK	FLUNDBIT
		EXTEND
		BZF	ENDLLJOB	# TO PICK UP THE TAG

		INDEX	WCHPHOLD
		TCF	WHATDISP

-2		TC	PHASCHNG	# KILL GROUP 5
		OCT	00035

P63DISPS	CAF	V06N63
DISPCOMN	TC	BANKCALL
		CADR	REGODSPR

ENDLLJOB	TCF	ENDOFJOB

P64DISPS	CA	TREDES		# HAS TREDES REACHED ZERO?
		EXTEND
		BZF	RED-OVER	# YES: CLEAR REDESIGNATION FLAG

		CS	FLAGWRD6	# NO:  IS REDFLAG SET?
		MASK	REDFLBIT
		EXTEND
		BZF	REDES-OK	# YES:  DO STATIC DISPLAY

		CAF	V06N64		# OTHERWISE USE FLASHING DISPLAY
		TC	BANKCALL
		CADR	REFLASHR
		TCF	GOTOP00H	# TERMINATE
		TCF	P64CEED		# PROCEED	PERMIT REDESIGNATIONS
		TCF	P64DISPS	# RECYCLE
# Page 815
		TCF	ENDLLJOB

P64CEED		CAF	ZERO
		TS	ELINCR1
		TS	AZINCR1

		TC	UPFLAG		# ENABLE REDESIGNATION LOGIC
		ADRES	REDFLAG

		TCF	ENDOFJOB

RED-OVER	TC	DOWNFLAG
		ADRES	REDFLAG
REDES-OK	CAF	V06N64
		TCF	DISPCOMN

VERTDISP	CAF	V06N60
		TCF	DISPCOMN

# **************************************************************************
# GUIDANCE FOR P65
# **************************************************************************

VERTGUID	CCS	WCHVERT
		TCF	P67VERT		# POSITIVE NON-ZERO ---> P67
		TCF	P66VERT		# +0
#
# 	THE P65 GUIDANCE EQUATION IS AS FOLLOWS --
#		      ____   ___
#		      V2FG - VGU
#		ACG = ----------
#		        TAUVERT

P65VERT		TC	INTPRET
		VLOAD	VSU
			V2FG
			VGU
		V/SC	GOTO
			TAUVERT
			AFCCALC1
# Page 816
# **********************************************************
# GUIDANCE FOR P66
# **********************************************************

P66VERT		TC	POSTJUMP
		CADR	P66VERTA

P67VERT		TC	PHASCHNG	# TERMINATE GROUP 3.
		OCT	00003

		TC	INTPRET
		VLOAD	GOTO
			V
			VHORCOMP

		SETLOC	P66LOC
		BANK
		COUNT*	$$/F2DPS

RODTASK		CAF	PRIO22
		TC	FINDVAC
		EBANK=	DVCNTR
		2CADR	RODCOMP

		TCF	TASKOVER

P66VERTA	TC	PHASCHNG	# TERMINATE GROUP 3.
		OCT	00003

		CAF	1SEC
		TC	TWIDDLE
		ADRES	RODTASK

RODCOMP		INHINT
		CAF	ZERO
		XCH	RODCOUNT
		EXTEND
		MP	RODSCAL1
		DAS	VDGVERT		# UPDATE DESIRED ALTITUDE RATE.

		EXTEND			# SET OLDPIPAX,Y,Z = PIPAX,Y,Z
		DCA	PIPAX
		DXCH	OLDPIPAX
		DXCH	RUPTREG1	# SET RUPTREG1,2,3 = OLDPIPAX,Y,Z
		CA	PIPAZ
		XCH	OLDPIPAZ
		XCH	RUPTREG3

		EXTEND			# SHAPSHOT TIME OF PIPA READING.
		DCA	TIME2
# Page 817
		DXCH	THISTPIP

		CA	OLDPIPAX
		AD	PIPATMPX
		TS	MPAC		# MPAC(X) = PIPAX + PIPATMPX
		CA	OLDPIPAY
		AD	PIPATMPY
		TS	MPAC +3		# MPAC(Y) = PIPAY + PIPATMPY
		CA	OLDPIPAZ
		AD	PIPATMPZ
		TS	MPAC +5		# MPAC(Z) = PIPAZ + PIPATMPZ

		CS	OLDPIPAX
		AD	TEMX
		AD	RUPTREG1
		TS	DELVROD
		CS	OLDPIPAY
		AD	TEMY
		AD	RUPTREG2
		TS	DELVROD +2
		CS	OLDPIPAZ
		AD	TEMZ
		AD	RUPTREG3
		TS	DELVROD +4

		CAF	ZERO
		TS	MPAC +1		# ZERO LO-ORDER MPAC COMPONENTS
		TS	MPAC +4
		TS	MPAC +6
		TS	TEMX		# ZERO TEMX, TEMY, AND TEMZ SO WE WILL
		TS	TEMY		#	KNOW WHEN READACCS CHANGES THEM.
		TS	TEMZ
		CS	ONE
		TS	MODE
		TC	INTPRET
ITRPNT1		VXSC	PDDL		# SCALE MPAC TO M/CS *2(-7) AND PUSH 	(6)
			KPIP1
			THISTPIP
		DSU
			PIPTIME
		STORE	30D		# 30-31D CONTAINS TIME IN CS SINCE PIPTIME
		DDV	PDVL		#					(8)
			4SEC(28)
			GDT/2
		VSU	VXSC		#					(6)
			VBIAS
		VSL2	VAD
			V
		VAD	STADR		#					(0)
		STOVL	24D		# STORE UPDATED VELOCITY IN 24-29D
# Page 818
			R
		UNIT
		STORE	14D
		DOT	SL1
			24D
		STODL	HDOTDISP	# UPDATE HDOTDISP RATE FOR NOUN 63.
			30D
		SL	DMP
			11D
			HDOTDISP
		DAD	DSU
			36D
			/LAND/
		STODL	HCALC1		# UPDATE HCALC1 FOR NOUN 63.
			HDOTDISP
		BDSU	DDV
			VDGVERT
			TAUROD
		PDVL	ABVAL		#				(2)
			GDT/2
		DDV	SR2
			GSCALE
		STORE	20D
		DAD			#				(0)
		PDVL	CALL		#				(2)
			UNITX
			CDU*NBSM
		DOT
			14D
		STORE	22D
		BDDV	STADR		#				(0)
		STOVL	/AFC/
			DELVROD
		VXSC	VAD
			KPIP1
			VBIAS
		ABVAL	PDDL		#				(2)
			THISTPIP
		DSU	PDDL		#				(4)
			LASTTPIP
			THISTPIP
		STODL	LASTTPIP	#				(2)
		DDV	BDDV		#				(0)
			SHFTFACT
		PDDL	DMP		#				(2)
			FWEIGHT
			BIT1H
		DDV	DDV
			MASS
			SCALEFAC
# Page 819
		DAD	PDDL		#				(4)
			0D
			20D
		DDV	DSU		#				(2)
			22D
		DMP	DAD
			LAG/TAU
			/AFC/
		PDDL	DDV		#				(4)
			MAXFORCE
			MASS
		PDDL	DDV		#				(6)
			MINFORCE
			MASS
		PUSH	BDSU		#				(8)
			2D
		BMN	DLOAD		#				(6)
			AFCSPOT
		DLOAD	PUSH		#				(6)
		BDSU	BPL
			2D
			AFCSPOT
		DLOAD			#				(4)
AFCSPOT		DLOAD			#				(2), (4), OR (6)
		SETPD			#				(2)
			2D
		STODL	/AFC/		#				(0)
ITRPNT2		EXIT
		DXCH	MPAC		# MPAC = MEASURED ACCELARATION.
		TC	BANKCALL
		CADR	THROTTLE +3
		TC	INTPRET
		VLOAD			# PICK UP UPDATED VELOCITY VECTOR.
			24D
VHORCOMP	VSL2	VAD
			DELVS
		VSR2	PDVL
			R
		UNIT	VXSC
			HDOTDISP
		VSL1	BVSU
		ABVAL
		STORE	VHORIZ
		EXIT
		TC	BANKCALL	# PUT UP V06N60 DISPLAY BUT AVOID PHASCHNG
		CADR	DISPEXIT +3

BIT1H		OCT	00001
SHFTFACT	2DEC	1 B-17
# Page 820
BIASFACT	2DEC	655.36 B-28

# *********************************************************************************
# REDESIGNATOR TRAP
# *********************************************************************************

