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.

015086,000002:                                                                                                  ## Copyright:   Public domain.
015087,000003:                                                                                                  ## Filename:    R63.agc
015088,000004:                                                                                                  ## Purpose:     A section of LUM69 revision 2.
015089,000005:                                                                                                  ##              It is part of the reconstructed source code for the flown
015090,000006:                                                                                                  ##              version of the flight software for the Lunar Module's (LM)
015091,000007:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 10. The code has
015092,000008:                                                                                                  ##              been recreated from a copy of Luminary revsion 069, using
015093,000009:                                                                                                  ##              changes present in Luminary 099 which were described in
015094,000010:                                                                                                  ##              Luminary memos 75 and 78. The code has been adapted such
015095,000011:                                                                                                  ##              that the resulting bugger words exactly match those specified
015096,000012:                                                                                                  ##              for LUM69 revision 2 in NASA drawing 2021152B, which gives
015097,000013:                                                                                                  ##              relatively high confidence that the reconstruction is correct.
015098,000014:                                                                                                  ## Reference:   pp. 351-354
015099,000015:                                                                                                  ## Assembler:   yaYUL
015100,000016:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
015101,000017:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
015102,000018:                                                                                                  ## Mod history: 2019-07-27 MAS  Created from Luminary 69.
015103,000019: 

Page 351

015105,000021:                                                                                                  #  SUBROUTINE NAME:      V89CALL
015106,000022:                                                                                                  #  MOD NO:       0                       DATE:           9 JAN 1968
015107,000023:                                                                                                  #  MOD BY:       DIGITAL DEVEL GROUP     LOG SECTION:    R63
015108,000024: 
015109,000025:                                                                                                  #  FUNCTIONAL DESCRIPTION:
015110,000026: 
015111,000027:                                                                                                  #  CALLED BY VERB 89 ENTER DURING P00.  PRIO 10 USED.  CALCULATES AND
015112,000028:                                                                                                  #  DISPLAYS FINAL FDAI BALL ANGLES TO POINT LM +X OR +Z AXIS AT CSM.
015113,000029: 
015114,000030:                                                                                                  #  1. KEY IN V 89 E ONLY IF IN PROG 00.  IF NOT IN P00, OPERATOR ERROR AND
015115,000031:                                                                                                  #  EXIT R63, OTHERWISE CONTINUE.
015116,000032: 
015117,000033:                                                                                                  #  2. IF IN P00, DO IMU STATUS CHECK ROUTINE (R02BOTH).  IF IMU ON AND ITS
015118,000034:                                                                                                  #  ORIENTATION KNOWN TO LGC, CONTINUE.
015119,000035: 
015120,000036:                                                                                                  #  3. FLASH DISPLAY V 04 N 06.  R2 INDICATES WHICH SPACECRAFT AXIS IS TO
015121,000037:                                                                                                  #  BE POINTED AT CSM.  INITIAL CHOICE IS PREFERRED (+Z) AXIS (R2=1).
015122,000038:                                                                                                  #  ASTRONAUT CAN CHANGE TO (+X) AXIS (R2 NOT =1) BY V 22 E 2 E.  CONTINUE
015123,000039:                                                                                                  #  AFTER KEYING IN PROCEED.
015124,000040: 
015125,000041:                                                                                                  #  4. BOTH VEHICLE STATE VECTORS UPDATED BY CONIC EQS.
015126,000042: 
015127,000043:                                                                                                  #  5. HALF MAGNITUDE UNIT LOS VECTOR (IN STABLE MEMBER COORDINATES) AND
015128,000044:                                                                                                  #  HALF MAGNITUDE UNIT SPACECRAFT AXIS VECTOR (IN BODY COORDINATES)
015129,000045:                                                                                                  #  PREPARED FOR VECPOINT.
015130,000046: 
015131,000047:                                                                                                  #  6. GIMBAL ANGLES FROM VECPOINT TRANSFORMED INTO FDAI BALL ANGLES BY
015132,000048:                                                                                                  #  BALLANGS.  FLASH DISPLAY V 06 N 18 AND AWAIT RESPONSE.
015133,000049: 
015134,000050:                                                                                                  #  7.    RECYCLE - RETURN TO STEP 4.
015135,000051:                                                                                                  #        TERMINATE - EXIT R63.
015136,000052:                                                                                                  #        PROCEED - RESET 3AXISFLG AND CALL R60LEM FOR ATTITUDE MANEUVER.
015137,000053: 
015138,000054:                                                                                                  #  CALLING SEQUENCE:     V 89 E.
015139,000055: 
015140,000056:                                                                                                  #  SUBROUTINES CALLED:   CHKPOOH, R02BOTH, GOXDSPF, CSMCONIC, LEMCONIC,
015141,000057:                                                                                                  #                        VECPOINT, BALLANGS, R60LEM.
015142,000058: 
015143,000059:                                                                                                  #  NORMAL EXIT MODES:    TC ENDEXT
015144,000060: 
015145,000061:                                                                                                  #  ALARMS:       1. OPERATOR ERROR IF NOT IN P00.
015146,000062:                                                                                                  #                2. PROGRAM ALARM IF IMU IS OFF.
015147,000063:                                                                                                  #                3. PROGRAM ALARM IF IMU ORIENTATION IS UNKNOWN.
015148,000064: 
015149,000065:                                                                                                  #  OUTPUT:       NONE
015150,000066: 
015151,000067:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED:  NONE
015152,000068: 
015153,000069:                                                                                                  #  DEBRIS:       OPTION1, +1, TDEC1, POINTVSM, SCAXIS, CPHI, CTHETA, CPSI,

