Source Code

This source code is very close to the Apollo Guidance Computer software for the Apollo 13 Lunar module. This revision of the Luminary 131 program is from December of 1969, whereas there was a later revision in January of 1970, and still another revision in February, which is the code that flew on the mission. As far as this transcription is concerned, it was originally from a copy made in 1991 of a printout from the collection of AGC developer Don Eyles for collector David Craig. It was subsequently scanned by Gary Neff, reprocessed for online presentation at the now-discontinued History of Recent Science and Technology (HRST) website of MIT's Dibner Institute (the full-quality scans being discarded in the process), and finally transcribed by Ron Burkey for the Virtual AGC Project. Although a high-quality replacement scan for a completely illegible page was later provided by Gary Neff, the reduced legibility of the reprocessed HRST posting nevertheless caused many errors to be introduced into the transcription. Accordingly, a second scan of the same physical printout was made in 2017 for the Virtual AGC Project's collection at the Internet Archive, and used to correct the transcription errors. All of the scanned materials mentioned, as well as other Luminary 131 related material, are available online. Don Eyles apprently made additional hand-written notes in printout between 1991 and 2017, so the two scans are not identical in that respect. The page-headings in the printout 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 the printout was made, not the date on which the program revision was released, although these happen to be very close together.

020183,000002:                                                                                                  ## Copyright:   Public domain.
020184,000003:                                                                                                  ## Filename:    R60_62.agc
020185,000004:                                                                                                  ## Purpose:     A section of Luminary 1C, revision 131.
020186,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
020187,000006:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 13.
020188,000007:                                                                                                  ##              This file is intended to be a faithful transcription, except
020189,000008:                                                                                                  ##              that the code format has been changed to conform to the
020190,000009:                                                                                                  ##              requirements of the yaYUL assembler rather than the 
020191,000010:                                                                                                  ##              original YUL assembler.
020192,000011:                                                                                                  ## Reference:   pp. 476-489
020193,000012:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
020194,000013:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
020195,000014:                                                                                                  ## Mod history: 05/14/03 RSB.   Began transcribing.
020196,000015:                                                                                                  ##              05/14/05 RSB    Corrected website reference above.
020197,000016:                                                                                                  ##              2017-01-06 RSB  Page numbers now agree with those on the
020198,000017:                                                                                                  ##                              original harcopy, as opposed to the PDF page
020199,000018:                                                                                                  ##                              numbers in 1701.pdf.
020200,000019:                                                                                                  ##              2017-01-27 RSB  Back-ported a comment-text fix identified in Luminary 69.
020201,000020:                                                                                                  ##              2017-02-23 RSB  Proofed comment text using octopus/ProoferComments.
020202,000021:                                                                                                  ##              2017-02-28 RSB  Fixed lingering typos.
020203,000022:                                                                                                  ##              2017-03-09 RSB  Comment text fixes noted in proofing Luminary 116.
020204,000023: 

Page 476

020206,000025:                                                                                                  #  MOD NO: 0                             DATE: 1 MAY 1968
020207,000026:                                                                                                  #  MOD BY: DIGITAL DEVEL GROUP           LOG SECTION R60,R62
020208,000027: 
020209,000028:                                                                                                  #  FUNCTIONAL DESCRIPTION:
020210,000029: 
020211,000030:                                                                                                  #  CALLED AS A GENERAL SUBROUTINE TO MANEUVER THE LM TO A SPECIFIED
020212,000031:                                                                                                  #  ATTITUDE.
020213,000032: 
020214,000033:                                                                                                  #  1. IF THE 3-AXIS FLAG IS NOT SET THE FINAL CDU ANGLES ARE
020215,000034:                                                                                                  #  CALCULATED (VECPOINT).
020216,000035: 
020217,000036:                                                                                                  #  2. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
020218,000037: 
020219,000038:                                                                                                  #  3. REQUEST FLASHING DISPLAY V50 N18 PLEASE PERFORM AUTO MANEUVER.
020220,000039: 
020221,000040:                                                                                                  #  4. IF PRIORITY DISPLAY FLAG IS SET DO A PHASECHANGE.  THEN AWAIT
020222,000041:                                                                                                  #  ASTRONAUT RESPONSE.
020223,000042: 
020224,000043:                                                                                                  #  5. DISPLAY RESPONSE RETURNS:
020225,000044: 
020226,000045:                                                                                                  #        A.      ENTER - RESET 3-AXIS FLAG AND RETURN TO CLIENT.
020227,000046: 
020228,000047:                                                                                                  #        B.      TERMINATE - IF IN P00 GO TO STEP 5A.  OTHERWISE CHECK IF R61 IS
020229,000048:                                                                                                  #                THE CALLING PROGRAM.  IF IN R61 AN EXIT IS MADE TO GOTOV56.  IF
020230,000049:                                                                                                  #                NOT IN R61 AN EXIT IS DONE VIA GOTOP00H.
020231,000050: 
020232,000051:                                                                                                  #        C.      PROCEED - CONTINUE WITH PROGRAM AT STEP 6.
020233,000052: 
020234,000053:                                                                                                  #  6. IF THE 3-AXIS FLAG IS NOT SET, THE FINAL CDU ANGLES ARE CALCULATED
020235,000054:                                                                                                  #  (VECPOINT).
020236,000055: 
020237,000056:                                                                                                  #  7. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
020238,000057: 
020239,000058:                                                                                                  #  8. IF THE G+N SWITCH IS NOT SET GO BACK TO STEP 3.
020240,000059:                                                                                                  #  
020241,000060:                                                                                                  #  9. IF THE AUTO SWITCH IS NOT SET GO BACK TO STEP 3.
020242,000061: 
020243,000062:                                                                                                  #  10. NONFLASHING DISPLAY V06N18 (FDAI ANGLES).
020244,000063: 
020245,000064:                                                                                                  #  11. DO A PHASECHANGE.
020246,000065: 
020247,000066:                                                                                                  #  12. DO A MANEUVER CALCULATION AND ICDU DRIVE ROUTINE TO ACHIEVE FINAL
020248,000067:                                                                                                  #  GIMBAL ANGLES (GOMANUR).
020249,000068: 
020250,000069:                                                                                                  #  13. AT END OF MANEUVER GO TO STEP 3.
020251,000070: 
020252,000071:                                                                                                  #        IF SATISFACTORY MANEUVER STEP 5A EXITS R60.
020253,000072:                                                                                                  #        FOR FURTHER ADJUSTMENT OF THE VEHICLE ATTITUDE ABOUT THE
020254,000073:                                                                                                  #        DESIRED VECTOR, THE ROUTINE MAY BE PERFORMED AGAIN STARTING AT