		BANK	11
		SETLOC	F2DPS*11
		BANK

		COUNT*	$$/F2DPS

PITFALL		XCH	BANKRUPT
		EXTEND
		QXCH	QRUPT

		TC	CHECKMM		# IF NOT IN P64, NO REASON TO CONTINUE
		DEC	64
		TCF	RESUME

		EXTEND
		READ	CHAN31
		COM
		MASK	ALL4BITS
		TS	ELVIRA
		CAF	TWO
		TS	ZERLINA
		CAF	FIVE
		TC	TWIDDLE
		ADRES	REDESMON
		TCF	RESUME

# REDESIGNATOR MONITOR (INITIATED BY PITFALL)

PREMON1		TS	ZERLINA
PREMON2		CAF	SEVEN
		TC	VARDELAY
REDESMON	EXTEND
		READ	31
		COM
		MASK	ALL4BITS
		XCH	ELVIRA
		TS	L
		CCS	ELVIRA		# DO ANY BITS APPEAR THIS PASS?
		TCF	PREMON2		# Y:	CONTINUE MONITOR

		CCS	L		# N:	ANY LAST PASS?
		TCF	COUNT'EM	#	Y: 	COUNT 'EM, RESET RUPT, TERMINATE
# Page 821
		CCS	ZERLINA		#	N: 	HAS ZERLINA REACHED ZERO YET?
		TCF	PREMON1		#		N:	DIMINISH ZERLINA, CONTINUE
RESETRPT	CAF	BIT12		#		Y:	RESET RUPT. TERMINATE
		EXTEND
		WOR	CHAN13
		TCF	TASKOVER

COUNT'EM	CAF	BIT13		# ARE WE IN ATTITUDE-HOLD?
		EXTEND
		RAND	CHAN31
		EXTEND
		BZF	RESETRPT	# YES: SKIP REDESIGNATION LOGIC.

		CA	L		# NO.
		MASK 	-AZBIT
		CCS	A
-AZ		CS	AZEACH
		ADS	AZINCR1
		CA	L
		MASK	+AZBIT
		CCS	A
+AZ		CA	AZEACH
		ADS	AZINCR1
		CA	L
		MASK	-ELBIT
		CCS	A
-EL		CS	ELEACH
		ADS	ELINCR1
		CA	L
		MASK	+ELBIT
		CCS	A
+EL		CA	ELEACH
		ADS	ELINCR1
		TCF	RESETRPT

# THESE EQUIVALENCES ARE BASED ON GSOP CHAPTER 4, REVISION 16 OF P64LM

+ELBIT		=	BIT2		# -PITCH
-ELBIT		=	BIT1		# +PITCH
+AZBIT		=	BIT5
-AZBIT		=	BIT6

# Page 822
ALL4BITS	OCT	00063
AZEACH		DEC	.03491		# 2 DEGREES
ELEACH		DEC	.00873		# 1/2 DEGREE

# ****************************************************************
# R.O.D. TRAP
# ****************************************************************

		BANK	20
		SETLOC	RODTRAP
		BANK
		COUNT*	$$/F2DPS	# ************************

DESCBITS	MASK	BIT7		# COME HERE FROM MARKRUPT CODING WITH BIT
		CCS	A		#	7 OR 6 OF CHANNEL 16 IN A; BIT 7 MEANS
		CS	TWO		#	- RATE INCREMENT, BIT 6 + INCREMENT.
		AD	ONE
		ADS	RODCOUNT
		TCF	RESUME		# TRAP IS RESET WHEN SWITCH IS RELEASED

		BANK	31
		SETLOC	F2DPS*31
		BANK

		COUNT*	$$/F2DPS

# ***********************************************************************************
# DOUBLE PRECISION ROOT FINDER SUBROUTINE (BY ALLAN KLUMPP)
# ***********************************************************************************
#
#	                                               N        N-1
#	ROOTPSRS FINDS ONE ROOT OF THE POWER SERIES A X  + A   X    + ... + A X + A
#	                                             N      N-1              1     0
# USING NETON'S METHOD STARTING WITH AN INITIAL GUESS FOR THE ROOT.  THE ENTERING DATA MUST BE AS FOLLOWS:
#	A	SP	LOC-3		ADRES FOR REFERENCING PWR COF TABL
#	L	SP	N-1		N IS THE DEGREE OF THE POWER SERIES
#	MPAC	DP	X		INITIAL GUESS FOR ROOT
#
#	LOC-2N	DP	A(0)
#		...
#	LOC	DP	A(N)
#	LOC+2	SP	PRECROOT	 PREC RQD OF ROOT (AS FRACT OF 1ST GUESS)
#
# Page 823
# THE DP RESULT IS LEFT IN MPAC UPON EXIT, AND A SP COUNT OF THE ITERATIONS TO CONVERGENCE IS LEFT IN MPAC+2.
# RETURN IS NORMALLY TO LOC(TC ROOTPSRS)+3.  IF ROOTPSRS FAILS TO CONVERGE TO IN 8 PASSES, RETURN IS TO LOC+1 AND
# OUTPUTS ARE NOT TO BE TRUSTED.
#
# PRECAUTION:  ROOTPSRS MAKES NO CHECKS FOR OVERFLOW OR FOR IMPROPER USAGE.  IMPROPER USAGE COULD
# PRECLUDE CONVERGENCE OR REQUIRE EXCESSIVE ITERATIONS.  AS A SPECIFIC EXAMPLE, ROOTPSRS FORMS A DERIVATIVE
# COEFFICIENT TABLE BY MULTIPLYINE EACH A(I) BY I, WHERE I RANGES FROM 1 TO N.  IF AN ELEMENT OF THE DERIVATIVE
# COEFFICIENT TABLE = 1 OR >1 IN MAGNITUDE, ONLY THE EXCESS IS RETAINED.  ROOTPSRS MAY CONVERGE ON THE COREECT
# ROOT NONETHELESS, BUT IT MAY TAKE AN EXCESSIVE NUMBER OF ITERATIONS.  THEREFORE THE USER SHOULD RECOGNIZE:
#	1.  USER'S RESPONSIBILITY TO ASSUR THAT I X A(I) < 1 IN MAGNITUDE FOR ALL I.
#	2.  USER'S RESPONSIBILITY TO ASSURE OVERFLOW WILL NOT OCCUR IN EVALUTATING EITHER THE RESIDUAL OR THE DERIVATIVE
#	    POWER SERIES.  THIS OVERFLOW WOULD BE PRODUCED BY SUBROUTINE POWRSERS, CALLED BY ROOTPSRS, AND MIGHT NOT
#	    PRECLUDE EVENTUAL CONVERGENCE.
#	3.  AT PRESENT, ERASABLE LOCATIONS ARE RESERVED ONLY FOR N UP TO 5.  AN N IN EXCESS OF 5 WILL PRODUCE CHAOS.
#	    ALL ERASABLES USED BY ROOTPSRS ARE UNSWITCHED LOCATED IN THE REGION FROM MPAC-33 OCT TO MPAC+7.
#	4.  THE ITERATION COUNT RETURNED IN MPAC+2 MAY BE USED TO DETECT ABNORMAL PERFORMANCE.

					# STORE ENTERING DATA, INITIALIZE ERASABLES
ROOTPSRS	EXTEND
		QXCH	RETROOT		# RETURN ADRES
		TS	PWRPTR		# PWR TABLE POINTER
		DXCH	MPAC +3		# PWR TABLE ADRES, N-1
		CA	DERTABLL
		TS	DERPTR		# DER TABL POINTER
		TS	MPAC +5		# DER TABL ADRES
		CCS	MPAC +4		# NO POWER SERIES DEGREE 1 OR LESS
		TS	MPAC +6		# N-2
		CA	ZERO		# MODE USED AS ITERATION COUNTER.  MODE
		TS	MODE		# MUST BE POS SO ABS WON'T COMP MPAC+3 ETC.

