Source Code
![]() |
This source code is very close to the Apollo Guidance Computer software for the
Apollo 13 Lunar module. This revision of the Luminary 131 program is from December
of 1969, whereas there was a later revision in January of 1970, and still another
revision in February, which is the code that flew on the mission.
As far as this transcription is concerned, it was originally from a copy made in 1991 of
a printout from the collection of AGC developer Don Eyles for collector David Craig.
It was subsequently scanned by Gary Neff, reprocessed for online
presentation at the now-discontinued History of Recent Science and Technology (HRST) website
of MIT's Dibner Institute (the full-quality scans being discarded in the process),
and finally transcribed by Ron Burkey for the Virtual AGC Project. Although a
high-quality replacement scan for a completely illegible page was later provided by Gary
Neff, the reduced legibility of the reprocessed HRST posting nevertheless caused many
errors to be introduced into the transcription. Accordingly, a second scan of the same physical
printout was made in 2017 for the Virtual AGC Project's collection at the Internet Archive,
and used to correct the transcription errors. All of the scanned materials mentioned,
as well as other Luminary 131 related material, are available online.
Don Eyles apprently made additional hand-written notes in printout between 1991 and 2017,
so the two scans are not identical in that respect. The page-headings in the printout read, in part:GAP: ASSEMBLE REVISION 131 OF AGC PROGRAM LUMINARY BY NASA 2021112-091 17:53 DEC. 19, 1969Note that the date is the date the printout was made, not the date on which the program revision was released, although these happen to be very close together. |
035211,000002: ## Copyright: Public domain.
035212,000003: ## Filename: P70-P71.agc
035213,000004: ## Purpose: A section of Luminary 1C, revision 131.
035214,000005: ## It is part of the source code for the Lunar Module's (LM)
035215,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
035216,000007: ## This file is intended to be a faithful transcription, except
035217,000008: ## that the code format has been changed to conform to the
035218,000009: ## requirements of the yaYUL assembler rather than the
035219,000010: ## original YUL assembler.
035220,000011: ## Reference: pp. 823-830
035221,000012: ## Contact: Ron Burkey <info@sandroid.org>.
035222,000013: ## Website: www.ibiblio.org/apollo
035223,000014: ## Mod history: 05/26/03 RSB. Began transcribing.
035224,000015: ## 2017-01-06 RSB Page numbers now agree with those on the
035225,000016: ## original hardcopy, as opposed to the PDF page
035226,000017: ## numbers in 1701.pdf.
035227,000018: ## 2017-02-26 RSB Proofed comment text using octopus/ProoferComments.
035228,000019: ## 2017-03-01 RSB Fixed lingering typos.
035229,000020: ## 2017-03-14 RSB Comment-text fixes noted in proofing Luminary 116.
035230,000021:
![]() |
Page 823 |
035232,000023: 21,2006 BANK 21
035233,000024: 21,2000 SETLOC R11
035234,000025: 21,2000 BANK
035235,000026:
035236,000027: 21,2006 E7,1515 EBANK= DVCNTR
035237,000028: 21,2006 COUNT* $$/R11
035238,000029:
035239,000030: 21,2006 40103 R10,R11 CS FLAGWRD7 # IS SERVICER STILL RUNNING?
035240,000031: 21,2007 74747 MASK AVEGFBIT
035241,000032: 21,2010 10000 CCS A
035242,000033: 21,2011 15261 TCF TASKOVER # LET AVGEND TAKE CARE OF GROUP 2.
035243,000034: 21,2012 11055 CCS PIPCTR
035244,000035: 21,2013 12015 TCF +2
035245,000036: 21,2014 12125 TCF LRHTASK # LAST PASS. CALL LRHTASK.
