Source Code

These source-code files were derived originally from the scan from MIT's Dibner Institute's now-discontinued website titled "History of Recent Science and Technology". It is believed that the original listing was preserved by AGC developer Don Eyles, copied/reduced by AGC developer Hugh Blair-Smith, passed by AGC developer James Kernan to collector David Craig, scanned by Gary Neff, and then passed to the Dibner Institute where unfortunately the high-quality scans were reduced in legibility as part of the online-presentation process, and the original scans discarded. The source code was transcribed from those images by Ron Burkey. The images from the Dibner Institute website, and unfortunately not the discarded original high-quality scans, though with a few high-quality replacement scans provided directly by Gary Neff, are now available at the Virtual AGC project website. Report any conversion errors to info@sandroid.org. Notations on the program listing read, in part:

	GAP:  ASSEMBLE REVISION 131 OF AGC PROGRAM LUMINARY BY NASA 2021112-091
	17:53 DEC. 19, 1969
Note that the date is the date of the printout, not the date of the program revision.

027608,000002:                                                                                                  ## Copyright:   Public domain.
027609,000003:                                                                                                  ## Filename:    GROUND_TRACKING_DETERMINATION_PROGRAM.agc
027610,000004:                                                                                                  ## Purpose:     A section of Luminary 1C, revision 131.
027611,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
027612,000006:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 13 and Apollo 14.
027613,000007:                                                                                                  ##              This file is intended to be a faithful transcription, except
027614,000008:                                                                                                  ##              that the code format has been changed to conform to the
027615,000009:                                                                                                  ##              requirements of the yaYUL assembler rather than the 
027616,000010:                                                                                                  ##              original YUL assembler.
027617,000011:                                                                                                  ## Reference:   pp. 661-664 of 1729.pdf.
027618,000012:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
027619,000013:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
027620,000014:                                                                                                  ## Mod history: 05/21/03 RSB.   Began transcribing. 
027621,000015:                                                                                                  ##              05/14/05 RSB    Corrected website reference above.
027622,000016: 

Page 661

027624,000018:                                                                                                  #  GROUND TRACKING DETERMINATION PROGRAM -- P21
027625,000019: 
027626,000020:                                                                                                  #  PROGRAM DESCRIPTION
027627,000021:                                                                                                  #        MOD NO -- 1
027628,000022:                                                                                                  #        MOD BY -- N. M. NEVILLE
027629,000023: 
027630,000024:                                                                                                  #  FUNCTIONAL DESCRIPTION --
027631,000025:                                                                                                  #        TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
027632,000026:                                                                                                  #        THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
027633,000027: 
027634,000028:                                                                                                  #  CALLING SEQUENCE --
027635,000029:                                                                                                  #        ASTRONAUT REQUEST THROUGH DSKY V37E21E
027636,000030: 
027637,000031:                                                                                                  #  SUBROUTINES CALLED --
027638,000032:                                                                                                  #        GOPERF4
027639,000033:                                                                                                  #        GOFLASH
027640,000034:                                                                                                  #        THISPREC
027641,000035:                                                                                                  #        OTHPREC
027642,000036:                                                                                                  #        LAT-LONG
027643,000037: 
027644,000038:                                                                                                  #  NORMAL EXIT MODES --
027645,000039:                                                                                                  #        ASTRONAUT REQUEST THROUGH DSKY TO TERMINATE PROGRAM V34E
027646,000040: 
027647,000041:                                                                                                  #  ALARM OR ABORT EXIT MODES --
027648,000042:                                                                                                  #        NONE
027649,000043: 
027650,000044:                                                                                                  #  OUTPUT --
027651,000045:                                                                                                  #        OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
027652,000046:                                                                                                  #        COMPUTED
027653,000047:                                                                                                  #                OPTION CODE     00002
027654,000048:                                                                                                  #                THIS            00001
027655,000049:                                                                                                  #                OTHER           00002
027656,000050:                                                                                                  #        DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS, MINUTES, SECONS
027657,000051:                                                                                                  #        DECIMAL DISPLAY OF LAT,LONG,ALT
027658,000052: 
027659,000053:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
027660,000054:                                                                                                  #        AX0     2DEC    4.652459653 E-5 RADIANS
027661,000055:                                                                                                  #        -AY0    2DEC    2.137535898 E-5 RADIANS
027662,000056:                                                                                                  #        AZ0     2DEC    .7753206164     REVOLUTIONS
027663,000057:                                                                                                  #        FOR LUNAR ORBITS 504LM VECTOR IS NEEDED:
027664,000058:                                                                                                  #        504LM   2DEC    -2.700340600 E-5 RADIANS
027665,000059:                                                                                                  #        504LM+2 2DEC    -7.514128400 E-4 RADIANS
027666,000060:                                                                                                  #        504LM+4 2DEC    -2.553198641 E-4 RADIANS
027667,000061: 
027668,000062:                                                                                                  #  DEBRIS