Page 477

020256,000075:                                                                                                  #        STEP 5C.
020257,000076: 
020258,000077:                                                                                                  #  CALLING SEQUENCE:     TC      BANKCALL
020259,000078:                                                                                                  #                        CADR    R60LEM
020260,000079: 
020261,000080:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED:     SCAXIS, POINTVSM (FOR VECPOINT)
020262,000081:                                                                                                  #                                        3AXISFLG.
020263,000082: 
020264,000083:                                                                                                  #  SUBROUTINES CALLED:   VECPOINT, BALLANGS, GOPERF2R, LINUS, GODSPER,
020265,000084:                                                                                                  #                        GOMANUR, DOWNFLAG, PHASCHNG, UPFLAG
020266,000085: 
020267,000086:                                                                                                  #  NORMAL EXIT MODES:    CAE     TEMPR60         (CALLERS RETURN ADDRESS)
020268,000087:                                                                                                  #                        TC      BANKJUMP
020269,000088: 
020270,000089:                                                                                                  #  ALARMS: NONE
020271,000090: 
020272,000091:                                                                                                  #  OUTPUT: NONE
020273,000092: 
020274,000093:                                                                                                  #  DEBRIS: CPHI, CTHETA, CPSI, 3AXISFLG, TBASE2
020275,000094: 
020276,000095: 34,2000                                           BANK     34                                    
020277,000096: 26,2000                                           SETLOC   MANUVER                               
020278,000097: 26,2000                                           BANK                                           
020279,000098: 
020280,000099: 26,2123     1163                                  EBANK=   TEMPR60                               
020281,000100: 
020282,000101: 26,2123                                           COUNT*   $$/R06                                
020283,000102: 26,2123           04645        R60LEM             TC       MAKECADR                              
020284,000103: 26,2124           55163                           TS       TEMPR60                               
020285,000104: 
020286,000105: 26,2125           34746        REDOMANN           CAF      3AXISBIT                              
020287,000106: 26,2126           70101                           MASK     FLAGWRD5                              #  IS 3-AXIS FLAG SET
020288,000107: 26,2127           10000                           CCS      A                                     
020289,000108: 26,2130           12136                           TCF      TOBALL                                #  YES
020290,000109: 26,2131           06042                           TC       INTPRET                               
020291,000110: 26,2132           77624                           CALL                                           
020292,000111: 26,2133           56040                                    VECPOINT                              #  TO COMPUTE FINAL ANGLES
020293,000112: 26,2134           00322                           STORE    CPHI                                  #  STORE FINAL ANGLES - CPHI, CTHETA, CPSI
020294,000113: 26,2135           77776                           EXIT                                           
020295,000114: 
020296,000115: 26,2136           05504        TOBALL             TC       UPFLAG                                #  INSURE THAT TOTAL ATTITUDE ERRORS ARE
020297,000116: 26,2137           00013                           ADRES    NEEDLFLG                              #  DISPLAYED ON FDAI ERROR NEEDLES
020298,000117: 26,2140           05516                           TC       DOWNFLAG                              
020299,000118: 26,2141           00000                           ADRES    NEED2FLG                              
020300,000119: 26,2142           04616                           TC       BANKCALL                              
020301,000120: 26,2143           54272                           CADR     BALLANGS                              #  TO CONVERT ANGLES TO FDAI
020302,000121: 26,2144           32260        TOBALLA            CAF      V06N18                                
020303,000122: 26,2145           04616                           TC       BANKCALL                              

