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 Colossus 249 (Apollo 9) 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 055 OF AGC PROGRAM COMANCHE BY NASA 2021113-051
	10:28 APR.  1,1969
Note that the date is the date of the printout, not the date of the program revision.

019997,000002:                                                                                                  ## Copyright:   Public domain.
019998,000003:                                                                                                  ## Filename:    GROUND_TRACKING_DETERMINATION_PROGRAM.agc
019999,000004:                                                                                                  ## Purpose:     Part of the source code for Comanche, build 055.
020000,000005:                                                                                                  ##              It is part of the source code for the Command Module's (CM)
020001,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), Apollo 11.
020002,000007:                                                                                                  ## Assembler:   yaYUL
020003,000008:                                                                                                  ## Reference:   pp. 456-459
020004,000009:                                                                                                  ## Contact:     Onno Hommes <ohommes@cmu.edu>.
020005,000010:                                                                                                  ## Website:     www.ibiblio.org/apollo.
020006,000011:                                                                                                  ## Mod history: 2009-05-07 OH   Transcription Batch 1 Assignment 
020007,000012:                                                                                                  ##              2009-05-20 RSB  Corrected a couple of DIMOFLAG to DIM0FLAG.
020008,000013:                                                                                                  ##              2016-12-10 RSB  Proofed comments with octopus/ProoferComments
020009,000014:                                                                                                  ##                              and fixed the errors found.
020010,000015:                                                                                                  ##              2016-12-10 RSB  All of the GOTOPOOH's should have been
020011,000016:                                                                                                  ##                              GOTOPOOH, and I've changed them back.
020012,000017:                                                                                                  ##
020013,000018:                                                                                                  ## The contents of the "Comanche055" files, in general, are transcribed 
020014,000019:                                                                                                  ## from scanned documents. 
020015,000020:                                                                                                  ##
020016,000021:                                                                                                  ##      Assemble revision 055 of AGC program Comanche by NASA
020017,000022:                                                                                                  ##      2021113-051.  April 1, 1969.  
020018,000023:                                                                                                  ##
020019,000024:                                                                                                  ##      This AGC program shall also be referred to as Colossus 2A
020020,000025:                                                                                                  ##
020021,000026:                                                                                                  ##      Prepared by
020022,000027:                                                                                                  ##                      Massachusetts Institute of Technology
020023,000028:                                                                                                  ##                      75 Cambridge Parkway
020024,000029:                                                                                                  ##                      Cambridge, Massachusetts
020025,000030:                                                                                                  ##
020026,000031:                                                                                                  ##      under NASA contract NAS 9-4065.
020027,000032:                                                                                                  ##
020028,000033:                                                                                                  ## Refer directly to the online document mentioned above for further information.
020029,000034:                                                                                                  ## Please report any errors to info@sandroid.org.
020030,000035: 