					# COMPUTE CRITERION TO STOP ITERATING
		EXTEND
		DCA	MPAC		# FETCH ROOT GUESS, KEEPING IT IN MPAC
		DXCH	ROOTPS		# AND IN ROOTPS
		INDEX	MPAC +3		# PWR TABLE ADRES
		CA	5		# PRECROOT TO A
		TC	SHORTMP		# YIELDS DP PRODUCT IN MPAC
		TC	USPRCADR
		CADR	ABS		# YIELDS ABVAL OF CRITERION ON DX IN MPAC
		DXCH	MPAC
		DXCH	DXCRIT		# CRITERION

					# SET UP DER COF TABL
# Page 824
		EXTEND
		INDEX	PWRPTR
		DCA	3
		DXCH	MPAC		# A(N) TO MPAC

		CA	MPAC +4		# N-1 TO A

DERCLOOP	TS	PWRCNT		# LOOP COUNTER
		AD	ONE
		TC	DMPNSUB		# YIELDS DERCOF = I X A(I) IN MPAC
		EXTEND
		INDEX	PWRPTR
		DCA	1
		DXCH	MPAC		# (I-1) TO MPAC, FETCHING DERCOF
		INDEX	DERPTR
		DXCH	3		# DERCOF TO DER TABLE
		CS	TWO
		ADS	PWRPTR		# DECREMENT PWR POINTER
		CS	TWO
		ADS	DERPTR		# DECREMENT DER POINTER
		CCS	PWRCNT
		TCF	DERCLOOP

					# CONVERGE ON ROOT
ROOTLOOP	EXTEND
		DCA	ROOTPS		# FETCH CURRENT ROOT
		DXCH	MPAC		# LEAVE IN MPAC
		EXTEND
		DCA	MPAC +5		# LOAD A, L WITH DER TABL ADRES, N-2
		TC	POWRSERS	# YIELDS DERIVATIVE IN MPAC

		EXTEND
		DCA	ROOTPS
		DXCH	MPAC		# CURRENT ROOT TO MPAC, FETCHING DERIVATIVE
		DXCH	BUF		# LEAVE DERIVATIVE IN BUF AS DIVISOR
		EXTEND
		DCA	MPAC +3		# LOAD A, L WITH PWR TABL ADRES, N-1
		TC	POWRSERS	# YIELDS RESIDUAL IN MPAC

		TC	USPRCADR
		CADR	DDV/BDDV	# YIELDS -DX IN MPAC

		EXTEND
		DCS	MPAC		# FETCH DX, LEAVING -DX IN MPAC
		DAS	ROOTPS		# CORRECTED ROOT NOW IN ROOTPS

		TC	USPRCADR
		CADR	ABS		# YIELDS ABS(DX) IN MPAC
		EXTEND
# Page 825
		DCS	DXCRIT
		DAS	MPAC		# ABS(DX)-ABS(DXCRIT) IN MPAC

		CA	MODE
		MASK	BIT4		# KLUMPP SAYS GIVE UP AFTER EIGHT PASSES
		CCS	A
BADROOT		TC	RETROOT

		INCR	MODE		# INCREMENT ITERATION COUNTER
		CCS	MPAC		# TEST HI ORDER DX
		TCF	ROOTLOOP
		TCF	TESTLODX
		TCF	ROOTSTOR
TESTLODX	CCS	MPAC +1		# TEST LO ORDER DX
		TCF	ROOTLOOP
		TCF	ROOTSTOR
		TCF	ROOTSTOR
ROOTSTOR	DXCH	ROOTPS
		DXCH	MPAC
		CA	MODE
		TS	MPAC +2		# STORE SP ITERATION COUNT IN MPAC+2
		INDEX	RETROOT
		TCF	2

DERTABLL	ADRES	DERCOFN -3

# ****************************************************************************
# TRASHY LITTLE SUBROUTINES
# ****************************************************************************

INTPRETX	INDEX	WCHPHASE	# SET X1 ON THE WAY TO THE INTERPRETER
		CS	TARGTDEX
		INDEX	FIXLOC
		TS	X1
		TCF	INTPRET

TDISPSET	CA	TTF/8
		EXTEND
		MP	TSCALINV
		DXCH	TTFDISP

		CA	EBANK5		# TREDES BECOMES ZERO TWO PASSES
		TS	EBANK		#	BEFORE TCGFAPPR IS REACHED
		EBANK=	TCGFAPPR
		CA	TCGFAPPR
		INCR	BBANK
		INCR	BBANK
		EBANK=	TTF/8
# Page 826
		AD	TTF/8
		EXTEND
		MP	TREDESCL
		AD	-DEC103
		AD	NEGMAX
		TS	L
		CS	L
		AD	L
		AD	+DEC99
		AD	POSMAX
		TS	TREDES
		CS	TREDES
		ADS	TREDES
		TC	Q

1406P00		TC	P00DOO
		OCT	01406
1406ALM		TC	ALARM
		OCT	01406
		TCF	RATESTOP

# *********************************************************************
# SPECIALIZED "PHASCHNG" SUBROUTINE
# *********************************************************************

		EBANK=	PHSNAME2
FASTCHNG	CA	EBANK3		# SPECIALIZED 'PHASCHNG' ROUTINE
		XCH	EBANK
		DXCH	L
		TS	PHSNAME3
		LXCH	EBANK
		EBANK=	E2DPS
		TC	A

# *************************************************************************************
# PARAMETER TABLE INDIRECT ADDRESSES
# *************************************************************************************

RDG		=	RBRFG
VDG		=	VBRFG
ADG		=	ABRFG
VDG2TTF		=	VBRFG*
ADG2TTF		=	ABRFG*
JDG2TTF		=	JBRFG*

# *************************************************************************************
# LUNAR LANDING CONSTANTS
# *************************************************************************************

# Page 827
TABLTTFL	ADRES	TABLTTF +3	# ADDRESS FOR REFERENCING TTF TABLE
TTFSCALE	=	BIT12
TSCALINV	=	BIT4
-DEC103		DEC	-103
+DEC99		DEC	+99
TREDESCL	DEC	-.08
180DEGS		DEC	+180
1/2DEG		DEC	+.00278
PROJMAX		DEC	.42262 B-3	# SIN(25')/8 TO COMPARE WITH PROJ
PROJMIN		DEC	.25882 B-3	# SIN(15')/8 TO COMPARE WITH PROJ
V06N63		VN	0663		# P63
V06N64		VN	0664		# P64
V06N60		VN	0660		# P65, P66, P67

		BANK	22
		SETLOC	LANDCNST
		BANK
		COUNT*	$$/F2DPS

HIGHESTF	2DEC	4.34546769 B-12
GSCALE		2DEC	100 B-11
3/8DP		2DEC	.375
3/4DP		2DEC	.750
DEPRCRIT	2DEC	-.02 B-1

# Page 828
# **************************************************************************
# **************************************************************************

