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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041252,000002: ## Copyright: Public domain.
041253,000003: ## Filename: TVCEXECUTIVE.agc
041254,000004: ## Purpose: A section of Comanche revision 051.
041255,000005: ## It is part of the reconstructed source code for the
041256,000006: ## original release of the flight software for the Command
041257,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
041258,000008: ## The code has been recreated from a copy of Comanche 055. It
041259,000009: ## has been adapted such that the resulting bugger words
041260,000010: ## exactly match those specified for Comanche 51 in NASA drawing
041261,000011: ## 2021153D, which gives relatively high confidence that the
041262,000012: ## reconstruction is correct.
041263,000013: ## Reference: pp. 945-950
041264,000014: ## Assembler: yaYUL
041265,000015: ## Contact: Ron Burkey <info@sandroid.org>.
041266,000016: ## Website: www.ibiblio.org/apollo/index.html
041267,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
041268,000018:
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Page 945
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041270,000020: # PROGRAM NAME.... TVCEXECUTIVE, CONSISTING OF TVCEXEC, NEEDLEUP, VARGAINS
041271,000021: # 1SHOTCHK, REPCHEK, CG.CORR, COPYCYCLES, ETC.
041272,000022: # LOG SECTION... TVCEXECUTIVE SUBROUTINE...DAPCSM
041273,000023: # MODIFIED BY SCHLUNDT 21 OCTOBER 1968
041274,000024:
041275,000025: # FUNCTIONAL DESCRIPTION....
041276,000026: # *A SELF-PERPETUATING WAITLIST TASK AT 1/2 SECOND INTERVALS WHICH:
041277,000027: # PREPARES THE ROLL DAP WITH OGA (CDUX)
041278,000028: # PREPARES THE ROLL FDAI NEEDLE (FLY-TO OGA ERROR)
041279,000029: # PREPARES THE ROLL PHASE PLANE OGAERR (FLY-FROM OGA ERROR)
041280,000030: # PREPARES THE TVC ROLLDAP TASK WAITLIST CALL (3 CS DELAY)
041281,000031: # UPDATES THE NEEDLES DISPLAY
041282,000032: # UPDATES VEHICLE MASS AND CALLS MASSPROP TO UPDATE INERTIA DATA
041283,000033: # UPDATES PITCH, YAW, AND ROLL DAP GAINS FROM MASSPROP DATA
041284,000034: # PERFORMS ONE-SHOT CORRECTION FOR TMC LOOP 0-3 SEC AFTER IGNITION
041285,000035: # PERFORMS REPETITIVE UPDATES FOR TMC LOOP AFTER THE ONE-SHOT CORR.
041286,000036:
041287,000037: # CALLING SEQUENCE....
041288,000038: # *TVCEXEC CALLED AS A WAITLIST TASK, IN PARTICULAR BY TVCINIT4 AND BY
041289,000039: # ITSELF, BOTH AT 1/2 SECOND INTERVALS
041290,000040:
041291,000041: # NORMAL EXIT MODE.... TASKOVER
041292,000042:
041293,000043: # ALARM OR ABORT EXIT MODES.... NONE
041294,000044:
041295,000045: # SUBROUTINES CALLED....NEEDLER, S40.15, MASSPROP, TASKOVER, IBNKCALL
041296,000046:
041297,000047: # OTHER INTERFACES....
041298,000048: # *TVCRESTART PACKAGE FOR RESTARTS
041299,000049: # *PITCHDAP, YAWDAP FOR VARIABLE GAINS AND ENGINE TRIM ANGLES
041300,000050:
041301,000051: # ERASABLE INITIALIZATION REQUIRED....
041302,000052: # *SEE TVCDAPON....TVCINIT4
041303,000053: # *VARK AND 1/CONACC (S40.15 OF TVCINITIALIZE)
041304,000054: # *PAD LOAD EREPFRAC
041305,000055: # *BITS 15,14 OF FLAGWRD6 (T5 BITS)
041306,000056: # *TVCEXPHS FOR RESTARTS
041307,000057: # *ENGINE-ON BIT (11.13) FOR RESTARTS
041308,000058: # *CDUX, OGAD
041309,000059:
041310,000060: # OUTPUT....
