Source Code
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These source-code files are part of a reconstructed copy of Comanche 44, the
initial release (though not the final mission release) of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Subsequent releases
were Comanche 45 and Comanche 45/2 (the flown release on Apollo 10). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 44, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 51
(separately previously reconstructed from an Apollo-era listing of Comanche 55,
flown on Apollo 11). Comanche 51 source code was then modified
by undoing changes known to have been made between revisions 44 and 51. The now-reconstructed
Comanche 44 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 match those on the Comanche 55 printout,
although the source code would likely have different page numbers in a contemporary
Comanche 44 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 51. Here's a guide to the Apollo documentation referenced
in those annotations:
In most cases, only the titles (rather than the full texts) of PCRs are known. In addition to the
explanatory annotations, there is also
a step-by-step 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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021723,000002: ## Copyright: Public domain.
021724,000003: ## Filename: R31.agc
021725,000004: ## Purpose: A section of Comanche revision 044.
021726,000005: ## It is part of the reconstructed source code for the
021727,000006: ## original release of the flight software for the Command
021728,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
021729,000008: ## The code has been recreated from a copy of Comanche 055. It
021730,000009: ## has been adapted such that the resulting bugger words
021731,000010: ## exactly match those specified for Comanche 44 in NASA drawing
021732,000011: ## 2021153D, which gives relatively high confidence that the
021733,000012: ## reconstruction is correct.
021734,000013: ## Assembler: yaYUL
021735,000014: ## Contact: Ron Burkey <info@sandroid.org>.
021736,000015: ## Website: www.ibiblio.org/apollo/index.html
021737,000016: ## Mod history: 2020-12-03 MAS Created from Comanche 51.
021738,000017:
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Page 505
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021740,000019: 34,2002 BANK 34
021741,000020: 31,2000 SETLOC R31
021742,000021: 31,2000 BANK
021743,000022:
021744,000023: 31,2000 COUNT* $$/R31
021745,000024:
021746,000025: 31,2000 35057 R31CALL CAF PRIO3
021747,000026: 31,2001 05147 TC FINDVAC
021748,000027: 31,2002 E4,1770 EBANK= SUBEXIT
021749,000028: 31,2002 02032 62064 2CADR V83CALL
021750,000029:
021751,000030: 31,2004 35041 DSPDELAY CAF 1SEC
021752,000031: 31,2005 04662 TC BANKCALL
021753,000032: 31,2006 01732 CADR DELAYJOB
021754,000033: 31,2007 31044 CA EXTVBACT
021755,000034: 31,2010 75004 MASK BIT12
021756,000035: 31,2011 00006 EXTEND
021757,000036: 31,2012 12004 BZF DSPDELAY
021758,000037:
021759,000038: 31,2013 30105 DISPN5X CA FLAGWRD9 # TEST R31FLAG (IN SUNDANCE R31FLAG WILL
021760,000039: 31,2014 75014 MASK BIT4 # ALWAYS BE SET AS R34 DOES NOT EXIST)
021761,000040: 31,2015 00006 EXTEND
021762,000041: 31,2016 12021 BZF +3
021763,000042: 31,2017 32136 CAF V16N54 # R31 USE NOUN 54
021764,000043: 31,2020 02022 TC +2
021765,000044: 31,2021 32137 CAF V16N53 # R34 USE NOUN 53
021766,000045: 31,2022 04662 TC BANKCALL
021767,000046: 31,2023 20561 CADR GOMARKF
021768,000047: 31,2024 05625 TC B5OFF
021769,000048: 31,2025 05625 TC B5OFF
021770,000049: 31,2026 12013 TCF DISPN5X
021771,000050:
021772,000051: 31,2027 06006 V83 TC INTPRET
021773,000052: 31,2030 77650 GOTO
021774,000053: 31,2031 62171 HAVEBASE # INTEG STATE VECTORS
021775,000054: 31,2032 06006 V83CALL TC INTPRET
021776,000055: 31,2033 77650 GOTO
021777,000056: 31,2034 62140 STATEXTP # EXTRAPOLATE STATE VECTORS
021778,000057: 31,2035 52375 COMPDISP VLOAD VSU
021779,000058: 31,2036 00001 RATT
021780,000059: 31,2037 02327 RONE
021781,000060: 31,2040 51406 PUSH ABVAL # RATT-RONE TO 0D PD= 6
021782,000061: 31,2041 02321 STORE RANGE # METERS B-29
021783,000062: 31,2042 77301 NORM VLOAD
021784,000063: 31,2043 00047 X1 # RATT-RONE PD= 0
021785,000064: 31,2044 77762 VSR1
021786,000065: 31,2045 53457 VSL* UNIT
021787,000066: 31,2046 20201 0,1
021788,000067: 31,2047 52315 PDVL VSU # UNIT(LOS) TO 0D PD= 6
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Page 506
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021790,000069: 31,2050 00007 VATT
021791,000070: 31,2051 02335 VONE
021792,000071: 31,2052 77641 DOT # (VATT-VONE).UNIT(LOS) PD= 0
021793,000072: 31,2053 77752 SL1
021794,000073: 31,2054 36323 STCALL RRATE # RANGE RATE M/CS B-7
021795,000074: 31,2055 47477 CDUTRIG # TO INITIALIZE FOR *NBSM*
021796,000075: 31,2056 77624 CALL
021797,000076: 31,2057 62311 R34LOS # NOTE. PDL MUST = 0.