Page 478

020305,000124: 26,2146           20711                           CADR     GOPERF2R                              #  DISPLAY PLEASE PERFORM AUTO MANEUVER
020306,000125: 26,2147           02246                           TC       R61TEST                               
020307,000126: 26,2150           02154                           TC       REDOMANC                              #  PROCEED
020308,000127: 26,2151           02201                           TC       ENDMANU1                              #  ENTER I.E. FINISHED WITH R60
020309,000128: 26,2152           02205                           TC       CHKLINUS                              #  TO CHECK FOR PRIORITY DISPLAYS
020310,000129: 26,2153           05155                           TC       ENDOFJOB                              
020311,000130: 
020312,000131: 26,2154           34746        REDOMANC           CAF      3AXISBIT                              
020313,000132: 26,2155           70101                           MASK     FLAGWRD5                              #  IS 3-AXIS FLAG SET
020314,000133: 26,2156           10000                           CCS      A                                     
020315,000134: 26,2157           12165                           TCF      TOBALLC                               #  YES
020316,000135: 26,2160           06042                           TC       INTPRET                               
020317,000136: 26,2161           77624                           CALL                                           
020318,000137: 26,2162           56040                                    VECPOINT                              #  TO COMPUTE FINAL ANGLES
020319,000138: 26,2163           00322                           STORE    CPHI                                  #  STORE ANGLES
020320,000139: 26,2164           77776                           EXIT                                           
020321,000140: 
020322,000141: 26,2165           04616        TOBALLC            TC       BANKCALL                              
020323,000142: 26,2166           54272                           CADR     BALLANGS                              #  TO CONVERT ANGLES TO FDAI
020324,000143: 26,2167           02261                           TC       G+N,AUTO                              #  CHECK AUTO MODE
020325,000144: 26,2170           10000                           CCS      A                                     
020326,000145: 26,2171           12144                           TCF      TOBALLA                               #  NOT AUTO, GO REREQUEST AUTO MANEUVER.
020327,000146: 
020328,000147: 26,2172           32260        AUTOMANV           CAF      V06N18                                #  STATIC DISPLAY DURING AUTO MANEUVER
020329,000148: 26,2173           04616                           TC       BANKCALL                              #                                        -
020330,000149: 26,2174           20452                           CADR     GODSPR                                #                                        -
020331,000150: 26,2175           02205                           TC       CHKLINUS                              #  TO CHECK FOR PRIORITY DISPLAYS
020332,000151: 
020333,000152: 26,2176           04616        STARTMNV           TC       BANKCALL                              #  PERFORM MANEUVER VIA KALCMANU
020334,000153: 26,2177           17741                           CADR     GOMANUR                               
020335,000154: 
020336,000155: 26,2200           12144        ENDMANUV           TCF      TOBALLA                               #  FINISHED MANEUVER.
020337,000156: 26,2201           05516        ENDMANU1           TC       DOWNFLAG                              #  RESET 3-AXIS FLAG
020338,000157: 26,2202           00124                           ADRES    3AXISFLG                              
020339,000158: 26,2203           31163                           CAE      TEMPR60                               #                                        -
020340,000159: 26,2204           04640                           TC       BANKJUMP                              #                                        -
020341,000160: 
020342,000161: 26,2205           40100        CHKLINUS           CS       FLAGWRD4                              
020343,000162: 26,2206           74740                           MASK     PDSPFBIT                              #  IS PRIORITY DISPLAY FLAG SET?
020344,000163: 26,2207           10000                           CCS      A                                     #                                        -
020345,000164: 26,2210           00002                           TC       Q                                     #  NO - EXIT
020346,000165: 26,2211           30002                           CA       Q                                     
020347,000166: 26,2212           54156                           TS       MPAC       +2                         #  SAVE RETURN
020348,000167: 26,2213           46250                           CS       THREE                                 #  OBTAIN LOCATION FOR RESTART
020349,000168: 26,2214           60133                           AD       BUF2                                  #  HOLDS Q OF LAST DISPLAY
020350,000169: 26,2215           55054                           TS       TBASE2                                
020351,000170: 
020352,000171: 26,2216           05353                           TC       PHASCHNG                              
020353,000172: 26,2217           00132                           OCT      00132                                 

Page 479

020355,000174: 26,2220           34745                           CAF      BIT7                                  
020356,000175: 26,2221           05464                           TC       LINUS                                 #  GO SET BITS FOR PRIORITY DISPLAY      -
020357,000176: 26,2222           00156                           TC       MPAC       +2                         
020358,000177: 
020359,000178: 26,2223           37717        RELINUS            CAF      PRIO26                                #  RESTORE ORIGINAL PRIORITY
020360,000179: 26,2224           05146                           TC       PRIOCHNG                              
020361,000180: 
020362,000181: 26,2225           34747                           CAF      TRACKBIT                              #  DON'T CONTINUE R60 UNLESS TRACKFLAG ON.
020363,000182: 26,2226           70075                           MASK     FLAGWRD1                              
020364,000183: 26,2227           10000                           CCS      A                                     
020365,000184: 26,2230           12243                           TCF      RER60                                 
020366,000185: 
020367,000186: 26,2231           34745                           CAF      RNDVZBIT                              #  IS IT P20?
020368,000187: 26,2232           70074                           MASK     FLAGWRD0                              
020369,000188: 26,2233           10000                           CCS      A                                     
020370,000189: 26,2234           02240                           TC       +4                                    #  YES
020371,000190: 26,2235           05353                           TC       PHASCHNG                              #  NO, MUST BE P25, SET 2.11 SPOT
020372,000191: 26,2236           40112                           OCT      40112                                 
020373,000192: 
020374,000193: 26,2237           05155                           TC       ENDOFJOB                              
020375,000194: 
020376,000195: 26,2240           05353                           TC       PHASCHNG                              #  SET 2.7 SPOT FOR P20
020377,000196: 26,2241           40072                           OCT      40072                                 
020378,000197: 
020379,000198: 26,2242           05155                           TC       ENDOFJOB                              
020380,000199: 
020381,000200: 26,2243           05504        RER60              TC       UPFLAG                                #  SET PRIO DISPLAY FLAG AFTER RESTART
020382,000201: 26,2244           00077                           ADRES    PDSPFLAG                              
020383,000202: 
020384,000203: 26,2245           01054                           TC       TBASE2                                
020385,000204: 
020386,000205: 26,2246           31010        R61TEST            CA       MODREG                                #  IF WE ARE IN P00 IT MUST BE V49 OR V89
020387,000206: 26,2247           00006                           EXTEND                                         
020388,000207: 26,2250           12201                           BZF      ENDMANU1                              #  THUS WE GO TO ENDEXT VIA USER
020389,000208: 
020390,000209: 26,2251           30100                           CA       FLAGWRD4                              #  ARE WE IN R61 (P20 OR P25)
020391,000210: 26,2252           74740                           MASK     PDSPFBIT                              
020392,000211: 26,2253           00006                           EXTEND                                         
020393,000212: 26,2254           16001                           BZF      GOTOPOOH                              #  NO
020394,000213: 26,2255           06025                           TC       GOTOV56                               #  YES
020395,000214: 
020396,000215: 26,2256           20100        BIT14+7            OCT      20100                                 #                                        -
020397,000216: 26,2257           00203        OCT203             OCT      203                                   
020398,000217: 26,2260           01422        V06N18             VN       0618                                  
020399,000218: 
020400,000219:                                                                                                  #  SUBROUTINE TO CHECK FOR G+N CONTROL, AUTO STABILIZATION
020401,000220: 
020402,000221:                                                                                                  #  RETURNS WITH C(A) = +         IF NOT SET FOR G+N, AUTO
020403,000222:                                                                                                  #  RETURNS WITH C(A) = +0        IF SWITCHES ARE SET
020404,000223: 
020405,000224: 26,2261           00006        G+N,AUTO           EXTEND                                         

