Source Code
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These source-code files are part of a reconstructed copy of Comanche 45, the
second release, though not the final mission release, of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Comanche 45 was
preceded by Comanche 44 and followed by Comanche 45/2 (the flown release). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 45, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 44 (itself previously accurately
reconstructed). Comanche 44 source code was then modified
by incorporating changes known from contemporary documentation to have been
made between revisions 44 and 45. The now-reconstructed Comanche 45 source code was
verified by assembling it and checking that the assembled code had
the expected known-correct memory-bank checksums.
Note that page numbers in the reconstructed code tend to match those in the Comanche 55, the
most-similar revision of Comanche for which we have access to an actual non-reconstructed hardcopy;
the source code would likely have different page numbers in a contemporary
Comanche 45 listing.
Annotations that were not present in the contemporary source code have been added to the reconstructed
code to justify each change relative to Comanche 44. Here's a guide to the Apollo documentation referenced
in those annotations:
There is also
a detailed commentary about the reconstruction process.
Comments expected to have been present in 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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034337,000002: ## Copyright: Public domain.
034338,000003: ## Filename: LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
034339,000004: ## Purpose: A section of Comanche revision 045.
034340,000005: ## It is part of the reconstructed source code for the
034341,000006: ## second release of the flight software for the Command
034342,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
034343,000008: ## The code has been recreated from a copy of Comanche 055. It
034344,000009: ## has been adapted such that the resulting bugger words
034345,000010: ## exactly match those specified for Comanche 45 in NASA drawing
034346,000011: ## 2021153D, which gives relatively high confidence that the
034347,000012: ## reconstruction is correct.
034348,000013: ## Assembler: yaYUL
034349,000014: ## Contact: Ron Burkey <info@sandroid.org>.
034350,000015: ## Website: www.ibiblio.org/apollo/index.html
034351,000016: ## Mod history: 2020-12-06 MAS Created from Comanche 44.
034352,000017:
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Page 785
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034354,000019: # LUNAR AND SOLAR EPHEMERIDES SUBROUTINES
034355,000020:
034356,000021: # FUNCTIONAL DESCRIPTION
034357,000022:
034358,000023: # THESE SUBROUTINES ARE USED TO DETERMINE THE POSITION AND VELOCITY
034359,000024: # VECTORS OF THE SUN AND THE MOON RELATIVE TO THE EARTH AT THE
034360,000025: # SPECIFIED GROUND ELAPSED TIME INPUT BY THE USER.
034361,000026:
034362,000027: # THE POSITION OF THE MOON IS STORED IN THE COMPUTER IN THE FORM OF
034363,000028: # A NINTH DEGREE POLYNOMIAL APPROXIMATION WHICH IS VALID OVER A 15
034364,000029: # DAY INTERVAL BEGINNING SHORTLY BEFORE LAUNCH. THEREFORE THE TIME
034365,000030: # INPUT BY THE USER SHOULD FALL WITHIN THIS 15 DAY INTERVAL.
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The 9th-degree polynomial spoken of here is a pad load, meaning
that it is not actually hardcoded into the software. Additional
information about calculating the polynomial can be found on the
Orbiter NASSP wiki, as well as information about calculation
of the
solar ephemerides.
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034373,000038:
034374,000039: # LSPOS COMPUTES THE POSITION VECTORS OF THE SUN AND THE MOON.
034375,000040:
034376,000041: # LUNPOS COMPUTES THE POSITION VECTOR OF THE MOON.
034377,000042:
034378,000043: # LUNVEL COMPUTES THE VELOCITY VECTOR OF THE MOON.
034379,000044:
034380,000045: # SOLPOS COMPUTES THE POSITION VECTOR OF THE SUN.
034381,000046:
034382,000047: # CALLING SEQUENCE
034383,000048:
034384,000049: # DLOAD CALL
034385,000050: # TIME GROUND ELAPSED TIME
034386,000051: # SUBROUTINE LSPOS OR LUNPOS OR LUNVEL OR SOLPOS
034387,000052:
034388,000053: # INPUT
034389,000054:
034390,000055: # 1) SPECIFIED GROUND ELAPSED TIME IN CS X B-28 LOADED IN MPAC.
034391,000056:
034392,000057: # 2) TIMEMO - TIME AT THE CENTER OF THE RANGE OVER WHICH THE LUNAR
034393,000058: # POSITION POLYNOMIAL IS VALID IN CS X B-42.