041311,000061: # *ROLL DAP OGANOW, FDAI NEEDLE (AK). AND PHASE PLANE OGAERR
041312,000062: # *VARIABLE GAINS FOR PITCH/YAW AND ROLL TVC DAPS
041313,000063: # *SINGLE-SHOT AND REPETITIVE CORRECTIONS TO ENGINE TRIM ANGLES
041314,000064: # PACTOFF AND YACTOFF
041315,000065:
041316,000066: # DEBRIS.... MUCH, BUT SHAREABLE WITH RCS/ENTRY, ALL IN EBANK6
041317,000067:
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Page 946
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041319,000069: 16,2720 BANK 16
041320,000070: 16,2000 SETLOC DAPROLL
041321,000071: 16,2000 BANK
041322,000072: 16,2720 E6,1702 EBANK= BZERO
041323,000073: 16,2720 COUNT* $$/TVCX
041324,000074:
041325,000075: 16,2720 40102 TVCEXEC CS FLAGWRD6 # CHECK FOR TERMINATION (BITS 15,14 READ
041326,000076: 16,2721 74105 MASK OCT60000 # 10 FROM TVCDAPON TO RCSDAPON)
041327,000077: 16,2722 00006 EXTEND
041328,000078: 16,2723 63134 BZMF TVCEXFIN # TERMINATE
041329,000079:
041330,000080: 16,2724 35036 CAF .5SEC # W.L. CALL TO PERPETUATE TVCEXEC
041331,000081: 16,2725 05245 TC WAITLIST
041332,000082: 16,2726 E6,1702 EBANK= BZERO
041333,000083: 16,2726 02720 34066 2CADR TVCEXEC
041334,000084:
041335,000085: 16,2730 30032 ROLLPREP CAE CDUX # UPDATE ROLL LADDERS (NO NEED TO RESTART-
041336,000086: 16,2731 57662 XCH OGANOW # PROTECT, SINCE ROLL DAPS RE-START)
041337,000087: 16,2732 57663 XCH OGAPAST
041338,000088:
041339,000089: 16,2733 31450 CAE OGAD # PREPARE ROLL FDAI NEEDLE WITH FLY-TO
041340,000090: 16,2734 00006 EXTEND # ERROR (COMMAND - MEASURED)
041341,000091: 16,2735 21662 MSU OGANOW
041342,000092: 16,2736 55476 TS AK # FLY-TO OGA ERROR, SC.AT B-1 REVS
041343,000093:
041344,000094: 16,2737 00006 EXTEND # PREPARE ROLL DAP PHASE PLANE OGAERR
041345,000095: 16,2740 77705 MP -BIT14
041346,000096: 16,2741 55664 TS OGAERR # PHASE-PLANE (FLY-FROM) OGAERROR,
041347,000097: # SC.AT B+0 REVS
041348,000098:
041349,000099: 16,2742 36214 CAF THREE # SET UP ROLL DAP TASK (ALLOW SOME TIME)
041350,000100: 16,2743 05245 TC WAITLIST
041351,000101: 16,2744 E6,1702 EBANK= BZERO
041352,000102: 16,2744 03272 34066 2CADR ROLLDAP
041353,000103:
041354,000104: 16,2746 04740 NEEDLEUP TC IBNKCALL # DO A NEEDLES UPDATE (RETURNS AFTER CADR)
041355,000105: 16,2747 42420 CADR NEEDLER # (NEEDLES RESTARTS ITSELF)
041356,000106:
041357,000107: 16,2750 35003 VARGAINS CAF BIT13 # CHECK ENGINE-ON BIT TO INHIBIT VARIABLE
041358,000108: 16,2751 00006 EXTEND # GAINS AND MASS IF ENGINE OFF
041359,000109: 16,2752 02011 RAND DSALMOUT # CHANNEL 11
041360,000110: 16,2753 10000 CCS A
041361,000111: 16,2754 12760 TCF +4 # ON, SO OK TO UPDATE GAINS AND MASS
041362,000112: 16,2755 35016 +5 CAF TWO # OFF, SO BYPASS MASS/GAIN UPDATES,
041363,000113: 16,2756 55651 TS TVCEXPHS # ALSO ENTRY FROM CCS BELOW WITH
041364,000114: 16,2757 13011 TCF 1SHOTCHK # VCNTR = -0 (V97 R40 ENGFAIL)
041365,000115: 16,2760 11643 CCS VCNTR # TEST FOR GAIN UPDATE TIME
041366,000116: 16,2761 12765 TCF +4 # NOT YET
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Page 947
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041368,000118: 16,2762 12771 TCF GAINCHNG # NOW
041369,000119: 16,2763 12763 TCF +0 # NOT USED
041370,000120: 16,2764 12755 TCF VARGAINS +5 # NO, LOTHRUST (S40.8 R40)
041371,000121:
041372,000122: 16,2765 55653 +4 TS VCNTRTMP # PROTECT VCNTR AND
041373,000123: 16,2766 31474 CAE CSMMASS # CSMMASS DURING AN IMPULSIVE BURN
041374,000124: 16,2767 55652 TS MASSTMP