Page 480

020407,000226: 26,2262           00030                           READ     CHAN30                                
020408,000227: 26,2263           74742                           MASK     BIT10                                 
020409,000228: 26,2264           10000                           CCS      A                                     
020410,000229: 26,2265           00002                           TC       Q                                     #  NOT IN G+N    C(A) = +
020411,000230: 26,2266           00006        ISITAUTO           EXTEND                                         #  CHECK FOR AUTO MODE
020412,000231: 26,2267           00031                           READ     CHAN31                                
020413,000232: 26,2270           74736                           MASK     BIT14                                 
020414,000233: 26,2271           00002                           TC       Q                                     #  (+) = NOT IN AUTO, (+0) = AOK
020415,000234: 

Page 481

020417,000236:                                                                                                  #  PROGRAM DESCRIPTION BALLANGS
020418,000237:                                                                                                  #  MOD NO.                               LOG SECTION R60,R62
020419,000238:                                                                                                  #  WRITTEN BY RAMA M. AIYAWAR
020420,000239: 
020421,000240:                                                                                                  #  FUNCTIONAL DESCRIPTION
020422,000241: 
020423,000242:                                                                                                  #        COMPUTES LM FDAI BALL DISPLAY ANGLES
020424,000243: 
020425,000244:                                                                                                  #  CALLING SEQUENCE
020426,000245: 
020427,000246:                                                                                                  #        TC      BALLANGS
020428,000247: 
020429,000248:                                                                                                  #  NORMAL EXIT MODE
020430,000249: 
020431,000250:                                                                                                  #        TC      BALLEXIT        (SAVED Q)
020432,000251: 
020433,000252:                                                                                                  #  ALARM OR EXIT MODE    NIL
020434,000253: 
020435,000254:                                                                                                  #  SUBROUTINES CALLED
020436,000255: 
020437,000256:                                                                                                  #        CD*TR*G
020438,000257:                                                                                                  #        ARCTAN
020439,000258: 
020440,000259:                                                                                                  #  INPUT
020441,000260: 
020442,000261:                                                                                                  #        CPHI,CTHETA,CPSI ARE THE ANGLES CORRESPONDING TO AOG, AIG, AMG.  THEY ARE
020443,000262:                                                                                                  #        SP,2S COMPLIMENT SCALED TO HALF REVOLUTION.
020444,000263: 
020445,000264:                                                                                                  #  OUTPUT
020446,000265: 
020447,000266:                                                                                                  #        FDAIX, FDAIY, FDAIZ ARE THE REQUIRED BALL ANGLES SCALED TO HALF REVOLUTION
020448,000267:                                                                                                  #        SP,2S COMPLIMENT.
020449,000268: 
020450,000269:                                                                                                  #        THESE ANGLES WILL BE DISPLAYED AS DEGREES AND HUNDREDTHS, IN THE ORDER ROLL, PITCH, YAW, USING NOUNS 18 & 19.
020451,000270: 
020452,000271:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
020453,000272: 
020454,000273:                                                                                                  #        CPHI, CTHETA, CPSI      EACH A SP REGISTER
020455,000274: 
020456,000275:                                                                                                  #  DEBRIS
020457,000276: 
020458,000277:                                                                                                  #        A,L,Q,MPAC,SINCDU,COSCDU,PUSHLIST,BALLEXIT
020459,000278: 
020460,000279:                                                                                                  #  NOMENCLATURE: CPHI, CTHETA, & CPSI REPRESENT THE OUTER, INNER, & MIDDLE GIMBAL ANGLES, RESPECTIVELY; OR
020461,000280:                                                                                                  #                EQUIVALENTLY, CDUX, CDUY, & CDUZ.
020462,000281: 
020463,000282:                                                                                                  #  NOTE:  ARCTAN CHECKS FOR OVERFLOW AND SHOULD BE ABLE TO HANDLE ANY SINGULARITIES.
020464,000283: 
020465,000284: 26,2000                                           SETLOC   BAWLANGS                              
020466,000285: 26,2000                                           BANK                                           
020467,000286: 
020468,000287: 26,2272                                           COUNT*   $$/BALL                               
020469,000288: 26,2272           04645        BALLANGS           TC       MAKECADR                              
020470,000289: 26,2273           55337                           TS       BALLEXIT                              
020471,000290: 26,2274           30321                           CA       CPHI                                  