035246,000037: 21,2015 55714 +2 TS PIPCTR1
035247,000038:
035248,000039: 21,2016 E7,1714 PIPCTR1 = LADQSAVE
035249,000040: 21,2016 1055 PIPCTR = PHSPRDT2
035250,000041: 21,2016 36010 CAF OCT31
035251,000042: 21,2017 05173 TC TWIDDLE
035252,000043: 21,2020 02006 ADRES R10,R11
035253,000044: 21,2021 34753 R10,R11A CAF HFLSHBIT
035254,000045: 21,2022 70107 FLASHH? MASK FLGWRD11
035255,000046: 21,2023 00006 EXTEND
035256,000047: 21,2024 12030 BZF FLASHV? # H FLASH OFF, SO LEAVE ALONE
035257,000048:
035258,000049: 21,2025 34747 CA HLITE
035259,000050: 21,2026 54001 TS L
035260,000051: 21,2027 04606 TC FLIP # FLIP H LITE
035261,000052:
035262,000053: 21,2030 34752 FLASHV? CA VFLSHBIT # VFLASHBIT MUST BE BIT 2.
035263,000054: 21,2031 70107 MASK FLGWRD11
035264,000055: 21,2032 00006 EXTEND
035265,000056: 21,2033 12037 BZF 10,11 # VFLASH OFF
035266,000057:
035267,000058: 21,2034 34751 CA VLITE
035268,000059: 21,2035 54001 TS L
035269,000060: 21,2036 04606 TC FLIP # FLIP V LITE
035270,000061:
035271,000062: 21,2037 30105 10,11 CA FLAGWRD9 # IS THE LETABORT FLAG SET ?
035272,000063: 21,2040 74743 MASK LETABBIT
035273,000064: 21,2041 00006 EXTEND
035274,000065: 21,2042 12145 BZF LANDISP # NO. PROCEED TO R10.
035275,000066:
035276,000067: 21,2043 41010 P71NOW? CS MODREG # YES. ARE WE IN P71 NOW?
035277,000068: 21,2044 62104 AD 1DEC71
035278,000069: 21,2045 00006 EXTEND
035279,000070: 21,2046 12145 BZF LANDISP # YES. PROCEED TO R10.
![]() |
Page 824 |
035281,000072: 21,2047 00006 EXTEND # NO. IS AN ABORT STAGE COMMANDED?
035282,000073: 21,2050 00030 READ CHAN30
035283,000074: 21,2051 40000 COM
035284,000075: 21,2052 54001 TS L
035285,000076: 21,2053 74750 MASK BIT4
035286,000077: 21,2054 10000 CCS A
035287,000078: 21,2055 12073 TCF P71A # YES.
035288,000079:
035289,000080: 21,2056 41010 P70NOW? CS MODREG # NO. ARE WE IN P70 NOW?
035290,000081: 21,2057 62103 AD 1DEC70
035291,000082: 21,2060 00006 EXTEND
035292,000083: 21,2061 12145 BZF LANDISP # YES. PROCEED TO R10.
035293,000084:
035294,000085: 21,2062 30001 CA L # NO. IS AN ABORT COMMANDED?
035295,000086: 21,2063 74753 MASK BIT1
035296,000087: 21,2064 10000 CCS A
035297,000088: 21,2065 12070 TCF P70A # YES.
035298,000089: 21,2066 12145 TCF LANDISP # NO. PROCEED TO R10.
035299,000090:
035300,000091: 21,2067 COUNT* $$/P70
035301,000092:
035302,000093: 21,2067 02105 P70 TC LEGAL?
035303,000094: 21,2070 44755 P70A CS ZERO
035304,000095: 21,2071 12074 TCF +3
035305,000096: 21,2072 02105 P71 TC LEGAL?
