Source Code

This is a reconstruction of the AGC program Luminary 99 Rev 0. It was the third release of the Lunar Module flight software targeted for use in Apollo 11, after Luminary 96 and 97. A bug (which had been around since at least Apollo 10, Luminary 69) was discovered in Rev 0 shortly before the Apollo 11 flight, resulting in a last minute revision into Rev 1, which is what actually flew rather than the Rev 0 presented here. A hardcopy of Rev 0 is known to exist — it belonged to AGC developer Allan Klumpp for many years — but unfortunately the Virtual AGC Project has not had access to that hardcopy. Thus the code you see here had been reconstructed (we believe accurately) rather than transcribed. The first step of the reconstruction of the Rev 0 source code was the transcription of the Rev 1 source code from a hardcopy in the MIT Museum collection. The process of reverting the active portion of the source code (i.e., other than program comments) from Rev 1 to Rev 0 was very minor, consisting only of moving the position of the STARTSB1 label in FRESH START AND RESTART. Allan had previously given us the checksums of the memory banks of Rev 0, and we have verified the program presented here has checksums identical to all banks of Allan's listing of Rev 0. The notations on Allan's Rev 0 program listing read, in part:

	GAP:  ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-051

A single program comment is known to differ between Rev 0 and Rev 1, but these are harder to reconstruct and verify than changes to the active portion of the code. Thus it is possible that there are additional differences between the program comments in Rev 0 and Rev 1 that are unknown to us, and therefore are not reflected in the code presented here.

013664,000002:                                                                                                  ## Copyright:   Public domain.
013665,000003:                                                                                                  ## Filename:    LEM_GEOMETRY.agc
013666,000004:                                                                                                  ## Purpose:     Part of the reconstructed source code for LMY99 Rev 0,
013667,000005:                                                                                                  ##              otherwise known as Luminary Rev 99, the third release
013668,000006:                                                                                                  ##              of the Apollo Guidance Computer (AGC) software for Apollo 11.
013669,000007:                                                                                                  ##              It differs from LMY99 Rev 1 (the flown version) only in the
013670,000008:                                                                                                  ##              placement of a single label. The corrections shown here have
013671,000009:                                                                                                  ##              been verified to have the same bank checksums as AGC developer
013672,000010:                                                                                                  ##              Allan Klumpp's copy of Luminary Rev 99, and so are believed
013673,000011:                                                                                                  ##              to be accurate. This file is intended to be a faithful 
013674,000012:                                                                                                  ##              recreation, except that the code format has been changed to 
013675,000013:                                                                                                  ##              conform to the requirements of the yaYUL assembler rather than 
013676,000014:                                                                                                  ##              the original YUL assembler.
013677,000015:                                                                                                  ##
013678,000016:                                                                                                  ## Assembler:   yaYUL
013679,000017:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
013680,000018:                                                                                                  ## Website:     www.ibiblio.org/apollo.
013681,000019:                                                                                                  ## Pages:       320-325
013682,000020:                                                                                                  ## Mod history: 2009-05-16 RSB  Adapted from the corresponding 
013683,000021:                                                                                                  ##                              Luminary131 file, using page 
013684,000022:                                                                                                  ##                              images from Luminary 1A.
013685,000023:                                                                                                  ##              2016-12-13 RSB  Proofed text comments with octopus/ProoferComments
013686,000024:                                                                                                  ##                              and corrected the errors found.
013687,000025:                                                                                                  ##              2017-03-07 RSB  Fixed comment-text error noticed while proofing
013688,000026:                                                                                                  ##                              Luminary 116.
013689,000027:                                                                                                  ##              2017-08-01 MAS  Created from LMY99 Rev 1.
013690,000028: 
013691,000029:                                                                                                  ## This source code has been transcribed or otherwise adapted from
013692,000030:                                                                                                  ## digitized images of a hardcopy from the MIT Museum.  The digitization
013693,000031:                                                                                                  ## was performed by Paul Fjeld, and arranged for by Deborah Douglas of
013694,000032:                                                                                                  ## the Museum.  Many thanks to both.  The images (with suitable reduction
013695,000033:                                                                                                  ## in storage size and consequent reduction in image quality as well) are
013696,000034:                                                                                                  ## available online at www.ibiblio.org/apollo.  If for some reason you
013697,000035:                                                                                                  ## find that the images are illegible, contact me at info@sandroid.org
013698,000036:                                                                                                  ## about getting access to the (much) higher-quality images which Paul
013699,000037:                                                                                                  ## actually created.
013700,000038:                                                                                                  ##
013701,000039:                                                                                                  ## The code has been modified to match LMY99 Revision 0, otherwise
013702,000040:                                                                                                  ## known as Luminary Revision 99, the Apollo 11 software release preceeding
013703,000041:                                                                                                  ## the listing from which it was transcribed. It has been verified to
013704,000042:                                                                                                  ## contain the same bank checksums as AGC developer Allan Klumpp's listing
013705,000043:                                                                                                  ## of Luminary Revision 99 (for which we do not have scans).
013706,000044:                                                                                                  ##
013707,000045:                                                                                                  ## Notations on Allan Klumpp's listing read, in part:
013708,000046:                                                                                                  ##
013709,000047:                                                                                                  ##      ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-51
013710,000048: 