Page 456

020032,000037:                                                                                                  #  GROUND TRACKING DETERMINATION PROGRAM P21
020033,000038: 
020034,000039:                                                                                                  #  PROGRAM DESCRIPTION
020035,000040:                                                                                                  #  MOD NO - 1
020036,000041:                                                                                                  #  MOD BY - N. M. NEVILLE
020037,000042:                                                                                                  #  FUNCTIONAL DECRIPTION-
020038,000043: 
020039,000044:                                                                                                  #  TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
020040,000045:                                                                                                  #  THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
020041,000046:                                                                                                  #  CALLING SEQUENCE-
020042,000047: 
020043,000048:                                                                                                  #  ASTRONAUT REQUEST THROUGH DSKY V37E21E
020044,000049:                                                                                                  #  SUBROUTINES CALLED-
020045,000050: 
020046,000051:                                                                                                  #  GOPERF4
020047,000052:                                                                                                  #  GOFLASH
020048,000053:                                                                                                  #  THISPREC
020049,000054:                                                                                                  #  OTHPREC
020050,000055:                                                                                                  #  LAT-LONG
020051,000056:                                                                                                  #  NORMAL EXIT MODES-
020052,000057: 
020053,000058:                                                                                                  #  ASTRONAUT REQUEST TROUGH DSKY TO TERMINATE PROGRAM V34E
020054,000059:                                                                                                  #  ALARM OR ABORT EXIT MODES-
020055,000060: 
020056,000061:                                                                                                  #  NONE
020057,000062:                                                                                                  #  OUTPUT-
020058,000063: 
020059,000064:                                                                                                  #  OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
020060,000065:                                                                                                  #  COMPUTED
020061,000066:                                                                                                  #           OPTION CODE  00002
020062,000067:                                                                                                  #           THIS         00001
020063,000068:                                                                                                  #           OTHER                00002
020064,000069:                                                                                                  #  DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS , MINUTES , SECONDS
020065,000070:                                                                                                  #  DECIMAL DISPLAY OF LAT,LONG,ALT
020066,000071:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
020067,000072: 
020068,000073:                                                                                                  #  AX0    2DEC   4.652459653 E-5   RADIANS       %68-69 CONSTANTS"
020069,000074: 
020070,000075:                                                                                                  #  -AY0   2DEC   2.147535898 E-5   RADIANS
020071,000076: 
020072,000077:                                                                                                  #  AZ0    2DEC   .7753206164       REVOLUTIONS
020073,000078:                                                                                                  #  FOR LUNAR ORBITS 504LM VECTOR IS NEEDED
020074,000079: 
020075,000080:                                                                                                  #  504LM  2DEC   -2.700340600 E-5  RADIANS
020076,000081: 
020077,000082:                                                                                                  #  504LM _2 2DEC -7.514128400 E-4  RADIANS
020078,000083: 
020079,000084:                                                                                                  #  504LM _4 2DEC _2.553198641 E-4  RADIANS
020080,000085: 
020081,000086:                                                                                                  #  NONE
020082,000087:                                                                                                  #  DEBRIS
020083,000088: 