035306,000097: 21,2073 34752 P71A CAF TWO
035307,000098: 21,2074 54002 +3 TS Q
035308,000099: 21,2075 00004 INHINT
035309,000100: 21,2076 00006 EXTEND
035310,000101: 21,2077 32102 DCA CNTABTAD
035311,000102: 21,2100 52006 DTCB
035312,000103:
035313,000104: 21,2101 E7,1515 EBANK= DVCNTR
035314,000105: 21,2101 03413 12067 CNTABTAD 2CADR CONTABRT
035315,000106:
035316,000107: 21,2103 00106 1DEC70 DEC 70 B-14
035317,000108: 21,2104 00107 1DEC71 DEC 71 B-14
035318,000109:
035319,000110: 05,3413 BANK 05
035320,000111: 05,2000 SETLOC ABORTS1
035321,000112: 05,2000 BANK
035322,000113: 05,3413 COUNT* $$/P70
035323,000114:
035324,000115: 05,3413 33416 CONTABRT CAF ABRTJADR
035325,000116: 05,3414 54017 TS BRUPT
035326,000117: 05,3415 50017 RESUME
035327,000118:
035328,000119: 05,3416 13417 ABRTJADR TCF ABRTJASK
035329,000120: 05,3417 33477 ABRTJASK CAF OCTAL27
035330,000121:
![]() |
Page 825 |
035332,000123: 05,3420 60002 AD Q
035333,000124: 05,3421 54001 TS L
035334,000125: 05,3422 40000 COM
035335,000126: 05,3423 52760 DXCH -PHASE4
035336,000127: 05,3424 50002 INDEX Q
035337,000128: 05,3425 33476 CAF MODE70
035338,000129: 05,3426 55010 TS MODREG
035339,000130:
035340,000131: 05,3427 55162 TS DISPDEX # INSURE DISPDEX IS POSITIVE.
035341,000132:
035342,000133: 05,3430 10002 CCS Q # SET APSFLAG IF P71.
035343,000134: 05,3431 40106 CS FLGWRD10 # SET APSFLAG PRIOR TO THE ENEMA.
035344,000135: 05,3432 74737 MASK APSFLBIT
035345,000136: 05,3433 26106 ADS FLGWRD10
035346,000137: 05,3434 43501 CS DAPBITS # DAPBITS = OCT 40640 = BITS 6,8,9,15
035347,000138: 05,3435 70111 MASK DAPBOOLS # RESET ULLAGE,DRIFT,XOVRIINH, AND PULSES
035348,000139: 05,3436 54111 TS DAPBOOLS
035349,000140:
035350,000141: 05,3437 33502 CAF 1DEGDB # INSURE DAP DEADBAND IS SET TO 1 DEGREE
035351,000142: 05,3440 55343 TS DB
035352,000143:
035353,000144: 05,3441 40101 CS FLAGWRD5 # SET ENGONFLG.
035354,000145: 05,3442 74745 MASK ENGONBIT
035355,000146: 05,3443 26101 ADS FLAGWRD5
035356,000147:
035357,000148: 05,3444 44355 CS PRIO30 # INSURE THAT THE ENGINE IS ON, IF ARMED.
035358,000149: 05,3445 00006 EXTEND
035359,000150: 05,3446 02011 RAND DSALMOUT
035360,000151: 05,3447 64737 AD BIT13
035361,000152: 05,3450 00006 EXTEND
035362,000153: 05,3451 01011 WRITE DSALMOUT
035363,000154:
035364,000155: 05,3452 34735 CAF LRBYBIT # TERMINATE R12.
035365,000156: 05,3453 54107 TS FLGWRD11
035366,000157:
035367,000158: 05,3454 40074 CS FLAGWRD0 # SET R10FLAG TO SUPPRESS OUTPUTS TO THE
035368,000159: 05,3455 74752 MASK R10FLBIT # CROSS-POINTER DISPLAY.
035369,000160: 05,3456 26074 ADS FLAGWRD0 # THE FOLLOWING ENEMA WILL REMOVE THE
035370,000161: # DISPLAY INERTIAL DATA OUTBIT.
035371,000162:
035372,000163: 05,3457 00006 EXTEND # LOAD TEVENT FOR THE DOWNLINK.
035373,000164: 05,3460 30025 DCA TIME2
035374,000165: 05,3461 53342 DXCH TEVENT
035375,000166:
035376,000167: 05,3462 00006 EXTEND
035377,000168: 05,3463 33475 DCA SVEXITAD
035378,000169: 05,3464 53252 DXCH AVGEXIT
035379,000170:
035380,000171: 05,3465 02653 TC ABTKLEAN # KILL GROUPS 1,3, AND 6.
