Source Code

These source-code files are part of a reconstructed copy of Luminary 69/2, the flown, final release of the Apollo 10 Lunar Module (LM) Apollo Guidance Computer (AGC) software.

The reconstruction is based on the source code of Luminary 69 — i.e., the initial, unflown version, "revision 0" — of which a contemporary listing was available. The code was then updated by incorporating the differences between Luminary 69 and Luminary 69/2, known from other contemporary documentation. The only such difference is the implementation in Luminary 69/2 of the "R-2 Lunar Potential Model", the source code for which was taken from program Luminary 99/1 (Apollo 11 LM), of which a contemporary listing was also available. Finally, the now-reconstructed Luminary 69/2 was then validated by assembling it to executable form and verifying that its memory banks had the correct checksums, known from still other contemporary documentation.

Note that page numbers in the reconstructed code match those in the original Luminary 69 program listing, or in the ORBITAL INTEGRATION log section, in Luminary 99/1. Page numbers would certainly differ somewhat in a contemporary Luminary 69/2 listing. Moreover, annotations that were not present in the contemporary source code have been added to the reconstructed code to justify each change in Luminary 69/2 relative to Luminary 69. Here's a guide to the Apollo documentation referenced in those annotations:
Comments from the original source code are prefixed with a single '#' symbol, whereas comments added later are prefixed by "##" or "###". Report any errors noted by creating an issue report at the Virtual AGC project's GitHub repository.

047183,000002:                                                                                                  ## Copyright:   Public domain.
047184,000003:                                                                                                  ## Filename:    INTERPRETIVE_CONSTANTS.agc
047185,000004:                                                                                                  ## Purpose:     A section of LUM69 revision 2.
047186,000005:                                                                                                  ##              It is part of the reconstructed source code for the flown
047187,000006:                                                                                                  ##              version of the flight software for the Lunar Module's (LM)
047188,000007:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 10. The code has
047189,000008:                                                                                                  ##              been recreated from a copy of Luminary revsion 069, using
047190,000009:                                                                                                  ##              changes present in Luminary 099 which were described in
047191,000010:                                                                                                  ##              Luminary memos 75 and 78. The code has been adapted such
047192,000011:                                                                                                  ##              that the resulting bugger words exactly match those specified
047193,000012:                                                                                                  ##              for LUM69 revision 2 in NASA drawing 2021152B, which gives
047194,000013:                                                                                                  ##              relatively high confidence that the reconstruction is correct.
047195,000014:                                                                                                  ## Reference:   pp. 1095-1096
047196,000015:                                                                                                  ## Assembler:   yaYUL
047197,000016:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
047198,000017:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
047199,000018:                                                                                                  ## Mod history: 2019-07-27 MAS  Created from Luminary 69.
047200,000019:                                                                                                  ##              2021-05-30 ABS  DFC-6 -> DEC-6, DFC-12 -> DEC-12
047201,000020: 

Page 1095

047203,000022: 23,2000                                           SETLOC   INTPRET1                              
047204,000023: 23,2000                                           BANK                                           
047205,000024: 
047206,000025: 23,2413                                           COUNT*   $$/ICONS                              
047207,000026: 23,2413           10000 00000  DP1/4TH            2DEC     .25                                   
047208,000027: 
047209,000028: 23,2415           00000 00000  UNITZ              2DEC     0          B-28                       
047210,000029: 
047211,000030: 23,2417           00000 00000  UNITY              2DEC     0          B-28                       
047212,000031: 
047213,000032: 23,2421           20000 00000  UNITX              2DEC     .5                                    
047214,000033: 
047215,000034: 23,2423           00000 00000  ZEROVECS           2DEC     0          B-28                       
047216,000035: 
047217,000036: 23,2425           00000 00000                     2DEC     0          B-28                       
047218,000037: 
047219,000038: 23,2427           00000 00000                     2DEC     0          B-28                       
047220,000039: 
047221,000040: 23,2431  23,2421               DPHALF             =        UNITX                                 
047222,000041: 23,2431           37777        DPPOSMAX           OCT      37777                                 
047223,000042: 23,2432           37777                           OCT      37777                                 
047224,000043: 

Page 1096

047226,000045:                                                                                                  #  INTERPRETIVE CONSTANTS IN THE OTHER HALF-MEMORY
047227,000046: 
047228,000047: 11,2000                                           SETLOC   INTPRET2                              
047229,000048: 11,2000                                           BANK                                           
047230,000049: 
047231,000050: 11,2266                                           COUNT*   $$/ICONS                              
047232,000051: 11,2266           00000 00000  ZUNIT              2DEC     0          B-28                       
047233,000052: 
047234,000053: 11,2270           00000 00000  YUNIT              2DEC     0          B-28                       
047235,000054: 
047236,000055: 11,2272           20000 00000  XUNIT              2DEC     .5                                    
047237,000056: 
047238,000057: 11,2274           00000 00000  ZEROVEC            2DEC     0          B-28                       
047239,000058: 
047240,000059: 11,2276           00000 00000                     2DEC     0          B-28                       
047241,000060: 
047242,000061: 11,2300           00000 00000                     2DEC     0          B-28                       
047243,000062: 
047244,000063: 11,2302           77777                           OCT      77777                                 #  -0, -6, -12 MUST REMAIN IN THIS ORDER
047245,000064: 11,2303           77771        DEC-6              DEC      -6         B-14                       
047246,000065: 11,2304           77763        DEC-12             DEC      -12        B-14                       
047247,000066: 11,2305           37777 37777  LODPMAX            2OCT     3777737777                            #  THESE TWO CONSTANTS MUST REMAIN
047248,000067: 
047249,000068: 11,2307           37777 37777  LODPMAX1           2OCT     3777737777                            #  ADJACENT AND THE SAME FOR INTEGRATION
047250,000069: 
047251,000070: 11,2311  11,2274               ZERODP             =        ZEROVEC                               
047252,000071: 11,2311  11,2272               HALFDP             =        XUNIT                                 
047253,000072: 
047254,000073: 

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