Source Code

These source-code files were from the printout at the MIT Museum, with many thanks to Deborah Douglas, the Museum's Curator of Science and Technology, for releasing it to us. The printout was digitally photographed by Paul Fjeld. A team of volunteers transcribed the source code manually from these images or, where appropriate, modified already-transcribed but similar source Luminary 131 (Apollo 13) source code to agree with the images from the printout. Note that the page images presented online are of reduced quality, and that higher-quality images are available. Report any conversion errors or legibility problems in page images to info@sandroid.org. Notations on the program listing read, in part:

	GAP:  ASSEMBLE REVISION 001 OF AGC PROGRAM LMY99 BY NASA 2021112-061
	20'35 OCT. 28,1968
Note that the date is the date of the printout, not the date of the program revision.

028020,000002:                                                                                                  ## Copyright:   Public domain.
028021,000003:                                                                                                  ## Filename:    GROUND_TRACKING_DETERMINATION_PROGRAM.agc
028022,000004:                                                                                                  ## Purpose:     Part of the source code for Luminary 1A build 099.
028023,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
028024,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), for Apollo 11.
028025,000007:                                                                                                  ## Assembler:   yaYUL
028026,000008:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
028027,000009:                                                                                                  ## Website:     www.ibiblio.org/apollo.
028028,000010:                                                                                                  ## Pages:       654-657
028029,000011:                                                                                                  ## Mod history: 2009-05-18 RSB  Adapted from the corresponding 
028030,000012:                                                                                                  ##                              Luminary131 file, using page 
028031,000013:                                                                                                  ##                              images from Luminary 1A.
028032,000014:                                                                                                  ##
028033,000015:                                                                                                  ## This source code has been transcribed or otherwise adapted from
028034,000016:                                                                                                  ## digitized images of a hardcopy from the MIT Museum.  The digitization
028035,000017:                                                                                                  ## was performed by Paul Fjeld, and arranged for by Deborah Douglas of
028036,000018:                                                                                                  ## the Museum.  Many thanks to both.  The images (with suitable reduction
028037,000019:                                                                                                  ## in storage size and consequent reduction in image quality as well) are
028038,000020:                                                                                                  ## available online at www.ibiblio.org/apollo.  If for some reason you
028039,000021:                                                                                                  ## find that the images are illegible, contact me at info@sandroid.org
028040,000022:                                                                                                  ## about getting access to the (much) higher-quality images which Paul
028041,000023:                                                                                                  ## actually created.
028042,000024:                                                                                                  ##
028043,000025:                                                                                                  ## Notations on the hardcopy document read, in part:
028044,000026:                                                                                                  ##
028045,000027:                                                                                                  ##      Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
028046,000028:                                                                                                  ##      16:27 JULY 14, 1969 
028047,000029: 