021798,000077: 31,2060 53575 R34ANG VLOAD UNIT
021799,000078: 31,2061 02327 RONE
021800,000079: 31,2062 77715 PDVL # UR TO 0D PD= 6
021801,000080: 31,2063 15333 THISAXIS # UNITX FOR CM, UNITZ FOR LM
021802,000081: 31,2064 77214 BON VLOAD # CHK R31FLAG. ON=R31 THETA, OFF=R34 PHI
021803,000082: 31,2065 04713 R31FLAG
021804,000083: 31,2066 62070 +2 # R31-THETA
021805,000084: 31,2067 00015 12D
021806,000085: 31,2070 77624 CALL
021807,000086: 31,2071 47646 *NBSM*
021808,000087: 31,2072 41505 VXM PUSH # UXORZ TO 6D PD=12D
021809,000088: 31,2073 01736 REFSMMAT
021810,000089: 31,2074 72431 VPROJ VSL2
021811,000090: 31,2075 00001 0D
021812,000091: 31,2076 53445 BVSU UNIT
021813,000092: 31,2077 00007 6D
021814,000093: 31,2100 47315 PDVL VXV # UP/2 TO 12D PD=18D
021815,000094: 31,2101 02327 RONE
021816,000095: 31,2102 02335 VONE
021817,000096: 31,2103 47256 UNIT VXV
021818,000097: 31,2104 02327 RONE
021819,000098: 31,2105 63241 DOT PDVL # SIGN TO 12D, UP/2 TO MPAC PD=18D
021820,000099: 31,2106 00015 12D
021821,000100: 31,2107 50372 VSL1 DOT # UP.UXORZ
021822,000101: 31,2110 00007 6D
021823,000102: 31,2111 72565 SIGN SL1
021824,000103: 31,2112 00015 12D
021825,000104: 31,2113 77726 ACOS
021826,000105: 31,2114 26325 STOVL RTHETA
021827,000106: 31,2115 02327 RONE
021828,000107: 31,2116 51041 DOT BPL
021829,000108: 31,2117 00007 6D
021830,000109: 31,2120 62125 +5
021831,000110: 31,2121 44345 DLOAD BDSU # IF UXORZ.R NEG, RTHETA = 1 - RTHETA
021832,000111: 31,2122 02325 RTHETA
021833,000112: 31,2123 15343 DPPOSMAX
021834,000113: 31,2124 02325 STORE RTHETA # RTHETA BETWEEN 0 AND 1 REV.
021835,000114: 31,2125 77776 EXIT
021836,000115: 31,2126 35013 CAF BIT5 # HAVE WE BEEN ANSWERED
021837,000116: 31,2127 71044 MASK EXTVBACT
021838,000117: 31,2130 00006 EXTEND
021839,000118: 31,2131 15534 BZF ENDEXT # YES, DIE
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Page 507
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021841,000120: 31,2132 41044 CS EXTVBACT
021842,000121: 31,2133 75004 MASK BIT12
021843,000122: 31,2134 27044 ADS EXTVBACT
021844,000123:
021845,000124: 31,2135 12027 TCF V83
021846,000125: 31,2136 04066 V16N54 VN 1654
021847,000126: 31,2137 04065 V16N53 VN 1653
021848,000127:
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Page 508
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021850,000129: # STATEXTP DOES AN INITIAL PRECISION EXTRAPOLATION OF THE
021851,000130: # LEM STATE VECTOR TO PRESENT TIME OR TO PIPTIME IF AV G
021852,000131: # IS ON AND SAVES AS BASE VECTOR. IF AV G IS ON RN + VN
021853,000132: # ARE USED AS THE CM STATE VECTOR AND THE INITIAL R RDOT
021854,000133: # RTHETA ARE COMPUTED WITH NO FURTHER INTEGRATION. IF AV
021855,000134: # G IS OFF A PRECISION EXTRAPOLATION IS MADE OF THE CM
021856,000135: # STATE VECTOR TO PRESENT TIME AND.....
