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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063385,000002: ## Copyright: Public domain.
063386,000003: ## Filename: ALARM_AND_ABORT.agc
063387,000004: ## Purpose: A section of Comanche revision 051.
063388,000005: ## It is part of the reconstructed source code for the
063389,000006: ## original release of the flight software for the Command
063390,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
063391,000008: ## The code has been recreated from a copy of Comanche 055. It
063392,000009: ## has been adapted such that the resulting bugger words
063393,000010: ## exactly match those specified for Comanche 51 in NASA drawing
063394,000011: ## 2021153D, which gives relatively high confidence that the
063395,000012: ## reconstruction is correct.
063396,000013: ## Reference: pp. 1493-1496
063397,000014: ## Assembler: yaYUL
063398,000015: ## Contact: Ron Burkey <info@sandroid.org>.
063399,000016: ## Website: www.ibiblio.org/apollo/index.html
063400,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
063401,000018:
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Page 1493
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063403,000020: # THE FOLLOWING SUBROUTINE MAY BE CALLED TO DISPLAY A NON-ABORTIVE ALARM CONDITION. IT MAY BE CALLED
063404,000021: # EITHER IN INTERRUPT OR UNDER EXECUTIVE CONTROL.
063405,000022:
063406,000023: # CALLING SEQUENCE IS AS FOLLOWS:
063407,000024: # TC ALARM
063408,000025: # OCT NNNNN
063409,000026: # (RETURNS HERE)
063410,000027:
063411,000028: 5650 BLOCK 02
063412,000029: 4000 SETLOC FFTAG7
063413,000030: 4000 BANK
063414,000031:
063415,000032: 5650 0375 EBANK= FAILREG
063416,000033:
063417,000034: 5650 COUNT 02/ALARM
063418,000035:
063419,000036: # ALARM TURNS ON THE PROGRAM ALARM LIGHT, BUT DOES NOT DISPLAY.
063420,000037:
063421,000038: 5650 00004 ALARM INHINT
063422,000039:
063423,000040: 5651 30002 CA Q
063424,000041: 5652 55363 ALARM2 TS ALMCADR
063425,000042: 5653 50002 INDEX Q
063426,000043: 5654 30000 CA 0
063427,000044: 5655 54001 BORTENT TS L
063428,000045:
063429,000046: 5656 30006 PRIOENT CA BBANK
063430,000047: 5657 00006 +1 EXTEND
063431,000048: 5660 04007 ROR SUPERBNK # ADD SUPER BITS.
063432,000049: 5661 55364 TS ALMCADR +1
063433,000050:
063434,000051: 5662 30002 LARMENT CA Q # STORE RETURN FOR ALARM
063435,000052: 5663 54061 TS ITEMP1
063436,000053:
063437,000054: 5664 30164 CA LOC
063438,000055: 5665 54057 TS LOCALARM
063439,000056: 5666 30165 CA BANKSET
063440,000057: 5667 54060 TS BANKALRM
063441,000058:
063442,000059: 5670 10375 CHKFAIL1 CCS FAILREG # IS ANYTHING IN FAILREG
063443,000060: 5671 15674 TCF CHKFAIL2 # YES TRY NEXT REG
063444,000061: 5672 22375 LXCH FAILREG
063445,000062: 5673 15706 TCF PROGLARM # TURN ALARM LIGHT ON FOR FIRST ALARM
063446,000063:
063447,000064: 5674 10376 CHKFAIL2 CCS FAILREG +1
063448,000065: 5675 15700 TCF FAIL3
063449,000066: 5676 22376 LXCH FAILREG +1
063450,000067: 5677 15711 TCF MULTEXIT
063451,000068:
063452,000069: 5700 30377 FAIL3 CA FAILREG +2
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Page 1494
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063454,000071: 5701 74777 MASK POSMAX