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1471

# Copyright: Public domain.

# Filename: LUNAR_LANDING_GUIDANCE_EQUATIONS.s

# Purpose: Part of the source code for Luminary 1A build 099.

# It is part of the source code for the Lunar Module's (LM)

# Apollo Guidance Computer (AGC), for Apollo 11.

# Assembler: yaYUL

# Contact: HARTMUTH GUTSCHE <[email protected]>.

# Website: www.ibiblio.org/apollo.

# Pages: 798-828

# Mod history: 2009-05-23 HG Transcribed from page images.

# 2009-06-05 RSB Fixed a goofy thing that was apparently

# legal in GAP but not in yaYUL. Eliminated

# a couple of lines of code that shouldn't

# have survived from Luminary 131 to here.

# 2009-06-07 RSB Fixed a typo.

# This source code has been transcribed or otherwise adapted from

# digitized images of a hardcopy from the MIT Museum. The digitization

# was performed by Paul Fjeld, and arranged for by Deborah Douglas of

# the Museum. Many thanks to both. The images (with suitable reduction

# in storage size and consequent reduction in image quality as well) are

# available online at www.ibiblio.org/apollo. If for some reason you

# find that the images are illegible, contact me at [email protected]

# about getting access to the (much) higher-quality images which Paul

# actually created.

# Notations on the hardcopy document read, in part:

# Assemble revision 001 of AGC program LMY99 by NASA 2021112-61

# 16:27 JULY 14, 1969

# Page 798

EBANK= E2DPS

COUNT* $$/F2DPS

# ********************************************************

# LUNAR LANDING FLIGHT SEQUENCE TABLES

# ********************************************************

# FLIGHT SEQUENCE TABLES ARE ARRANGED BY FUNCTION. THEY ARE REFERENCED USING AS AN INDEX THE REGISTER WCHPHASE:

# WCHPHASE = -1 ---> IGNALG

# WCHPHASE = 0 ---> BRAKQUAD

# WCHPHASE = 1 ---> APPRQUAD

# WCHPHASE = 2 ---> VERTICAL

#*********************************************************

# ROUTINES FOR STARTING NEW GUIDANCE PHASES:

TCF TTFINCR # IGNALG

NEWPHASE TCF TTFINCR # BRAKQUAD

TCF STARTP64 # APPRQUAD

TCF P65START # VERTICAL

# PRE-GUIDANCE COMPUTATIONS:

TCF CALCRGVG # IGNALG

PREGUIDE TCF RGVGCALC # BRAKQUAD

TCF REDESIG # APPRQUAD

TCF RGVGCALC # VERTICAL

# GUIDANCE EQUATIONS:

TCF TTF/8CL # IGNALG

WHATGUID TCF TTF/8CL # BRAKQUAD

TCF TTF/8CL # APPRQUAD

TCF VERTGUID # VERTICAL

# POST GUIDANCE EQUATION COMPUTATIONS:

TCF CGCALC # IGNALG

AFTRGUID TCF CGCALC # BRAKQUAD

TCF CGCALC # APPRQUAD

TCF STEER? # VERTICAL

# Page 799

# WINDOW VECTOR COMPUTATIONS:

TCF EXGSUB # IGNALG

WHATEXIT TCF EXBRAK # BRAKQUAD

TCF EXNORM # APPRQUAD

# DISPLAY ROUTINES:

WHATDISP TCF P63DISPS # BRAKQUAD

TCF P64DISPS # APPRQUAD

TCF VERTDISP # VERTICAL

# ALARM ROUTINE FOR TTF COMPUTATION:

TCF 1406P00 # IGNALG

WHATALM TCF 1406ALM # BRAKQUAD

TCF 1406ALM # APPRQUAD

# INDICES FOR REFERENCING TARGET PARAMETERS

OCT 0 # IGNALG

TARGTDEX OCT 0 # BRAKQUAD

OCT 34 # APPRQUAD

#************************************************************************

# ENTRY POINTS: ?GUIDSUB FOR THE IGNITION ALGORITHM, LUNLAND FOR SERVOUT

#************************************************************************

# IGNITION ALGORITHM ENTRY: DELIVERS N PASSES OF QUADRATIC GUIDANCE

?GUIDSUB EXIT

CAF TWO # N = 3

TS NGUIDSUB

TCF GUILDRET +2

GUIDSUB TS NGUIDSUB # ON SUCCEEDING PASSES SKIP TTFINCR

TCF CALCRGVG

# NORMAL ENTRY: CONTROL COMES HERE FROM SERVOUT

LUNLAND TC PHASCHNG

OCT 00035 # GROUP 5: RETAIN ONLY PIPA TASK

TC PHASCHNG

OCT 05023 # GROUP 3: PROTECT GUIDANCE WITH PRIO 21

OCT 21000 # JUST HIGHER THAN SERVICER'S PRIORITY

# Page 800

#*******************************************************************

# GUILDENSTERN: AUTO-MODES MONITOR (R13)

#*******************************************************************

COUNT* $$/R13

# HERE IS THE PHILOSOPHY OF GUILDENSTERN: ON EVERY APPEARANCE OR DISAPPEARANCE OF THE MANUAL THROTTLE

# DISCRETE TO SELECT P67 OR P66 RESPECTIVELY: ON EVERY APPEARANCE OF THE ATTITUDE-HOLD DISCRETE TO SELECT P66

# UNLESS THE CURRENT PROGRAM IS P67 IN WHICH CASE THERE IS NO CHANGE

GUILDEN EXTEND # IS UN-AUTO-THROTTLE DISCRETE PRESENT?

# STERN # RSB 2009: Not originally a comment.

READ CHAN30

MASK BIT5

CCS A

TCF STARTP67 # YES

P67NOW? TC CHECKMM # NO: ARE WE IN P67 NOW?

DEC 67

TCF STABL? # NO

STARTP66 TC FASTCHNG # YES

TC NEWMODEX

DEC66 DEC 66

EXTEND

DCA HDOTDISP # SET DESIRED ALTITUDE RATE = CURRENT

DXCH VDGVERT # ALTITUDE RATE.

STRTP66A TC INTPRET

SLOAD PUSH

PBIASZ

SLOAD PUSH

PBIASY

SLOAD VDEF

PBIASX

VXSC SET

BIASFACT

RODFLAG

STOVL VBIAS

TEMX

VCOMP

STOVL OLDPIPAX

ZEROVECS

STODL DELVROD

RODSCALE

STODL RODSCAL1

PIPTIME

STORE LASTTPIP

EXIT

CAF ZERO

TS FCOLD

TS FWEIGHT

TS FWEIGHT +1

VRTSTART TS WCHVERT

# Page 801

CAF TWO # WCHPHASE = 2 ---> VERTICAL: P65,P66,P67

TS WCHPHOLD

TS WCHPHASE

TC BANKCALL # TEMPORARY, I HOPE HOPE HOPE

CADR STOPRATE # TEMPORARY, I HOPE HOPE HOPE

TC DOWNFLAG # PERMIT X-AXIS OVERRIDE

ADRES XOVINFLG

TC DOWNFLAG

ADRES REDFLAG

TCF VERTGUID

STARTP67 TC NEWMODEX # NO HARM IN "STARTING" P67 OVER AND OVER

DEC 67 # SO NO NEED FOR A FASTCHNG AND NO NEED

CAF ZERO # TO SEE IF ALREADY IN P67.

TS RODCOUNT

CAF TEN

TCF VRTSTART

STABL? CAF BIT13 # IS UN-ATTITUDE-HOLD DISCRETE PRESENT?

EXTEND

RAND CHAN31

CCS A

TCF GUILDRET # YES ALL'S WELL

P66NOW? CS MODREG

AD DEC66

EXTEND

BZF RESTART?

CA RODCOUNT # NO. HAS THE ROD SWITCH BEEN "CLICKED"?

EXTEND

BZF GUILDRET # NO. CONTINUE WITH AUTOMATIC LANDING

TCF STARTP66 # YES. SWITCH INTO THE ROD MODE.

RESTART? CA FLAGWRD1 # HAS THERE BEEN A RESTART?

MASK RODFLBIT

EXTEND

BZF STRTP66A # YES. REINITIALIZE BUT LEAVE VDGVERT AS

# IS.

TCF VERTGUID # NO: CONTINUE WITH R.O.D.

# *******************************************************************************

# INITIALIZATION FOR THIS PASS

# *******************************************************************************

COUNT* $$/F2DPS

GUILDRET CAF ZERO

TS RODCOUNT

# Page 802

+2 EXTEND

DCA TPIP

DXCH TPIPOLD

TC FASTCHNG

EXTEND

DCA PIPTIME1

DXCH TPIP

EXTEND

DCA TTF/8

DXCH TTF/8TMP

CCS FLPASS0

TCF TTFINCR

BRSPOT1 INDEX WCHPHASE

TCF NEWPHASE

# ******************************************************************

# ROUTINES TO START NEW PHASES

# ******************************************************************

P65START TC NEWMODEX

DEC 65

CS TWO

TS WCHVERT

TC DOWNFLAG # PERMIT X-AXIS OVERRIDE

ADRES XOVINFLG

TCF TTFINCR

STARTP64 TC NEWMODEX

DEC 64

CA DELTTFAP # AUGMENT TTF/8

ADS TTF/8TMP

CA BIT12 # ENABLE RUPT10

EXTEND

WOR CHAN13

TC DOWNFLAG # INITIALIZE REDESIGNATION FLAG

ADRES REDFLAG

# (CONTINUE TO TTFINCR)

# *********************************************************************************

# INCREMENT TTF/8, UPDATE LAND FOR LUNAR ROTATION, DO OTHER USEFUL THINGS

# *********************************************************************************

# TTFINCR COMPUTATIONS ARE AS FOLLOWS --

# Page 803

# TTF/8 UPDATED FOR TIME SINCE LAST PASS:

# TTF/8 = TTF/8 + (TPIP - TPIPOLD)/8

# LANDING SITE VECTOR UPDATED FOR LUNAR ROTATION:

# ____ ____ ____ __

# LAND = /LAND/ UNIT(LAND - LAND(TPIP - TPIPOLD) * WM)

# SLANT RANGE TO LANDING SITE, FOR DISPLAY:

# ____ _

# RANGEDSP = ABVAL(LAND - R)

TTFINCR TC INTPRET

DLOAD DSU

TPIP

TPIPOLD

SLR PUSH # SHIFT SCALES DELTA TIME TO 2(17) CSECS

11D

VXSC VXV

LAND

BVSU RTB

LAND

NORMUNIT

VXSC VSL1

/LAND/

STODL LANDTEMP

EXIT

DXCH MPAC

DAS TTF/8TMP # NOW HAVE INCREMENTED TTF/8 IN TTF/8TMP

TC FASTCHNG

EXTEND

DCA TTF/8TMP

DXCH TTF/8

EXTEND

DCA LANDTEMP

DXCH LAND

EXTEND

DCA LANDTEMP +2

DXCH LAND +2

EXTEND

DCA LANDTEMP +4

DXCH LAND +4

# Page 804

TC TDISPSET

TC FASTCHNG # SINCE REDESIG MAY CHANGE LANDTEMP

BRSPOT2 INDEX WCHPHASE

TCF PREGUIDE

# *********************************************************************

# LANDING SITE PERTURBATION EQUATIONS

# *********************************************************************

REDESIG CA FLAGWRD6 # IS REDFLAG SET?

MASK REDFLBIT

EXTEND

BZF RGVGCALC # NO: SKIP REDESIGNATION LOGIC

CA TREDES # YES: HAS TREDES REACHED ZERO?