Page 457

020085,000090:                                                                                                  #  CENTRALS-A,Q,L
020086,000091:                                                                                                  #  OTHER-THOSE USED BY THE ABOVE LISTED SUBROUTINES
020087,000092:                                                                                                  #  SEE LEMPREC, LAT-LONG
020088,000093: 
020089,000094: 33,3776  30,2000                                  SBANK=   LOWSUPER                              #  FOR LOW 2CADR'S.
020090,000095: 
020091,000096: 33,3776                                           BANK     33                                    
020092,000097: 37,2000                                           SETLOC   P20S                                  
020093,000098: 37,2000                                           BANK                                           
020094,000099: 
020095,000100: 37,2001  E4,1715                                  EBANK=   P21TIME                               
020096,000101: 37,2001                                           COUNT    24/P21                                
020097,000102: 
020098,000103: 37,2001           35017        PROG21             CAF      ONE                                   
020099,000104: 37,2002           55132                           TS       OPTION2                               #  ASSUMED VEHICLE IS LM, R2 = 00001
020100,000105: 37,2003           35016                           CAF      BIT2                                  #   OPTION 2
020101,000106: 37,2004           04662                           TC       BANKCALL                              
020102,000107: 37,2005           21055                           CADR     GOPERF4                               
020103,000108: 37,2006           04106                           TC       GOTOPOOH                              #  TERMINATE
020104,000109: 37,2007           02011                           TC       +2                                    #  PROCEED VALUE OF ASSUMED VEHICLE OK
020105,000110: 37,2010           02003                           TC       -5                                    #  R2 LOADED THROUGH DSKY
020106,000111: 37,2011           32152        P21PROG1           CAF      V6N34                                 #  LOAD DESIRED TIME OF LAT-LONG.
020107,000112: 37,2012           04662                           TC       BANKCALL                              
020108,000113: 37,2013           20720                           CADR     GOFLASH                               
020109,000114: 37,2014           04106                           TC       GOTOPOOH                              #  TERM
020110,000115: 37,2015           02017                           TC       +2                                    #  PROCEED VALUES OK
020111,000116: 37,2016           02011                           TC       -5                                    #  TIME LOADED THROUGH DSKY
020112,000117: 37,2017           06006                           TC       INTPRET                               
020113,000118: 37,2020           77745                           DLOAD                                          
020114,000119: 37,2021           01046                                    DSPTEM1                               
020115,000120: 37,2022           34041                           STCALL   TDEC1                                 #  INTEG TO TIME SPECIFIED IN TDEC
020116,000121: 37,2023           27442                                    INTSTALL                              
020117,000122: 37,2024           43014                           BON      SET                                   
020118,000123: 37,2025           01303                                    P21FLAG                               
020119,000124: 37,2026           76044                                    P21CONT                               #  ON...RECYCLE USING BASE VECTOR
020120,000125: 37,2027           01474                                    VINTFLAG                              #  OFF..1ST PASS CALC BASE VECTOR
020121,000126: 37,2030           70535                           SLOAD    SR1                                   
020122,000127: 37,2031           01133                                    OPTION2                               
020123,000128: 37,2032           43030                           BHIZ     CLEAR                                 
020124,000129: 37,2033           76035                                    +2                                    #  ZERO..THIS VEHICLE (CM)
020125,000130: 37,2034           01674                                    VINTFLAG                              #  ONE...OTHER VEHICLE(LM)
020126,000131: 37,2035           43014                           CLEAR    CLEAR                                 
020127,000132: 37,2036           01676                                    DIM0FLAG                              
020128,000133: 37,2037           01673                                    INTYPFLG                              #  PRECISION
020129,000134: 37,2040           77624                           CALL                                           
020130,000135: 37,2041           27162                                    INTEGRV                               #  CALCULATE
020131,000136: 37,2042           77650                           GOTO                                           #  .AND
020132,000137: 37,2043           76065                                    P21VSAVE                              #  ..SAVE BASE VECTOR
020133,000138: 37,2044           77775        P21CONT            VLOAD                                          #  RECYCLE..INTEG FROM BASE VECTOR                       
020134,000139: 37,2045           03605                                    P21BASER                              