Page 482

020473,000292: 26,2275           54771                           TS       CDUSPOT    +4                         
020474,000293: 26,2276           30322                           CA       CTHETA                                
020475,000294: 26,2277           54765                           TS       CDUSPOT                               
020476,000295: 26,2300           30323                           CA       CPSI                                  
020477,000296: 26,2301           54767                           TS       CDUSPOT    +2                         
020478,000297: 
020479,000298: 26,2302           06042                           TC       INTPRET                               
020480,000299: 26,2303           45001                           SETPD    CALL                                  
020481,000300: 26,2304           00001                                    0D                                    
020482,000301: 26,2305           47545                                    CD*TR*G                               
020483,000302: 
020484,000303: 26,2306           41345                           DLOAD    DMP                                   
020485,000304: 26,2307           00742                                    SINCDUX                               #  SIN (OGA)
020486,000305: 26,2310           00746                                    COSCDUZ                               #  COS (MGA)
020487,000306: 
020488,000307: 26,2311           57552                           SL1      DCOMP                                 #  SCALE
020489,000308: 26,2312           65336                           ARCSIN   PDDL                                  #  YAW = ARCSIN(-SXCZ) INTO 0 PD
020490,000309: 26,2313           00740                                    SINCDUZ                               
020491,000310: 26,2314           14023                           STODL    SINTH                                 #  (SINTH = 18D IN PD)
020492,000311: 26,2315           00746                                    COSCDUZ                               
020493,000312: 26,2316           72405                           DMP      SL1                                   #  RESCALE
020494,000313: 26,2317           00750                                    COSCDUX                               
020495,000314: 26,2320           34021                           STCALL   COSTH                                 #  (COSTH = 16D IN PD)
020496,000315: 26,2321           26506                                    ARCTAN                                
020497,000316: 26,2322           41325                           PDDL     DMP                                   #  ROLL = ARCTAN(SZ/CZCX) INTO 2 PD
020498,000317: 26,2323           00740                                    SINCDUZ                               
020499,000318: 26,2324           00742                                    SINCDUX                               
020500,000319: 26,2325           41512                           SL2      PUSH                                  #  SXSZ INTO 4 PD
020501,000320: 26,2326           65205                           DMP      PDDL                                  #  SXSZCY INTO 4 PD
020502,000321: 26,2327           00744                                    COSCDUY                               
020503,000322: 26,2330           65205                           DMP      PDDL                                  #  SXSZSY INTO 6 PD
020504,000323: 26,2331           00736                                    SINCDUY                               
020505,000324: 26,2332           00750                                    COSCDUX                               
020506,000325: 26,2333           72405                           DMP      SL1                                   #  CXCY
020507,000326: 26,2334           00744                                    COSCDUY                               
020508,000327: 26,2335           45425                           DSU      STADR                                 #  PULL UP FROM 6 PD
020509,000328: 26,2336           63756                           STODL    COSTH                                 #  COSTH = CXCY - SXSZSY
020510,000329: 26,2337           00736                                    SINCDUY                               
020511,000330: 26,2340           72405                           DMP      SL1                                   
020512,000331: 26,2341           00750                                    COSCDUX                               #  CXSY
020513,000332: 26,2342           45415                           DAD      STADR                                 #  PULL UP FROM 4 PD
020514,000333: 26,2343           43754                           STCALL   SINTH                                 #  SINTH = CXSY + SXSZCY
020515,000334: 26,2344           26506                                    ARCTAN                                #  RETURNS WITH D(MPAC) = PITCH
020516,000335: 26,2345           55525                           PDDL     VDEF                                  #  PITCH INTO 2 PD, ROLL INTO MPAC FROM 2PD
020517,000336: 26,2346           77634                           RTB                                            #  VDEF MAKES V(MPAC) = ROLL, PITCH, YAW
020518,000337: 26,2347           21621                                    V1STO2S                               
020519,000338: 26,2350           02345                           STORE    FDAIX                                 #  MODE IS TP
020520,000339: 26,2351           77776                           EXIT                                           
020521,000340: 
020522,000341: 26,2352           31337        ENDBALL            CA       BALLEXIT                              
020523,000342: 

Page 483

020525,000344: 26,2353           04640                           TC       BANKJUMP                              
020526,000345: 

