Source Code
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These source-code files are part of a reconstructed copy of Luminary 98, a
development version of the Apollo 11 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Luminary 99 revision 1 previously
transcribed from a digitized copy of that program. The code was then updated
by undoing changes described in original Luminary memo 85, using asterisks
indicating changed lines in the listing as a guide. While no listing of this
version is known to exist, nor are the memory-bank checksums available,
the reconstruction is believed to be correct because it was an an intermediate
step in reconstructing Luminary 97 whose reconstruction was
verified by matching memory-bank checksums to those listed in drawing 2021152G.
Note that page numbers in the reconstructed code match those on the Luminary 099
revision 001 printout, although the added code would likely have changed page
numbers for a real Luminary 98 listing.
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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013076,000002: ## Copyright: Public domain.
013077,000003: ## Filename: LEM_GEOMETRY.agc
013078,000004: ## Purpose: A section of Luminary revision 98.
013079,000005: ## It is part of the reconstructed source code for the a
013080,000006: ## development version of the flight software for the Lunar
013081,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 11.
013082,000008: ## The code has been recreated from a copy of Luminary 99
013083,000009: ## revision 001, using asterisks indicating changed lines in
013084,000010: ## the listing and Luminary Memo #85, which lists changes between
013085,000011: ## Luminary 98 and 99.
013086,000012: ## Reference: pp. 320-325
013087,000013: ## Assembler: yaYUL
013088,000014: ## Contact: Ron Burkey <info@sandroid.org>.
013089,000015: ## Website: www.ibiblio.org/apollo/index.html
013090,000016: ## Mod history: 2019-07-28 MAS Created from Luminary 99.
013091,000017:
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Page 320
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013093,000019: 23,2041 BANK 23
013094,000020: 13,2000 SETLOC LEMGEOM
013095,000021: 13,2000 BANK
013096,000022:
013097,000023: 13,2070 30,2000 SBANK= LOWSUPER
013098,000024: 13,2070 E5,1642 EBANK= XSM
013099,000025:
013100,000026: # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
013101,000027: # THE CONIC R,V AND THE DEVIATIONS R,V. THE STATE VECTORS ARE CONVERTED TO
013102,000028: # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
013103,000029: # R-OTHER,V-OTHER FOR DOWNLINK. THE ROUTINES NAMES ARE SWITCHED IN THE
013104,000030: # OTHER VEHICLES COMPUTER.
013105,000031:
013106,000032: # INPUT
013107,000033: # STATE VECTOR IN TEMPORARY STORAGE AREA
013108,000034: # IF STATE VECTOR IS SCALED POS B27 AND VEL B5
013109,000035: # SET X2 TO +2
013110,000036: # IF STATE VECTOR IS SCALED POS B29 AND VEL B7
013111,000037: # SET X2 TO 0
013112,000038:
013113,000039: # OUTPUT
013114,000040: # R(T) IN RN, V(T) IN VN, T IN PIPTIME
013115,000041: # OR
013116,000042: # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER)
013117,000043:
013118,000044: 13,2070 COUNT* $$/GEOM
013119,000045: 13,2070 43414 SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG.
013120,000046: 13,2071 04756 AVEMIDSW
013121,000047: 13,2072 26073 +1
013122,000048: 13,2073 53775 VLOAD VSL*
013123,000049: 13,2074 01521 TDELTAV
013124,000050: 13,2075 57605 0 -7,2
013125,000051: 13,2076 53655 VAD VSL*
013126,000052: 13,2077 01535 RCV
013127,000053: 13,2100 57576 0,2
013128,000054: 13,2101 25221 STOVL RN
013129,000055: 13,2102 01527 TNUV
013130,000056: 13,2103 53257 VSL* VAD
013131,000057: 13,2104 57602 0 -4,2
013132,000058: 13,2105 01543 VCV
013133,000059: 13,2106 77657 VSL*
013134,000060: 13,2107 57576 0,2
013135,000061: 13,2110 15227 STODL VN
013136,000062: 13,2111 01517 TET
013137,000063: 13,2112 01235 STORE PIPTIME
013138,000064: 13,2113 77616 RVQ
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Page 321
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013140,000066: 13,2114 53775 SVDWN1 VLOAD VSL*
013141,000067: 13,2115 01521 TDELTAV
013142,000068: 13,2116 57605 0 -7,2
013143,000069: 13,2117 53655 VAD VSL*
013144,000070: 13,2120 01535 RCV
013145,000071: 13,2121 57576 0,2
013146,000072: 13,2122 25720 STOVL R-OTHER
013147,000073: 13,2123 01527 TNUV
013148,000074: 13,2124 53257 VSL* VAD
013149,000075: 13,2125 57602 0 -4,2
013150,000076: 13,2126 01543 VCV
013151,000077: 13,2127 77657 VSL*
013152,000078: 13,2130 57576 0,2
013153,000079: 13,2131 01726 STORE V-OTHER
013154,000080: 13,2132 77616 RVQ
013155,000081:
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Page 322
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013157,000083: # THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
013158,000084: # GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
013159,000085: # ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
013160,000086: # ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE
013161,000087: # SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
013162,000088:
013163,000089: # THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
013164,000090:
013165,000091: # S(2) = 180 + S(1)
013166,000092: # T(2) = 180 - T(1)
013167,000093:
013168,000094: # THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
013169,000095:
013170,000096: 13,2133 00041 RRANGLES STORE 32D
013171,000097: 13,2134 57545 DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT
013172,000098: 13,2135 00043 34D # ANGLE LATER, WE CAN FIND THE MODE 1
013173,000099: 13,2136 67401 SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF
013174,000100: 13,2137 00001 0 # THE Y COMPONENT, THE ASIN GIVING AN
013175,000101: 13,2140 44206 PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG
013176,000102: 13,2141 24005 LODPHALF
013177,000103: 13,2142 14005 STODL 4 # MODE 2 TRUNNION TO 4.
