R60_62.agc
# Copyright: Public domain.
# Filename: R60_R62.agc
# 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: Ron Burkey <info@sandroid.org>.
# Website: www.ibiblio.org/apollo.
# Pages: 472-485
# Mod history: 2009-05-17 RSB Adapted from the corresponding
# Luminary131 file, using page
# images from Luminary 1A.
#
# 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 2021112-061
# 16:27 JULY 14, 1969
# Page 472
# MOD NO: 0 DATE: 1 MAY 1968
# MOD BY: DIGITAL DEVEL GROUP LOG SECTION R60,R62
#
# FUNCTIONAL DESCRIPTION:
#
# CALLED AS A GENERAL SUBROUTINE TO MANEUVER THE LM TO A SPECIFIED
# ATTITUDE.
#
# 1. IF THE 3-AXIS FLAG IS NOT SET THE FINAL CDU ANGLES ARE
# CALCULATED (VECPOINT).
#
# 2. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
#
# 3. REQUEST FLASHING DISPLAY V50 N18 PLEASE PERFORM AUTO MANEUVER.
#
# 4. IF PRIORITY DISPLAY FLAG IS SET DO A PHASECHANGE. THEN AWAIT
# ASTRONAUT RESPONSE.
#
# 5. DISPLAY RESPONSE RETURNS:
#
# A. ENTER - RESET 3-AXIS FLAG AND RETURN TO CLIENT.
#
# B. TERMINATE - IF IN P00 GO TO STEP 5A. OTHERWISE CHECK IF R61 IS
# THE CALLING PROGRAM. IF IN R61 AN EXIT IS MADE TO GOTOV56. IF
# NOT IN R61 AN EXIT IS DONE VIA GOTOPOOH.
#
# C. PROCEED - CONTINUE WITH PROGRAM AT STEP 6.
#
# 6. IF THE 3-AXISFLAG IS NOT SET, THE FINAL CDU ANGLES ARE CALCULATED
# (VECPOINT).
#
# 7. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
#
# 8. IF THE G+N SWITCH IS NOT SET GO BACK TO STEP 3.
#
# 9. IF THE AUTO SWITCH IS NOT SET GO BACK TO STEP 3.
#
# 10. NONFLASHING DISPLAY V06N18 (FDAI ANGLES).
#
# 11. DO A PHASECHANGE.
#
# 12. DO A MANEUVER CALCULATION AND ICDU DRIVE ROUTINE TO ACHIEVE FINAL
#
# GIMBAL ANGLES (GOMANUR).
# 13. AT END OF MANEUVER GO TO STEP 3.
#
# IF SATISFACTORY MANEUVER STEP 5A EXITS R60.
# FOR FURTHER ADJUSTMENT OF THE VEHICLE ATTITUDE ABOUT THE
# DESIRED VECTOR, THE ROUTINE MAY BE PERFORMED AGAIN STARTING AT
# Page 473
# STEP 5C.
#
# CALLING SEQUENCE: TC BANKCALL
# CADR R60LEM
#
# ERASABLE INITIALIZATION REQUIRED : SCAXIS, POINTVSM (FOR VECPOINT)
# 3AXISFLG.