Page 320

013712,000050: 23,2041                                           BANK     23                                    
013713,000051: 13,2000                                           SETLOC   LEMGEOM                               
013714,000052: 13,2000                                           BANK                                           
013715,000053: 
013716,000054: 13,2070  30,2000                                  SBANK=   LOWSUPER                              
013717,000055: 13,2070  E5,1642                                  EBANK=   XSM                                   
013718,000056: 
013719,000057:                                                                                                  #  THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
013720,000058:                                                                                                  #  THE CONIC R,V AND THE DEVIATIONS R,V.  THE STATE VECTORS ARE CONVERTED TO
013721,000059:                                                                                                  #  METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
013722,000060:                                                                                                  #  R-OTHER,V-OTHER FOR DOWNLINK.  THE ROUTINES NAMES ARE SWITCHED IN THE
013723,000061:                                                                                                  #  OTHER VEHICLES COMPUTER.
013724,000062: 
013725,000063:                                                                                                  #  INPUT
013726,000064:                                                                                                  #        STATE VECTOR IN TEMPORARY STORAGE AREA
013727,000065:                                                                                                  #        IF STATE VECTOR IS SCALED POS B27 AND VEL B5
013728,000066:                                                                                                  #                SET X2 TO +2
013729,000067:                                                                                                  #        IF STATE VECTOR IS SCALED POS B29 AND VEL B7
013730,000068:                                                                                                  #                SET X2 TO 0
013731,000069: 
013732,000070:                                                                                                  #  OUTPUT
013733,000071:                                                                                                  #        R(T) IN RN, V(T) IN VN, T IN PIPTIME
013734,000072:                                                                                                  #  OR
013735,000073:                                                                                                  #        R(T) IN R-OTHER, V(T) IN V-OTHER        (T IS DEFINED BY T-OTHER)
013736,000074: 
013737,000075: 13,2070                                           COUNT*   $$/GEOM                               
013738,000076: 13,2070           43414        SVDWN2             BOF      RVQ                                   #  SW=1=AVETOMID DOING W-MATRIX INTEG.
013739,000077: 13,2071           04756                                    AVEMIDSW                              
013740,000078: 13,2072           26073                                    +1                                    
013741,000079: 13,2073           53775                           VLOAD    VSL*                                  
013742,000080: 13,2074           01521                                    TDELTAV                               
013743,000081: 13,2075           57605                                    0          -7,2                       
013744,000082: 13,2076           53655                           VAD      VSL*                                  
013745,000083: 13,2077           01535                                    RCV                                   
013746,000084: 13,2100           57576                                    0,2                                   
013747,000085: 13,2101           25221                           STOVL    RN                                    
013748,000086: 13,2102           01527                                    TNUV                                  
013749,000087: 13,2103           53257                           VSL*     VAD                                   
013750,000088: 13,2104           57602                                    0          -4,2                       
013751,000089: 13,2105           01543                                    VCV                                   
013752,000090: 13,2106           77657                           VSL*                                           
013753,000091: 13,2107           57576                                    0,2                                   
013754,000092: 13,2110           15227                           STODL    VN                                    
013755,000093: 13,2111           01517                                    TET                                   
013756,000094: 13,2112           01235                           STORE    PIPTIME                               
013757,000095: 13,2113           77616                           RVQ                                            