021857,000136:
021858,000137: # THE CM + LM STATE VECTORS ARE INTEGRATED TO PRES TIME
021859,000138: # USING PRECISION OR CONIC AS SURFFLAG IS SET OR CLEAR.
021860,000139:
021861,000140: # IF AV G IS ON THEN SUBSEQUENT PASSES WILL PROVIDE
021862,000141: # USE OF RN + VN AS CM STATE VECTOR AND THE LM STATE
021863,000142: # VECTOR WILL BE PRECISION INTEGRATED USING LEMPREC
021864,000143:
021865,000144: # IF SURFFLAG IS SET.
021866,000145: # CM STATE VECTOR RONE VONE + LM STATE VECTOR RATT
021867,000146: # VATT ARE USED IN COMPUTING R RDOT RTHETA.
021868,000147:
021869,000148:
021870,000149: 31,2140 43034 STATEXTP RTB BOF # INITIAL INTEGRATION
021871,000150: 31,2141 45510 LOADTIME
021872,000151: 31,2142 03751 V37FLAG
021873,000152: 31,2143 62146 +3 # AV G OFF, USE PRES TIME
021874,000153: 31,2144 77624 CALL
021875,000154: 31,2145 62273 GETRVN # ON, USE RN VN PIPTIME
021876,000155: 31,2146 02343 STORE BASETIME # PRES TIME OR PIPTIME
021877,000156: 31,2147 34041 STCALL TDEC1
021878,000157: 31,2150 27105 LEMPREC
021879,000158: 31,2151 77775 VLOAD # BASE VECTOR, LM
021880,000159: 31,2152 00017 RATT1
021881,000160: 31,2153 26225 STOVL BASEOTP # POS.
021882,000161: 31,2154 00025 VATT1
021883,000162: 31,2155 02241 STORE BASEOTV # VEL.
021884,000163: 31,2156 71214 BON DLOAD
021885,000164: 31,2157 03711 V37FLAG
021886,000165: 31,2160 62035 COMPDISP # COMPUTE R RDOT RTHETA FROM
021887,000166: # RONE(RN) VONE(VN) RATT+VATT(LEMPREC)
021888,000167: 31,2161 00015 TAT
021889,000168: 31,2162 34041 STCALL TDEC1
021890,000169: 31,2163 27071 CSMPREC
021891,000170: 31,2164 77775 VLOAD # BASE VECTOR, CM
021892,000171: 31,2165 00017 RATT1
021893,000172: 31,2166 26255 STOVL BASETHP # POS.
021894,000173: 31,2167 00025 VATT1
021895,000174: 31,2170 02263 STORE BASETHV # VEL.
021896,000175: 31,2171 47014 HAVEBASE BON RTB # SUBSEQUENT INTEGRATIONS
021897,000176: 31,2172 03711 V37FLAG
021898,000177: 31,2173 62256 GETRVN5
021899,000178: 31,2174 45510 LOADTIME
021900,000179: 31,2175 34041 STCALL TDEC1 # AV G OFF. SET INTEG. OF CM
021901,000180: 31,2176 27442 INTSTALL
021902,000181: 31,2177 43175 VLOAD CLEAR
021903,000182: 31,2200 02255 BASETHP
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Page 509
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021905,000184: 31,2201 00263 MOONFLAG
021906,000185: 31,2202 25535 STOVL RCV
021907,000186: 31,2203 02263 BASETHV
021908,000187: 31,2204 15543 STODL VCV
021909,000188: 31,2205 02343 BASETIME
021910,000189: 31,2206 43014 BOF SET # GET APPROPRIATE MOONFLAG SETTING
021911,000190: 31,2207 04343 MOONTHIS
021912,000191: 31,2210 62212 +2
021913,000192: 31,2211 00063 MOONFLAG
021914,000193: 31,2212 77614 CLEAR
021915,000194: 31,2213 01673 INTYPFLG
021916,000195: 31,2214 43014 BON SET
021917,000196: 31,2215 04307 SURFFLAG
021918,000197: 31,2216 62220 +2 # PREC. IF LM DOWN
021919,000198: 31,2217 01473 INTYPFLG # CONIC IF LM NOT DOWN
021920,000199: 31,2220 35517 STCALL TET
021921,000200: 31,2221 27135 INTEGRVS # INTEGRATION --- AT LAST---
021922,000201: 31,2222 77775 VLOAD
021923,000202: 31,2223 00001 RATT