041375,000125: 16,2770 13002 TCF EXECCOPY
041376,000126:
041377,000127: 16,2771 04740 GAINCHNG TC IBNKCALL # UPDATE IXX, IAVG, IAVG/TLX
041378,000128: 16,2772 13422 CADR FIXCW # MASSPROP ENTRY (ALREADY INITIALIZED)
041379,000129: 16,2773 04740 TC IBNKCALL # UPDATE 1/CONACC, VARK
041380,000130: 16,2774 36462 CADR S40.15 # (S40.15 IS IN TVCINITIALIZE)
041381,000131: 16,2775 41637 CS TENMDOT # UPDATE MASS FOR NEXT 10 SEC. OF BURN
041382,000132: 16,2776 61474 AD CSMMASS
041383,000133: 16,2777 55652 TS MASSTMP # KG B+16
041384,000134:
041385,000135: 16,3000 34374 CAF NINETEEN # RESET THE VARIABLE-GAIN UPDATE COUNTER
041386,000136: 16,3001 55653 TS VCNTRTMP
041387,000137:
041388,000138: 16,3002 25651 EXECCOPY INCR TVCEXPHS # RESTART-PROTECT THE COPYCYCLE (1)
041389,000139:
041390,000140: 16,3003 31652 CAE MASSTMP # CSMMASS KG B+16
041391,000141: 16,3004 55474 TS CSMMASS
041392,000142:
041393,000143: 16,3005 31653 CAE VCNTRTMP # VCNTR
041394,000144: 16,3006 55643 TS VCNTR
041395,000145: 16,3007 55444 TS V97VCNTR # FOR ENGFAIL (R41) MASS UPDATES AT SPSOFF
041396,000146:
041397,000147: 16,3010 25651 INCR TVCEXPHS # COPYCYCLE OVER (2)
041398,000148:
041399,000149: 16,3011 11447 1SHOTCHK CCS CNTR # CHECK TIME FOR ONE-SHOT OR REPCORR
041400,000150: 16,3012 13016 TCF +4 # NOT YET
041401,000151: 16,3013 13031 TCF 1SHOTOK # NOW
041402,000152: 16,3014 13022 TCF REPCHEK # ONE-SHOT OVER, ON TO REPCORR
041403,000153: 16,3015 13031 TCF 1SHOTOK # NOW (ONE-SHOT ONLY, NO REPCORR)
041404,000154:
041405,000155: 16,3016 55676 +4 TS CNTRTMP # COUNT DOWN
041406,000156: 16,3017 36211 CAF SIX # SETUP TVCEXPHS FOR ENTRY AT CNTRCOPY
041407,000157: 16,3020 55651 TS TVCEXPHS
041408,000158: 16,3021 13132 TCF CNTRCOPY
041409,000159:
041410,000160: 16,3022 31642 REPCHEK CAE REPFRAC # CHECK FOR REPETITIVE UPDATES
041411,000161: 16,3023 00006 EXTEND
041412,000162: 16,3024 63134 BZMF TVCEXFIN # NO, OVER-AND-OUT
041413,000163: 16,3025 55446 TS TEMPDAP +1 # YES, SET UP CORRECTION FRACTION
041414,000164: 16,3026 35015 CAF FOUR # SET UP TVCEXPHS FOR ENTRY AT CORSETUP
041415,000165: 16,3027 55651 TS TVCEXPHS
041416,000166: 16,3030 13043 TCF CORSETUP
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041418,000168: 16,3031 35003 1SHOTOK CAF BIT13 # CHECK ENGINE-ON BIT, NOT PERMITTING
041419,000169: 16,3032 00006 EXTEND # ONE-SHOT DURING ENGINE-SHUTDOWN
041420,000170: 16,3033 02011 RAND DSALMOUT
041421,000171: 16,3034 10000 CCS A
041422,000172: 16,3035 13037 TCF +2 # ONE-SHOT OK
041423,000173: 16,3036 13134 TCF TVCEXFIN # NO, TERMINATE
041424,000174:
041425,000175: 16,3037 25651 INCR TVCEXPHS # (3)
041426,000176:
041427,000177: 16,3040 33137 TEMPSET CAF FCORFRAC # SET UP CORRECTION FRACTION
041428,000178: 16,3041 55446 TS TEMPDAP +1
041429,000179:
041430,000180: 16,3042 25651 INCR TVCEXPHS # ENTRY FROM REPCHEK AT NEXT LOCATION (4)
041431,000181:
041432,000182: 16,3043 31466 CORSETUP CAE DAPDATR1 # CHECK FOR LEM-OFF/ON
041433,000183: 16,3044 75003 MASK BIT13 # (NOTE, SHOWS LEM-OFF)
041434,000184: 16,3045 00006 EXTEND
041435,000185: 16,3046 13050 BZF +2 # LEM IS ON, PICK UP TEMPDAP+1
041436,000186: 16,3047 31446 CAE TEMPDAP +1 # LEM IS OFF, PICK UP 2(TEMPDAP+1)
041437,000187: 16,3050 61446 AD TEMPDAP +1
041438,000188: 16,3051 55445 TS TEMPDAP # CG.CORR USES TEMPDAP
041439,000189:
041440,000190: 16,3052 37716 CAF NEGONE # SET UP FOR CNTR = -1 (ONE-SHOT DONE)
041441,000191: 16,3053 55676 TS CNTRTMP # (COPYCYCLE AT .CNTRCOPY.)