#
# SUBROUTINES CALLED: VECPOINT, BALLANGS, GOPERF2R, LINUS, GODSPER,
# GOMANUR, DOWNFLAG, PHASCHNG, UPFLAG
#
# NORMAL EXIT MODES: CAE TEMPR60 (CALLERS RETURN ADDRESS)
# TC BANKJUMP
#
# ALARMS: NONE
#
# OUTPUT: NONE
#
# DEBRIS: CPHI, CTHETA, CPSI, 3AXISFLG, TBASE2
BANK 34
SETLOC MANUVER
BANK
EBANK= TEMPR60
COUNT* $$/R06
R60LEM TC MAKECADR
TS TEMPR60
REDOMANN CAF 3AXISBIT
MASK FLAGWRD5 # IS 3-AXIS FLAG SET
CCS A
TCF TOBALL # YES
TC INTPRET
CALL
VECPOINT # TO COMPUTE FINAL ANGLES
STORE CPHI # STORE FINAL ANGLES - CPHI,CTHETA,CPSI
EXIT
TOBALL TC BANKCALL
CADR BALLANGS # TO CONVERT ANGLES TO FDAI
TOBALLA CAF V06N18
TC BANKCALL
CADR GOPERF2R # DISPLAY PLEASE PERFORM AUTO MANEUVER
TC R61TEST
TC REDOMANC # PROCEED
TC ENDMANU1 # ENTER I.E. FINISHED WITH R60
# Page 474
TC CHKLINUS # TO CHECK FOR PRIORITY DISPLAYS
TC ENDOFJOB
REDOMANC CAF 3AXISBIT
MASK FLAGWRD5 # IS 3-AXIS FLAG SET
CCS A
TCF TOBALLC # YES
TC INTPRET
CALL
VECPOINT # TO COMPUTE FINAL ANGLES
STORE CPHI # STORE ANGLES
EXIT
TOBALLC TC BANKCALL
CADR BALLANGS # TO CONVERT ANGLES TO FDAI
TC G+N,AUTO # CHECK AUTO MODE
CCS A
TCF TOBALLA # NOT AUTO, GO REREQUEST AUTO MANEUVER.
AUTOMANV CAF V06N18 # STATIC DISPLAY DURING AUTO MANEUVER
TC BANKCALL
CADR GODSPR
TC CHKLINUS # TO CHECK FOR PRIORITY DISPLAYS
STARTMNV TC BANKCALL # PERFORM MANEUVER VIA KALCMANU
CADR GOMANUR
ENDMANUV TCF TOBALLA # FINISHED MANEUVER.
ENDMANU1 TC DOWNFLAG # RESET 3-AXIS FLAG
ADRES 3AXISFLG
CAE TEMPR60
TC BANKJUMP
CHKLINUS CS FLAGWRD4
MASK PDSPFBIT # IS PRIORITY DISPLAY FLAG SET?
CCS A
TC Q # NO - EXIT
CA Q
TS MPAC +2 # SAVE RETURN
CS THREE # OBTAIN LOCATION FOR RESTART
AD BUF2 # HOLDS Q OF LAST DISPLAY
TS TBASE2
TC PHASCHNG
OCT 00132
CAF BIT7
TC LINUS # GO SET BITS FOR PRIORITY DISPLAY
TC MPAC +2
# Page 475
RELINUS CAF PRIO26 # RESTORE ORIGINAL PRIORITY
TC PRIOCHNG
CAF TRACKBIT # DON'T CONTINUE R60 UNLESS TRACKFLAG ON.
MASK FLAGWRD1
CCS A
TCF RER60
CAF RNDVZBIT # IS IT P20?