063455,000072: 5702 10000 CCS A
063456,000073: 5703 15715 TCF MULTFAIL
063457,000074: 5704 22377 LXCH FAILREG +2
063458,000075: 5705 15711 TCF MULTEXIT
063459,000076:
063460,000077: 5706 41036 PROGLARM CS DSPTAB +11D
063461,000078: 5707 77765 MASK OCT40400
063462,000079: 5710 27036 ADS DSPTAB +11D
063463,000080:
063464,000081: 5711 56061 MULTEXIT XCH ITEMP1 # OBTAIN RETURN ADDRESS IN A
063465,000082: 5712 00003 RELINT
063466,000083: 5713 50000 INDEX A
063467,000084: 5714 00001 TC 1
063468,000085:
063469,000086: 5715 30001 MULTFAIL CA L
063470,000087: 5716 65001 AD BIT15
063471,000088: 5717 54377 TS FAILREG +2
063472,000089:
063473,000090: 5720 15711 TCF MULTEXIT
063474,000091:
063475,000092: # PRIOLARM DISPLAYS V05N09 VIA PRIODSPR WITH 3 RETURNS TO THE USER FROM THE ASTRONAUT AT CALL LOC +1,+2,+3 AND
063476,000093: # AN IMMEDIATE RETURN TO THE USER AT CALL LOC +4. EXAMPLE FOLLOWS,
063477,000094: # CAF OCTXX ALARM CODE
063478,000095: # TC BANKCALL
063479,000096: # CADR PRIOLARM
063480,000097:
063481,000098: # ... ...
063482,000099: # ... ...
063483,000100: # ... ... ASTRONAUT RETURN
063484,000101: # TC PHASCHNG IMMEDIATE RETURN TO USER. RESTART
063485,000102: # OCT X.1 PHASE CHANGE FOR PRIO DISPLAY
063486,000103:
063487,000104: 10,3766 BANK 10
063488,000105: 10,2000 SETLOC DISPLAYS
063489,000106: 10,2000 BANK
063490,000107:
063491,000108: 10,3766 COUNT 10/DSPLA
063492,000109: 10,3766 00004 PRIOLARM INHINT # * * * KEEP IN DISPLAY ROUTINES BANK
063493,000110: 10,3767 54001 TS L # SAVE ALARM CODE
063494,000111:
063495,000112: 10,3770 30133 CA BUF2 # 2 CADR OF PRIOLARM USER
063496,000113: 10,3771 55363 TS ALMCADR
063497,000114: 10,3772 30134 CA BUF2 +1
063498,000115: 10,3773 05657 TC PRIOENT +1 # * LEAVE L ALONE
063499,000116: 10,3774 77467 -2SEC DEC -200 B-14 # *** DONT MOVE
063500,000117: 10,3775 35050 CAF V05N09
063501,000118: 10,3776 12726 TCF PRIODSPR
063502,000119:
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Page 1495
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063504,000121:
063505,000122: 5721 BLOCK 02
063506,000123: 6000 SETLOC FFTAG13
063507,000124: 6000 BANK
063508,000125:
063509,000126: 7755 COUNT 02/ALARM
063510,000127:
063511,000128: 7755 00004 BAILOUT INHINT
063512,000129: 7756 30002 CA Q
063513,000130: 7757 55363 TS ALMCADR
063514,000131:
063515,000132: 7760 04662 TC BANKCALL
063516,000133: 7761 40000 CADR VAC5STOR
063517,000134:
063518,000135: 7762 51363 INDEX ALMCADR
063519,000136: 7763 30000 CAF 0
063520,000137: 7764 05655 TC BORTENT
063521,000138: 7765 40400 OCT40400 OCT 40400
063522,000139:
063523,000140: 7766 00004 INHINT
063524,000141: 7767 35016 WHIMPER CA TWO
063525,000142: 7770 60005 AD Z
063526,000143: 7771 54017 TS BRUPT
063527,000144: 7772 50017 RESUME
063528,000145: 7773 04701 TC POSTJUMP # RESUME SENDS CONTROL HERE
063529,000146: 7774 12651 CADR ENEMA
063530,000147:
063531,000148: 4000 SETLOC FFTAG7
063532,000149: 4000 BANK
063533,000150:
063534,000151: 5721 00004 POODOO INHINT
063535,000152: 5722 30002 CA Q
063536,000153: 5723 55363 TS ALMCADR
063537,000154:
063538,000155: 5724 04662 TC BANKCALL
063539,000156: 5725 40000 CADR VAC5STOR # STORE ERASABLES FOR DEBUGGING PURPOSES.