Page 484

020528,000347:                                                                                                  #  PROGRAM DESCRIPTION - VECPOINT
020529,000348: 
020530,000349:                                                                                                  #  THIS INTERPRETIVE SUBROUTINE MAY BE USED TO POINT A SPACECRAFT AXIS IN A DESIRED DIRECTION.  THE AXIS
020531,000350:                                                                                                  #  TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN SUCCESSIVE LOCATIONS OF ERASABLE MEMORY
020532,000351:                                                                                                  #  BEGINNING WITH THE LOCATION CALLED SCAXIS.  THE COMPONENTS OF THIS VECTOR ARE GIVEN IN SPACECRAFT COORDINATES.
020533,000352:                                                                                                  #  THE DIRECTION IN WHICH THIS AXIS IS TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN
020534,000353:                                                                                                  #  SUCCESSIVE LOCATIONS OF ERASABLE MEMORY BEGINNING WITH THE ADDRESS CALLED POINTVSM.  THE COMPONENTS OF THIS
020535,000354:                                                                                                  #  VECTOR ARE GIVEN IN STABLE MEMBER COORDINATES.  WITH THIS INFORMATION VECPOINT COMPUTES A SET OF THREE GIMBAL
020536,000355:                                                                                                  #  ANGLES (2S COMPLEMENT) CORESPONDING TO THE CROSS-PRODUCT ROTATION BETWEEN SCAXIS AND POINTVSM AND STORES THEM
020537,000356:                                                                                                  #  IN T(MPAC) BEFORE RETURNING TO THE CALLER.
020538,000357: 
020539,000358:                                                                                                  #  THIS ROTATION, HOWEVER, MAY BRING THE S/C INTO GIMBAL LOCK.  WHEN POINTING A VECTOR IN THE Y-Z PLANE,
020540,000359:                                                                                                  #  THE TRANSPONDER AXIS, OR THE AOT FOR THE LEM, THE PROGRAM WILL CORRECT THIS PROBLEM BY ROTATING THE CROSS-
020541,000360:                                                                                                  #  PRODUCT ATTITUDE ABOUT POINTVSM BY A FIXED AMOUNT SUFFICIENT TO ROTATE THE DESIRED S/C ATTITUDE OUT OF GIMBAL
020542,000361:                                                                                                  #  LOCK.  IF THE AXIS TO BE POINTED IS MORE THAN 40.6 DEGREES BUT LESS THAN 60.5 DEG FROM THE +X (OR -X) AXIS,
020543,000362:                                                                                                  #  THE ADDITIONAL ROTATION TO AVOID GIMAL LOCK IS 35 DEGREES.  IF THE AXIS IS MORE THAN 60.5 DEGEES FROM +X (OR -X)
020544,000363:                                                                                                  #  THE ADDITIONAL ROTATION IS 35 DEGREES.  THE GIMBAL ANGLES CORRESPONDING TO THIS ATTITUDE ARE THEN COMPUTED AND
020545,000364:                                                                                                  #  STORED AS 2S COMPLIMENT ANGLES IN T(MPAC) BEFORE RETURNING TO THE CALLER.
020546,000365: 
020547,000366:                                                                                                  #  WHEN POINTING THE X-AXIS, OR THE THRUST VECTOR, OR ANY VECTOR WITHIN 40.6 DEG OF THE X-AXIS, VECPOINT
020548,000367:                                                                                                  #  CANNOT CORRECT FOR A CROSS-PRODUCT ROTATION INTO GIMBAL LOCK.  IN THIS CASE A PLATFORM REALIGNMENT WOULD BE
020549,000368:                                                                                                  #  REQUIRED TO POINT THE VECTOR IN THE DESIRED DIRECTION.  AT PRESENT NO INDICATION IS GIVEN FOR THIS SITUATION
020550,000369:                                                                                                  #  EXCEPT THAT THE FINAL MIDDLE GIMBAL ANGLE IN MPAC +2 IS GREATER THAN 59 DEGREES.
020551,000370: 
020552,000371:                                                                                                  #  CALLING SEQUENCE -
020553,000372: 
020554,000373:                                                                                                  #        1)      LOAD SCAXIS, POINTVSM
020555,000374:                                                                                                  #        2)      CALL
020556,000375:                                                                                                  #                        VECPOINT
020557,000376: 
020558,000377:                                                                                                  #  RETURNS WITH
020559,000378: 
020560,000379:                                                                                                  #        1)      DESIRED OUTER GIMBAL ANGLE IN MPAC
020561,000380:                                                                                                  #        2)      DESIRED INNER GIMBAL ANGLE IN MPAC +1
020562,000381:                                                                                                  #        3)      DESIRED MIDDLE GIMBAL ANGLE IN MPAC +2
020563,000382: 
020564,000383:                                                                                                  #  ERASABLES USED -
020565,000384: 
020566,000385:                                                                                                  #        1)      SCAXIS          6
020567,000386:                                                                                                  #        2)      POINTVSM        6
020568,000387:                                                                                                  #        3)      MIS             18
020569,000388:                                                                                                  #        4)      DEL             18
020570,000389:                                                                                                  #        5)      COF             6
020571,000390:                                                                                                  #        6)      VECQTEMP        1
020572,000391:                                                                                                  #        7)      ALL OF VAC AREA 43
020573,000392: 
020574,000393:                                                                                                  #                        TOTAL   99
020575,000394: 
020576,000395: 27,2000                                           SETLOC   VECPT                                 
020577,000396: 27,2000                                           BANK                                           