EXTEND

BZF RGVGCALC # YES: SKIP REDESIGNATION LOGIC

INHINT

CA ELINCR1

TS ELINCR

CA AZINCR1

TS AZINCR

TC FASTCHNG

CA ZERO

TS ELINCR1

TS AZINCR1

TS ELINCR +1

TS AZINCR +1

CA FIXLOC # SET PD TO 0

TS PUSHLOC

TC INTPRET

VLOAD VSU

LAND

R # ____ _

RTB PUSH # PUSH DOWN UNIT (LAND - R)

NORMUNIT

VXV VSL1

YNBPIP # ___ ____ _

VXSC PDDL # PUSH DOWN - ELINCR(YNB * UNIT(LAND - R))

ELINCR

AZINCR

VXSC VSU

YNBPIP

VAD PUSH # RESULTING VECTOR IS 1/2 REAL SIZE

# Page 805

DLOAD DSU # MAKE SURE REDESIGNATION IS NOT

0 # TOO CLOSE TO THE HORIZON.

DEPRCRIT

BMN DLOAD

REDES1

DEPRCRIT

STORE 0

REDES1 DLOAD DSU

LAND

DDV VXSC

VAD UNIT

VXSC VSL1

/LAND/

STORE LANDTEMP

EXIT # LOOKANGL WILL BE COMPUTED AT RGVGCALC

TC FASTCHNG

EXTEND

DCA LANDTEMP

DXCH LAND

EXTEND

DCA LANDTEMP +2

DXCH LAND +2

EXTEND

DCA LANDTEMP +4

DXCH LAND +4

TCF RGVGCALC

# *********************************************************************

# COMPUTE STATE IN GUIDANCE COORDINATES

# *********************************************************************

# RGVGCALC COMPUTATIONS ARE AS FOLLOWS:--

# VELOCITY RELATIVE TO THE SURFACE

# _______ _ _ __

# ANGTERM = V + R * WM

# STATE IN GUIDANCE COORDINTES:

# ___ * _ ____

# RGU = CG (R - LAND)

# ___ * _ __ _

# VGU = CG (V - WM * R)

# Page 806 actually starts one line earlier but that would separate the markers from their variables

# HORIZONTAL VELOCITY FOR DISPLAY

# VHORIZ = 8 ABVAL (0, VG , VG )

# 2 1

# DEPRESSION ANGLE FOR DISPLAY:

# _ ____ ______

# LOOKANGL = ARCSIN(UNIT(R - LAND).XMBPIP)

CALCRGVG TC INTPRET # IN IGNALG, COMPUTE V FROM INTEGRATION

VLOAD MXV # OUTPUT AND TRIM CORRECTION TERM

VATT1 # COMPUTED LAST PASS AND LEFT IN UNFC/2

REFSMMAT

VSR1 VAD

UNFC/2

STORE V

EXIT

RGVGCALC TC INTPRET # ENTER HERE TO RECOMPUTE RG AND VG

VLOAD VXV

VAD VSR2 # RESCALE TO UNITS OF 2(9) M/CS

STORE ANGTERM

MXV

CG # NO SHIFT SINCE ANGTERM IS DOUBLE SIZED

STORE VGU

PDDL VDEF # FORM (0,VG ,VG ) IN UNITS OF 2(10) M/CS

ZEROVECS # 2 1

ABVAL SL3

STOVL VHORIZ # VHORIZ FOR DISPLAY DURING P65.

R # _ ____

VSU PUSH # PUSH DOWN R - LAND

LAND

MXV VSL1

STORE RGU

ABVAL

STOVL RANGEDSP

RTB DOT # NOW IN MPAC IS SINE(LOOKANGL)/4

NORMUNIT

XNBPIP

EXIT

CA FIXLOC # RESET PUSH DOWN POINTER

TS PUSHLOC

# Page 807

CA MPAC # COMPUTE LOOKANGLE ITSELF

DOUBLE

TC BANKCALL

CADR SPARCSIN -1

AD 1/2DEG

EXTEND

MP 180DEGS

TS LOOKANGL # LOOKANGL FOR DISPLAY DURING P64

BRSPOT3 INDEX WCHPHASE

TCF WHATGUID

# **************************************************************************

# TTF/8 COMPUTATION

# **************************************************************************

TTF/8CL TC INTPRETX

DLOAD*

JDG2TTF,1

STODL* TABLTTF +6 # A(3) = 8 JDG TO TABLTTF

ADG2TTF,1 # 2

STODL TABLTTF +4 # A(2) = 6 ADG TO TABLTTF

VGU +4 # 2

DMP DAD*

3/4DP

VDG2TTF,1

STODL* TABLTTF +2 # A(1) = (6 VGU + 18 VDG )/8 TO TABLTTF

RDG +4,1 # 2 2

DSU DMP

RGU +4

3/8DP

STORE TABLTTF # A(0) = -24 (RGU - RDG )/64 TO TABLTTF

EXIT # 2 2

CA BIT8

TS TABLTTF +10 # FRACTIONAL PRECISION FOR TTF TO TABLE

EXTEND

DCA TTF/8

DXCH MPAC # LOADS TTF/8 (INITIAL GUESS) INTO MPAC

CAF TWO # DEGREE - ONE

TS L

CAF TABLTTFL

TC ROOTPSRS # YIELDS TTF/8 IN MPAC

INDEX WCHPHASE

TCF WHATALM

EXTEND # GOOD RETURN

DCA MPAC # FETCH TTF/8 KEEPING IT IN MPAC

DXCH TTF/8 # CORRECTED TTF/8

# Page 808

TC TDISPSET

# (CONTINUE TO QUADGUID)

# *********************************************************************************

# MAIN GUIDANCE EQUATION

# *********************************************************************************

# AS PUBLISHED --

# ___ __ ___ __

# ___ ___ 6(VDG + VG) 12(RDG - RG)

# ACG = ADG + ----------- + ------------

# TTF (TTF)(TTF)

# AS HERE PROGRAMMED --

# ___ __

# 3 (1/4(RDG - RG) ___ __)

# - (------------- + VDG + VG)

# ___ 4 ( TTF/8 ) ___

# ACG = ---------------------------- + ADG

# TTF/8

QUADGUID CS TTF/8

AD LEADTIME # LEADTIME IS A NEGATIVE NUMBER

AD POSMAX # SAFEGUARD THE COMPUTATIONS THAT FOLLOW

TS L # BY FORCING -TTF*LEADTIME > OR = ZERO

CS L

AD L

EXTEND

DV TTF/8

TS BUF # - RATIO OF LAG-DIMINISHED TTF TO TTF

EXTEND

SQUARE

TS BUF +1

AD BUF

XCH BUF +1 # RATIO SQUARED - RATIO

AD BUF +1

TS MPAC # COEFFICIENT FOR VGU TERM

AD BUF +1

INDEX FIXLOC

TS 26D # COEFFICIENT FOR RDG-RGU TERM

AD BUF +1

INDEX FIXLOC

TS 28D # COEFFICIENT FOR VDG TERM

AD BUF

AD POSMAX

# Page 809

AD BUF +1

INDEX FIXLOC

TS 30D # COEFFICIENT FOR ADG TERM

CAF ZERO

TS MODE

TC INTPRETX

VXSC PDDL

VGU

28D

VXSC* PDVL*

VDG,1

RDG,1

VSU V/SC

RGU

TTF/8

VSR2 VXSC

26D

VAD VAD

V/SC VXSC

TTF/8

3/4DP

PDDL VXSC*

30D

ADG,1

VAD

AFCCALC1 VXM VSL1 # VERGUID COMES HERE

PDVL V/SC

GDT/2

GSCALE

BVSU STADR

STORE UNFC/2 # UNFC/2 NEED NOT BE UNITIZED

ABVAL

AFCCALC2 STODL /AFC/ # MAGNITUDE OF AFC FOR THROTTLE

UNFC/2 # VERTICAL COMPONENT

DSQ PDDL

UNFC/2 +2 # OUT-OF-PLANE

DSQ PDDL

HIGHESTF

DDV DSQ

MASS # 2 2 2

DSU DSU # AMAXHORIZ = SQRT(ATOTAL - A - A )