MASK FLAGWRD0
CCS A
TC +4 # YES
TC PHASCHNG # NO, MUST BE P25, SET 2.11 SPOT
OCT 40112
TC ENDOFJOB
TC PHASCHNG # SET 2.7 SPOT FOR P20
OCT 40072
TC ENDOFJOB
RER60 TC UPFLAG # SET PRIO DISPLAY FLAG AFTER RESTART
ADRES PDSPFLAG
TC TBASE2
R61TEST CA MODREG # IF WE ARE IN P00 IT MUST BE V49 OR V89
EXTEND
BZF ENDMANU1 # THUS WE GO TO ENDEXT VIA USER
CA FLAGWRD4 # ARE WE IN R61 (P20 OR P25)
MASK PDSPFBIT
EXTEND
BZF GOTOPOOH # NO
TC GOTOV56 # YES
BIT14+7 OCT 20100
OCT203 OCT 203
V06N18 VN 0618
# SUBROUTINE TO CHECK FOR G+N CONTROL. AUTO STABILIZATION
#
# RETURNS WITH C(A) = + IF NOT SET FOR G+N, AUTO
# RETURNS WITH C(A) = +0 IF SWITCHES ARE SET
G+N,AUTO EXTEND
READ CHAN30
MASK BIT10
CCS A
TC Q # NOT IN G+N C(A) = +
# Page 476
ISITAUTO EXTEND # CHECK FOR AUTO MODE
READ CHAN31
MASK BIT14
TC Q # (+) = NOT IN AUTO, (+0) = AOK
# Page 477
# PROGRAM DESCRIPTION BALLANGS
# MOD NO. LOG SECTION R60,R62
#
# WRITTEN BY RAMA M.AIYAWAR
# FUNCTIONAL DESCRIPTION
#
# COMPUTES LM FDAI BALL DISPLAY ANGLES
# CALLING SEQUENCE
#
# TC BALLANGS
# NORMAL EXIT MODE
#
# TC BALLEXIT # (SAVED Q)
#
# ALARM OR EXIT MODE NIL
# SUBROUTINES CALLED
# CD*TR*G
# ARCTAN
#
# INPUT
#
# CPHI,CTHETA,CPSI ARE THE ANGLES CORRESPONDING TO AOG,AIG,AMG. THEY ARE
# SP,2S COMPLIMENT SCALED TO HALF REVOLUTION.
# OUTPUT
#
# FDAIX,FDAIY,FDAIZ ARE THE REQUIRED BALL ANGLES SCALED TO HALF REVOLUTION
# SP,2S COMPLIMENT.
# THESE ANGLES WILL BE DISPLAYED AS DEGREES AND HUNDREDTHS. IN THE ORDER ROLL, PITCH, YAW, USING NOUNS 18 & 19.
#
# ERASABLE INITIALIZATION REQUIRED
#
# CPHI,CTHETA,CPSI EACH A SP REGISTER
# DEBRIS
#
# A,L,Q,MPAC,SINCDU,COSCDU,PUSHLIS,BALLEXIT
#
#
# NOMENCLATURE: CPHI, CTHETA, & CPSI REPRESENT THE OUTER, INNER, & MIDDLE GIMBAL ANGLES, RESPECTIVELY; OR
# EQUIVALENTLY, CDUX, CDUY, & CDUZ.
#
# NOTE: ARCTAN CHECKS FOR OVERFLOW AND SHOULD BE ABLE TO HANDLE ANY SINGULARITIES.
SETLOC BAWLANGS
BANK
COUNT* $$/BALL
BALLANGS TC MAKECADR
TS BALLEXIT
CA CPHI
# Page 478
TS CDUSPOT +4
CA CTHETA
TS CDUSPOT
CA CPSI
TS CDUSPOT +2
TC INTPRET
SETPD CALL
0D
CD*TR*G
DLOAD DMP
SINCDUX # SIN (OGA)
COSCDUZ # COS (MGA)
SL1 DCOMP # SCALE
ARCSIN PDDL # YAW = ARCSIN(-SXCZ) INTO 0 PD
SINCDUZ
STODL SINTH # (SINTH = 18D IN PD)
COSCDUZ
DMP SL1 # RESCALE
COSCDUX
STCALL COSTH # (COSTH= 16D IN PD)