Page 485

020579,000398: 27,2032                                           COUNT*   $$/VECPT                              
020580,000399: 
020581,000400: 27,2032  E6,1675                                  EBANK=   BCDU                                  
020582,000401: 
020583,000402: 27,2032           40020        VECPNT1            STQ      BOV                                   #  THIS ENTRY USES DESIRED CDUS
020584,000403: 27,2033           03324                                    VECQTEMP                              #  NOT PRESENT - ENTER WITH CDUD'S IN MPAC
020585,000404: 27,2034           56035                                    VECPNT2                               
020586,000405: 27,2035           52164        VECPNT2            AXC,2    GOTO                                  
020587,000406: 27,2036           03245                                    MIS                                   
020588,000407: 27,2037           56046                                    STORANG                               
020589,000408: 27,2040           40020        VECPOINT           STQ      BOV                                   #  SAVE RETURN ADDRESS
020590,000409: 27,2041           03324                                    VECQTEMP                              
020591,000410: 27,2042           56043                                    VECLEAR                               #  AND CLEAR OVFIND
020592,000411: 27,2043           47164        VECLEAR            AXC,2    RTB                                   
020593,000412: 27,2044           03245                                    MIS                                   #  READ THE PRESENT CDU ANGLES AND
020594,000413: 27,2045           44403                                    READCDUK                              #  STORE THEM IN PD25, 26, 27
020595,000414: 27,2046           34032        STORANG            STCALL   25D                                   
020596,000415: 27,2047           44410                                    CDUTODCM                              #  S/C AXES TO STABLE MEMBER AXES (MIS)
020597,000416: 27,2050           61375                           VLOAD    VXM                                   
020598,000417: 27,2051           03773                                    POINTVSM                              #  RESOLVE THE POINTING DIRECTION VF INTO
020599,000418: 27,2052           03246                                    MIS                                   #  INITIAL S/C AXES (VF = POINTVSM)
020600,000419: 27,2053           77656                           UNIT                                           
020601,000420: 27,2054           00035                           STORE    28D                                   
020602,000421:                                                                                                  #  PD 28 29 30 31 32 33
020603,000422: 27,2055           53435                           VXV      UNIT                                  #  TAKE THE CROSS PRODUCT VF X VI
020604,000423: 27,2056           03765                                    SCAXIS                                #  WHERE VI = SCAXIS
020605,000424: 27,2057           57400                           BOV      VCOMP                                 
020606,000425: 27,2060           56170                                    PICKAXIS                              
020607,000426: 27,2061           17270                           STODL    COF                                   #  CHECK MAGNITUDE
020608,000427: 27,2062           00045                                    36D                                   #  OF CROSS PRODUCT
020609,000428: 27,2063           50025                           DSU      BMN                                   #  VECTOR, IF LESS
020610,000429: 27,2064           14415                                    DPB-14                                #  THAN B-14 ASSUME
020611,000430: 27,2065           56170                                    PICKAXIS                              #  UNIT OPERATION
020612,000431: 27,2066           50375                           VLOAD    DOT                                   #  INVALID.
020613,000432: 27,2067           03765                                    SCAXIS                                
020614,000433: 27,2070           00035                                    28D                                   
020615,000434: 27,2071           65552                           SL1      ARCCOS                                
020616,000435: 27,2072           77624        COMPMATX           CALL                                           #  NOW COMPUTE THE TRANSFORMATION FROM
020617,000436: 27,2073           44527                                    DELCOMP                               #  FINAL S/C AXES TO INITIAL S/C AXES MFI
020618,000437: 27,2074           75160                           AXC,1    AXC,2                                 
020619,000438: 27,2075           03245                                    MIS                                   #  COMPUTE THE TRANSFORMATION FROM FINAL
020620,000439: 27,2076           02230                                    KEL                                   #  S/C AXES TO STABLE MEMBER AXES
020621,000440: 27,2077           77624                           CALL                                           #  MFS = MIS MFI
020622,000441: 27,2100           44312                                    MXM3                                  #  (IN PD LIST)
020623,000442: 
020624,000443: 27,2101           51545                           DLOAD    ABS                                   
020625,000444: 27,2102           00007                                    6                                     #  MFS6 = SIN(CPSI)                      $2
020626,000445: 27,2103           50025                           DSU      BMN                                   
020627,000446: 27,2104           14402                                    SINGIMLC                              #  = SIN(59 DEGS)                        $2
020628,000447: 27,2105           56160                                    FINDGIMB                              #  /CPSI/ LESS THAN 59 DEGS

Page 486

020630,000449:                                                                                                  #  I.E. DESIRED ATTITUDE NOT IN GIMBAL LOCK
020631,000450: 
020632,000451: 27,2106           51545                           DLOAD    ABS                                   #  CHECK TO SEE IF WE ARE POINTING
020633,000452: 27,2107           03765                                    SCAXIS                                #  THE THRUST AXIS
020634,000453: 27,2110           51025                           DSU      BPL                                   
020635,000454: 27,2111           14404                                    SINVEC1                               #  SIN 49.4 DEGS                         $2
020636,000455: 27,2112           56160                                    FINDGIMB                              #  IF SO, WE ARE TRYING TO POINT IT INTO
020637,000456: 27,2113           77775                           VLOAD                                          #  GIMBAL LOCK, ABORT COULD GO HERE
020638,000457: 27,2114           77626                           STADR                                          
020639,000458: 27,2115           50515                           STOVL    MIS        +12D                       
020640,000459: 27,2116           77626                           STADR                                          #  STORE MFS (IN PD LIST) IN MIS
020641,000460: 27,2117           50523                           STOVL    MIS        +6                         
020642,000461: 27,2120           77626                           STADR                                          
020643,000462: 27,2121           50531                           STOVL    MIS                                   
020644,000463: 27,2122           03254                                    MIS        +6                         #  INNER GIMBAL AXIS IN FINAL S/C AXES
020645,000464: 27,2123           57444                           BPL      VCOMP                                 #  LOCATE THE IG AXIS DIRECTION CLOSEST TO
020646,000465: 27,2124           56125                                    IGSAMEX                               #  FINAL X S/C AXIS
020647,000466: 
020648,000467: 27,2125           50035        IGSAMEX            VXV      BMN                                   #  FIND THE SHORTEST WAY OF ROTATING THE 
020649,000468: 27,2126           03765                                    SCAXIS                                #  S/C OUT OF GIMBAL LOCK BY A ROTATION 
020650,000469: 27,2127           56134                                    U=SCAXIS                              #  ABOUT +- SCAXIS, I.E. IF  (IG (SGN MFS3)
020651,000470:                                                                                                  #  X SCAXIS . XF) LESS THAN 0, U = SCAXIS
020652,000471:                                                                                                  #  OTHERWISE U = -SCAXIS
020653,000472: 
020654,000473: 27,2130           57575                           VLOAD    VCOMP                                 
020655,000474: 27,2131           03765                                    SCAXIS                                
020656,000475: 27,2132           37270                           STCALL   COF                                   #  ROTATE ABOUT -SCAXIS
020657,000476: 27,2133           56137                                    CHEKAXIS                              
020658,000477: 27,2134           77775        U=SCAXIS           VLOAD                                          
020659,000478: 27,2135           03765                                    SCAXIS                                
020660,000479: 27,2136           03270                           STORE    COF                                   #  ROTATE ABOUT + SCAXIS
020661,000480: 27,2137           51545        CHEKAXIS           DLOAD    ABS                                   
020662,000481: 27,2140           03765                                    SCAXIS                                #  SEE IF WE ARE POINTING THE AOT
020663,000482: 27,2141           51025                           DSU      BPL                                   
020664,000483: 27,2142           14406                                    SINVEC2                               #  SIN 29.5 DEGS                         $2
020665,000484: 27,2143           56147                                    PICKANG1                              #  IF SO, ROTATE 50 DEGS ABOUT +- SCAXIS
020666,000485: 27,2144           52145                           DLOAD    GOTO                                  #  IF NOT, MUST BE POINTING THE TRANSPONDER
020667,000486: 27,2145           14412                                    VECANG2                               #  OR SOME VECTOR IN THE Y, OR Z PLANE
020668,000487: 27,2146           56151                                    COMPMFSN                              #  IN THIS CASE ROTATE 35 DEGS TO GET OUT
020669,000488:                                                                                                  #  OF GIMBAL LOCK (VECANG2 $360)
020670,000489: 27,2147           77745        PICKANG1           DLOAD                                          
020671,000490: 27,2150           14410                                    VECANG1                               #  = 50 DEGS                             $ 360
020672,000491: 27,2151           77624        COMPMFSN           CALL                                           
020673,000492: 27,2152           44527                                    DELCOMP                               #  COMPUTE THE ROTATION ABOUT SCAXIS TO
020674,000493: 27,2153           75160                           AXC,1    AXC,2                                 #  BRING MFS OUT OF GIMBAL LOCK
020675,000494: 27,2154           03245                                    MIS                                   
020676,000495: 27,2155           02230                                    KEL                                   
020677,000496: 27,2156           77624                           CALL                                           #  COMPUTE THE NEW TRANSFORMATION FROM
020678,000497: 27,2157           44312                                    MXM3                                  #  DESIRED S/C AXES TO STABLE MEMBER AXES
020679,000498:                                                                                                  #  WHICH WILL ALIGN VI WITH VF AND AVOID

