Source Code
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These source-code files are part of a reconstructed copy of Comanche 51, the
initial release (though not the final mission release) of the Apollo 11
Command Module (CM) Apollo Guidance Computer (AGC) software. The flown, final
release was Comanche 55. The reconstruction is believed to be exactly accurate,
but in the absence of an actual Apollo-era listing of Comanche 51, some
explanation of the reconstruction process is needed to insure confidence in
that accuracy.
The starting point was the source code of Comanche 55, whose original source code
is available. Comanche 55 source code was then modified by undoing changes known
to have been made between revisions 51 and 55. The most-significant steps involved
reverting changes related to the R-2 lunar potential model, the details of which
were known from the previous, separate, independent reconstruction of the Apollo 10
Lunar Module software Luminary 69/2. The now-reconstructed
Comanche 51 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 or Luminary 69 printouts, although
the source code would likely have different page numbers in a contemporary Comanche 51 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 55. Here's a guide
to some of the Apollo documentation relevant to those annotations:
Among documentation not actually referenced in the annotations, there is
a short writeup about the reconstruction process in our software repository
that may be helpful in understanding it from a different perspective. There's also
a handy table
that lists what the number of memory-words should be for each routine in Comanche 51,
which could make a nice double-check; however, we've not performed that double-check ourselves.
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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017777,000002: ## Copyright: Public domain.
017778,000003: ## Filename: KALCMANU_STEERING.agc
017779,000004: ## Purpose: A section of Comanche revision 051.
017780,000005: ## It is part of the reconstructed source code for the
017781,000006: ## original release of the flight software for the Command
017782,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
017783,000008: ## The code has been recreated from a copy of Comanche 055. It
017784,000009: ## has been adapted such that the resulting bugger words
017785,000010: ## exactly match those specified for Comanche 51 in NASA drawing
017786,000011: ## 2021153D, which gives relatively high confidence that the
017787,000012: ## reconstruction is correct.
017788,000013: ## Reference: pp. 414-419
017789,000014: ## Assembler: yaYUL
017790,000015: ## Contact: Ron Burkey <info@sandroid.org>.
017791,000016: ## Website: www.ibiblio.org/apollo/index.html
017792,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
017793,000018: ## 2021-05-30 ABS ZEROERROR -> ZEROEROR
017794,000019:
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Page 414
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017796,000021: # GENERATION OF STEERING COMMANDS FOR DIGITAL AUTOPILOT FREE FALL MANEUVERS
017797,000022:
017798,000023: # NEW COMMANDS WILL BE GENERATED EVERY ONE SECOND DURING THE MANEUVER
017799,000024:
017800,000025: 15,2000 BANK 15