013178,000104:
013179,000105: 13,2143 24007 LO6ZEROS
013180,000106: 13,2144 24043 STOVL 34D # UNIT THE PROJECTION OF THE VECTOR
013181,000107: 13,2145 00041 32D # IN THE X-Z PLANE
013182,000108: 13,2146 41056 UNIT BOVB # IF OVERFLOW, TARGET VECTOR IS ALONG Y
013183,000109: 13,2147 52421 LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF
013184,000110: 13,2150 14041 STODL 32D # PROJECTION VECTOR.
013185,000111: 13,2151 00041 32D
013186,000112: 13,2152 44142 SR1 STQ
013187,000113: 13,2153 00051 S2
013188,000114: 13,2154 14023 STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARB.
013189,000115: 13,2155 00045 36D
013190,000116: 13,2156 77742 SR1
013191,000117: 13,2157 34021 STCALL COSTH
013192,000118: 13,2160 47320 ARCTRIG
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Page 323
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013194,000120: 13,2161 43206 PUSH DAD # MODE 1 SHAFT TO 2.
013195,000121: 13,2162 24005 LODPHALF
013196,000122: 13,2163 24007 STOVL 6
013197,000123: 13,2164 00005 4
013198,000124: 13,2165 77634 RTB # FIND MODE 2 CDU ANGLES.
013199,000125: 13,2166 21635 2V1STO2S
013200,000126: 13,2167 25112 STOVL MODEB
013201,000127: 13,2170 00001 0
013202,000128: 13,2171 77634 RTB # MODE 1 ANGLES TO MODE A.
013203,000129: 13,2172 21635 2V1STO2S
013204,000130: 13,2173 01110 STORE MODEA
013205,000131: 13,2174 77776 EXIT
013206,000132:
013207,000133: 13,2175 40110 CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2.
013208,000134: 13,2176 74740 MASK ANTENBIT
013209,000135: 13,2177 10000 CCS A
013210,000136: 13,2200 12204 TCF +4
013211,000137:
013212,000138: 13,2201 53110 DXCH MODEA
013213,000139: 13,2202 53112 DXCH MODEB
013214,000140: 13,2203 53110 DXCH MODEA
013215,000141:
013216,000142: 13,2204 06037 TC INTPRET
013217,000143: 13,2205 77650 GOTO
013218,000144: 13,2206 00051 S2
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Page 324
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013220,000146: # GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED
013221,000147: # LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
013222,000148: # -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
013223,000149:
013224,000150: 23,2000 SETLOC INFLIGHT
013225,000151: 23,2000 BANK
013226,000152:
013227,000153: 23,2041 COUNT* $$/GEOM
013228,000154:
013229,000155: 23,2041 47135 RRNB SLOAD RTB
013230,000156: 23,2042 03753 TANGNB
013231,000157: 23,2043 21576 CDULOGIC
013232,000158: 23,2044 41401 SETPD PUSH # TRUNNION ANGLE TO 0
013233,000159: 23,2045 00001 0
013234,000160: 23,2046 57556 SIN DCOMP
013235,000161: 23,2047 14043 STODL 34D # Y COMPONENT
013236,000162:
013237,000163: 23,2050 41546 COS PUSH # .5 COS(T) TO 0
013238,000164: 23,2051 47135 SLOAD RTB
013239,000165: 23,2052 03754 TANGNB +1
013240,000166: 23,2053 21576 CDULOGIC
013241,000167: 23,2054 71406 RRNB1 PUSH COS # SHAFT ANGLE TO 2
013242,000168: 23,2055 72405 DMP SL1
013243,000169: 23,2056 00001 0
013244,000170: 23,2057 14045 STODL 36D # Z COMPONENT
013245,000171:
013246,000172: 23,2060 41356 SIN DMP
013247,000173: 23,2061 77752 SL1
013248,000174: 23,2062 24041 STOVL 32D
013249,000175: 23,2063 00041 32D
013250,000176: 23,2064 77616 RVQ
013251,000177:
013252,000178: # THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY
013253,000179:
013254,000180: 23,2065 14025 RRNBMPAC STODL 20D # SAVE SHAFT CDU IN 21.
013255,000181: 23,2066 00155 MPAC # SET MODE TO DP. (THE PRECEEDING STORE
013256,000182: # MAY BE DP, TP OR VECTOR.)
013257,000183: 23,2067 40234 RTB SETPD
013258,000184: 23,2070 21576 CDULOGIC
013259,000185: 23,2071 00001 0
013260,000186: 23,2072 73406 PUSH SIN # TRUNNION ANGLE TO 0
013261,000187: 23,2073 77676 DCOMP
013262,000188: 23,2074 14043 STODL 34D # Y COMPONENT
013263,000189: 23,2075 41546 COS PUSH # .5COS(T) TO 0
013264,000190: 23,2076 47135 SLOAD RTB # PICK UP CDU'S.
013265,000191: 23,2077 00026 21D
013266,000192: 23,2100 21576 CDULOGIC
013267,000193: 23,2101 77650 GOTO
013268,000194: 23,2102 46054 RRNB1
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Page 325
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013271,000197:
013272,000198:
End of include-file LEM_GEOMETRY.agc. Parent file is MAIN.agc