Page 458

020136,000141: 37,2046           25535                           STOVL    RCV                                   #  ..POS
020137,000142: 37,2047           03613                                    P21BASEV                              
020138,000143: 37,2050           15543                           STODL    VCV                                   #  ..VEL
020139,000144: 37,2051           02316                                    P21TIME                               
020140,000145: 37,2052           01517                           STORE    TET                                   #  ..TIME
020141,000146: 37,2053           43014                           CLEAR    CLEAR                                 
020142,000147: 37,2054           01676                                    DIM0FLAG                              
020143,000148: 37,2055           00263                                    MOONFLAG                              
020144,000149: 37,2056           53135                           SLOAD    BZE                                   
020145,000150: 37,2057           03604                                    P21ORIG                               
020146,000151: 37,2060           76063                                    +3                                    #  ZERO = EARTH
020147,000152: 37,2061           77614                           SET                                            #  ...2 = MOON
020148,000153: 37,2062           00063                                    MOONFLAG                              
020149,000154: 37,2063           77624                           CALL                                           
020150,000155: 37,2064           27135                                    INTEGRVS                              
020151,000156: 37,2065           77745        P21VSAVE           DLOAD                                          #  SAVE CURRENT BASE VECTOR
020152,000157: 37,2066           00015                                    TAT                                   
020153,000158: 37,2067           26316                           STOVL    P21TIME                               #  ..TIME
020154,000159: 37,2070           00017                                    RATT1                                 
020155,000160: 37,2071           27605                           STOVL    P21BASER                              #  ..POS B-29 OR B-27
020156,000161: 37,2072           00025                                    VATT1                                 
020157,000162: 37,2073           03613                           STORE    P21BASEV                              #  ..VEL B-7  OR B-5
020158,000163: 37,2074           53646                           ABVAL    SL*                                   
020159,000164: 37,2075           57576                                    0,2                                   
020160,000165: 37,2076           27623                           STOVL    P21VEL                                #  /VEL/ FOR N73 DSP
020161,000166: 37,2077           00001                                    RATT                                  
020162,000167: 37,2100           50256                           UNIT     DOT                                   
020163,000168: 37,2101           00007                                    VATT                                  #  U(R).(V)
020164,000169: 37,2102           67471                           DDV      ASIN                                  #  U(R).U(V)
020165,000170: 37,2103           03623                                    P21VEL                                
020166,000171: 37,2104           03625                           STORE    P21GAM                                #  SIN-1 U(R).U(V), -90 TO +90
020167,000172: 37,2105           43134                           SXA,2    SET                                   
020168,000173: 37,2106           03603                                    P21ORIG                               #  0 = EARTH  2 = MOON
020169,000174: 37,2107           01063                                    P21FLAG                               
020170,000175: 37,2110           67214        P21DSP             CLEAR    SLOAD                                 #  GENERATE DISPLAY DATA
020171,000176: 37,2111           01663                                    LUNAFLAG                              
020172,000177: 37,2112           00050                                    X2                                    
020173,000178: 37,2113           43054                           BZE      SET                                   
020174,000179: 37,2114           76116                                    +2                                    #  0 = EARTH
020175,000180: 37,2115           01463                                    LUNAFLAG                              
020176,000181: 37,2116           77775                           VLOAD                                          
020177,000182: 37,2117           00001                                    RATT                                  
020178,000183: 37,2120           16152                           STODL    ALPHAV                                
020179,000184: 37,2121           00015                                    TAT                                   
020180,000185: 37,2122           45014                           CLEAR    CALL                                  
020181,000186: 37,2123           00662                                    ERADFLAG                              
020182,000187: 37,2124           26370                                    LAT-LONG                              
020183,000188: 37,2125           77605                           DMP                                            #  MPAC = ALT, METERS B-29
020184,000189: 37,2126           36154                                    K.01                                  
020185,000190: 37,2127           03621                           STORE    P21ALT                                #  ALT/100 FOR N73 DSP

Page 459

020187,000192: 37,2130           77776                           EXIT                                           
020188,000193: 37,2131           32151                           CAF      V06N43                                #  DISPLAY LAT,LONG,ALT
020189,000194: 37,2132           04662                           TC       BANKCALL                              #  LAT,LONG = REVS B0 BOTH EARTH/MOON
020190,000195: 37,2133           20720                           CADR     GOFLASH                               #  ALT = METERS B-29  BOTH EARTH/MOON
020191,000196: 37,2134           04106                           TC       GOTOPOOH                              #  TERM
020192,000197: 37,2135           04106                           TC       GOTOPOOH                              
020193,000198: 37,2136           06006                           TC       INTPRET                               #  V32E RECYCLE
020194,000199: 37,2137           43345                           DLOAD    DAD                                   
020195,000200: 37,2140           02316                                    P21TIME                               
020196,000201: 37,2141           36146                                    600SEC                                #  600 SECONDS OR 10 MIN
020197,000202: 37,2142           01046                           STORE    DSPTEM1                               
020198,000203: 37,2143           77634                           RTB                                            
020199,000204: 37,2144           76011                                    P21PROG1                              
020200,000205: 
020201,000206: 37,2145           00003 25140  600SEC             2DEC     60000      B-28                       #  10 MIN
020202,000207: 
020203,000208: 37,2147           00001        P21ONENN           OCT      00001                                 #  NEEDED TO DETERMINE VEHICLE
020204,000209: 37,2150           00000                           OCT      00000                                 #  TO BE INTEGRATED
020205,000210: 37,2151           01453        V06N43             VN       00643                                 
020206,000211: 37,2152           01442        V6N34              VN       00634                                 
020207,000212: 37,2153           00243 32703  K.01               2DEC     .01                                   
020208,000213: 

End of include-file GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc.  Parent file is MAIN.agc