017801,000026:
017802,000027: 22,2000 SETLOC KALCMON1
017803,000028: 22,2000 BANK
017804,000029:
017805,000030: 22,3026 E6,1661 EBANK= BCDU
017806,000031:
017807,000032: 22,3026 COUNT 22/KALC
017808,000033:
017809,000034: 22,3026 41332 NEWDELHI CS HOLDFLAG # SEE IF MANEUVER HAS BEEN INTERRUPTED
017810,000035: 22,3027 00006 EXTEND # BY ASTRONAUT
017811,000036: 22,3030 62726 BZMF NOGO -2 # IF SO, TERMINATE KALCMANU
017812,000037: 22,3031 06006 NEWANGL TC INTPRET
017813,000038: 22,3032 75160 AXC,1 AXC,2
017814,000039: 22,3033 03320 MIS # COMPUTE THE NEW MATRIX FROM S/C TO
017815,000040: 22,3034 03425 DEL # STABLE MEMBER AXES
017816,000041: 22,3035 77624 CALL
017817,000042: 22,3036 44304 MXM3
017818,000043: 22,3037 45575 VLOAD STADR
017819,000044: 22,3040 50442 STOVL MIS +12D # CALCULATE NEW DESIRED CDU ANGLES
017820,000045: 22,3041 77626 STADR
017821,000046: 22,3042 50450 STOVL MIS +6D
017822,000047: 22,3043 77626 STADR
017823,000048: 22,3044 74456 STORE MIS
017824,000049: 22,3045 45160 AXC,1 CALL
017825,000050: 22,3046 03320 MIS
017826,000051: 22,3047 44655 DCMTOCDU # PICK UP THE NEW CDU ANGLES FROM MATRIX
017827,000052: 22,3050 77634 RTB
017828,000053: 22,3051 45552 V1STO2S
017829,000054: 22,3052 03267 STORE NCDU # NEW CDU ANGLES
017830,000055: 22,3053 77414 BONCLR EXIT
017831,000056: 22,3054 01215 CALCMAN2
017832,000057: 22,3055 40065 MANUSTAT # TO START MANEUVER
017833,000058: 22,3056 35016 CAF TWO # +0 OTHERWISE
017834,000059: 22,3057 55664 INCRDCDU TS KSPNDX
017835,000060: 22,3060 60000 DOUBLE
017836,000061: 22,3061 55665 TS KDPNDX
017837,000062: 22,3062 51664 INDEX KSPNDX
017838,000063: 22,3063 31666 CA NCDU # NEW DESIRED CDU ANGLES
017839,000064: 22,3064 00006 EXTEND
017840,000065: 22,3065 51664 INDEX KSPNDX
017841,000066: 22,3066 21661 MSU BCDU # INITIAL S/C ANGLE OR PREVIOUS DESIRED
017842,000067: 22,3067 00006 EXTEND # CDU ANGLES
017843,000068: 22,3070 73002 MP QUADROT
017844,000069: 22,3071 51665 INDEX KDPNDX
017845,000070: 22,3072 53576 DXCH DELCDUX # ANGLE INCREMENTS TO BE ADDED TO
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017847,000072: 22,3073 51664 INDEX KSPNDX # DCDU EVERY TENTH SEC
017848,000073: 22,3074 31666 CA NCDU # BY LEM DAP
017849,000074: 22,3075 51664 INDEX KSPNDX
017850,000075: 22,3076 57661 XCH BCDU
017851,000076: 22,3077 51665 INDEX KDPNDX
017852,000077: 22,3100 55646 TS CDUXD
017853,000078: 22,3101 11664 CCS KSPNDX
017854,000079: 22,3102 13057 TCF INCRDCDU # LOOP FOR THREE AXES
017855,000080:
017856,000081: 22,3103 00003 RELINT
017857,000082: # COMPARE PRESENT TIME WITH TIME TO TERMINATE MANEUVER
017858,000083:
017859,000084: 22,3104 03115 TMANUCHK TC TIMECHK
017860,000085: 22,3105 04701 TC POSTJUMP
017861,000086: 22,3106 40131 CADR CONTMANU
017862,000087:
017863,000088: 22,3107 35017 CAF ONE
017864,000089: 22,3110 05245 MANUSTAL TC WAITLIST
017865,000090: 22,3111 E6,1661 EBANK= BCDU
017866,000091: 22,3111 02000 42066 2CADR MANUSTOP
017867,000092:
017868,000093: 22,3113 00003 RELINT
017869,000094: 22,3114 15217 TCF ENDOFJOB
017870,000095:
017871,000096:
017872,000097: 22,3115 00006 TIMECHK EXTEND
017873,000098: 22,3116 40025 DCS TIME2
017874,000099: 22,3117 53673 DXCH TTEMP
017875,000100: 22,3120 00006 EXTEND
017876,000101: 22,3121 31717 DCA TM