BPL DLOAD # 1 0

AFCCALC3

ZEROVECS

AFCCALC3 SQRT DAD

UNFC/2 +4

# Page 810

BPL BDSU

AFCCLEND

UNFC/2 +4

STORE UNFC/2 +4

AFCCLEND EXIT

TC FASTCHNG

CA WCHPHASE # PREPARE FOR PHASE SWITCHING LOGIC

TS WCHPHOLD

INCR FLPASS0 # INCREMENT PASS COUNTER

BRSPOT4 INDEX WCHPHASE

TCF AFTRGUID

# ***********************************************************************

# ERECT GUIDANCE-STABLE MEMBER TRANSFORMATION MATRIX

# ***********************************************************************

CGCALC CAF EBANK5

TS EBANK

EBANK= TCGIBRAK

EXTEND

INDEX WCHPHASE

INDEX TARGTDEX

DCA TCGFBRAK

INCR BBANK

EBANK= TTF/8

AD TTF/8

XCH L

AD TTF/8

CCS A

CCS L

TCF EXTLOGIC

NOOP

TC INTPRETX

VLOAD UNIT

LAND

STODL CG

TTF/8

DMP* VXSC

GAINBRAK,1 # NUMERO MYSTERIOSO

ANGTERM

VAD

LAND

VSU RTB

NORMUNIT

# Page 811

VXV RTB

LAND

NORMUNIT

STOVL CG +6 # SECOND ROW

VXV VSL1

CG +6

STORE CG +14

EXIT

# (CONTINUE TO EXTLOGIC)

# ***********************************************************************

# PREPARE TO EXIT

# ***********************************************************************

# DECIDE (1) HOW TO EXIT, AND (2) WHETHER TO SWITCH PHASES

EXTLOGIC INDEX WCHPHASE # WCHPHASE = 1 APPRQUAD

CA TENDBRAK # WCHPHASE = 0 BRAKQUAD

AD TTF/8

EXSPOT1 EXTEND

INDEX WCHPHASE

BZMF WHATEXIT

TC FASTCHNG

CA WCHPHOLD

AD ONE

TS WCHPHASE

CA ZERO

TS FLPASS0 # RESET FLPASS0

INDEX WCHPHOLD

TCF WHATEXIT

# ***********************************************************************

# ROUTINES FOR EXITING FROM LANDING GUIDANCE

# ***********************************************************************

# 1. EXGSUB IS THE RETURN WHEN GUIDSUB IS CALLED BY THE IGNITION ALGORITHM.

# 2. EXBRAK IN THE EXIT USED DURING THE BRAKING PHASE. IN THIS CASE UNIT(R) IS THE WINDOW POINTING VECTOR.

# 3. EXNORM IS THE EXIT USED AT OTHER TIMES DURING THE BURN.

# (EXOVFLOW IS A SUBROUTINE OF EXBRAK AND EXNORM CALLED WHEN OVERFLOW OCCURRED ANYWHERE IN GUIDANCE.)

EXGSUB TC INTPRET # COMPUTE TRIM VELOCITY CORRECTION TERM.

# Page 812

VLOAD RTB

UNFC/2

NORMUNIT

VXSC VXSC

ZOOMTIME

TRIMACCL

STORE UNFC/2

EXIT

CCS NGUIDSUB

TCF GUIDSUB

CCS NIGNLOOP

TCF +3

TC ALARM

OCT 01412

+3 TC POSTJUMP

CADR DDUMCALC

EXBRAK TC INTPRET

VLOAD

UNIT/R/

STORE UNWC/2

EXIT

TCF STEER?

EXNORM TC INTPRET

VLOAD VSU

LAND

RTB

NORMUNIT

STORE UNWC/2 # UNIT(LAND - R) IS TENTATIVE CHOICE

VXV DOT

XNBPIP

CG +6

EXIT # WITH PROJ IN MPAC 1/8 REAL SIZE

CS MPAC # GET COEFFICIENT FOR CG +14

AD PROJMAX

AD POSMAX

TS BUF

CS BUF

ADS BUF # RESULT IS 0 IF PROJMAX - PROJ NEGATIVE

CS PROJMIN # GET COEFFICIENT FOR UNIT(LAND - R)

AD MPAC

AD POSMAX

TS BUF +1

CS BUF +1

# Page 813

ADS BUF +1 # RESULT IS 0 IF PROJ - PROJMIN NEGATIVE

CAF FOUR

UNWCLOOP MASK SIX

TS Q

CA EBANK5

TS EBANK

EBANK= CG

CA BUF

EXTEND

INDEX Q

MP CG +14

INCR BBANK

EBANK= UNWC/2

INDEX Q

DXCH UNWC/2

EXTEND

MP BUF +1

INDEX Q

DAS UNWC/2

CCS Q

TCF UNWCLOOP

INCR BBANK

EBANK= PIF

STEER? CA FLAGWRD2 # IF STEERSW DOWN NO OUTPUTS

MASK STEERBIT

EXTEND

BZF RATESTOP

EXVERT CA OVFIND # IF OVERFLOW ANYWHERE IN GUIDANCE

EXTEND # DON'T CALL THROTTLE OR FINDCDUW

BZF +13

EXOVFLOW TC ALARM # SOUND THE ALARM NON-ABORTIVELY

OCT 01410

RATESTOP CAF BIT13 # ARE WE IN ATTITUDE-HOLD?

EXTEND

RAND CHAN31

EXTEND

BZF DISPEXIT # YES

TC BANKCALL # NO: DO A STOPRATE

CADR STOPRATE

TCF DISPEXIT

GDUMP1 TC THROTTLE

# Page 814

TC INTPRET

CALL

FINDCDUW -2

EXIT

# (CONTINUE TO DISPEXIT)

# ***********************************************************************

# GUIDANCE LOOP DISPLAYS

# ***********************************************************************

DISPEXIT EXTEND # KILL GROUP 3: DISPLAYS WILL BE

DCA NEG0 # RESTORED BY NEXT GUIDANCE CYCLE.

DXCH -PHASE3

+3 CS FLAGWRD8 # IF FLUNDISP IS SET, NO DISPLAY THIS PASS

MASK FLUNDBIT

EXTEND

BZF ENDLLJOB # TO PICK UP THE TAG

INDEX WCHPHOLD

TCF WHATDISP

-2 TC PHASCHNG # KILL GROUP 5

OCT 00035

P63DISPS CAF V06N63

DISPCOMN TC BANKCALL

CADR REGODSPR

ENDLLJOB TCF ENDOFJOB

P64DISPS CA TREDES # HAS TREDES REACHED ZERO?

EXTEND

BZF RED-OVER # YES: CLEAR REDESIGNATION FLAG

CS FLAGWRD6 # NO: IS REDFLAG SET?

MASK REDFLBIT

EXTEND

BZF REDES-OK # YES: DO STATIC DISPLAY

CAF V06N64 # OTHERWISE USE FLASHING DISPLAY

TC BANKCALL

CADR REFLASHR

TCF GOTOP00H # TERMINATE

TCF P64CEED # PROCEED PERMIT REDESIGNATIONS

TCF P64DISPS # RECYCLE

# Page 815

TCF ENDLLJOB

P64CEED CAF ZERO

TS ELINCR1

TS AZINCR1

TC UPFLAG # ENABLE REDESIGNATION LOGIC

ADRES REDFLAG

TCF ENDOFJOB

RED-OVER TC DOWNFLAG

ADRES REDFLAG

REDES-OK CAF V06N64

TCF DISPCOMN

VERTDISP CAF V06N60

TCF DISPCOMN

# **************************************************************************

# GUIDANCE FOR P65

# **************************************************************************

VERTGUID CCS WCHVERT

TCF P67VERT # POSITIVE NON-ZERO ---> P67

TCF P66VERT # +0

# THE P65 GUIDANCE EQUATION IS AS FOLLOWS --

# ____ ___

# V2FG - VGU

# ACG = ----------

# TAUVERT

P65VERT TC INTPRET

VLOAD VSU

V2FG

VGU

V/SC GOTO

TAUVERT

AFCCALC1

# Page 816

# **********************************************************

# GUIDANCE FOR P66

# **********************************************************

P66VERT TC POSTJUMP

CADR P66VERTA

P67VERT TC PHASCHNG # TERMINATE GROUP 3.

OCT 00003

TC INTPRET

VLOAD GOTO

VHORCOMP

SETLOC P66LOC

BANK

COUNT* $$/F2DPS

RODTASK CAF PRIO22

TC FINDVAC

EBANK= DVCNTR

2CADR RODCOMP

TCF TASKOVER

P66VERTA TC PHASCHNG # TERMINATE GROUP 3.

OCT 00003

CAF 1SEC

TC TWIDDLE

ADRES RODTASK

RODCOMP INHINT

CAF ZERO

XCH RODCOUNT

EXTEND

MP RODSCAL1

DAS VDGVERT # UPDATE DESIRED ALTITUDE RATE.

EXTEND # SET OLDPIPAX,Y,Z = PIPAX,Y,Z

DCA PIPAX

DXCH OLDPIPAX

DXCH RUPTREG1 # SET RUPTREG1,2,3 = OLDPIPAX,Y,Z

CA PIPAZ

XCH OLDPIPAZ

XCH RUPTREG3

EXTEND # SHAPSHOT TIME OF PIPA READING.