Page 321

013759,000097: 13,2114           53775        SVDWN1             VLOAD    VSL*                                  
013760,000098: 13,2115           01521                                    TDELTAV                               
013761,000099: 13,2116           57605                                    0          -7,2                       
013762,000100: 13,2117           53655                           VAD      VSL*                                  
013763,000101: 13,2120           01535                                    RCV                                   
013764,000102: 13,2121           57576                                    0,2                                   
013765,000103: 13,2122           25720                           STOVL    R-OTHER                               
013766,000104: 13,2123           01527                                    TNUV                                  
013767,000105: 13,2124           53257                           VSL*     VAD                                   
013768,000106: 13,2125           57602                                    0          -4,2                       
013769,000107: 13,2126           01543                                    VCV                                   
013770,000108: 13,2127           77657                           VSL*                                           
013771,000109: 13,2130           57576                                    0,2                                   
013772,000110: 13,2131           01726                           STORE    V-OTHER                               
013773,000111: 13,2132           77616                           RVQ                                            
013774,000112: 

Page 322

013776,000114:                                                                                                  #  THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
013777,000115:                                                                                                  #  GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET.  THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
013778,000116:                                                                                                  #  ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB.  THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
013779,000117:                                                                                                  #  ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2.  MODE
013780,000118:                                                                                                  #  SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
013781,000119: 
013782,000120:                                                                                                  #  THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
013783,000121: 
013784,000122:                                                                                                  #        S(2) = 180 + S(1)
013785,000123:                                                                                                  #        T(2) = 180 - T(1)
013786,000124: 
013787,000125:                                                                                                  #  THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
013788,000126: 
013789,000127: 13,2133           00041        RRANGLES           STORE    32D                                   
013790,000128: 13,2134           57545                           DLOAD    DCOMP                                 #  SINCE WE WILL FIND THE MODE 1 SHAFT
013791,000129: 13,2135           00043                                    34D                                   #  ANGLE LATER, WE CAN FIND THE MODE 1
013792,000130: 13,2136           67401                           SETPD    ASIN                                  #  TRUNNION BY SIMPLY TAKING THE ARCSIN OF
013793,000131: 13,2137           00001                                    0                                     #  THE Y COMPONENT, THE ASIN GIVING AN
013794,000132: 13,2140           44206                           PUSH     BDSU                                  #  ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG
013795,000133: 13,2141           24005                                    LODPHALF                              
013796,000134: 13,2142           14005                           STODL    4                                     #  MODE 2 TRUNNION TO 4.
013797,000135: 
013798,000136: 13,2143           24007                                    LO6ZEROS                              
013799,000137: 13,2144           24043                           STOVL    34D                                   #  UNIT THE PROJECTION OF THE VECTOR
013800,000138: 13,2145           00041                                    32D                                   #        IN THE X-Z PLANE
013801,000139: 13,2146           41056                           UNIT     BOVB                                  #  IF OVERFLOW, TARGET VECTOR IS ALONG Y
013802,000140: 13,2147           52421                                    LUNDESCH                              #  CALL FOR MANEUVER UNLESS ON LUNAR SURF
013803,000141: 13,2150           14041                           STODL    32D                                   #  PROJECTION VECTOR.
013804,000142: 13,2151           00041                                    32D                                   
013805,000143: 13,2152           44142                           SR1      STQ                                   
013806,000144: 13,2153           00051                                    S2                                    
013807,000145: 13,2154           14023                           STODL    SINTH                                 #  USE ARCTRIG SINCE SHAFT COULD BE ARB.
013808,000146: 13,2155           00045                                    36D                                   
013809,000147: 13,2156           77742                           SR1                                            
013810,000148: 13,2157           34021                           STCALL   COSTH                                 
013811,000149: 13,2160           47320                                    ARCTRIG                               