017877,000102: 22,3122 21673 DAS TTEMP
017878,000103: 22,3123 11672 CCS TTEMP
017879,000104: 22,3124 00002 TC Q
017880,000105: 22,3125 13127 TCF +2
017881,000106: 22,3126 13137 TCF 2NDRETRN
017882,000107: 22,3127 11673 CCS TTEMP +1
017883,000108: 22,3130 00002 TC Q
017884,000109: 22,3131 13133 TCF MANUOFF
017885,000110: 22,3132 40000 COM
017886,000111: 22,3133 65041 MANUOFF AD 1SEC
017887,000112: 22,3134 00006 EXTEND
017888,000113: 22,3135 63137 BZMF 2NDRETRN
017889,000114: 22,3136 24002 INCR Q
017890,000115: 22,3137 24002 2NDRETRN INCR Q
017891,000116: 22,3140 24002 INCR Q
017892,000117: 22,3141 00002 TC Q
017893,000118:
017894,000119: 20,2000 SETLOC MANUSTUF
017895,000120: 20,2000 BANK
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017897,000122: 20,2065 77776 MANUSTAT EXIT # INITIALIZATION ROUTINE
017898,000123: 20,2066 00006 EXTEND # FOR AUTOMATIC MANEUVERS
017899,000124: 20,2067 30025 DCA TIME2
017900,000125: 20,2070 21717 DAS TM # TM+T0 MANEUVER COMPLETION TIME
017901,000126: 20,2071 45041 CS 1SEC
017902,000127: 20,2072 54001 TS L
017903,000128: 20,2073 45021 CS ZERO
017904,000129: 20,2074 21717 DAS TM # (TM+T0)-1
017905,000130: 20,2075 00004 INHINT
017906,000131: 20,2076 45017 CS ONE # ENABLE AUTOPILOT TO PERFORM
017907,000132: 20,2077 55332 TS HOLDFLAG # AUTOMATIC MANEUVERS
017908,000133: 20,2100 41130 CS RATEINDX # SEE IF MANEUVERING AT HIGH RATE
017909,000134: 20,2101 66211 AD SIX
017910,000135: 20,2102 00006 EXTEND
017911,000136: 20,2103 62105 BZMF HIGHGAIN
017912,000137: 20,2104 12110 TCF +4
017913,000138: 20,2105 41501 HIGHGAIN CS RCSFLAGS # IF SO, SET HIGH RATE FLAG (BIT 15 OF
017914,000139: 20,2106 75001 MASK BIT15 # RCSFLAGS)
017915,000140: 20,2107 27501 ADS RCSFLAGS
017916,000141: 20,2110 53711 DXCH BRATE # X-AXIS MANEUVER RATE
017917,000142: 20,2111 53526 DXCH WBODY
017918,000143: 20,2112 53713 DXCH BRATE +2 # Y-AXIS MANEUVER RATE
017919,000144: 20,2113 53530 DXCH WBODY1
017920,000145: 20,2114 53715 DXCH BRATE +4 # Z-AXIS MANEUVER RATE
017921,000146: 20,2115 53532 DXCH WBODY2
017922,000147: 20,2116 31675 CA BIASTEMP +1 # INSERT ATTITUDE ERROR BIASES
017923,000148: 20,2117 55564 TS BIAS # INTO AUTOPILOT
017924,000149: 20,2120 31677 CA BIASTEMP +3
017925,000150: 20,2121 55565 TS BIAS1
017926,000151: 20,2122 31701 CA BIASTEMP +5
017927,000152: 20,2123 55566 TS BIAS2
017928,000153: 20,2124 30025 CA TIME1
017929,000154: 20,2125 65041 AD 1SEC
017930,000155: 20,2126 57671 XCH NEXTIME
017931,000156: 20,2127 04701 TC POSTJUMP
017932,000157: 20,2130 45056 CADR INCRDCDU -1
017933,000158:
017934,000159: 20,2131 00004 CONTMANU INHINT # CONTINUE WITH UPDATE PROCESS
017935,000160: 20,2132 40025 CS TIME1
017936,000161: 20,2133 61671 AD NEXTIME
017937,000162: 20,2134 10000 CCS A
017938,000163: 20,2135 65017 AD ONE
017939,000164: 20,2136 12141 TCF MANUCALL
017940,000165: 20,2137 65001 AD NEGMAX
017941,000166: 20,2140 40000 COM
017942,000167: 20,2141 05245 MANUCALL TC WAITLIST
017943,000168: 20,2142 E6,1661 EBANK= BCDU
017944,000169: 20,2142 02150 40066 2CADR UPDTCALL
017945,000170:
017946,000171: 20,2144 00003 RELINT
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017948,000173: 20,2145 35041 CAF 1SEC # INCREMENT TIME FOR NEXT UPDATE
017949,000174: 20,2146 27671 ADS NEXTIME