![]() |
Page 826 |
035382,000173: 05,3466 36250 CAF THREE # SET UP 4.3SPOT FOR GOABORT
035383,000174: 05,3467 54001 TS L
035384,000175: 05,3470 40000 COM
035385,000176: 05,3471 52760 DXCH -PHASE4
035386,000177:
035387,000178: 05,3472 04635 TC POSTJUMP
035388,000179: 05,3473 12763 CADR ENEMA
035389,000180:
035390,000181: 05,3474 E7,1515 EBANK= DVCNTR
035391,000182: 05,3474 03746 64067 SVEXITAD 2CADR SERVEXIT
035392,000183:
035393,000184: 05,3476 00106 MODE70 DEC 70 B-14
035394,000185: 05,3477 00027 OCTAL27 OCT 27
035395,000186: 05,3500 00107 MODE71 DEC 71 B-14
035396,000187:
035397,000188: 05,3501 40640 DAPBITS OCT 40640
035398,000189:
035399,000190: 05,3502 00554 1DEGDB OCT 00554
035400,000191: 32,3533 BANK 32
035401,000192: 32,2000 SETLOC ABORTS
035402,000193: 32,2000 BANK
035403,000194:
035404,000195: 32,3533 COUNT* $$/P70
035405,000196:
035406,000197: 32,3533 34751 GOABORT CAF FOUR
035407,000198: 32,3534 55515 TS DVCNTR
035408,000199:
035409,000200: 32,3535 33743 CAF WHICHADR
035410,000201: 32,3536 55455 TS WHICH
035411,000202:
035412,000203: 32,3537 06042 TC INTPRET
035413,000204: 32,3540 43014 CLEAR CLEAR
035414,000205: 32,3541 04665 FLRCS
035415,000206: 32,3542 04265 FLUNDISP
035416,000207: 32,3543 43014 CLEAR SET
035417,000208: 32,3544 03670 IDLEFLAG
035418,000209: 32,3545 06464 ACC4-2FL
035419,000210: 32,3546 45014 SET CALL
035420,000211: 32,3547 04462 P7071FLG
035421,000212: 32,3550 61071 INITCDUW
035422,000213: 32,3551 77776 EXIT
035423,000214:
035424,000215: 32,3552 05321 TC CHECKMM
035425,000216: 32,3553 00106 70DEC DEC 70 B-14
035426,000217: 32,3554 13667 TCF P71RET
035427,000218:
035428,000219: 32,3555 06042 P70INIT TC INTPRET
035429,000220: 32,3556 77624 CALL
035430,000221: 32,3557 65716 TGOCOMP
035431,000222: 32,3560 54345 DLOAD SL
![]() |
Page 827 |
035433,000224: 32,3561 34003 MDOTDPS
035434,000225: 32,3562 20205 4D
035435,000226: 32,3563 77665 BDDV
035436,000227: 32,3564 01244 MASS
035437,000228: 32,3565 16271 STODL TBUP
035438,000229: 32,3566 01244 MASS
035439,000230: 32,3567 70471 DDV SR1
035440,000231: 32,3570 16015 K(1/DV)
035441,000232: 32,3571 03635 STORE 1/DV1
035442,000233: 32,3572 03637 STORE 1/DV2
035443,000234: 32,3573 03641 STORE 1/DV3
035444,000235: 32,3574 77665 BDDV
035445,000236: 32,3575 25742 K(AT)
035446,000237: 32,3576 16263 STODL AT
035447,000238: 32,3577 34015 100PCTTO
035448,000239: 32,3600 02267 STORE TTO
035449,000240: 32,3601 57535 SLOAD DCOMP
035450,000241: 32,3602 26002 DPSVEX
035451,000242: 32,3603 77702 SR2
035452,000243: 32,3604 36265 STCALL VE
035453,000244: 32,3605 60275 COMMINIT
035454,000245: 32,3606 77745 INJTARG DLOAD
035455,000246: 32,3607 02567 ABTRDOT
035456,000247: 32,3610 36273 STCALL RDOTD # INITIALIZE RDOTD.
035457,000248: 32,3611 57313 YCOMP # COMPUTE Y
035458,000249: 32,3612 45246 ABS DSU
035459,000250: 32,3613 02565 YLIM # /Y/-DYMAX
035460,000251: 32,3614 75240 BMN SIGN # IF <0, XR<.5DEG, LEAVE YCO AT 0
035461,000252: 32,3615 65620 YOK # IF >0, FIX SIGN OF DEFICIT, THIS IS YCO.