ARCTAN
PDDL DMP # ROLL = ARCTAN(SZ/CZCX) INTO 2 PD
SINCDUZ
SINCDUX
SL2 PUSH # SXSZ INTO 4 PD
DMP PDDL # SXSZCY INTO 4 PD
COSCDUY
DMP PDDL # SXSZSY INTO 6 PD
SINCDUY
COSCDUX
DMP SL1 # CXCY
COSCDUY
DSU STADR # PULL UP FROM 6 PD
STODL COSTH # COSTH = CXCY - SXSZSY
SINCDUY
DMP SL1
COSCDUX # CXSY
DAD STADR # PULL UP FROM 4 PD
STCALL SINTH # SINTH = CXSY + SXSZCY
ARCTAN # RETURNS WITH D(MPAC) = PITCH
PDDL VDEF # PITCH INTO 2 PD, ROLL INTO MPAC FROM 2PD
RTB # VDEF MAKES V(MPAC) = ROLL, PITCH, YAW
V1STO2S
STORE FDAIX # MODE IS TP
EXIT
ENDBALL CA BALLEXIT
# Page 479
TC BANKJUMP
# Page 480
# PROGRAM DESCRIPTION - VECPOINT
#
#
# THIS INTERPRETIVE SUBROUTINE MAY BE USED TO POINT A SPACECRAFT AXIS IN A DESIRED DIRECTION. THE AXIS
# TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN SUCCESSIVE LOCATIONS OF ERASABLE MEMORY
# BEGINNING WITH THE LOCATION CALLED SCAXIS. THE COMPONENTS OF THIS VECTOR ARE GIVEN IN SPACECRAFT COORDINATES.
# THE DIRECTION IN WHICH THIS AXIS IS TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN
# SUCCESSIVE LOCATIONS OF ERASABLE MEMORY BEGINNING WITH THE ADDRESS CALLED POINTVSM. THE COMPONENTS OF THIS
# VECTOR ARE GIVEN IN STABLE MEMBER COORDINATES. WITH THIS INFORMATION VECPOINT COMPUTES A SET OF THREE GIMBAL
# ANGLES (2S COMPLEMENT) CORESPONDING TO THE CROSS-PRODUCT ROTATION BETWE EN SCAXIS AND POINTVSM AND STORES THEM
# IN T(MPAC) BEFORE RETURNING TO THE CALLER.
# THIS ROTATION, HOWEVER, MAY BRING THE S/C INTO GIMBAL LOCK. WHEN POINTING A VECTOR IN THE Y-Z PLANE,
# THE TRANSPONDER AXIS, OR THE AOT FOR THE LEM, THE PROGRAM WILL CORRECT THIS PROBLEM BY ROTATING THE CROSS-
# PRODUCT ATTITUDE ABOUT POINTVSM BY A FIXED AMOUNT SUFFICIENT TO ROTATE THE DESIRED S/C ATTITUDE OUT OF GIMBAL
# LOCK. IF THE AXIS TO BE POINTED IS MORE THAN 40.6 DEGREES BUT LESS THAN 60.5 DEG FROM THE +X (OR-X) AXIS,
# THE ADDITIONAL ROTATION TO AVOID GIMAL LOCK IS 35 DEGREES. IF THE AXIS IS MORE THAN 60.5 DEGEES FROM +X (OR -X)
# THE ADDITIONAL ROTATION IS 35 DEGREES. THE GIMBAL ANGLES CORRESPONDING TO THIS ATTITUDE ARE THEN COMPUTED AND
# STORED AS 2S COMPLIMENT ANGLES IN T(MPAC) BEFORE RETURNING TO THE CALLER.
# WHEN POINTING THE X-AXIS, OR THE THRUST VECTOR, OR ANY VECTOR WITHIN 40.6 DEG OF THE X-AXIS, VECPOINT
# CANNOT CORRECT FOR A CROSS-PRODUCT ROTATION INTO GIMBAL LOCK. IN THIS CASE A PLATFORM REALIGNMENT WOULD BE
# REQUIRED TO POINT THE VECTOR IN THE DESIRED DIRECTION. AT PRESENT NO INDICATION IS GIVEN FOR THIS SITUATION
# EXCEPT THAT THE FINAL MIDDLE GIMBAL ANGLE IN MPAC +2 IS GREATER THAN 59 DEGREES.
