Source Code
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This is a reconstructed version of Luminary 130, the initial AGC program released
in November 1969 for the Apollo 13 LM. Three more releases
followed before the flown revision was finally manufactured in February 1970.
This reconstruction was created from a previous transcription of the original listing of
Luminary 131, combined with Luminary memo #129 which describes the small difference
between the Luminary 130 and 131. The reconstructed source code was verified by
matching memory-bank checksums to those listed for Luminary 130 in drawing 2021152G.
In this source code, program comments from the original (Luminary 131) code are
prefixed with '#', while those added later by the Virtual AGC project are prefixed
with '##'.
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013471,000002: ## Copyright: Public domain.
013472,000003: ## Filename: LEM_GEOMETRY.agc
013473,000004: ## Purpose: A section of the reconstructed source code for Luminary 130.
013474,000005: ## This was the original program released for the Apollo 13 LM,
013475,000006: ## although several more revisions would follow. It has been
013476,000007: ## reconstructed from a listing of Luminary 131, from which it
013477,000008: ## differs on only two lines in P70-P71. The difference is
013478,000009: ## described in detail in Luminary memo #129, which was used
013479,000010: ## to perform the reconstruction. This file is intended to be a
013480,000011: ## faithful reconstruction, except that the code format has been
013481,000012: ## changed to conform to the requirements of the yaYUL assembler
013482,000013: ## rather than the original YUL assembler.
013483,000014: ## Reference: pp. 322-327
013484,000015: ## Contact: Ron Burkey <info@sandroid.org>.
013485,000016: ## Website: www.ibiblio.org/apollo/index.html
013486,000017: ## Mod history: 05/10/03 RSB. Began transcribing.
013487,000018: ## 05/14/05 RSB Corrected website reference above.
013488,000019: ## 2010-08-24 JL Fixed page 330 number.
013489,000020: ## 2017-01-06 RSB Page numbers now agree with those on the
013490,000021: ## original harcopy, as opposed to the PDF page
013491,000022: ## numbers in 1701.pdf.
013492,000023: ## 2017-02-23 RSB Proofed comment text using octopus/ProoferComments.
013493,000024: ## 2017-03-07 RSB Fixed comment-text error noted while proofing
013494,000025: ## Luminary 116.
013495,000026: ## 2018-09-04 MAS Copied from Luminary 131 for Luminary 130.
013496,000027:
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Page 322
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013498,000029: 23,2041 BANK 23
013499,000030: 13,2000 SETLOC LEMGEOM
013500,000031: 13,2000 BANK
013501,000032:
013502,000033: 13,2070 30,2000 SBANK= LOWSUPER
013503,000034: 13,2070 E5,1642 EBANK= XSM
013504,000035:
013505,000036: # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
013506,000037: # THE CONIC R,V AND THE DEVIATIONS R,V. THE STATE VECTORS ARE CONVERTED TO
013507,000038: # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
013508,000039: # R-OTHER,V-OTHER FOR DOWNLINK. THE ROUTINES NAMES ARE SWITCHED IN THE
013509,000040: # OTHER VEHICLES COMPUTER.
013510,000041:
013511,000042: # INPUT
013512,000043: # STATE VECTOR IN TEMPORARY STORAGE AREA
013513,000044: # IF STATE VECTOR IS SCALED POS B27 AND VEL B5
013514,000045: # SET X2 TO +2
013515,000046: # IF STATE VECTOR IS SCALED POS B29 AND VEL B7
013516,000047: # SET X2 TO 0
013517,000048:
013518,000049: # OUTPUT
013519,000050: # R(T) IN RN, V(T) IN VN, T IN PIPTIME
013520,000051: # OR
013521,000052: # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER)
013522,000053:
013523,000054: 13,2070 COUNT* $$/GEOM
013524,000055: 13,2070 43414 SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG.