035462,000253: 32,3616 02335 Y
035463,000254: 32,3617 03633 STORE YCO
035464,000255: 32,3620 45345 YOK DLOAD DSU
035465,000256: 32,3621 03633 YCO
035466,000257: 32,3622 02335 Y
035467,000258: 32,3623 77661 SR
035468,000259: 32,3624 20606 5D
035469,000260: 32,3625 03643 STORE XRANGE
035470,000261: 32,3626 45014 SET CALL
035471,000262: 32,3627 04461 FLVR
035472,000263: 32,3630 71554 THETCOMP
035473,000264: 32,3631 51025 DSU BPL
035474,000265: 32,3632 02561 THETCRIT
035475,000266: 32,3633 65637 +4
035476,000267: 32,3634 52175 VLOAD GOTO
035477,000268: 32,3635 02551 J1PARM
035478,000269: 32,3636 65642 STORPARM
035479,000270: 32,3637 43175 +4 VLOAD SET # IF J2 IS USED, SET THE
035480,000271: 32,3640 02555 J2PARM # ABORT TARGETING FLAG
035481,000272: 32,3641 04470 ABTTGFLG
035482,000273: 32,3642 16621 STORPARM STODL JPARM
![]() |
Page 828 |
035484,000275: 32,3643 03631 RCO
035485,000276: 32,3644 02625 STORE RP
035486,000277: 32,3645 77414 SET EXIT
035487,000278: 32,3646 04471 ROTFLAG
035488,000279:
035489,000280: 32,3647 03725 UPTHROT TC THROTUP
035490,000281:
035491,000282: 32,3650 05353 TC PHASCHNG
035492,000283: 32,3651 04024 OCT 04024
035493,000284:
035494,000285: 32,3652 05504 TC UPFLAG
035495,000286: 32,3653 00216 ADRES FLAP
035496,000287:
035497,000288: 32,3654 04616 UPTHROT1 TC BANKCALL # VERIFY THAT THE PANEL SWITCHES
035498,000289: 32,3655 73707 CADR P40AUTO # ARE PROPERLY SET.
035499,000290:
035500,000291: 32,3656 03725 TC THROTUP
035501,000292:
035502,000293: 32,3657 35027 CAF PRIO17 # LET SERVICER FINISH BEFORE CONNECTING
035503,000294: 32,3660 05146 TC PRIOCHNG # ASCENT GUIDANCE EQUATIONS.
035504,000295:
035505,000296: 32,3661 00006 EXTEND
035506,000297: 32,3662 33745 DCA ATMAGAD
035507,000298: 32,3663 53252 DXCH AVGEXIT
035508,000299:
035509,000300: 32,3664 05353 GRP4OFF TC PHASCHNG # TERMINATE USE OF GROUP 4.
035510,000301: 32,3665 00004 OCT 00004
035511,000302:
035512,000303: 32,3666 15155 TCF ENDOFJOB
035513,000304:
035514,000305: 32,3667 05516 P71RET TC DOWNFLAG
035515,000306: 32,3670 00215 ADRES LETABORT
035516,000307:
035517,000308: 32,3671 36000 CAF THRESH2 # SET DVMON THRESHOLD TO THE ASCENT VALUE.