#
# CALLING SEQUENCE -
# 1) LOAD SCAXIS, POINTVSM
# 2) CALL
# VECPOINT
#
# RETURNS WITH
#
# 1) DESIRED OUTER GIMBAL ANGLE IN MPAC
# 2) DESIRED INNER GIMBAL ANGLE IN MPAC +1
# 3) DESIRED MIDDLE GIMBAL ANGLE IN MPAC +2
#
# ERASABLES USED -
#
# 1) SCAXIS 6
# 2) POINTVSM 6
# 3) MIS 18
# 4) DEL 18
# 5) COF 6
# 6) VECQTEMP 1
# 7) ALL OF VAC AREA 43
#
# TOTAL 99
SETLOC VECPT
BANK
# Page 481
COUNT* $$/VECPT
EBANK= BCDU
VECPNT1 STQ BOV # THIS ENTRY USES DESIRED CDUS
VECQTEMP # NOT PRESENT-ENTER WITH CDUD'S IN MPAC
VECPNT2
VECPNT2 AXC,2 GOTO
MIS
STORANG
VECPOINT STQ BOV # SAVE RETURN ADDRESS
VECQTEMP
VECLEAR # AND CLEAR OVFIND
VECLEAR AXC,2 RTB
MIS # READ THE PRESENT CDU ANGLES AND
READCDUK # STORE THEM IN PD25, 26, 27
STORANG STCALL 25D
CDUTODCM # S/C AXES TO STABLE MEMBER AXES (MIS)
VLOAD VXM
POINTVSM # RESOLVE THE POINTING DIRECTION VF INTO
MIS # INITIAL S/C AXES ( VF = POINTVSM)
UNIT
STORE 28D
# PD 28 29 30 31 32 33
VXV UNIT # TAKE THE CROSS PRODUCT VF X VI
SCAXIS # WHERE VI = SCAXIS
BOV VCOMP
PICKAXIS
STODL COF # CHECK MAGNITUDE
36D # OF CROSS PRODUCT
DSU BMN # VECTOR, IF LESS
DPB-14 # THAN B-14 ASSUME
PICKAXIS # UNIT OPERATION
VLOAD DOT # INVALID.
SCAXIS
28D
SL1 ARCCOS
COMPMATX CALL # NOW COMPUTE THE TRANSFORMATION FROM
DELCOMP # FINAL S/C AXES TO INITIAL S/C AXES MFI
AXC,1 AXC,2
MIS # COMPUTE THE TRANSFORMATION FROM FINAL
KEL # S/C AXES TO STABLE MEMBER AXES
CALL # MFS = MIS MFI
MXM3 # (IN PD LIST)
DLOAD ABS
6 # MFS6 = SIN(CPSI) $2
DSU BMN
SINGIMLC # = SIN(59 DEGS) $2
FINDGIMB # /CPSI/ LESS THAN 59 DEGS
# Page 482
# I.E. DESIRED ATTITUDE NOT IN GIMBAL LOCK
DLOAD ABS # CHECK TO SEE IF WE ARE POINTING
SCAXIS # THE THRUST AXIS
DSU BPL
SINVEC1 # SIN 49.4 DEGS $2
FINDGIMB # IF SO, WE ARE TRYING TO POINT IT INTO
VLOAD # GIMBAL LOCK, ABORT COULD GO HERE
STADR
STOVL MIS +12D
STADR # STORE MFS (IN PD LIST) IN MIS
STOVL MIS +6
STADR
STOVL MIS
MIS +6 # INNER GIMBAL AXIS IN FINAL S/C AXES
BPL VCOMP # LOCATE THE IG AXIS DIRECTION CLOSEST TO
IGSAMEX # FINAL X S/C AXIS
IGSAMEX VXV BMN # FIND THE SHORTEST WAY OF ROTATING THE
SCAXIS # S/C OUT OF GIMBAL LOCK BY A ROTATION
U=SCAXIS # ABOUT +- SCAXIS, I.E. IF (IG (SGN MFS3)
# X SCAXIS . XF) LESS THAN 0, U = SCAXIS
# OTHERWISE U = -SCAXIS
VLOAD VCOMP