Page 662

027670,000064:                                                                                                  #        CENTRALS -- A,C,L
027671,000065:                                                                                                  #        OTHER -- THOSE USED BY THE ABOVE LISTED SUBROUTINES
027672,000066:                                                                                                  #        SEE LEMPREC, LAT-LONG
027673,000067: 
027674,000068: 35,2455  30,2000                                  SBANK=   LOWSUPER                              #  FOR LOW 2CADR'S.
027675,000069: 
027676,000070: 33,2200                                           BANK     33                                    
027677,000071: 24,2000                                           SETLOC   P20S                                  
027678,000072: 24,2000                                           BANK                                           
027679,000073: 
027680,000074: 24,3506  E7,1762                                  EBANK=   P21TIME                               
027681,000075: 24,3506                                           COUNT*   $$/P21                                
027682,000076: 24,3506           34753        PROG21             CAF      ONE                                   
027683,000077: 24,3507           55144                           TS       OPTION2                               #  ASSUMED VEHICLE IS LM, R2 = 00001
027684,000078: 24,3510           34752                           CAF      BIT2                                  #  OPTION 2
027685,000079: 24,3511           04616                           TC       BANKCALL                              
027686,000080: 24,3512           20634                           CADR     GOPERF4                               
027687,000081: 24,3513           06001                           TC       GOTOP00H                              #  TERMINATE
027688,000082: 24,3514           03516                           TC       +2                                    #  PROCEED VALUE OF ASSUMED VEHICLE OK
027689,000083: 24,3515           03510                           TC       -5                                    #  R2 LOADED THROUGH DSKY
027690,000084: 24,3516           34755                           CAF      ZERO                                  #  INITIAL TIME = PRESENT TIME
027691,000085: 24,3517           55044                           TS       DSPTEM1                               
027692,000086: 24,3520           55045                           TS       DSPTEM1    +1                         
027693,000087: 24,3521           33675        P21PROG1           CAF      V6N34                                 #  LOAD DESIRED TIME OF LAT-LONG.
027694,000088: 24,3522           04616                           TC       BANKCALL                              
027695,000089: 24,3523           20477                           CADR     GOFLASH                               
027696,000090: 24,3524           06001                           TC       GOTOP00H                              #  TERM
027697,000091: 24,3525           03527                           TC       +2                                    #  PROCEED VALUES OK
027698,000092: 24,3526           03521                           TC       -5                                    #  TIME LOADED THROUGH DSKY
027699,000093: 24,3527           06042                           TC       INTPRET                               
027700,000094: 24,3530           53145                           DLOAD    BZE                                   
027701,000095: 24,3531           01045                                    DSPTEM1                               
027702,000096: 24,3532           51667                                    P21PRTM                               
027703,000097: 24,3533           34041        P21PROG2           STCALL   TDEC1                                 #  INTEG TO TIME SPECIFIED IN TDEC1
027704,000098: 24,3534           27410                                    INTSTALL                              
027705,000099: 24,3535           43014                           BON      CLEAR                                 
027706,000100: 24,3536           00304                                    P21FLAG                               
027707,000101: 24,3537           51555                                    P21CONT                               #  ON -- RECYCLE USING BASE VECTOR
027708,000102: 24,3540           01674                                    VINTFLAG                              #  OFF -- 1ST PASS CALL BASE VECTOR
027709,000103: 24,3541           70535                           SLOAD    SR1                                   
027710,000104: 24,3542           01145                                    OPTION2                               
027711,000105: 24,3543           43030                           BHIZ     SET                                   
027712,000106: 24,3544           51546                                    +2                                    #  ZERO -- THIS VEHICLE (LM)
027713,000107: 24,3545           01474                                    VINTFLAG                              #  ONE -- OTHER VEHICLE (CM)
027714,000108: 24,3546           43014                           CLEAR    CLEAR                                 
027715,000109: 24,3547           01676                                    DIM0FLAG                              
027716,000110: 24,3550           01673                                    INTYPFLG                              #  PRECISION
027717,000111: 24,3551           77624                           CALL                                           
027718,000112: 24,3552           27133                                    INTEGRV                               #      CALCULATE
027719,000113: 24,3553           77650                           GOTO                                           #        AND