Page 352

015155,000071:                                                                                                  #                3AXISFLG.
015156,000072: 
015157,000073: 06,3715  E4,1612                                  EBANK=   RONE                                  
015158,000074: 32,2227                                           BANK     32                                    
015159,000075: 26,2000                                           SETLOC   BAWLANGS                              
015160,000076: 26,2000                                           BANK                                           
015161,000077: 
015162,000078: 26,2000                                           COUNT*   $$/R63                                
015163,000079: 26,2000           04616        V89CALL            TC       BANKCALL                              #  IMU STATUS CHECK.  RETURNS IF ORIENTATION
015164,000080: 26,2001           11175                           CADR     R02BOTH                               #  KNOWN.  ALARMS IF NOT.
015165,000081: 26,2002           36244                           CAF      THREE                                 #  ALLOW ASTRONAUT TO SELECT DESIRED
015166,000082: 26,2003           55051                           TS       OPTIONX                               #  TRACKING ATTITUDE AXIS.
015167,000083: 26,2004           34753                           CAF      ONE                                   
015168,000084: 26,2005           55052                           TS       OPTIONX    +1                         
015169,000085: 26,2006           32075                           CAF      VB04N12                               #  V 04 N 12
015170,000086: 26,2007           04616                           TC       BANKCALL                              
015171,000087: 26,2010           20351                           CADR     GOFLASH                               
015172,000088: 26,2011           05472                           TC       ENDEXT                                #  TERMINATE
015173,000089: 26,2012           02014                           TC       +2                                    #  PROCEED
015174,000090: 26,2013           02006                           TC       -5                                    #  DATA IN. OPTION1+1 = 1 FOR Z AXIS
015175,000091: 26,2014           06036        V89RECL            TC       INTPRET                               #                    = 2 FOR X AXIS
015176,000092: 26,2015           43234                           RTB      DAD                                   
015177,000093: 26,2016           21462                                    LOADTIME                              #  READ PRESENT TIME
015178,000094: 26,2017           14100                                    DP1MIN                                
015179,000095: 26,2020           02211                           STORE    TSTART82                              #  SAVE TIME FOR LEMCONIC CALL
015180,000096: 26,2021           34041                           STCALL   TDEC1                                 #  STORE TIME FOR CSMCONIC CALL
015181,000097: 26,2022           27066                                    CSMCONIC                              #  CSM STATE VECTOR UPDATE
015182,000098: 26,2023           77775                           VLOAD                                          #  CSMCONIC LEFT R VECTOR IN RATT
015183,000099: 26,2024           00001                                    RATT                                  
015184,000100: 26,2025           16213                           STODL    RONE                                  #  SAVE FOR LINE OF SIGHT (LOS) COMPUTATION
015185,000101: 26,2026           02211                                    TSTART82                              
015186,000102: 26,2027           34041                           STCALL   TDEC1                                 #  STORE TIME FOR LEMCONIC CALL
015187,000103: 26,2030           27100                                    LEMCONIC                              #  LEM STATE VECTOR UPDATE
015188,000104: 26,2031           52375                           VLOAD    VSU                                   #  CSM POSITION - LEM POSITION = LOS
015189,000105: 26,2032           02213                                    RONE                                  #  LOS VECTOR LEFT IN MPAC
015190,000106: 26,2033           00001                                    RATT                                  
015191,000107: 26,2034           47121                           MXV      RTB                                   #  (REFSMMAT X LOS).  TRANSFORMS LOS FROM
015192,000108: 26,2035           01734                                    REFSMMAT                              #  REFERENCE COORD TO STAB MEMB COORD.
015193,000109: 26,2036           21700                                    NORMUNIT                              
015194,000110: 26,2037           03767                           STORE    POINTVSM                              #  STORE LOS FOR VECPOINT CALL
015195,000111: 26,2040           77776                           EXIT                                           
015196,000112: 26,2041           41052                           CS       OPTIONX    +1                         #  1 FOR Z AXIS.  2 FOR X AXIS.
015197,000113: 26,2042           64753                           AD       ONE                                   
015198,000114: 26,2043           00006                           EXTEND                                         
015199,000115: 26,2044           12071                           BZF      ALINEZ                                
015200,000116: 26,2045           06036        ALINEX             TC       INTPRET                               #  X AXIS ALIGNMENT
015201,000117: 26,2046           77775                           VLOAD                                          
015202,000118: 26,2047           06422                                    UNITX                                 #  READ (.5, 0, 0)