DCA TIME2

# Page 817

DXCH THISTPIP

CA OLDPIPAX

AD PIPATMPX

TS MPAC # MPAC(X) = PIPAX + PIPATMPX

CA OLDPIPAY

AD PIPATMPY

TS MPAC +3 # MPAC(Y) = PIPAY + PIPATMPY

CA OLDPIPAZ

AD PIPATMPZ

TS MPAC +5 # MPAC(Z) = PIPAZ + PIPATMPZ

CS OLDPIPAX

AD TEMX

AD RUPTREG1

TS DELVROD

CS OLDPIPAY

AD TEMY

AD RUPTREG2

TS DELVROD +2

CS OLDPIPAZ

AD TEMZ

AD RUPTREG3

TS DELVROD +4

CAF ZERO

TS MPAC +1 # ZERO LO-ORDER MPAC COMPONENTS

TS MPAC +4

TS MPAC +6

TS TEMX # ZERO TEMX, TEMY, AND TEMZ SO WE WILL

TS TEMY # KNOW WHEN READACCS CHANGES THEM.

TS TEMZ

CS ONE

TS MODE

TC INTPRET

ITRPNT1 VXSC PDDL # SCALE MPAC TO M/CS *2(-7) AND PUSH (6)

KPIP1

THISTPIP

DSU

PIPTIME

STORE 30D # 30-31D CONTAINS TIME IN CS SINCE PIPTIME

DDV PDVL # (8)

4SEC(28)

GDT/2

VSU VXSC # (6)

VBIAS

VSL2 VAD

VAD STADR # (0)

STOVL 24D # STORE UPDATED VELOCITY IN 24-29D

# Page 818

UNIT

STORE 14D

DOT SL1

24D

STODL HDOTDISP # UPDATE HDOTDISP RATE FOR NOUN 63.

30D

SL DMP

11D

HDOTDISP

DAD DSU

36D

/LAND/

STODL HCALC1 # UPDATE HCALC1 FOR NOUN 63.

HDOTDISP

BDSU DDV

VDGVERT

TAUROD

PDVL ABVAL # (2)

GDT/2

DDV SR2

GSCALE

STORE 20D

DAD # (0)

PDVL CALL # (2)

UNITX

CDU*NBSM

DOT

14D

STORE 22D

BDDV STADR # (0)

STOVL /AFC/

DELVROD

VXSC VAD

KPIP1

VBIAS

ABVAL PDDL # (2)

THISTPIP

DSU PDDL # (4)

LASTTPIP

THISTPIP

STODL LASTTPIP # (2)

DDV BDDV # (0)

SHFTFACT

PDDL DMP # (2)

FWEIGHT

BIT1H

DDV DDV

MASS

SCALEFAC

# Page 819

DAD PDDL # (4)

20D

DDV DSU # (2)

22D

DMP DAD

LAG/TAU

/AFC/

PDDL DDV # (4)

MAXFORCE

MASS

PDDL DDV # (6)

MINFORCE

MASS

PUSH BDSU # (8)

BMN DLOAD # (6)

AFCSPOT

DLOAD PUSH # (6)

BDSU BPL

AFCSPOT

DLOAD # (4)

AFCSPOT DLOAD # (2), (4), OR (6)

SETPD # (2)

STODL /AFC/ # (0)

ITRPNT2 EXIT

DXCH MPAC # MPAC = MEASURED ACCELARATION.

TC BANKCALL

CADR THROTTLE +3

TC INTPRET

VLOAD # PICK UP UPDATED VELOCITY VECTOR.

24D

VHORCOMP VSL2 VAD

DELVS

VSR2 PDVL

UNIT VXSC

HDOTDISP

VSL1 BVSU

ABVAL

STORE VHORIZ

EXIT

TC BANKCALL # PUT UP V06N60 DISPLAY BUT AVOID PHASCHNG

CADR DISPEXIT +3

BIT1H OCT 00001

SHFTFACT 2DEC 1 B-17

# Page 820

BIASFACT 2DEC 655.36 B-28

# *********************************************************************************

# REDESIGNATOR TRAP

# *********************************************************************************

BANK 11

SETLOC F2DPS*11

BANK

COUNT* $$/F2DPS

PITFALL XCH BANKRUPT

EXTEND

QXCH QRUPT

TC CHECKMM # IF NOT IN P64, NO REASON TO CONTINUE

DEC 64

TCF RESUME

EXTEND

READ CHAN31

COM

MASK ALL4BITS

TS ELVIRA

CAF TWO

TS ZERLINA

CAF FIVE

TC TWIDDLE

ADRES REDESMON

TCF RESUME

# REDESIGNATOR MONITOR (INITIATED BY PITFALL)

PREMON1 TS ZERLINA

PREMON2 CAF SEVEN

TC VARDELAY

REDESMON EXTEND

COM

MASK ALL4BITS

XCH ELVIRA

TS L

CCS ELVIRA # DO ANY BITS APPEAR THIS PASS?

TCF PREMON2 # Y: CONTINUE MONITOR

CCS L # N: ANY LAST PASS?

TCF COUNT'EM # Y: COUNT 'EM, RESET RUPT, TERMINATE

# Page 821

CCS ZERLINA # N: HAS ZERLINA REACHED ZERO YET?

TCF PREMON1 # N: DIMINISH ZERLINA, CONTINUE

RESETRPT CAF BIT12 # Y: RESET RUPT. TERMINATE

EXTEND

WOR CHAN13

TCF TASKOVER

COUNT'EM CAF BIT13 # ARE WE IN ATTITUDE-HOLD?

EXTEND

RAND CHAN31

EXTEND

BZF RESETRPT # YES: SKIP REDESIGNATION LOGIC.

CA L # NO.

MASK -AZBIT

CCS A

-AZ CS AZEACH

ADS AZINCR1

CA L

MASK +AZBIT

CCS A

+AZ CA AZEACH

ADS AZINCR1

CA L

MASK -ELBIT

CCS A

-EL CS ELEACH

ADS ELINCR1

CA L

MASK +ELBIT

CCS A

+EL CA ELEACH

ADS ELINCR1

TCF RESETRPT

# THESE EQUIVALENCES ARE BASED ON GSOP CHAPTER 4, REVISION 16 OF P64LM

+ELBIT = BIT2 # -PITCH

-ELBIT = BIT1 # +PITCH

+AZBIT = BIT5

-AZBIT = BIT6

# Page 822

ALL4BITS OCT 00063

AZEACH DEC .03491 # 2 DEGREES

ELEACH DEC .00873 # 1/2 DEGREE

# ****************************************************************

# R.O.D. TRAP

# ****************************************************************

BANK 20

SETLOC RODTRAP

BANK

COUNT* $$/F2DPS # ************************

DESCBITS MASK BIT7 # COME HERE FROM MARKRUPT CODING WITH BIT

CCS A # 7 OR 6 OF CHANNEL 16 IN A; BIT 7 MEANS

CS TWO # - RATE INCREMENT, BIT 6 + INCREMENT.