Page 663

027721,000115: 24,3554           51576                                    P21VSAVE                              #  SAVE BASE VECTOR
027722,000116: 24,3555           77775        P21CONT            VLOAD                                          
027723,000117: 24,3556           03676                                    P21BASER                              #  RECYCLE -- INTEG FROM BASE VECTOR
027724,000118: 24,3557           25535                           STOVL    RCV                                   #  --POS
027725,000119: 24,3560           03704                                    P21BASEV                              
027726,000120: 24,3561           15543                           STODL    VCV                                   #  --VEL
027727,000121: 24,3562           03763                                    P21TIME                               
027728,000122: 24,3563           01517                           STORE    TET                                   #  --TIME
027729,000123: 24,3564           43014                           CLEAR    CLEAR                                 
027730,000124: 24,3565           01676                                    DIM0FLAG                              
027731,000125: 24,3566           00263                                    MOONFLAG                              
027732,000126: 24,3567           53135                           SLOAD    BZE                                   
027733,000127: 24,3570           01163                                    P21ORIG                               
027734,000128: 24,3571           51574                                    +3                                    #  ZERO = EARTH
027735,000129: 24,3572           77614                           SET                                            #     2 = MOON
027736,000130: 24,3573           00063                                    MOONFLAG                              
027737,000131: 24,3574           77624                 +3        CALL                                           
027738,000132: 24,3575           27106                                    INTEGRVS                              
027739,000133: 24,3576           77745        P21VSAVE           DLOAD                                          #  SAVE CURRENT BASE VECTOR
027740,000134: 24,3577           00015                                    TAT                                   
027741,000135: 24,3600           27763                           STOVL    P21TIME                               #  --TIME
027742,000136: 24,3601           00017                                    RATT1                                 
027743,000137: 24,3602           27676                           STOVL    P21BASER                              #  --POS B-29 OR B-27
027744,000138: 24,3603           00025                                    VATT1                                 
027745,000139: 24,3604           03704                           STORE    P21BASEV                              #  --VEL B-07 OR B-05
027746,000140: 24,3605           53646                           ABVAL    SL*                                   
027747,000141: 24,3606           57576                                    0,2                                   
027748,000142: 24,3607           27712                           STOVL    P21VEL                                #  VEL/ FOR N91 DISP
027749,000143: 24,3610           00001                                    RATT                                  
027750,000144: 24,3611           50256                           UNIT     DOT                                   
027751,000145: 24,3612           00007                                    VATT                                  #  U(R).V
027752,000146: 24,3613           67471                           DDV      ASIN                                  #  U(R).U(V)
027753,000147: 24,3614           03712                                    P21VEL                                
027754,000148: 24,3615           03714                           STORE    P21GAM                                #  SIN-1 U(R).U(V) , -90 TO +90
027755,000149: 24,3616           67334                           SXA,2    SLOAD                                 
027756,000150: 24,3617           01162                                    P21ORIG                               #  0 = EARTH
027757,000151: 24,3620           01145                                    OPTION2                               
027758,000152: 24,3621           46142                           SR1      BHIZ                                  
027759,000153: 24,3622           51625                                    +3                                    
027760,000154: 24,3623           77650                           GOTO                                           
027761,000155: 24,3624           51630                                    +4                                    
027762,000156: 24,3625           77614                 +3        BON                                            
027763,000157: 24,3626           04307                                    SURFFLAG                              
027764,000158: 24,3627           51632                                    P21DSP                                
027765,000159: 24,3630           77614                 +4        SET                                            
027766,000160: 24,3631           00064                                    P21FLAG                               
027767,000161: 24,3632           67214        P21DSP             CLEAR    SLOAD                                 #  GENERATE DISPLAY DATA
027768,000162: 24,3633           01663                                    LUNAFLAG                              
027769,000163: 24,3634           00050                                    X2                                    
027770,000164: 24,3635           43054                           BZE      SET                                   

