Source Code
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These source-code files are part of a reconstructed copy of Luminary 173, the
second (unflown) release of the Apollo 14 Lunar Module (LM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with reconstructed source code for Luminary 178. Changes
between revision 173 and 178 were backed out, as described by Luminary memo 167
(revision 1). The reconstruction was verified by matching memory-bank checksums
to those listed in drawing 2021152N. Note that page numbers in the reconstructed
code match those for the baseline log section mentioned in each file's changelog;
the page numbers for a real Luminary 173 listing would be different.
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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013915,000002: ## Copyright: Public domain.
013916,000003: ## Filename: LEM_GEOMETRY.agc
013917,000004: ## Purpose: A section of Luminary revision 173.
013918,000005: ## It is part of the reconstructed source code for the second
013919,000006: ## (unflown) release of the flight software for the Lunar
013920,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 14.
013921,000008: ## The code has been recreated from a reconstructed copy of
013922,000009: ## Luminary 178, as well as Luminary memo 167 (revision 1).
013923,000010: ## It has been adapted such that the resulting bugger words
013924,000011: ## exactly match those specified for Luminary 173 in NASA
013925,000012: ## drawing 2021152N, which gives relatively high confidence
013926,000013: ## that the reconstruction is correct.
013927,000014: ## Reference: pp. 325-330
013928,000015: ## Assembler: yaYUL
013929,000016: ## Contact: Ron Burkey <info@sandroid.org>.
013930,000017: ## Website: www.ibiblio.org/apollo/index.html
013931,000018: ## Mod history: 2019-09-18 MAS Created from Luminary 178.
013932,000019:
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Page 332
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013934,000021: 23,2041 BANK 23
013935,000022: 13,2000 SETLOC LEMGEOM
013936,000023: 13,2000 BANK
013937,000024:
013938,000025: 13,2070 30,2000 SBANK= LOWSUPER
013939,000026: 13,2070 E5,1642 EBANK= XSM
013940,000027:
013941,000028: # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING
013942,000029: # THE CONIC R,V AND THE DEVIATIONSR,V. THE STATE VECTORS ARE CONVERTED TO
013943,000030: # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR
013944,000031: # R-OTHER , V-OTHER FOR DOWNLINK. THE ROUTINES NAMES ARE SWITCHED IN THE
013945,000032: # OTHER VEHICLES COMPUTER.
013946,000033:
013947,000034: # INPUT
013948,000035: # STATE VECTOR IN TEMPORARY STORAGE AREA
013949,000036: # IF STATE VECTOR IS SCALED POS B27 AND VEL B5
013950,000037: # SET X2 TO +2
013951,000038: # IF STATE VECTOR IS SCALED POS B29 AND VEL B7
013952,000039: # SET X2 TO 0
013953,000040:
013954,000041: # OUTPUT
013955,000042: # R(T) IN RN, V(T) IN VN, T IN PIPTIME
013956,000043: # OR
013957,000044: # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER)
013958,000045:
013959,000046: 13,2070 COUNT* $$/GEOM
013960,000047: 13,2070 43414 SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG.
013961,000048: 13,2071 04756 AVEMIDSW
013962,000049: 13,2072 26073 +1
013963,000050: 13,2073 53775 VLOAD VSL*
013964,000051: 13,2074 01521 TDELTAV
013965,000052: 13,2075 57605 0 -7,2
013966,000053: 13,2076 53655 VAD VSL*
013967,000054: 13,2077 01535 RCV
013968,000055: 13,2100 57576 0,2
013969,000056: 13,2101 25220 STOVL RN
013970,000057: 13,2102 01527 TNUV
013971,000058: 13,2103 53257 VSL* VAD
013972,000059: 13,2104 57602 0 -4,2
013973,000060: 13,2105 01543 VCV
013974,000061: 13,2106 77657 VSL*
013975,000062: 13,2107 57576 0,2
013976,000063: 13,2110 15226 STODL VN
013977,000064: 13,2111 01517 TET
013978,000065: 13,2112 01234 STORE PIPTIME
013979,000066: 13,2113 77616 RVQ
013980,000067:
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Page 326
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013982,000069: 13,2114 53775 SVDWN1 VLOAD VSL*
013983,000070: 13,2115 01521 TDELTAV
013984,000071: 13,2116 57605 0 -7,2
013985,000072: 13,2117 53655 VAD VSL*
013986,000073: 13,2120 01535 RCV
013987,000074: 13,2121 57576 0,2
013988,000075: 13,2122 25716 STOVL R-OTHER
013989,000076: 13,2123 01527 TNUV
013990,000077: 13,2124 53257 VSL* VAD
013991,000078: 13,2125 57602 0 -4,2
013992,000079: 13,2126 01543 VCV
013993,000080: 13,2127 77657 VSL*
013994,000081: 13,2130 57576 0,2
013995,000082: 13,2131 01724 STORE V-OTHER
013996,000083: 13,2132 77616 RVQ
013997,000084:
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Page 327
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013999,000086: # THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH
014000,000087: # GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE
014001,000088: # ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION
014002,000089: # ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE
014003,000090: # SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE.
014004,000091:
014005,000092: # THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS
014006,000093:
014007,000094: # S(2) = 180 + S(1)
014008,000095: # T(2) = 180 - T(1)
014009,000096:
014010,000097: # THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT.