SCAXIS
STCALL COF # ROTATE ABOUT -SCAXIS
CHEKAXIS
U=SCAXIS VLOAD
SCAXIS
STORE COF # ROTATE ABOUT + SCAXIS
CHEKAXIS DLOAD ABS
SCAXIS # SEE IF WE ARE POINTING THE AOT
DSU BPL
SINVEC2 # SIN 29.5 DEGS $2
PICKANG1 # IF SO, ROTATE 50 DEGS ABOUT +- SCAXIS
DLOAD GOTO # IF NOT, MUST BE POINTING THE TRANSPONDER
VECANG2 # OR SOME VECTOR IN THE Y, OR Z PLANE
COMPMFSN # IN THIS CASE ROTATE 35 DEGS TO GET OUT
# OF GIMBAL LOCK (VECANG2 $360)
PICKANG1 DLOAD
VECANG1 # = 50 DEGS $ 360
COMPMFSN CALL
DELCOMP # COMPUTE THE ROTATION ABOUT SCAXIS TO
AXC,1 AXC,2 # BRING MFS OUT OF GIMBAL LOCK
MIS
KEL
CALL # COMPUTE THE NEW TRANSFORMATION FROM
MXM3 # DESIRED S/C AXES TO STABLE MEMBER AXES
# WHICH WILL ALIGN VI WITH VF AND AVOID
# Page 483
# GIMBAL LOCK
FINDGIMB AXC,1 CALL
0 # EXTRACT THE COMMANDED CDU ANGLES FROM
DCMTOCDU # THIS MATRIX
RTB SETPD
V1STO2S # CONVERT TO 2:S COMPLEMENT
0
GOTO
VECQTEMP # RETURN TO CALLER
PICKAXIS VLOAD DOT # IF VF X VI = 0, FIND VF . VI
28D
SCAXIS
BMN TLOAD
ROT180
25D
GOTO # IF VF = VI, CDU DESIRED = PRESENT CDU
VECQTEMP # PRESENT CDU ANGLES
BANK 35
SETLOC MANUVER1
BANK
ROT180 VLOAD VXV # IF VF, VI ANTIPARALLEL, 180 DEG ROTATION
MIS +6 # IS REQUIRED. Y STABLE MEMBER AXIS IN
HIDPHALF # INITIAL S/C AXES.
UNIT VXV # FIND Y(SM) X X(I)
SCAXIS # FIND UNIT(VI X UNIT(Y(SM) X X(I)))
UNIT BOV # I.E. PICK A VECTOR IN THE PLANE OF X(I),
PICKX # Y(SM) PERPENDICULAR TO VI
STODL COF
36D # CHECK MAGNITUDE
DSU BMN # OF THIS VECTOR.
DPB-14 # IF LESS THAN B-14,
PICKX # PICK X-AXIS.
VLOAD
COF
XROT STODL COF
HIDPHALF
GOTO
COMPMATX
PICKX VLOAD GOTO # PICK THE XAXIS IN THIS CASE
HIDPHALF
XROT
SINGIMLC 2DEC .4285836003 # =SIN(59) $2
SINVEC1 2DEC .3796356537 # =SIN(49.4) $2
SINVEC2 2DEC .2462117800 # =SIN(29.5) $2
VECANG1 2DEC .1388888889 # = 50 DEGREES $360
# Page 484
VECANG2 2DEC .09722222222 # = 35 DEGREES $360
1BITDP OCT 0 # KEEP THIS BEFORE DPB(-14) *********
DPB-14 OCT 00001
OCT 00000
# Page 485
# ROUTINE FOR INITIATING AUTOMATIC MANEUVER VIA KEYBOARD (V49)
BANK 34
SETLOC R62
BANK
EBANK= BCDU
COUNT* $$/R62
R62DISP EQUALS R62FLASH
R62FLASH CAF V06N22 # FLASH V06N22 AND
TC BANKCALL # ICDU ANGLES
CADR GOFLASH
TCF ENDEXT # TERMINATE
TCF GOMOVE # PROCEED
TCF R62FLASH # ENTER
# ASTRONAUT MAY LOAD NEW ICDUS AT THIS
# POINT
GOMOVE TC UPFLAG # SET FOR 3-AXIS MANEUVER
ADRES 3AXISFLG
TC BANKCALL
CADR R60LEM
TCF ENDEXT # END R62