Page 654

028049,000031:                                                                                                  #  GROUND TRACKING DETERMINATION PROGRAM -- P21
028050,000032:                                                                                                  #  PROGRAM DESCRIPTION
028051,000033:                                                                                                  #        MOD NO -- 1
028052,000034:                                                                                                  #        MOD BY -- N. M. NEVILLE
028053,000035: 
028054,000036:                                                                                                  #  FUNCTIONAL DESCRIPTION --
028055,000037:                                                                                                  #        TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
028056,000038:                                                                                                  #        THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
028057,000039: 
028058,000040:                                                                                                  #  CALLING SEQUENCE --
028059,000041:                                                                                                  #        ASTRONAUT REQUEST THROUGH DSKY V37E21E
028060,000042: 
028061,000043:                                                                                                  #  SUBROUTINES CALLED --
028062,000044:                                                                                                  #        GOPERF4
028063,000045:                                                                                                  #        GOFLASH
028064,000046:                                                                                                  #        THISPREC
028065,000047:                                                                                                  #        OTHPREC
028066,000048:                                                                                                  #        LAT-LONG
028067,000049: 
028068,000050:                                                                                                  #  NORMAL EXIT MODES --
028069,000051:                                                                                                  #        ASTRONAUT REQUEST THROUGH DSKY TO TERMINATE PROGRAM V34E
028070,000052: 
028071,000053:                                                                                                  #  ALARM OR ABORT EXIT MODES --
028072,000054:                                                                                                  #        NONE
028073,000055: 
028074,000056:                                                                                                  #  OUTPUT --
028075,000057:                                                                                                  #        OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
028076,000058:                                                                                                  #        COMPUTED
028077,000059:                                                                                                  #                OPTION CODE     00002
028078,000060:                                                                                                  #                THIS            00001
028079,000061:                                                                                                  #                OTHER           00002
028080,000062:                                                                                                  #        DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS, MINUTES, SECONDS
028081,000063:                                                                                                  #        DECIMAL DISPLAY OF LAT,LONG,ALT
028082,000064: 
028083,000065:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
028084,000066:                                                                                                  #        AX0             2DEC    4.652459653 E-5 RADIANS         $68-69 CONSTANTS*
028085,000067:                                                                                                  #        -AY0            2DEC    2.137535898 E-5 RADIANS
028086,000068:                                                                                                  #        AZ0             2DEC    .7753206164     REVOLUTIONS
028087,000069:                                                                                                  #        FOR LUNAR ORBITS 504LM VECTOR IS NEEDED:
028088,000070:                                                                                                  #        504LM           2DEC    -2.700340600 E-5 RADIANS
028089,000071:                                                                                                  #        504LM _2        2DEC    -7.514128400 E-4 RADIANS
028090,000072:                                                                                                  #        504LM _4        2DEC    _2.553198641 E-4 RADIANS
028091,000073: 
028092,000074:                                                                                                  #        NONE
028093,000075: 
028094,000076:                                                                                                  #  DEBRIS

Page 655

028096,000078:                                                                                                  #        CENTRALS -- A,Q,L
028097,000079:                                                                                                  #        OTHER -- THOSE USED BY THE ABOVE LISTED SUBROUTINES
028098,000080:                                                                                                  #        SEE LEMPREC, LAT-LONG
028099,000081: 
028100,000082: 35,2545  30,2000                                  SBANK=   LOWSUPER                              #  FOR LOW 2CADR'S.
028101,000083: 
028102,000084: 33,2200                                           BANK     33                                    
028103,000085: 24,2000                                           SETLOC   P20S                                  
028104,000086: 24,2000                                           BANK                                           
028105,000087: 
028106,000088: 24,3505  E7,1762                                  EBANK=   P21TIME                               
028107,000089: 24,3505                                           COUNT*   $$/P21                                
028108,000090: 24,3505           34753        PROG21             CAF      ONE                                   
028109,000091: 24,3506           55145                           TS       OPTION2                               #  ASSUMED VEHICLE IS LM, R2 = 00001
028110,000092: 24,3507           34752                           CAF      BIT2                                  #  OPTION 2
028111,000093: 24,3510           04616                           TC       BANKCALL                              
028112,000094: 24,3511           20633                           CADR     GOPERF4                               
028113,000095: 24,3512           06001                           TC       GOTOP00H                              #  TERMINATE
028114,000096: 24,3513           03515                           TC       +2                                    #  PROCEED VALUE OF ASSUMED VEHICLE OK
028115,000097: 24,3514           03507                           TC       -5                                    #  R2 LOADED THROUGH DSKY
028116,000098: 24,3515           33665        P21PROG1           CAF      V6N34                                 #  LOAD DESIRED TIME OF LAT-LONG.
028117,000099: 24,3516           04616                           TC       BANKCALL                              
028118,000100: 24,3517           20476                           CADR     GOFLASH                               
028119,000101: 24,3520           06001                           TC       GOTOP00H                              #  TERM
028120,000102: 24,3521           03523                           TC       +2                                    #  PROCEED VALUES OK
028121,000103: 24,3522           03515                           TC       -5                                    #  TIME LOADED THROUGH DSKY
028122,000104: 24,3523           06037                           TC       INTPRET                               
028123,000105: 24,3524           77745                           DLOAD                                          
028124,000106: 24,3525           01046                                    DSPTEM1                               
028125,000107: 24,3526           34041                           STCALL   TDEC1                                 #  INTEG TO TIME SPECIFIED IN TDEC
028126,000108: 24,3527           27414                                    INTSTALL                              
028127,000109: 24,3530           43014                           BON      CLEAR                                 
028128,000110: 24,3531           00304                                    P21FLAG                               
028129,000111: 24,3532           51550                                    P21CONT                               #  ON -- RECYCLE USING BASE VECTOR
028130,000112: 24,3533           01674                                    VINTFLAG                              #  OFF -- 1ST PASS CALL BASE VECTOR
028131,000113: 24,3534           70535                           SLOAD    SR1                                   
028132,000114: 24,3535           01146                                    OPTION2                               
028133,000115: 24,3536           43030                           BHIZ     SET                                   
028134,000116: 24,3537           51541                                    +2                                    #  ZERO -- THIS VEHICLE (LM)
028135,000117: 24,3540           01474                                    VINTFLAG                              #  ONE -- OTHER VEHICLE (CM)
028136,000118: 24,3541           43014                           CLEAR    CLEAR                                 
028137,000119: 24,3542           01676                                    DIM0FLAG                              
028138,000120: 24,3543           01673                                    INTYPFLG                              #  PRECISION
028139,000121: 24,3544           77624                           CALL                                           
028140,000122: 24,3545           27134                                    INTEGRV                               #     CALCULATE
028141,000123: 24,3546           77650                           GOTO                                           #        AND
028142,000124: 24,3547           51571                                    P21VSAVE                              #  SAVE BASE VECTOR
028143,000125: 24,3550           77775        P21CONT            VLOAD                                          
028144,000126: 24,3551           03676                                    P21BASER                              #  RECYCLE -- INTEG FROM BASE VECTOR
028145,000127: 24,3552           25535                           STOVL    RCV                                   #  --POS