034394,000059:
034395,000060: # 3) VECOEM - VECTOR COEFFICIENTS OF THE LUNAR POSITION POLYNOMIAL
034396,000061: # LOADED IN DESCENDING SEQUENCE IN METERS/CS**N X B-2
034397,000062:
034398,000063: # 4) RESO - POSITION VECTOR OF THE SUN RELATIVE TO THE EARTH AT
034399,000064: # TIMEMO IN METERS X B-38.
034400,000065:
034401,000066: # 5) VESO - VELOCITY VECTOR OF THE SUN RELATIVE TO THE EARTH AT
034402,000067: # TIMEMO IN METERS/CS X B-9.
034403,000068: #
034404,000069: # 6) OMEGAES - ANGULAR VELOCITY OF THE VECTOR RESO AT TIMEMO IN
034405,000070: # REV/CS X B+26.
034406,000071:
034407,000072: # ALL EXCEPT THE FIRST INPUT ARE INCLUDED IN THE PRE-LAUNCH
034408,000073: # ERASABLE DATA LOAD.
034409,000074:
034410,000075: # OUTPUT - LSPOS
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Page 786
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034412,000077:
034413,000078: # 1) 2D OF VAC AREA CONTAINS THE POSITION VECTOR OF THE SUN RELATIVE
034414,000079: # TO THE EARTH AT TIME INPUT BY THE USER IN METERS X B-38.
034415,000080:
034416,000081: # 2) MPAC CONTAINS THE POSITION VECTOR OF THE MOON RELATIVE TO THE
034417,000082: # EARTH AT TIME INPUT BY THE USER IN METERS X B-29.
034418,000083:
034419,000084: # OUTPUT - LUNPOS
034420,000085:
034421,000086: # MPAC CONTAINS THE POSITION VECTOR OF THE MOON RELATIVE TO THE
034422,000087: # EARTH AT THE TIME INPUT BY USER IN METERS X B-29.
034423,000088:
034424,000089: # OUTPUT - LUNVEL
034425,000090:
034426,000091: # MPAC CONTAINS THE VELOCITY VECTOR OF THE MOON RELATIVE TO THE
034427,000092: # EARTH AT TIME INPUT BY THE USER IN METERS/CS X B-7.
034428,000093:
034429,000094: # OUTPUT - SOLPOS
034430,000095:
034431,000096: # MPAC CONTAINS THE POSITION VECTOR OF THE SUN RELATIVE TO THE EARTH
034432,000097: # AT TIME INPUT BY THE USER IN METERS X B-38.
034433,000098:
034434,000099: # SUBROUTINES USED
034435,000100:
034436,000101: # NONE
034437,000102:
034438,000103: # REMARKS
034439,000104:
034440,000105: # THE VAC AREA IS USED FOR STORAGE OF INTERMEDIATE AND FINAL RESULTS
034441,000106: # OF COMPUTATIONS.
034442,000107:
034443,000108: # S1, X1 AND X2 ARE USED BY THESE SUBROUTINES.
034444,000109:
034445,000110: # PRELAUNCH ERASABLE DATA LOAD ARE ONLY ERASABLE STORAGE USED BY
034446,000111: # THESE SUBROUTINES.
034447,000112:
034448,000113: # RESTARTS DURING OPERATION OF THESE SUBROUTINES MUST BE HANDLED BY
034449,000114: # THE USER.
034450,000115:
034451,000116: 36,2454 BANK 36
034452,000117: 26,2000 SETLOC EPHEM
034453,000118: 26,2000 BANK
034454,000119:
034455,000120: 26,2110 COUNT* $$/EPHEM
034456,000121: 26,2110 E7,1777 EBANK= END-E7
034457,000122: 26,2110 77774 LSPOS AXT,2 # COMPUTES POSITION VECTORS OF BOTH THE
034458,000123: 26,2111 54161 RESA # SUN AND THE MOON. THE POSITION VECTOR
034459,000124: 26,2112 52170 AXT,1 GOTO # OF THE SUN IS STORED IN 2D OF THE VAC
034460,000125: 26,2113 54143 RES # AREA. THE POSITION VECTOR OF THE MOON
034461,000126: 26,2114 54126 LSTIME # IS STORED IN MPAC.
034462,000127: 26,2115 52170 LUNPOS AXT,1 GOTO # COMPUTES THE POSITION VECTOR OF THE MOON
034463,000128: 26,2116 54162 REM # AND STORES IT IN MPAC.
