210 lines
5.0 KiB
ArmAsm
210 lines
5.0 KiB
ArmAsm
# Copyright: Public domain.
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# Filename: LEM_GEOMETRY.agc
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# Purpose: Part of the source code for Luminary 1A build 099.
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# It is part of the source code for the Lunar Module's (LM)
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# Apollo Guidance Computer (AGC), for Apollo 11.
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# Assembler: yaYUL
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# Contact: Ron Burkey <info@sandroid.org>.
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# Website: www.ibiblio.org/apollo.
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# Pages: 320-325
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# Mod history: 2009-05-16 RSB Adapted from the corresponding
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# Luminary131 file, using page
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# images from Luminary 1A.
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#
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# This source code has been transcribed or otherwise adapted from
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# digitized images of a hardcopy from the MIT Museum. The digitization
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# was performed by Paul Fjeld, and arranged for by Deborah Douglas of
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# the Museum. Many thanks to both. The images (with suitable reduction
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# in storage size and consequent reduction in image quality as well) are
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# available online at www.ibiblio.org/apollo. If for some reason you
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# find that the images are illegible, contact me at info@sandroid.org
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# about getting access to the (much) higher-quality images which Paul
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# actually created.
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#
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# Notations on the hardcopy document read, in part:
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#
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# Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
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# 16:27 JULY 14, 1969
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# Page 320
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BANK 23
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SETLOC LEMGEOM
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BANK
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SBANK= LOWSUPER
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EBANK= XSM
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# THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
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# THE CONIC R,V AND THE DEVIATIONS R,V. THE STATE VECTORS ARE CONVERTED TO
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# METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
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# R-OTHER,V-OTHER FOR DOWNLINK. THE ROUTINES' NAMES ARE SWITCHED IN THE
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# OTHER VEHICLE'S COMPUTER.
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#
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# INPUT
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# STATE VECTOR IN TEMPORARY STORAGE AREA
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# IF STATE VECTOR IS SCALED POS B27 AND VEL B5
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# SET X2 TO +2
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# IF STATE VECTOR IS SCALED POS B29 AND VEL B7
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# SET X2 TO 0
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#
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# OUTPUT
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# R(T) IN RN, V(T) IN VN, T IN PIPTIME
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# OR
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# R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER)
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COUNT* $$/GEOM
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SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG.
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AVEMIDSW
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+1
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VLOAD VSL*
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TDELTAV
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0 -7,2
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VAD VSL*
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RCV
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0,2
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STOVL RN
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TNUV
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VSL* VAD
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0 -4,2
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VCV
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VSL*
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0,2
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STODL VN
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TET
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STORE PIPTIME
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RVQ
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# Page 321
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SVDWN1 VLOAD VSL*
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TDELTAV
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0 -7,2
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VAD VSL*
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RCV
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0,2
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STOVL R-OTHER
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TNUV
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VSL* VAD
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0 -4,2
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VCV
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VSL*
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0,2
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STORE V-OTHER
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RVQ
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# Page 322
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# THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
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# GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
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# ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
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# ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE
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# SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
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#
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# THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
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#
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# S(2) = 180 + S(1)
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# T(2) = 180 - T(1)
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#
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# THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
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RRANGLES STORE 32D
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DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT
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34D # ANGLE LATER, WE CAN FIND THE MODE 1
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SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF
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0 # THE Y COMPONENT, THE ASIN GIVIN AN
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PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG.
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LODPHALF
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STODL 4 # MODE 2 TRUNNION TO 4.
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LO6ZEROS
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STOVL 34D # UNIT THE PROJECTION OF THE VECTOR
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32D # IN THE X-Z PLANE
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UNIT BOVB # IF OVERFLOW, TARGET VECTOR IS ALONG Y
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LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF
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STODL 32D # PROJECTION VECTOR.
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32D
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SR1 STQ
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S2
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STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARB.
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36D
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SR1
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STCALL COSTH
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ARCTRIG
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# Page 323
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PUSH DAD # MODE 1 SHAFT TO 2.
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LODPHALF
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STOVL 6
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4
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RTB # FIND MODE 2 CDU ANGLES.
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2V1STO2S
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STOVL MODEB
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0
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RTB # MODE 1 ANGLES TO MODE A.
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2V1STO2S
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STORE MODEA
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EXIT
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CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2.
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MASK ANTENBIT
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CCS A
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TCF +4
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DXCH MODEA
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DXCH MODEB
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DXCH MODEA
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TC INTPRET
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GOTO
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S2
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# Page 324
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# GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED
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# LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
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# -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
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SETLOC INFLIGHT
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BANK
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COUNT* $$/GEOM
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RRNB SLOAD RTB
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TANGNB
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CDULOGIC
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SETPD PUSH # TRUNNION ANGLE TO 0
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0
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SIN DCOMP
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STODL 34D # Y COMPONENT
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COS PUSH # .5 COS(T) TO 0
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SLOAD RTB
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TANGNB +1
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CDULOGIC
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RRNB1 PUSH COS # SHAFT ANGLE TO 2
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DMP SL1
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0
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STODL 36D # Z COMPONENT
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SIN DMP
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SL1
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STOVL 32D
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32D
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RVQ
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# THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY
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RRNBMPAC STODL 20D # SAVE SHAFT CDU IN 21.
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MPAC # SET MODE TO DP. (THE PRECEEDING STORE
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# MAY BE DP, TP OR VECTOR.)
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RTB SETPD
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CDULOGIC
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0
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PUSH SIN # TRUNNION ANGLE TO 0
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DCOMP
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STODL 34D # Y COMPONENT
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COS PUSH # .5COS(T) TO 0
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SLOAD RTB # PICK UP CDU'S.
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21D
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CDULOGIC
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GOTO
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RRNB1
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# Page 325
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# (This page has nothing on it.)
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