041442,000192:
041443,000193: 16,3054 00006 CG.CORR EXTEND # PITCH TMC LOOP
041444,000194: 16,3055 31606 DCA PDELOFF
041445,000195: 16,3056 53673 DXCH PACTTMP
041446,000196: 16,3057 00006 EXTEND
041447,000197: 16,3060 41606 DCS PDELOFF
041448,000198: 16,3061 20001 DDOUBL
041449,000199: 16,3062 20001 DDOUBL
041450,000200: 16,3063 53612 DXCH TTMP1
041451,000201: 16,3064 00006 EXTEND
041452,000202: 16,3065 31602 DCA DELPBAR
041453,000203: 16,3066 20001 DDOUBL
041454,000204: 16,3067 20001 DDOUBL
041455,000205: 16,3070 21612 DAS TTMP1
041456,000206: 16,3071 00006 EXTEND
041457,000207: 16,3072 31612 DCA TTMP1
041458,000208: 16,3073 00006 EXTEND
041459,000209: 16,3074 71445 MP TEMPDAP
041460,000210: 16,3075 21673 DAS PACTTMP
041461,000211:
041462,000212: 16,3076 00006 EXTEND # YAW TMC LOOP
041463,000213: 16,3077 31610 DCA YDELOFF
041464,000214: 16,3100 53675 DXCH YACTTMP
041465,000215: 16,3101 00006 EXTEND
041466,000216: 16,3102 41610 DCS YDELOFF
041467,000217: 16,3103 20001 DDOUBL
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Page 949
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041469,000219: 16,3104 20001 DDOUBL
041470,000220: 16,3105 53612 DXCH TTMP1
041471,000221: 16,3106 00006 EXTEND
041472,000222: 16,3107 31604 DCA DELYBAR
041473,000223: 16,3110 20001 DDOUBL
041474,000224: 16,3111 20001 DDOUBL
041475,000225: 16,3112 21612 DAS TTMP1
041476,000226: 16,3113 00006 EXTEND
041477,000227: 16,3114 31612 DCA TTMP1
041478,000228: 16,3115 00006 EXTEND
041479,000229: 16,3116 71445 MP TEMPDAP
041480,000230: 16,3117 21675 DAS YACTTMP
041481,000231:
041482,000232: 16,3120 25651 CORCOPY INCR TVCEXPHS # RESTART PROTECT THE COPYCYCLE (5)
041483,000233:
041484,000234: 16,3121 00006 EXTEND # TRIM-ESTIMATES, AND
041485,000235: 16,3122 31673 DCA PACTTMP
041486,000236: 16,3123 55423 TS PACTOFF # TRIMS
041487,000237: 16,3124 53606 DXCH PDELOFF
041488,000238:
041489,000239: 16,3125 00006 EXTEND
041490,000240: 16,3126 31675 DCA YACTTMP
041491,000241: 16,3127 55424 TS YACTOFF
041492,000242: 16,3130 53610 DXCH YDELOFF
041493,000243:
041494,000244: 16,3131 25651 INCR TVCEXPHS # ENTRY FROM 1SHOTCHK AT NEXT LOCATION (6)
041495,000245:
041496,000246: 16,3132 31676 CNTRCOPY CAE CNTRTMP # UPDATE CNTR (RESTARTS OK, FOLLOWS CPYCY)
041497,000247: 16,3133 55447 TS CNTR
041498,000248:
041499,000249: 16,3134 35021 TVCEXFIN CAF ZERO # RESET TVCEXPHS
041500,000250: 16,3135 55651 TS TVCEXPHS
041501,000251: 16,3136 15324 TCF TASKOVER # TVCEXECUTIVE FINISHED
041502,000252:
041503,000253: 16,3137 10000 FCORFRAC OCT 10000 # ONE-SHOT CORRECTION FRACTION
041504,000254:
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041507,000257:
041508,000258:
End of include-file TVCEXECUTIVE.agc. Parent file is MAIN.agc