021924,000203: 31,2224 26327 STOVL RONE
021925,000204: 31,2225 00007 VATT
021926,000205: 31,2226 16335 STODL VONE # GET SET FOR CONIC EXTRAP.,OTHER
021927,000206: 31,2227 00015 TAT
021928,000207: 31,2230 45014 BON CALL
021929,000208: 31,2231 04307 SURFFLAG
021930,000209: 31,2232 62267 GETRVN6 # LEMPREC IF LM DOWN
021931,000210: 31,2233 27442 INTSTALL # ..CONIC IF NOT DOWN
021932,000211: 31,2234 77614 SET
021933,000212: 31,2235 01473 INTYPFLG
021934,000213: 31,2236 00041 OTHINT STORE TDEC1 # ENTERED IF AV G ON TO INTEG LM
021935,000214: 31,2237 43175 VLOAD CLEAR
021936,000215: 31,2240 02225 BASEOTP
021937,000216: 31,2241 00263 MOONFLAG
021938,000217: 31,2242 25535 STOVL RCV
021939,000218: 31,2243 02241 BASEOTV
021940,000219: 31,2244 15543 STODL VCV
021941,000220: 31,2245 02343 BASETIME
021942,000221: 31,2246 43014 BOF SET
021943,000222: 31,2247 04343 MOONTHIS
021944,000223: 31,2250 62252 +2
021945,000224: 31,2251 00063 MOONFLAG
021946,000225: 31,2252 35517 STCALL TET
021947,000226: 31,2253 27135 INTEGRVS
021948,000227: 31,2254 77650 GOTO
021949,000228: 31,2255 62035 COMPDISP # COMPUTE R RDOT RTHETA
021950,000229: 31,2256 77624 GETRVN5 CALL # AV G ON
021951,000230: 31,2257 62273 GETRVN
021952,000231: 31,2260 45014 BON CALL
021953,000232: 31,2261 04307 SURFFLAG
021954,000233: 31,2262 62267 GETRVN6 # LM DOWN, LMPREC
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Page 510
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021956,000235: 31,2263 27442 INTSTALL
021957,000236: 31,2264 52014 CLEAR GOTO
021958,000237: 31,2265 01673 INTYPFLG
021959,000238: 31,2266 62236 OTHINT
021960,000239: 31,2267 34041 GETRVN6 STCALL TDEC1
021961,000240: 31,2270 27105 LEMPREC
021962,000241: 31,2271 77650 GOTO
021963,000242: 31,2272 62035 COMPDISP # COMPUTE R RDOT RTHETA
021964,000243: 31,2273 77620 GETRVN STQ
021965,000244: 31,2274 00000 0D
021966,000245: 31,2275 52175 VLOAD GOTO # AV G ON, RONE = RN VONE = VN
021967,000246: 31,2276 01171 RN # AND USE PIPTIME
021968,000247: 31,2277 62300 +1
021969,000248: 31,2300 36327 STCALL RONE
021970,000249: 31,2301 62302 +1
021971,000250: 31,2302 52175 VLOAD GOTO
021972,000251: 31,2303 01177 VN
021973,000252: 31,2304 62305 +1
021974,000253: 31,2305 16335 STODL VONE
021975,000254: 31,2306 01205 PIPTIME
021976,000255: 31,2307 77650 GOTO
021977,000256: 31,2310 00000 0D
021978,000257: 31,2000 SETLOC R34
021979,000258: 31,2000 BANK
021980,000259: 31,2311 77776 R34LOS EXIT
021981,000260: 31,2312 30036 CA CDUS
021982,000261: 31,2313 50120 INDEX FIXLOC
021983,000262: 31,2314 54011 TS 9D
021984,000263: 31,2315 30035 CA CDUT
021985,000264: 31,2316 50120 INDEX FIXLOC
021986,000265: 31,2317 54013 TS 11D
021987,000266: 31,2320 30120 CA FIXLOC
021988,000267: 31,2321 66211 AD SIX
021989,000268: 31,2322 40000 COM
021990,000269: 31,2323 50120 INDEX FIXLOC
021991,000270: 31,2324 54046 TS X1
021992,000271: 31,2325 06006 TC INTPRET
021993,000272: 31,2326 77624 CALL
021994,000273: 31,2327 46000 SXTNB
021995,000274: 31,2330 34015 STCALL 12D
021996,000275: 31,2331 62060 R34ANG
End of include-file R31.agc. Parent file is MAIN.agc