Page 656

028147,000129: 24,3553           03704                                    P21BASEV                              
028148,000130: 24,3554           15543                           STODL    VCV                                   #  --VEL
028149,000131: 24,3555           03763                                    P21TIME                               
028150,000132: 24,3556           01517                           STORE    TET                                   #  --TIME
028151,000133: 24,3557           43014                           CLEAR    CLEAR                                 
028152,000134: 24,3560           01676                                    DIM0FLAG                              
028153,000135: 24,3561           00263                                    MOONFLAG                              
028154,000136: 24,3562           53135                           SLOAD    BZE                                   
028155,000137: 24,3563           01164                                    P21ORIG                               
028156,000138: 24,3564           51567                                    +3                                    #  ZERO = EARTH
028157,000139: 24,3565           77614                           SET                                            #  ---2 = MOON
028158,000140: 24,3566           00063                                    MOONFLAG                              
028159,000141: 24,3567           77624                 +3        CALL                                           
028160,000142: 24,3570           27107                                    INTEGRVS                              
028161,000143: 24,3571           77745        P21VSAVE           DLOAD                                          #  SAVE CURRENT BASE VECTOR
028162,000144: 24,3572           00015                                    TAT                                   
028163,000145: 24,3573           27763                           STOVL    P21TIME                               #  --TIME
028164,000146: 24,3574           00017                                    RATT1                                 
028165,000147: 24,3575           27676                           STOVL    P21BASER                              #  --POS B-29 OR B-27
028166,000148: 24,3576           00025                                    VATT1                                 
028167,000149: 24,3577           03704                           STORE    P21BASEV                              #  --VEL B-07 OR B-05
028168,000150: 24,3600           53646                           ABVAL    SL*                                   
028169,000151: 24,3601           57576                                    0,2                                   
028170,000152: 24,3602           27712                           STOVL    P21VEL                                #  VEL/ FOR N91 DISP
028171,000153: 24,3603           00001                                    RATT                                  
028172,000154: 24,3604           50256                           UNIT     DOT                                   
028173,000155: 24,3605           00007                                    VATT                                  #  U(R).V
028174,000156: 24,3606           67471                           DDV      ASIN                                  #  U(R).U(V)
028175,000157: 24,3607           03712                                    P21VEL                                
028176,000158: 24,3610           03714                           STORE    P21GAM                                #  SIN-1 U(R).U(V) , -90 TO +90
028177,000159: 24,3611           67334                           SXA,2    SLOAD                                 
028178,000160: 24,3612           01163                                    P21ORIG                               #  0 = EARTH
028179,000161: 24,3613           01146                                    OPTION2                               
028180,000162: 24,3614           46142                           SR1      BHIZ                                  
028181,000163: 24,3615           51620                                    +3                                    
028182,000164: 24,3616           77650                           GOTO                                           
028183,000165: 24,3617           51623                                    +4                                    
028184,000166: 24,3620           77614                 +3        BON                                            
028185,000167: 24,3621           04307                                    SURFFLAG                              
028186,000168: 24,3622           51625                                    P21DSP                                
028187,000169: 24,3623           77614                 +4        SET                                            
028188,000170: 24,3624           00064                                    P21FLAG                               
028189,000171: 24,3625           67214        P21DSP             CLEAR    SLOAD                                 #  GENERATE DISPLAY DATA
028190,000172: 24,3626           01663                                    LUNAFLAG                              
028191,000173: 24,3627           00050                                    X2                                    
028192,000174: 24,3630           43054                           BZE      SET                                   
028193,000175: 24,3631           51633                                    +2                                    #  0 = EARTH
028194,000176: 24,3632           01463                                    LUNAFLAG                              
028195,000177: 24,3633           77775                           VLOAD                                          
028196,000178: 24,3634           00001                                    RATT                                  