035518,000309: 32,3672 55250 TS DVTHRUSH
035519,000310:
035520,000311: 32,3673 06042 TC INTPRET
035521,000312: 32,3674 77624 CALL
035522,000313: 32,3675 60251 P12INIT
035523,000314: 32,3676 45014 BON CALL
035524,000315: 32,3677 04707 FLAP
035525,000316: 32,3700 65704 OLDTIME
035526,000317: 32,3701 65716 TGOCOMP # IF FLAP=0, TGO=T-TIG
035527,000318: 32,3702 77650 GOTO
035528,000319: 32,3703 65606 INJTARG
035529,000320: 32,3704 72545 OLDTIME DLOAD SL1 # IF FLAP=1,TGO=2 TGO
035530,000321: 32,3705 03517 TGO
035531,000322: 32,3706 03502 STORE TGO1
035532,000323: 32,3707 77776 EXIT
035533,000324:
![]() |
Page 829 |
035535,000326: 32,3710 05353 TC PHASCHNG
035536,000327: 32,3711 04024 OCT 04024
035537,000328:
035538,000329: 32,3712 00006 EXTEND
035539,000330: 32,3713 31502 DCA TGO1
035540,000331: 32,3714 53517 DXCH TGO
035541,000332: 32,3715 13654 TCF UPTHROT1
035542,000333:
035543,000334: 32,3716 E7,1501 TGO1 = VGBODY
035544,000335:
035545,000336: # ************************************************************************
035546,000337:
035547,000338: 21,2105 BANK 21
035548,000339: 21,2000 SETLOC R11
035549,000340: 21,2000 BANK
035550,000341: 21,2105 COUNT* $$/P70
035551,000342:
035552,000343: 21,2105 40774 LEGAL? CS MMNUMBER # IS THE DESIRED PGM ALREADY IN PROGRESS?
035553,000344: 21,2106 61010 AD MODREG
035554,000345: 21,2107 00006 EXTEND
035555,000346: 21,2110 12121 BZF ABORTALM
035556,000347:
035557,000348: 21,2111 40105 CS FLAGWRD9 # ARE THE ABORTS ENABLED?
035558,000349: 21,2112 74743 MASK LETABBIT
035559,000350: 21,2113 10000 CCS A
035560,000351: 21,2114 12121 TCF ABORTALM
035561,000352:
035562,000353: 21,2115 30103 CA FLAGWRD7 # IS SERVICER ON THE AIR?
035563,000354: 21,2116 74747 MASK AVEGFBIT
035564,000355: 21,2117 10000 CCS A
035565,000356: 21,2120 00002 TC Q # YES. ALL IS WELL.
035566,000357: 21,2121 04364 ABORTALM TC FALTON
035567,000358: 21,2122 04457 TC RELDSP
035568,000359: 21,2123 04635 TC POSTJUMP
035569,000360: 21,2124 21051 CADR PINBRNCH
035570,000361:
035571,000362: 32,3716 BANK 32
035572,000363: 32,2000 SETLOC ABORTS
035573,000364: 32,2000 BANK
035574,000365:
035575,000366: 32,3716 COUNT* $$/P70
035576,000367:
035577,000368: # ************************************************************************
035578,000369:
035579,000370: 32,3716 45234 TGOCOMP RTB DSU
035580,000371: 32,3717 21574 LOADTIME
035581,000372: 32,3720 03442 TIG
035582,000373: 32,3721 77661 SL
035583,000374: 32,3722 20214 11D
035584,000375: 32,3723 03517 STORE TGO
![]() |
Page 830 |
035586,000377: 32,3724 77616 RVQ
035587,000378:
035588,000379: # ************************************************************************
035589,000380:
035590,000381: 32,3725 34737 THROTUP CAF BIT13
035591,000382: 32,3726 54055 TS THRUST
035592,000383: 32,3727 34750 CAF BIT4
035593,000384: 32,3730 00006 EXTEND
035594,000385: 32,3731 05014 WOR CHAN14
035595,000386: 32,3732 00002 TC Q
035596,000387:
035597,000388: # ************************************************************************
035598,000389:
035599,000390: 32,3733 00000 01750 10SECS 2DEC 1000 B-28
035600,000391: 32,3735 00021 33400 HINJECT 2DEC 18288 B-24 # 60,000 FEET EXPRESSED IN METERS.
035601,000392: 32,3737 11021 00000 (TGO)A 2DEC 37000 B-17
035602,000393: 32,3741 00507 25605 K(AT) 2DEC .02 # SCALING CONSTANT
035603,000394: 32,3743 02114 WHICHADR REMADR ABRTABLE
035604,000395:
035605,000396: # ************************************************************************
035606,000397:
035607,000398: 32,3744 E7,1515 EBANK= DVCNTR
035608,000399: 32,3744 03372 70067 ATMAGAD 2CADR ATMAG
End of include-file P70-P71.agc. Parent file is MAIN.agc