034464,000129: 26,2117 54126 LSTIME
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Page 787
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034466,000131: 26,2120 52170 LUNVEL AXT,1 GOTO # COMPUTES THE VELOCITY VECTOR OF THE MOON
034467,000132: 26,2121 54173 VEM # AND STORES IT IN MPAC.
034468,000133: 26,2122 54126 LSTIME
034469,000134: 26,2123 76020 SOLPOS STQ AXT,1 # COMPUTES THE POSITION VECTOR OF THE SUN
034470,000135: 26,2124 00047 X2 # AND STORES IT IN MPAC.
034471,000136: 26,2125 54143 RES
034472,000137: 26,2126 54201 LSTIME SETPD SR
034473,000138: 26,2127 00001 0D
034474,000139: 26,2130 20617 14D
034475,000140: 26,2131 57571 TAD DCOMP
034476,000141: 26,2132 01707 TEPHEM
034477,000142: 26,2133 57571 TAD DCOMP
034478,000143: 26,2134 02034 TIMEMO
034479,000144: 26,2135 66261 SL SSP
034480,000145: 26,2136 20221 16D
034481,000146: 26,2137 00051 S1
034482,000147: 26,2140 00006 6D
034483,000148: 26,2141 77650 GOTO
034484,000149: 26,2142 00046 X1
034485,000150: 26,2143 41206 RES PUSH DMP # PD- 2
034486,000151: 26,2144 02147 OMEGAES
034487,000152: 26,2145 71406 PUSH COS # PD- 4
034488,000153: 26,2146 65361 VXSC PDDL # PD- 8
034489,000154: 26,2147 02133 RESO
034490,000155: 26,2150 63356 SIN PDVL # PD-10
034491,000156: 26,2151 02133 RESO
034492,000157: 26,2152 53406 PUSH UNIT # PD-16
034493,000158: 26,2153 53435 VXV UNIT
034494,000159: 26,2154 02141 VESO
034495,000160: 26,2155 76435 VXV VSL1 # PD-10
034496,000161: 26,2156 53361 VXSC VAD # PD-02
034497,000162: 26,2157 52172 VSL1 GOTO # RES IN METERS X B-38 IN MPAC.
034498,000163: 26,2160 00047 X2
034499,000164: 26,2161 14003 RESA STODL 2D # RES IN METERS X B-38 IN 2D OF VAC. PD- 0
034500,000165: 26,2162 63370 REM AXT,1 PDVL # PD- 2
034501,000166: 26,2163 00066 54D
034502,000167: 26,2164 02037 VECOEM
034503,000168: 26,2165 52761 REMA VXSC VAD*
034504,000169: 26,2166 00001 0D
034505,000170: 26,2167 02133 VECOEM +60D,1
034506,000171: 26,2170 72500 TIX,1 VSL2 # REM IN METERS X B-29 IN MPAC.
034507,000172: 26,2171 54165 REMA
034508,000173: 26,2172 77616 RVQ
034509,000174: 26,2173 65370 VEM AXT,1 PDDL # PD- 2
034510,000175: 26,2174 00060 48D
034511,000176: 26,2175 14214 NINEB4
034512,000177: 26,2176 74206 PUSH VXSC # PD- 4
034513,000178: 26,2177 02037 VECOEM
034514,000179: 26,2200 77761 VEMA VXSC
034515,000180: 26,2201 00001 0D
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Page 788
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034517,000182: 26,2202 14005 STODL 4D # PD- 2
034518,000183: 26,2203 41425 DSU PUSH # PD- 4
034519,000184: 26,2204 14216 ONEB4
034520,000185: 26,2205 53357 VXSC* VAD
034521,000186: 26,2206 02125 VECOEM +54D,1
034522,000187: 26,2207 00005 4D
034523,000188: 26,2210 72500 TIX,1 VSL2 # VEM IN METERS/CS X B-7 IN MPAC.
034524,000189: 26,2211 54200 VEMA
034525,000190: 26,2212 77616 RVQ
034526,000191: 26,2213 22000 00000 NINEB4 2DEC 9.0 B-4
034527,000192:
034528,000193: 26,2215 02000 00000 ONEB4 2DEC 1.0 B-4
034529,000194:
034530,000195:
034531,000196:
End of include-file LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc. Parent file is MAIN.agc