Page 664

027772,000166: 24,3636           51640                                    +2                                    #  0 = EARTH
027773,000167: 24,3637           01463                                    LUNAFLAG                              
027774,000168: 24,3640           77775                           VLOAD                                          
027775,000169: 24,3641           00001                                    RATT                                  
027776,000170: 24,3642           16032                           STODL    ALPHAV                                
027777,000171: 24,3643           00015                                    TAT                                   
027778,000172: 24,3644           45014                           CLEAR    CALL                                  
027779,000173: 24,3645           00662                                    ERADFLAG                              
027780,000174: 24,3646           26347                                    LAT-LONG                              
027781,000175: 24,3647           77605                           DMP                                            #  MPAC = ALT, METERS B-29
027782,000176: 24,3650           11677                                    K.01                                  
027783,000177: 24,3651           03716                           STORE    P21ALT                                #  ALT/100 FOR N91 DISP
027784,000178: 24,3652           77776                           EXIT                                           
027785,000179: 24,3653           33674                           CAF      V06N43                                #  DISPLAY LAT, LONG, ALT
027786,000180: 24,3654           04616                           TC       BANKCALL                              #  LAT, LONG = 1/2 REVS B0
027787,000181: 24,3655           20477                           CADR     GOFLASH                               #  ALT = KM B14
027788,000182: 24,3656           06001                           TC       GOTOP00H                              #  TERM
027789,000183: 24,3657           06001                           TC       GOTOP00H                              
027790,000184: 24,3660           06042                           TC       INTPRET                               #  V32E RECYCLE
027791,000185: 24,3661           43345                           DLOAD    DAD                                   
027792,000186: 24,3662           03763                                    P21TIME                               
027793,000187: 24,3663           11673                                    600SEC                                #  600 SECONDS OR 10 MIN
027794,000188: 24,3664           01045                           STORE    DSPTEM1                               
027795,000189: 24,3665           77634                           RTB                                            
027796,000190: 24,3666           51521                                    P21PROG1                              
027797,000191: 24,3667           52034        P21PRTM            RTB      GOTO                                  
027798,000192: 24,3670           21574                                    LOADTIME                              
027799,000193: 24,3671           51533                                    P21PROG2                              
027800,000194: 24,3672           00003 25140  600SEC             2DEC     60000      B-28                       #  10 MIN
027801,000195: 
027802,000196: 24,3674           01453        V06N43             VN       00643                                 
027803,000197: 24,3675           01442        V6N34              VN       00634                                 
027804,000198: 24,3676           00243 32703  K.01               2DEC     .01                                   
027805,000199: 

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