017950,000175: 20,2147 15217 TCF ENDOFJOB
017951,000176:
017952,000177:
017953,000178: 20,2150 37663 UPDTCALL CAF PRIO26 # CALL FOR UPDATE
017954,000179: 20,2151 05147 TC FINDVAC # OF STEERING COMMANDS
017955,000180: 20,2152 E6,1661 EBANK= BCDU
017956,000181: 20,2152 03026 44066 2CADR NEWDELHI
017957,000182:
017958,000183: 20,2154 05324 TC TASKOVER
017959,000184:
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017961,000186: # ROUTINE FOR TERMINATING AUTOMATIC MANEUVERS
017962,000187:
017963,000188: 21,2000 SETLOC KALCMON3
017964,000189: 21,2000 BANK
017965,000190:
017966,000191: 21,2000 04537 MANUSTOP TC STOPYZ
017967,000192: 21,2001 04740 TC IBNKCALL
017968,000193: 21,2002 45144 CADR LOADYZ
017969,000194:
017970,000195: 21,2003 31155 ENDROLL CA CPHI
017971,000196: 21,2004 55646 TS CDUXD # SET CDUXD TO THE COMMANDED OUTER GIMBAL
017972,000197: 21,2005 04526 TC STOPRATE
017973,000198: 21,2006 31327 ENDMANU CA ATTPRIO # RESTORE USERS PRIORITY
017974,000199: 21,2007 54063 TS NEWPRIO
017975,000200:
017976,000201: 21,2010 35021 CA ZERO # ZERO ATTCADR
017977,000202: 21,2011 53326 DXCH ATTCADR
017978,000203:
017979,000204: 21,2012 05160 TC SPVAC # RETURN TO USER OF GOMANUR
017980,000205:
017981,000206: 21,2013 05324 TC TASKOVER
017982,000207:
017983,000208: 4000 SETLOC STOPRAT
017984,000209: 4000 BANK
017985,000210: 4526 35021 STOPRATE CAF ZERO
017986,000211: 4527 55575 TS DELCDUX
017987,000212: 4530 55576 TS DELCDUX +1 # ZERO ROLL INCREMENTAL ANGLES
017988,000213: 4531 55525 TS WBODY # RATE
017989,000214: 4532 55526 TS WBODY +1
017990,000215: 4533 55564 TS BIAS # BIAS
017991,000216:
017992,000217: 4534 45001 CS BIT15 # MAKE SURE HIGH RATE FLAG (BIT 15 OF
017993,000218: 4535 71501 MASK RCSFLAGS # RCSFLAGS) IS RESET.
017994,000219: 4536 55501 TS RCSFLAGS
017995,000220:
017996,000221: 4537 35021 STOPYZ CAF ZERO
017997,000222: 4540 55577 TS DELCDUY # ZERO PITCH, YAW
017998,000223: 4541 55600 TS DELCDUY +1 # INCREMENTAL ANGLES
017999,000224: 4542 55601 TS DELCDUZ
018000,000225: 4543 55602 TS DELCDUZ +1
018001,000226: 4544 55527 TS WBODY1 # RATES
018002,000227: 4545 55530 TS WBODY1 +1
018003,000228: 4546 55531 TS WBODY2
018004,000229: 4547 55532 TS WBODY2 +1
018005,000230: 4550 55565 TS BIAS1 # BIASES
018006,000231: 4551 55566 TS BIAS2
018007,000232: 4552 00002 TC Q
018008,000233:
018009,000234: 20,2000 SETLOC MANUSTUF
018010,000235: 20,2000 BANK
018011,000236:
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018013,000238: 20,2155 30032 ZEROEROR CA CDUX # PICK UP CDU ANGLES AND STORE IN
018014,000239: 20,2156 55646 TS CDUXD # CDU DESIRED
018015,000240: 20,2157 30033 CA CDUY
018016,000241: 20,2160 55650 TS CDUYD
018017,000242: 20,2161 30034 CA CDUZ
018018,000243: 20,2162 55652 TS CDUZD
018019,000244: 20,2163 00002 TC Q
018020,000245:
018021,000246: 22,2000 SETLOC KALCMON1
018022,000247: 22,2000 BANK
018023,000248:
018024,000249: 22,3142 31155 LOADCDUD CA CPHI # STORE TERMINAL ANGLES INTO
018025,000250: 22,3143 55646 TS CDUXD # COMMAND ANGLES
018026,000251: 22,3144 31156 LOADYZ CA CTHETA
018027,000252: 22,3145 55650 TS CDUYD
018028,000253: 22,3146 31157 CA CPSI
018029,000254: 22,3147 55652 TS CDUZD
018030,000255: 22,3150 00002 TC Q
End of include-file KALCMANU_STEERING.agc. Parent file is MAIN.agc