Source Code
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These source code files are an attempted reconstruction of Sundance revision 306, the Apollo 9
LM (Lunar Module) AGC (Apollo Guidance Computer) flight software, created from binary dumps of
original core rope program modules, as follows:
- B1 — Revision 292
- B2 — Revision 302
- B3 — Revision 302
- B4 — Revision 302
- B5 — Revision 292
- B6 — Revision 306
These dumps were then modified using memos, checklists, observed address changes, and the
Sundance GSOPs to get the entire program to match Sundance revision 306 as closely as possible.
Without more information, it is not possible to say how close it actually is; however, this
code should be quite close. It is capable of flying the whole Apollo 9 mission using the original
checklists and padload.
Since only binary dumps (rather than listings) of Sundance are available as source material,
all comments and labels are approximate.
They have been taken from other AGC programs where possible, or, in some places, written
from scratch to match what we believe would have been in the original listing.
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011743,000002: ## Copyright: Public domain.
011744,000003: ## Filename: LEM_GEOMETRY.agc
011745,000004: ## Purpose: A section of an attempt to reconstruct Sundance revision 306
011746,000005: ## as closely as possible with available information. Sundance
011747,000006: ## 306 is the source code for the Lunar Module's (LM) Apollo
011748,000007: ## Guidance Computer (AGC) for Apollo 9. This program was created
011749,000008: ## using the mixed-revision SundanceXXX as a starting point, and
011750,000009: ## pulling back features from Luminary 69 believed to have been
011751,000010: ## added based on memos, checklists, observed address changes,
011752,000011: ## or the Sundance GSOPs.
011753,000012: ## Assembler: yaYUL
011754,000013: ## Contact: Ron Burkey <info@sandroid.org>.
011755,000014: ## Website: www.ibiblio.org/apollo/index.html
011756,000015: ## Mod history: 2020-07-24 MAS Created from SundanceXXX.
011757,000016: ## 2021-05-30 ABS Replaced use of ANTENBIT with BIT12 to match
011758,000017: ## Luminary 69.
011759,000018:
011760,000019:
011761,000020:
011762,000021: 23,2000 BANK 23
011763,000022: 13,2000 SETLOC LEMGEOM
011764,000023: 13,2000 BANK
011765,000024:
011766,000025: 13,2042 30,2000 SBANK= LOWSUPER
011767,000026: 13,2042 E5,1642 EBANK= XSM
011768,000027:
011769,000028: # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
011770,000029: # THE CONIC R,V AND THE DEVIATIONSR,V. THE STATE VECTORS ARE CONVERTED TO
011771,000030: # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
011772,000031: # R-OTHER , V-OTHER FOR DOWNLINK. THE ROUTINES NAMES ARE SWITCHED IN THE
011773,000032: # OTHER VEHICLES COMPUTER.
011774,000033:
011775,000034: # INPUT
011776,000035: # STATE VECTOR IN TEMPORARY STORAGE AREA
011777,000036: # IF STATE VECTOR IS SCALED POS B27 AND VEL B5
011778,000037: # SET X2 TO +2
011779,000038: # IF STATE VECTOR IS SCALED POS B29 AND VEL B7
011780,000039: # SET X2 TO 0
011781,000040:
011782,000041: # OUTPUT
011783,000042: # R(T) IN RN, V(T) IN VN, T IN PIPTIME
011784,000043: # OR
011785,000044: # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER)
011786,000045:
011787,000046: 13,2042 COUNT* $$/GEOM
011788,000047: 13,2042 43414 SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG.
011789,000048: 13,2043 04756 AVEMIDSW
011790,000049: 13,2044 26045 +1
011791,000050: 13,2045 53775 VLOAD VSL*
011792,000051: 13,2046 01521 TDELTAV
011793,000052: 13,2047 57605 0 -7,2
011794,000053: 13,2050 53655 VAD VSL*
011795,000054: 13,2051 01535 RCV
011796,000055: 13,2052 57576 0,2
011797,000056: 13,2053 25220 STOVL RN
011798,000057: 13,2054 01527 TNUV
011799,000058: 13,2055 53257 VSL* VAD
011800,000059: 13,2056 57602 0 -4,2
011801,000060: 13,2057 01543 VCV
011802,000061: 13,2060 77657 VSL*
011803,000062: 13,2061 57576 0,2
011804,000063: 13,2062 15226 STODL VN
011805,000064: 13,2063 01517 TET
011806,000065: 13,2064 01234 STORE PIPTIME
011807,000066: 13,2065 77616 RVQ
011808,000067: 13,2066 53775 SVDWN1 VLOAD VSL*
011809,000068: 13,2067 01521 TDELTAV
011810,000069: 13,2070 57605 0 -7,2
011811,000070: 13,2071 53655 VAD VSL*
011812,000071: 13,2072 01535 RCV
011813,000072: 13,2073 57576 0,2
011814,000073: 13,2074 25722 STOVL R-OTHER
011815,000074: 13,2075 01527 TNUV
011816,000075: 13,2076 53257 VSL* VAD
011817,000076: 13,2077 57602 0 -4,2
011818,000077: 13,2100 01543 VCV
011819,000078: 13,2101 77657 VSL*
011820,000079: 13,2102 57576 0,2
011821,000080: 13,2103 01730 STORE V-OTHER
011822,000081: 13,2104 77616 RVQ
011823,000082:
011824,000083: # THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
011825,000084: # GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
011826,000085: # ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
011827,000086: # ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE
011828,000087: # SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
011829,000088:
011830,000089: # THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
011831,000090:
011832,000091: # S(2) = 180 + S(1)
011833,000092: # T(2) = 180 - T(1)
011834,000093:
011835,000094: # THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
011836,000095:
011837,000096: 13,2105 00041 RRANGLES STORE 32D
011838,000097: 13,2106 57545 DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT
011839,000098: 13,2107 00043 34D # ANGLE LATER, WE CAN FIND THE MODE 1
011840,000099: 13,2110 67401 SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF
011841,000100: 13,2111 00001 0 # THE Y COMPONENT, THE ASIN GIVING AN
011842,000101: 13,2112 44206 PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG
011843,000102: 13,2113 22274 LODPHALF
011844,000103: 13,2114 14005 STODL 4 # MODE 2 TRUNNION TO 4.