013525,000056: 13,2071 04756 AVEMIDSW
013526,000057: 13,2072 26073 +1
013527,000058: 13,2073 53775 VLOAD VSL*
013528,000059: 13,2074 01521 TDELTAV
013529,000060: 13,2075 57605 0 -7,2
013530,000061: 13,2076 53655 VAD VSL*
013531,000062: 13,2077 01535 RCV
013532,000063: 13,2100 57576 0,2
013533,000064: 13,2101 25220 STOVL RN
013534,000065: 13,2102 01527 TNUV
013535,000066: 13,2103 53257 VSL* VAD
013536,000067: 13,2104 57602 0 -4,2
013537,000068: 13,2105 01543 VCV
013538,000069: 13,2106 77657 VSL*
013539,000070: 13,2107 57576 0,2
013540,000071: 13,2110 15226 STODL VN
013541,000072: 13,2111 01517 TET
013542,000073: 13,2112 01234 STORE PIPTIME
013543,000074: 13,2113 77616 RVQ
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Page 323
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013545,000076: 13,2114 53775 SVDWN1 VLOAD VSL*
013546,000077: 13,2115 01521 TDELTAV
013547,000078: 13,2116 57605 0 -7,2
013548,000079: 13,2117 53655 VAD VSL*
013549,000080: 13,2120 01535 RCV
013550,000081: 13,2121 57576 0,2
013551,000082: 13,2122 25720 STOVL R-OTHER
013552,000083: 13,2123 01527 TNUV
013553,000084: 13,2124 53257 VSL* VAD
013554,000085: 13,2125 57602 0 -4,2
013555,000086: 13,2126 01543 VCV
013556,000087: 13,2127 77657 VSL*
013557,000088: 13,2130 57576 0,2
013558,000089: 13,2131 01726 STORE V-OTHER
013559,000090: 13,2132 77616 RVQ
013560,000091:
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Page 324
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013562,000093: # THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
013563,000094: # GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
013564,000095: # ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
013565,000096: # ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE
013566,000097: # SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
013567,000098:
013568,000099: # THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
013569,000100:
013570,000101: # S(2) = 180 + S(1)
013571,000102: # T(2) = 180 - T(1)
013572,000103:
013573,000104: # THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
013574,000105:
013575,000106: 13,2133 00041 RRANGLES STORE 32D
013576,000107: 13,2134 57545 DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT
013577,000108: 13,2135 00043 34D # ANGLE LATER, WE CAN FIND THE MODE 1
013578,000109: 13,2136 67401 SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF
013579,000110: 13,2137 00001 0 # THE Y COMPONENT, THE ASIN GIVING AN
013580,000111: 13,2140 44206 PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG
013581,000112: 13,2141 24005 LODPHALF
013582,000113: 13,2142 14005 STODL 4 # MODE 2 TRUNNION TO 4.
013583,000114: 13,2143 24007 LO6ZEROS
013584,000115: 13,2144 24043 STOVL 34D # UNIT THE PROJECTION OF THE VECTOR
013585,000116: 13,2145 00041 32D # IN THE X-Z PLANE
013586,000117: 13,2146 41056 UNIT BOVB # IF OVERFLOW, TARGET VECTOR IS ALONG Y
013587,000118: 13,2147 52432 LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF
013588,000119: 13,2150 14041 STODL 32D # PROJECTION VECTOR.
013589,000120: 13,2151 00041 32D
013590,000121: 13,2152 44142 SR1 STQ
013591,000122: 13,2153 00051 S2
013592,000123: 13,2154 14023 STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARB.
013593,000124: 13,2155 00045 36D
013594,000125: 13,2156 77742 SR1
013595,000126: 13,2157 34021 STCALL COSTH
013596,000127: 13,2160 47322 ARCTRIG
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Page 325
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013598,000129: 13,2161 43206 PUSH DAD # MODE 1 SHAFT TO 2.
013599,000130: 13,2162 24005 LODPHALF
013600,000131: 13,2163 24007 STOVL 6
013601,000132: 13,2164 00005 4
013602,000133: 13,2165 77634 RTB # FIND MODE 2 CDU ANGLES.