Page 353

015204,000120: 26,2050           37761        V89CALL1           STCALL   SCAXIS                                #  STORE SELECTED ALIGNMENT AXIS
015205,000121: 26,2051           56016                                    VECPOINT                              #  PUTS DESIRED GIM ANG (OG,IG,MG) IN TMPAC
015206,000122: 26,2052           00322                           STORE    CPHI                                  #  STORE GIMBAL ANGLES FOR BALLANGS CALL.
015207,000123: 26,2053           77776                           EXIT                                           
015208,000124: 26,2054           04616                           TC       BANKCALL                              
015209,000125: 26,2055           54244                           CADR     BALLANGS                              #  PUTS DESIRED BALL ANGLES IN FDAIX,Y,Z
015210,000126: 26,2056           32076                           CAF      VB06N18                               #  V 06 N 18
015211,000127: 26,2057           04616                           TC       BANKCALL                              #  NOUN 18 REFERS TO FDAIX,Y,Z
015212,000128: 26,2060           20351                           CADR     GOFLASH                               
015213,000129: 26,2061           05472                           TC       ENDEXT                                #  TERMINATE
015214,000130: 26,2062           02064                           TC       +2                                    #  PROCEED
015215,000131: 26,2063           02014                           TC       V89RECL                               #  RECYCLE
015216,000132: 26,2064           05516                           TC       DOWNFLAG                              #  RESET 3 AXIS FLAG
015217,000133: 26,2065           00124                           ADRES    3AXISFLG                              #  RESET BIT6 FLAG WORD 5
015218,000134: 26,2066           04616                           TC       BANKCALL                              #  PERFORMS LEM MANEUVER TO ALIGN SELECTED
015219,000135: 26,2067           54101                           CADR     R60LEM                                #  SPACECRAFT AXIS TO CSM.
015220,000136: 26,2070           15472                           TCF      ENDEXT                                #  TERMINATE R63
015221,000137: 
015222,000138: 26,2071           06036        ALINEZ             TC       INTPRET                               #  Z AXIS ALIGNMENT
015223,000139: 26,2072           52175                           VLOAD    GOTO                                  
015224,000140: 26,2073           06416                                    UNITZ                                 #  READ (0, 0, .5)
015225,000141: 26,2074           54050                                    V89CALL1                              
015226,000142: 
015227,000143: 26,2075           01014        VB04N12            VN       412                                   
015228,000144: 26,2076           01422        VB06N18            VN       0618                                  

Page 354

015230,000146: 26,2077           00000 13560  DP1MIN             2DEC     6000       B-28                       
015231,000147: 

End of include-file R63.agc.  Parent file is MAIN.agc