### FILE="Main.annotation"
## Copyright:	Public domain.
## Filename:	KALCMANU_STEERING.agc
## Purpose:	Part of the source code for Colossus, build 249.
##		It is part of the source code for the Command Module's (CM)
##		Apollo Guidance Computer (AGC), for Apollo 9.
## Assembler:	yaYUL
## Reference:	pp. 407-412.
## Contact:	Ron Burkey <info@sandroid.org>.
## Website:	www.ibiblio.org/apollo.
## Mod history:	08/10/04 RSB.	Began adapting from corresponding Luminary131
##				source file.
##		2017-01-06 RSB	Page numbers now agree with those on the
##				original harcopy, as opposed to the PDF page
##				numbers in 1701.pdf.
##		2017-01-15 RSB	Cross-diff'd comment text (not whitespace)
##				vs the already-proofed corresponding Colossus
##				237 and Comanche 55 source-code files
##				and corrected errors found.  No differences
##				remained afterward.
##		2017-01-28 RSB	WTIH -> WITH.
##		2021-05-30 ABS	ZEROERROR -> ZEROEROR
##
## The contents of the "Colossus249" files, in general, are transcribed 
## from a scanned copy of the program listing.  Notations on this
## document read, in part:
##
##	Assemble revision 249 of AGC program Colossus by NASA
##	2021111-041.  October 28, 1968.  
##
##	This AGC program shall also be referred to as
##				Colossus 1A
##
##	Prepared by
##			Massachusetts Institute of Technology
##			75 Cambridge Parkway
##			Cambridge, Massachusetts
##	under NASA contract NAS 9-4065.
##
## Refer directly to the online document mentioned above for further information.
## Please report any errors (relative to the scanned pages) to info@sandroid.org.
##
## In some cases, where the source code for Luminary 131 overlaps that of 
## Colossus 249, this code is instead copied from the corresponding Luminary 131
## source file, and then is proofed to incorporate any changes.

## Page 407
# GENERATION OF STEERING COMMANDS FOR DIGITAL AUTOPILOT FREE FALL MANEUVERS
#
# NEW COMMANDS WILL BE GENERATED EVERY ONE SECOND DURING THE MANEUVER

		BANK	15
		SETLOC	KALCMON1
		BANK
		
		EBANK=	BCDU
		
		COUNT	22/KALC
		
NEWDELHI	CS	HOLDFLAG	# SEE IF MANEUVER HAS BEEN INTERRUPTED
		EXTEND			# BY ASTRONAUT
		BZMF	NOGO	-2	# IF SO, TERMINATE KALCMANU
NEWANGL		TC	INTPRET
		AXC,1	AXC,2
			MIS		# COMPUTE THE NEW MATRIX FROM S/C TO
			DEL		# STABLE MEMBER AXES
		CALL
			MXM3
		VLOAD	STADR
		STOVL	MIS +12D	# CALCULATE NEW DESIRED CDU ANGLES
		STADR
		STOVL	MIS +6D
		STADR
		STORE	MIS
		AXC,1	CALL
			MIS
			DCMTOCDU	# PICK UP THE NEW CDU ANGLES FROM MATRIX
		RTB	
			V1STO2S
		STORE	NCDU		# NEW CDU ANGLES
		BONCLR	EXIT
			CALCMAN2
			MANUSTAT	# TO START MANEUVER
		CAF	TWO		# 	+0 OTHERWISE
INCRDCDU	TS	KSPNDX
		DOUBLE
		TS	KSPNDX +1
		INDEX	KSPNDX
		CA	NCDU		# NEW DESIRED CDU ANGLES
		EXTEND
		INDEX	KSPNDX
		MSU	BCDU		# INITIAL S/C ANGLE OR PREVIOUS DESIRED
		EXTEND			# CDU ANGLES
		MP	DT/TAU
		INDEX	KDPNDX
		DXCH	DELCDUX		# ANGLE INCREMENTS TO BE ADDED TO
## Page 408
		INDEX	KSPNDX		# DCDU EVERY TENTH SEC
		CA	NCDU		# BY LEM DAP
		INDEX	KSPNDX
		XCH	BCDU
		INDEX	KSPNDX +1
		TS	CDUXD
		CCS	KSPNDX
		TCF	INCRDCDU	# LOOP FOR THREE AXES
		
		RELINT
		
# COMPARE PRESENT TIME WITH TIME TO TERMINATE MANEUVER

TMANUCHK	TC	TIMECHK
		TCF	CONTMANU
		CAF	ONE
MANUSTAL	TC	WAITLIST
		EBANK=	BCDU
		2CADR	MANUSTOP
		
		RELINT
		TCF	ENDOFJOB
		
TIMECHK		EXTEND
		DCS	TIME2
		DXCH	TTEMP
		EXTEND
		DCA	TM
		DAS	TTEMP
		CCS	TTEMP
		TC	Q
		TCF	+2
		TCF	2NDRETRN
		CCS	TTEMP +1
		TC	Q
		TCF	MANUOFF
		COM
MANUOFF		AD	ONESEC +1
		EXTEND
		BZMF	2NDRETRN
		INCR	Q
2NDRETRN	INCR	Q
		TC	Q
		