013603,000134: 13,2166 21636 2V1STO2S
013604,000135: 13,2167 25111 STOVL MODEB
013605,000136: 13,2170 00001 0
013606,000137: 13,2171 77634 RTB # MODE 1 ANGLES TO MODE A.
013607,000138: 13,2172 21636 2V1STO2S
013608,000139: 13,2173 01107 STORE MODEA
013609,000140: 13,2174 77776 EXIT
013610,000141:
013611,000142: 13,2175 40110 CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2.
013612,000143: 13,2176 74740 MASK ANTENBIT
013613,000144: 13,2177 10000 CCS A
013614,000145: 13,2200 12204 TCF +4
013615,000146:
013616,000147: 13,2201 53107 DXCH MODEA
013617,000148: 13,2202 53111 DXCH MODEB
013618,000149: 13,2203 53107 DXCH MODEA
013619,000150:
013620,000151: 13,2204 06042 TC INTPRET
013621,000152: 13,2205 77650 GOTO
013622,000153: 13,2206 00051 S2
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Page 326
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013624,000155: # GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED
013625,000156: # LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
013626,000157: # -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
013627,000158:
013628,000159: 23,2000 SETLOC INFLIGHT
013629,000160: 23,2000 BANK
013630,000161:
013631,000162: 23,2041 COUNT* $$/GEOM
013632,000163:
013633,000164: 23,2041 47135 RRNB SLOAD RTB
013634,000165: 23,2042 03753 TANGNB
013635,000166: 23,2043 21577 CDULOGIC
013636,000167: 23,2044 41401 SETPD PUSH # TRUNNION ANGLE TO 0
013637,000168: 23,2045 00001 0
013638,000169: 23,2046 57556 SIN DCOMP
013639,000170: 23,2047 14043 STODL 34D # Y COMPONENT
013640,000171:
013641,000172: 23,2050 41546 COS PUSH # .5 COS(T) TO 0
013642,000173: 23,2051 47135 SLOAD RTB
013643,000174: 23,2052 03754 TANGNB +1
013644,000175: 23,2053 21577 CDULOGIC
013645,000176: 23,2054 71406 RRNB1 PUSH COS # SHAFT ANGLE TO 2
013646,000177: 23,2055 72405 DMP SL1
013647,000178: 23,2056 00001 0
013648,000179: 23,2057 14045 STODL 36D # Z COMPONENT
013649,000180:
013650,000181: 23,2060 41356 SIN DMP
013651,000182: 23,2061 77752 SL1
013652,000183: 23,2062 24041 STOVL 32D
013653,000184: 23,2063 00041 32D
013654,000185: 23,2064 77616 RVQ
013655,000186:
013656,000187: # THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY
013657,000188:
013658,000189: 23,2065 14025 RRNBMPAC STODL 20D # SAVE SHAFT CDU IN 21.
013659,000190: 23,2066 00155 MPAC # SET MODE TO DP. (THE PRECEEDING STORE
013660,000191: # MAY BE DP, TP OR VECTOR.)
013661,000192: 23,2067 40234 RTB SETPD
013662,000193: 23,2070 21577 CDULOGIC
013663,000194: 23,2071 00001 0
013664,000195: 23,2072 73406 PUSH SIN # TRUNNION ANGLE TO 0
013665,000196: 23,2073 77676 DCOMP
013666,000197: 23,2074 14043 STODL 34D # Y COMPONENT
013667,000198: 23,2075 41546 COS PUSH # .5COS(T) TO 0
013668,000199: 23,2076 47135 SLOAD RTB # PICK UP CDU'S.
013669,000200: 23,2077 00026 21D
013670,000201: 23,2100 21577 CDULOGIC
013671,000202: 23,2101 77650 GOTO
013672,000203: 23,2102 46054 RRNB1
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Page 327
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013675,000206:
013676,000207:
End of include-file LEM_GEOMETRY.agc. Parent file is MAIN.agc