014011,000098:
014012,000099: 13,2133 00041 RRANGLES STORE 32D
014013,000100: 13,2134 57545 DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT
014014,000101: 13,2135 00043 34D # ANGLE LATER, WE CAN FIND THE MODE 1
014015,000102: 13,2136 67401 SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF
014016,000103: 13,2137 00001 0 # THE Y COMPONENT, THE ASIN GIVING AN
014017,000104: 13,2140 44206 PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG
014018,000105: 13,2141 24005 LODPHALF
014019,000106: 13,2142 14005 STODL 4 # MODE 2 TRUNNION TO 4.
014020,000107:
014021,000108: 13,2143 24007 LO6ZEROS
014022,000109: 13,2144 24043 STOVL 34D # UNIT THE PROJECTION OF THE VECTOR
014023,000110: 13,2145 00041 32D # IN THE X-Z PLANE
014024,000111: 13,2146 41056 UNIT BOVB # IF OVERFLOW,TARGET VECTOR IS ALONG Y
014025,000112: 13,2147 52412 LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF
014026,000113: 13,2150 14041 STODL 32D # PROJECTION VECTOR.
014027,000114: 13,2151 00041 32D
014028,000115: 13,2152 44142 SR1 STQ
014029,000116: 13,2153 00051 S2
014030,000117: 13,2154 14023 STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARB.
014031,000118: 13,2155 00045 36D
014032,000119: 13,2156 77742 SR1
014033,000120: 13,2157 34021 STCALL COSTH
014034,000121: 13,2160 47316 ARCTRIG
014035,000122:
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Page 328
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014037,000124: 13,2161 43206 PUSH DAD # MODE 1 SHAFT TO 2.
014038,000125: 13,2162 24005 LODPHALF
014039,000126: 13,2163 24007 STOVL 6
014040,000127: 13,2164 00005 4
014041,000128: 13,2165 77634 RTB # FIND MODE 2 CDU ANGLES.
014042,000129: 13,2166 21636 2V1STO2S
014043,000130: 13,2167 25111 STOVL MODEB
014044,000131: 13,2170 00001 0
014045,000132: 13,2171 77634 RTB # MODE 1 ANGLES TO MODE A.
014046,000133: 13,2172 21636 2V1STO2S
014047,000134: 13,2173 01107 STORE MODEA
014048,000135: 13,2174 77776 EXIT
014049,000136:
014050,000137: 13,2175 40110 CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2.
014051,000138: 13,2176 74740 MASK ANTENBIT
014052,000139: 13,2177 10000 CCS A
014053,000140: 13,2200 12204 TCF +4
014054,000141:
014055,000142: 13,2201 53107 DXCH MODEA
014056,000143: 13,2202 53111 DXCH MODEB
014057,000144: 13,2203 53107 DXCH MODEA
014058,000145:
014059,000146: 13,2204 06042 TC INTPRET
014060,000147: 13,2205 77650 GOTO
014061,000148: 13,2206 00051 S2
014062,000149:
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Page 329
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014064,000151: # GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1,FIND THE ASSOCIATED
014065,000152: # LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T),
014066,000153: # -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D.
014067,000154:
014068,000155: 23,2000 SETLOC INFLIGHT
014069,000156: 23,2000 BANK
014070,000157:
014071,000158: 23,2041 COUNT* $$/GEOM
014072,000159:
014073,000160: 23,2041 47135 RRNB SLOAD RTB
014074,000161: 23,2042 03753 TANGNB
014075,000162: 23,2043 21577 CDULOGIC
014076,000163: 23,2044 41401 SETPD PUSH # TRUNNION ANGLE TO 0
014077,000164: 23,2045 00001 0
014078,000165: 23,2046 57556 SIN DCOMP
014079,000166: 23,2047 14043 STODL 34D # Y COMPONENT
014080,000167:
014081,000168: 23,2050 41546 COS PUSH # .5 COS(T) TO 0
014082,000169: 23,2051 47135 SLOAD RTB
014083,000170: 23,2052 03754 TANGNB +1
014084,000171: 23,2053 21577 CDULOGIC
014085,000172: 23,2054 71406 RRNB1 PUSH COS # SHAFT ANGLE TO 2
014086,000173: 23,2055 72405 DMP SL1
014087,000174: 23,2056 00001 0
014088,000175: 23,2057 14045 STODL 36D # Z COMPONENT
014089,000176:
014090,000177: 23,2060 41356 SIN DMP
014091,000178: 23,2061 77752 SL1
014092,000179: 23,2062 24041 STOVL 32D
014093,000180: 23,2063 00041 32D
014094,000181: 23,2064 77616 RVQ
014095,000182:
014096,000183: # THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY
014097,000184:
014098,000185: 23,2065 14025 RRNBMPAC STODL 20D # SAVE SHAFT CDU IN 21.
014099,000186: 23,2066 00155 MPAC # SET MODE TO DP. (THE PRECEEDING STORE
014100,000187: # MAY BE DP, TP OR VECTOR.)
014101,000188: 23,2067 40234 RTB SETPD
014102,000189: 23,2070 21577 CDULOGIC
014103,000190: 23,2071 00001 0
014104,000191: 23,2072 73406 PUSH SIN # TRUNNION ANGLE TO 0
014105,000192: 23,2073 77676 DCOMP
014106,000193: 23,2074 14043 STODL 34D # Y COMPONENT
014107,000194: 23,2075 41546 COS PUSH # .5COS(T) TO 0
014108,000195: 23,2076 47135 SLOAD RTB # PICK UP CDU'S.
014109,000196: 23,2077 00026 21D
014110,000197: 23,2100 21577 CDULOGIC
014111,000198: 23,2101 77650 GOTO
014112,000199: 23,2102 46054 RRNB1
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Page 330
Note: This page is empty in the printout of the assembly listing.
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End of include-file LEM_GEOMETRY.agc. Parent file is MAIN.agc