063540,000157:
063541,000158: 5726 51363 INDEX ALMCADR
063542,000159: 5727 30000 CAF 0
063543,000160: 5730 05655 ABORT2 TC BORTENT
063544,000161: 5731 77770 OCT77770 OCT 77770 # DONT MOVE
063545,000162: 5732 35012 CA V37FLBIT # IS AVERAGE G ON
063546,000163: 5733 70103 MASK FLAGWRD7
063547,000164: 5734 10000 CCS A
063548,000165: 5735 07766 TC WHIMPER -1 # YES. DONT DO POODOO. DO BAILOUT.
063549,000166:
063550,000167: 5736 05560 TC DOWNFLAG
063551,000168: 5737 00067 ADRES STATEFLG
063552,000169:
063553,000170: 5740 05560 TC DOWNFLAG
063554,000171:
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Page 1496
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063556,000173: 5741 00236 ADRES REINTFLG
063557,000174:
063558,000175: 5742 05560 TC DOWNFLAG
063559,000176: 5743 00054 ADRES NODOFLAG
063560,000177:
063561,000178: 5744 04662 TC BANKCALL
063562,000179: 5745 12501 CADR MR.KLEAN
063563,000180: 5746 07767 TC WHIMPER
063564,000181:
063565,000182: 5747 00004 CCSHOLE INHINT
063566,000183: 5750 30002 CA Q
063567,000184: 5751 55363 TS ALMCADR
063568,000185: 5752 04662 TC BANKCALL
063569,000186: 5753 40000 CADR VAC5STOR
063570,000187: 5754 35756 CA OCT1103
063571,000188: 5755 05730 TC ABORT2
063572,000189: 5756 01103 OCT1103 OCT 1103
063573,000190: 5757 00004 CURTAINS INHINT
063574,000191: 5760 30002 CA Q
063575,000192: 5761 05652 TC ALARM2
063576,000193: 5762 00217 OCT217 OCT 00217
063577,000194: 5763 01363 TC ALMCADR # RETURN TO USER
063578,000195:
063579,000196: 5764 5217 DOALARM EQUALS ENDOFJOB
063580,000197:
063581,000198: # CALLING SEQUENCE FOR VARALARM
063582,000199:
063583,000200: # CAF (ALARM)
063584,000201: # TC VARALARM
063585,000202:
063586,000203: # VARALARM TURNS ON PROGRAM ALARM LIGHT BUT DOES NOT DISPLAY
063587,000204:
063588,000205: 5764 00004 VARALARM INHINT
063589,000206:
063590,000207: 5765 54001 TS L # SAVE USERS ALARM CODE
063591,000208:
063592,000209: 5766 30002 CA Q # SAVE USERS Q
063593,000210: 5767 55363 TS ALMCADR
063594,000211:
063595,000212: 5770 05656 TC PRIOENT
063596,000213: 5771 00014 OCT14 OCT 14 # DONT MOVE
063597,000214:
063598,000215: 5772 01363 TC ALMCADR # RETURN TO USER
063599,000216:
063600,000217: 5773 7755 ABORT EQUALS BAILOUT # *** TEMPORARY UNTIL ABORT CALLS OUT
End of include-file ALARM_AND_ABORT.agc. Parent file is MAIN.agc