011845,000104:
011846,000105: 13,2115 22276 LO6ZEROS
011847,000106: 13,2116 24043 STOVL 34D # UNIT THE PROJECTION OF THE VECTOR
011848,000107: 13,2117 00041 32D # IN THE X-Z PLANE
011849,000108: 13,2120 41056 UNIT BOVB # IF OVERFLOW, TARGET VECTOR IS ALONG Y
011850,000109: 13,2121 52400 LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF
011851,000110: 13,2122 14041 STODL 32D # PROJECTION VECTOR.
011852,000111: 13,2123 00041 32D
011853,000112: 13,2124 44142 SR1 STQ
011854,000113: 13,2125 00051 S2
011855,000114: 13,2126 14023 STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARB.
011856,000115: 13,2127 00045 36D
011857,000116: 13,2130 77742 SR1
011858,000117: 13,2131 34021 STCALL COSTH
011859,000118: 13,2132 47114 ARCTRIG
011860,000119: 13,2133 43206 PUSH DAD # MODE 1 SHAFT TO 2.
011861,000120: 13,2134 22274 LODPHALF
011862,000121: 13,2135 24007 STOVL 6
011863,000122: 13,2136 00005 4
011864,000123: 13,2137 77634 RTB # FIND MODE 2 CDU ANGLES.
011865,000124: 13,2140 21533 2V1STO2S
011866,000125: 13,2141 25115 STOVL MODEB
011867,000126: 13,2142 00001 0
011868,000127: 13,2143 77634 RTB # MODE 1 ANGLES TO MODE A.
011869,000128: 13,2144 21533 2V1STO2S
011870,000129: 13,2145 01113 STORE MODEA
011871,000130: 13,2146 77776 EXIT
011872,000131:
011873,000132: 13,2147 41101 CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2.
011874,000133: 13,2150 75013 MASK BIT12
011875,000134: 13,2151 10000 CCS A
011876,000135: 13,2152 12156 TCF +4
011877,000136:
011878,000137: 13,2153 53113 DXCH MODEA
011879,000138: 13,2154 53115 DXCH MODEB
011880,000139: 13,2155 53113 DXCH MODEA
011881,000140:
011882,000141: 13,2156 06014 TC INTPRET
011883,000142: 13,2157 77650 GOTO
011884,000143: 13,2160 00051 S2
011885,000144: # GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED
011886,000145: # LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
011887,000146: # -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
011888,000147:
011889,000148: 23,2000 SETLOC INFLIGHT
011890,000149: 23,2000 BANK
011891,000150:
011892,000151: 23,2000 COUNT* $$/GEOM
011893,000152:
011894,000153: 23,2000 47135 RRNB SLOAD RTB
011895,000154: 23,2001 03744 TANGNB
011896,000155: 23,2002 21457 CDULOGIC
011897,000156: 23,2003 41401 SETPD PUSH # TRUNNION ANGLE TO 0
011898,000157: 23,2004 00001 0
011899,000158: 23,2005 57556 SIN DCOMP
011900,000159: 23,2006 14043 STODL 34D # Y COMPONENT
011901,000160:
011902,000161: 23,2007 41546 COS PUSH # .5 COS(T) TO 0
011903,000162: 23,2010 47135 SLOAD RTB
011904,000163: 23,2011 03745 TANGNB +1
011905,000164: 23,2012 21457 CDULOGIC
011906,000165: 23,2013 71406 PUSH COS # SHAFT ANGLE TO 2
011907,000166: 23,2014 72405 DMP SL1
011908,000167: 23,2015 00001 0
011909,000168: 23,2016 14045 STODL 36D # Z COMPONENT
011910,000169:
011911,000170: 23,2017 41356 SIN DMP
011912,000171: 23,2020 77752 SL1
011913,000172: 23,2021 24041 STOVL 32D
011914,000173: 23,2022 00041 32D
011915,000174: 23,2023 77616 RVQ
End of include-file LEM_GEOMETRY.agc. Parent file is MAIN.agc