Page 657

028198,000180: 24,3635           16032                           STODL    ALPHAV                                
028199,000181: 24,3636           00015                                    TAT                                   
028200,000182: 24,3637           45014                           CLEAR    CALL                                  
028201,000183: 24,3640           00662                                    ERADFLAG                              
028202,000184: 24,3641           26351                                    LAT-LONG                              
028203,000185: 24,3642           77605                           DMP                                            #  MPAC = ALT, METERS B-29
028204,000186: 24,3643           11667                                    K.01                                  
028205,000187: 24,3644           03716                           STORE    P21ALT                                #  ALT/100 FOR N91 DISP
028206,000188: 24,3645           77776                           EXIT                                           
028207,000189: 24,3646           33664                           CAF      V06N43                                #  DISPLAY LAT, LONG, ALT
028208,000190: 24,3647           04616                           TC       BANKCALL                              #  LAT, LONG = 1/2 REVS B0
028209,000191: 24,3650           20476                           CADR     GOFLASH                               #  ALT = KM B14
028210,000192: 24,3651           06001                           TC       GOTOP00H                              #  TERM
028211,000193: 24,3652           06001                           TC       GOTOP00H                              
028212,000194: 24,3653           06037                           TC       INTPRET                               #  V32E RECYCLE
028213,000195: 24,3654           43345                           DLOAD    DAD                                   
028214,000196: 24,3655           03763                                    P21TIME                               
028215,000197: 24,3656           11663                                    600SEC                                #  600 SECONDS OR 10 MIN
028216,000198: 24,3657           01046                           STORE    DSPTEM1                               
028217,000199: 24,3660           77634                           RTB                                            
028218,000200: 24,3661           51515                                    P21PROG1                              
028219,000201: 24,3662           00003 25140  600SEC             2DEC     60000      B-28                       #  10 MIN
028220,000202: 
028221,000203: 24,3664           01453        V06N43             VN       00643                                 
028222,000204: 24,3665           01442        V6N34              VN       00634                                 
028223,000205: 24,3666           00243 32703  K.01               2DEC     .01                                   
028224,000206: 

End of include-file GROUND_TRACKING_DETERMINATION_PROGRAM.agc.  Parent file is MAIN.agc