Page 323

013813,000151: 13,2161           43206                           PUSH     DAD                                   #  MODE 1 SHAFT TO 2.
013814,000152: 13,2162           24005                                    LODPHALF                              
013815,000153: 13,2163           24007                           STOVL    6                                     
013816,000154: 13,2164           00005                                    4                                     
013817,000155: 13,2165           77634                           RTB                                            #  FIND MODE 2 CDU ANGLES.
013818,000156: 13,2166           21635                                    2V1STO2S                              
013819,000157: 13,2167           25112                           STOVL    MODEB                                 
013820,000158: 13,2170           00001                                    0                                     
013821,000159: 13,2171           77634                           RTB                                            #  MODE 1 ANGLES TO MODE A.
013822,000160: 13,2172           21635                                    2V1STO2S                              
013823,000161: 13,2173           01110                           STORE    MODEA                                 
013824,000162: 13,2174           77776                           EXIT                                           
013825,000163: 
013826,000164: 13,2175           40110                           CS       RADMODES                              #  SWAP MODEA AND MODEB IF RR IN MODE 2.
013827,000165: 13,2176           74740                           MASK     ANTENBIT                              
013828,000166: 13,2177           10000                           CCS      A                                     
013829,000167: 13,2200           12204                           TCF      +4                                    
013830,000168: 
013831,000169: 13,2201           53110                           DXCH     MODEA                                 
013832,000170: 13,2202           53112                           DXCH     MODEB                                 
013833,000171: 13,2203           53110                           DXCH     MODEA                                 
013834,000172: 
013835,000173: 13,2204           06037                           TC       INTPRET                               
013836,000174: 13,2205           77650                           GOTO                                           
013837,000175: 13,2206           00051                                    S2                                    

Page 324

013839,000177:                                                                                                  #  GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED
013840,000178:                                                                                                  #  LINE OF SIGHT IN NAV BASE AXES.  THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
013841,000179:                                                                                                  #  -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
013842,000180: 
013843,000181: 23,2000                                           SETLOC   INFLIGHT                              
013844,000182: 23,2000                                           BANK                                           
013845,000183: 
013846,000184: 23,2041                                           COUNT*   $$/GEOM                               
013847,000185: 
013848,000186: 23,2041           47135        RRNB               SLOAD    RTB                                   
013849,000187: 23,2042           03753                                    TANGNB                                
013850,000188: 23,2043           21576                                    CDULOGIC                              
013851,000189: 23,2044           41401                           SETPD    PUSH                                  #  TRUNNION ANGLE TO 0
013852,000190: 23,2045           00001                                    0                                     
013853,000191: 23,2046           57556                           SIN      DCOMP                                 
013854,000192: 23,2047           14043                           STODL    34D                                   #  Y COMPONENT
013855,000193: 
013856,000194: 23,2050           41546                           COS      PUSH                                  #  .5 COS(T) TO 0
013857,000195: 23,2051           47135                           SLOAD    RTB                                   
013858,000196: 23,2052           03754                                    TANGNB     +1                         
013859,000197: 23,2053           21576                                    CDULOGIC                              
013860,000198: 23,2054           71406        RRNB1              PUSH     COS                                   #  SHAFT ANGLE TO 2
013861,000199: 23,2055           72405                           DMP      SL1                                   
013862,000200: 23,2056           00001                                    0                                     
013863,000201: 23,2057           14045                           STODL    36D                                   #  Z COMPONENT
013864,000202: 
013865,000203: 23,2060           41356                           SIN      DMP                                   
013866,000204: 23,2061           77752                           SL1                                            
013867,000205: 23,2062           24041                           STOVL    32D                                   
013868,000206: 23,2063           00041                                    32D                                   
013869,000207: 23,2064           77616                           RVQ                                            
013870,000208: 
013871,000209:                                                                                                  #  THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY
013872,000210: 
013873,000211: 23,2065           14025        RRNBMPAC           STODL    20D                                   #  SAVE SHAFT CDU IN 21.
013874,000212: 23,2066           00155                                    MPAC                                  #  SET MODE TO DP.  (THE PRECEEDING STORE
013875,000213:                                                                                                  #  MAY BE DP, TP OR VECTOR.)
013876,000214: 23,2067           40234                           RTB      SETPD                                 
013877,000215: 23,2070           21576                                    CDULOGIC                              
013878,000216: 23,2071           00001                                    0                                     
013879,000217: 23,2072           73406                           PUSH     SIN                                   #  TRUNNION ANGLE TO 0
013880,000218: 23,2073           77676                           DCOMP                                          
013881,000219: 23,2074           14043                           STODL    34D                                   #  Y COMPONENT
013882,000220: 23,2075           41546                           COS      PUSH                                  #  .5COS(T) TO 0
013883,000221: 23,2076           47135                           SLOAD    RTB                                   #  PICK UP CDU'S.
013884,000222: 23,2077           00026                                    21D                                   
013885,000223: 23,2100           21576                                    CDULOGIC                              
013886,000224: 23,2101           77650                           GOTO                                           
013887,000225: 23,2102           46054                                    RRNB1                                 

Page 325
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013890,000228: 
013891,000229: 

End of include-file LEM_GEOMETRY.agc.  Parent file is MAIN.agc