DT/TAU		DEC	.1

MANUSTAT	EXIT			# INITIALIZATION ROUTINE
		EXTEND			# FOR AUTOMATIC MANEUVERS
		DCA	TIME2
		DAS	TM		# TM+T0		MANEUVER COMPLETION TIME
		EXTEND
## Page 409
		DCS	ONESEC
		DAS	TM		# (TM+T0)-1
		INHINT
		CS	ONE		# ENABLE AUTOPILOT TO PERFORM
		TS	HOLDFLAG	# AUTOMATIC MANEUVERS
		CS	RATEINDX	# SEE IF MANEUVERING AT HIGH RATE
		AD	SIX
		EXTEND
		BZMF	HIGHGAIN
		TCF	+4
HIGHGAIN	CS	RCSFLAGS	# IF SO, SET HIGH RATE FLAG (BIT 15 OF
		MASK	BIT15		# RCSFLAGS)
		ADS	RCSFLAGS
		DXCH	BRATE		# X-AXIS MANEUVER RATE
		DXCH	WBODY
		DXCH	BRATE	+2	# Y-AXIS MANEUVER RATE
		DXCH	WBODY1
		DXCH	BRATE	+4	# Z-AXIS MANEUVER RATE
		DXCH	WBODY2
		CA	BIASTEMP +1	# INSERT ATTITUDE ERROR BIASES
		TS	BIAS		# INTO AUTOPILOT
		CA	BIASTEMP +3
		TS	BIAS1
		CA	BIASTEMP +5
		TS	BIAS2
		CA	TIME1
		AD	ONESEC +1
		XCH	NEXTIME
		TCF	INCRDCDU -1
		
ONESEC		DEC	0
		DEC	100
		
CONTMANU	INHINT
		CS	TIME1		# CONTINUE WITH UPDATE PROCESS
		AD	NEXTIME
		CCS	A
		AD	ONE
		TCF	MANUCALL
		AD	NEGMAX
		COM
MANUCALL	TC	WAITLIST
		EBANK=	BCDU
		2CADR	UPDTCALL
		RELINT
		CAF	ONESEC +1	# INCREMENT TIME FOR NEXT UPDATE
		ADS	NEXTIME
		TCF	ENDOFJOB
## Page 410
		
UPDTCALL	CAF	PRIO26		# CALL FOR UPDATE
		TC	FINDVAC		# OF STEERING COMMANDS
		EBANK=	BCDU
		2CADR	NEWDELHI

		TC	TASKOVER
		
## Page 411
# ROUTINE FOR TERMINATING AUTOMATIC MANEUVERS

MANUSTOP	TC	STOPYZ
		TC	LOADYZ

ENDROLL		CA	CPHI	
		TS	CDUXD		# SET CDUXD TO THE COMMANDED OUTER GIMBAL
		TC	STOPRATE
ENDMANU		CA	ATTPRIO		# RESTORE USERS PRIORITY
		TS	NEWPRIO
		
		CA	ZERO		# ZERO ATTCADR
		DXCH	ATTCADR
		
		TC	SPVAC		# RETURN TO USER OF GOMANUR
		
		TC	TASKOVER
		
STOPRATE	CAF	ZERO
		TS	DELCDUX
		TS	DELCDUX	+1	# ZERO ROLL INCREMENTAL ANGLES
		TS	WBODY		# RATE
		TS	WBODY	+1
		TS	BIAS		# BIAS
		
		CS	BIT15		# MAKE SURE HIGH RATE FLAG (BIT 15 OF
		MASK	RCSFLAGS	# RCSFLAGS) IS RESET.
		TS	RCSFLAGS
		
STOPYZ		CAF	ZERO
		TS	DELCDUY		# ZERO PITCH, YAW
		TS	DELCDUY	+1	# INCREMENTAL ANGLES
		TS	DELCDUZ
		TS	DELCDUZ	+1
		TS	WBODY1		# RATES
		TS	WBODY1	+1
		TS	WBODY2
		TS	WBODY2	+1
		TS	BIAS1		# BIASES
		TS	BIAS2
		TC	Q
		
ZEROEROR	CA	CDUX		# PICK UP CDU ANGLES AND STORE IN
		TS	CDUXD		# CDU DESIRED
		CA	CDUY
		TS	CDUYD
		CA	CDUZ
		TS	CDUZD
		TC	Q

## Page 412
LOADCDUD	CA	CPHI		# STORE TERMINAL ANGLES INTO
		TS	CDUXD		# COMMAND ANGLES
LOADYZ		CA	CTHETA
		TS	CDUYD
		CA	CPSI
		TS	CDUZD
		TC	Q