AD ONE

ADS RODCOUNT

TCF RESUME # TRAP IS RESET WHEN SWITCH IS RELEASED

BANK 31

SETLOC F2DPS*31

BANK

COUNT* $$/F2DPS

# ***********************************************************************************

# DOUBLE PRECISION ROOT FINDER SUBROUTINE (BY ALLAN KLUMPP)

# ***********************************************************************************

# N N-1

# ROOTPSRS FINDS ONE ROOT OF THE POWER SERIES A X + A X + ... + A X + A

# N N-1 1 0

# USING NETON'S METHOD STARTING WITH AN INITIAL GUESS FOR THE ROOT. THE ENTERING DATA MUST BE AS FOLLOWS:

# A SP LOC-3 ADRES FOR REFERENCING PWR COF TABL

# L SP N-1 N IS THE DEGREE OF THE POWER SERIES

# MPAC DP X INITIAL GUESS FOR ROOT

# LOC-2N DP A(0)

# ...

# LOC DP A(N)

# LOC+2 SP PRECROOT PREC RQD OF ROOT (AS FRACT OF 1ST GUESS)

# Page 823

# THE DP RESULT IS LEFT IN MPAC UPON EXIT, AND A SP COUNT OF THE ITERATIONS TO CONVERGENCE IS LEFT IN MPAC+2.

# RETURN IS NORMALLY TO LOC(TC ROOTPSRS)+3. IF ROOTPSRS FAILS TO CONVERGE TO IN 8 PASSES, RETURN IS TO LOC+1 AND

# OUTPUTS ARE NOT TO BE TRUSTED.

# PRECAUTION: ROOTPSRS MAKES NO CHECKS FOR OVERFLOW OR FOR IMPROPER USAGE. IMPROPER USAGE COULD

# PRECLUDE CONVERGENCE OR REQUIRE EXCESSIVE ITERATIONS. AS A SPECIFIC EXAMPLE, ROOTPSRS FORMS A DERIVATIVE

# COEFFICIENT TABLE BY MULTIPLYINE EACH A(I) BY I, WHERE I RANGES FROM 1 TO N. IF AN ELEMENT OF THE DERIVATIVE

# COEFFICIENT TABLE = 1 OR >1 IN MAGNITUDE, ONLY THE EXCESS IS RETAINED. ROOTPSRS MAY CONVERGE ON THE COREECT

# ROOT NONETHELESS, BUT IT MAY TAKE AN EXCESSIVE NUMBER OF ITERATIONS. THEREFORE THE USER SHOULD RECOGNIZE:

# 1. USER'S RESPONSIBILITY TO ASSUR THAT I X A(I) < 1 IN MAGNITUDE FOR ALL I.

# 2. USER'S RESPONSIBILITY TO ASSURE OVERFLOW WILL NOT OCCUR IN EVALUTATING EITHER THE RESIDUAL OR THE DERIVATIVE

# POWER SERIES. THIS OVERFLOW WOULD BE PRODUCED BY SUBROUTINE POWRSERS, CALLED BY ROOTPSRS, AND MIGHT NOT

# PRECLUDE EVENTUAL CONVERGENCE.

# 3. AT PRESENT, ERASABLE LOCATIONS ARE RESERVED ONLY FOR N UP TO 5. AN N IN EXCESS OF 5 WILL PRODUCE CHAOS.

# ALL ERASABLES USED BY ROOTPSRS ARE UNSWITCHED LOCATED IN THE REGION FROM MPAC-33 OCT TO MPAC+7.

# 4. THE ITERATION COUNT RETURNED IN MPAC+2 MAY BE USED TO DETECT ABNORMAL PERFORMANCE.

# STORE ENTERING DATA, INITIALIZE ERASABLES

ROOTPSRS EXTEND

QXCH RETROOT # RETURN ADRES

TS PWRPTR # PWR TABLE POINTER

DXCH MPAC +3 # PWR TABLE ADRES, N-1

CA DERTABLL

TS DERPTR # DER TABL POINTER

TS MPAC +5 # DER TABL ADRES

CCS MPAC +4 # NO POWER SERIES DEGREE 1 OR LESS

TS MPAC +6 # N-2

CA ZERO # MODE USED AS ITERATION COUNTER. MODE

TS MODE # MUST BE POS SO ABS WON'T COMP MPAC+3 ETC.

# COMPUTE CRITERION TO STOP ITERATING

EXTEND

DCA MPAC # FETCH ROOT GUESS, KEEPING IT IN MPAC

DXCH ROOTPS # AND IN ROOTPS

INDEX MPAC +3 # PWR TABLE ADRES

CA 5 # PRECROOT TO A

TC SHORTMP # YIELDS DP PRODUCT IN MPAC

TC USPRCADR

CADR ABS # YIELDS ABVAL OF CRITERION ON DX IN MPAC

DXCH MPAC

DXCH DXCRIT # CRITERION

# SET UP DER COF TABL

# Page 824

EXTEND

INDEX PWRPTR

DCA 3

DXCH MPAC # A(N) TO MPAC

CA MPAC +4 # N-1 TO A

DERCLOOP TS PWRCNT # LOOP COUNTER

AD ONE

TC DMPNSUB # YIELDS DERCOF = I X A(I) IN MPAC

EXTEND

INDEX PWRPTR

DCA 1

DXCH MPAC # (I-1) TO MPAC, FETCHING DERCOF

INDEX DERPTR

DXCH 3 # DERCOF TO DER TABLE

CS TWO

ADS PWRPTR # DECREMENT PWR POINTER

CS TWO

ADS DERPTR # DECREMENT DER POINTER

CCS PWRCNT

TCF DERCLOOP

# CONVERGE ON ROOT

ROOTLOOP EXTEND

DCA ROOTPS # FETCH CURRENT ROOT

DXCH MPAC # LEAVE IN MPAC

EXTEND

DCA MPAC +5 # LOAD A, L WITH DER TABL ADRES, N-2

TC POWRSERS # YIELDS DERIVATIVE IN MPAC

EXTEND

DCA ROOTPS

DXCH MPAC # CURRENT ROOT TO MPAC, FETCHING DERIVATIVE

DXCH BUF # LEAVE DERIVATIVE IN BUF AS DIVISOR

EXTEND

DCA MPAC +3 # LOAD A, L WITH PWR TABL ADRES, N-1

TC POWRSERS # YIELDS RESIDUAL IN MPAC

TC USPRCADR

CADR DDV/BDDV # YIELDS -DX IN MPAC

EXTEND

DCS MPAC # FETCH DX, LEAVING -DX IN MPAC

DAS ROOTPS # CORRECTED ROOT NOW IN ROOTPS

TC USPRCADR

CADR ABS # YIELDS ABS(DX) IN MPAC

EXTEND

# Page 825

DCS DXCRIT

DAS MPAC # ABS(DX)-ABS(DXCRIT) IN MPAC

CA MODE

MASK BIT4 # KLUMPP SAYS GIVE UP AFTER EIGHT PASSES

CCS A

BADROOT TC RETROOT

INCR MODE # INCREMENT ITERATION COUNTER

CCS MPAC # TEST HI ORDER DX

TCF ROOTLOOP

TCF TESTLODX

TCF ROOTSTOR

TESTLODX CCS MPAC +1 # TEST LO ORDER DX

TCF ROOTLOOP

TCF ROOTSTOR

ROOTSTOR DXCH ROOTPS

DXCH MPAC

CA MODE

TS MPAC +2 # STORE SP ITERATION COUNT IN MPAC+2

INDEX RETROOT

TCF 2

DERTABLL ADRES DERCOFN -3

# ****************************************************************************

# TRASHY LITTLE SUBROUTINES

# ****************************************************************************

INTPRETX INDEX WCHPHASE # SET X1 ON THE WAY TO THE INTERPRETER

CS TARGTDEX

INDEX FIXLOC

TS X1

TCF INTPRET

TDISPSET CA TTF/8

EXTEND

MP TSCALINV

DXCH TTFDISP

CA EBANK5 # TREDES BECOMES ZERO TWO PASSES

TS EBANK # BEFORE TCGFAPPR IS REACHED

EBANK= TCGFAPPR

CA TCGFAPPR

INCR BBANK

EBANK= TTF/8

# Page 826

AD TTF/8

EXTEND

MP TREDESCL

AD -DEC103

AD NEGMAX

TS L

CS L

AD L

AD +DEC99

AD POSMAX

TS TREDES

CS TREDES

ADS TREDES

TC Q

1406P00 TC P00DOO

OCT 01406

1406ALM TC ALARM

OCT 01406

TCF RATESTOP

# *********************************************************************

# SPECIALIZED "PHASCHNG" SUBROUTINE

# *********************************************************************

EBANK= PHSNAME2

FASTCHNG CA EBANK3 # SPECIALIZED 'PHASCHNG' ROUTINE

XCH EBANK

DXCH L

TS PHSNAME3

LXCH EBANK

EBANK= E2DPS

TC A

# *************************************************************************************

# PARAMETER TABLE INDIRECT ADDRESSES

# *************************************************************************************

RDG = RBRFG

VDG = VBRFG

ADG = ABRFG

VDG2TTF = VBRFG*

ADG2TTF = ABRFG*

JDG2TTF = JBRFG*

# *************************************************************************************

# LUNAR LANDING CONSTANTS

# *************************************************************************************

# Page 827

TABLTTFL ADRES TABLTTF +3 # ADDRESS FOR REFERENCING TTF TABLE

TTFSCALE = BIT12

TSCALINV = BIT4

-DEC103 DEC -103

+DEC99 DEC +99

TREDESCL DEC -.08

180DEGS DEC +180

1/2DEG DEC +.00278

PROJMAX DEC .42262 B-3 # SIN(25')/8 TO COMPARE WITH PROJ

PROJMIN DEC .25882 B-3 # SIN(15')/8 TO COMPARE WITH PROJ

V06N63 VN 0663 # P63

V06N64 VN 0664 # P64

V06N60 VN 0660 # P65, P66, P67

BANK 22

SETLOC LANDCNST

BANK

COUNT* $$/F2DPS

HIGHESTF 2DEC 4.34546769 B-12

GSCALE 2DEC 100 B-11

3/8DP 2DEC .375

3/4DP 2DEC .750

DEPRCRIT 2DEC -.02 B-1

# Page 828

# **************************************************************************

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