Page 487

020681,000500:                                                                                                  #  GIMBAL LOCK
020682,000501: 27,2160           45160        FINDGIMB           AXC,1    CALL                                  
020683,000502: 27,2161           00000                                    0                                     #  EXTRACT THE COMMANDED CDU ANGLES FROM
020684,000503: 27,2162           44654                                    DCMTOCDU                              #  THIS MATRIX
020685,000504: 27,2163           40234                           RTB      SETPD                                 
020686,000505: 27,2164           21621                                    V1STO2S                               #  CONVERT TO 2:S COMPLEMENT
020687,000506: 27,2165           00001                                    0                                     
020688,000507: 27,2166           77650                           GOTO                                           
020689,000508: 27,2167           03324                                    VECQTEMP                              #  RETURN TO CALLER
020690,000509: 
020691,000510: 27,2170           50375        PICKAXIS           VLOAD    DOT                                   #  IF VF X VI = 0, FIND VF . VI
020692,000511: 27,2171           00035                                    28D                                   
020693,000512: 27,2172           03765                                    SCAXIS                                
020694,000513: 27,2173           72240                           BMN      TLOAD                                 
020695,000514: 27,2174           54354                                    ROT180                                
020696,000515: 27,2175           00032                                    25D                                   
020697,000516: 27,2176           77650                           GOTO                                           #  IF VF = VI, CDU DESIRED = PRESENT CDU
020698,000517: 27,2177           03324                                    VECQTEMP                              #  PRESENT CDU ANGLES
020699,000518: 
020700,000519: 35,2000                                           BANK     35                                    
020701,000520: 26,2000                                           SETLOC   MANUVER1                              
020702,000521: 26,2000                                           BANK                                           
020703,000522: 26,2354           47375        ROT180             VLOAD    VXV                                   #  IF VF, VI ANTIPARALLEL, 108 DEG ROTATION
020704,000523: 26,2355           03254                                    MIS        +6                         #  IS REQUIRED.  Y STABLE MEMBER AXIS IN
020705,000524: 26,2356           06522                                    HIDPHALF                              #  INITIAL S/C AXES.
020706,000525: 26,2357           47256                           UNIT     VXV                                   #  FIND Y(SM) X X(I)
020707,000526: 26,2360           03765                                    SCAXIS                                #  FIND UNIT(VI X UNIT(Y(SM) X X(I)))
020708,000527: 26,2361           40056                           UNIT     BOV                                   #  I.E. PICK A VECTOR IN THE PLANE OF X(I),
020709,000528: 26,2362           54376                                    PICKX                                 #  Y(SM) PERPENDICULAR TO VI
020710,000529: 26,2363           17270                           STODL    COF                                   
020711,000530: 26,2364           00045                                    36D                                   #  CHECK MAGNITUDE
020712,000531: 26,2365           50025                           DSU      BMN                                   #  OF THIS VECTOR.
020713,000532: 26,2366           14415                                    DPB-14                                #  IF LESS THAN B-14,
020714,000533: 26,2367           54376                                    PICKX                                 #  PICK X-AXIS.
020715,000534: 26,2370           77775                           VLOAD                                          
020716,000535: 26,2371           03270                                    COF                                   
020717,000536: 26,2372           17270        XROT               STODL    COF                                   
020718,000537: 26,2373           06522                                    HIDPHALF                              
020719,000538: 26,2374           77650                           GOTO                                           
020720,000539: 26,2375           56072                                    COMPMATX                              
020721,000540: 26,2376           52175        PICKX              VLOAD    GOTO                                  #  PICK THE XAXIS IN THIS CASE
020722,000541: 26,2377           06522                                    HIDPHALF                              
020723,000542: 26,2400           54372                                    XROT                                  
020724,000543: 26,2401           15555 35172  SINGIMLC           2DEC     .4285836003                            #  = SIN(59)                     $2
020725,000544: 26,2403           14113 36326  SINVEC1            2DEC     .3796356537                            #  = SIN(49.4)                   $2
020726,000545: 26,2405           07701 35703  SINVEC2            2DEC     .2462117800                            #  = SIN(29.5)                   $2
020727,000546: 26,2407           04343 21616  VECANG1            2DEC     .1388888889                            #  = 50 DEGREES                          $360

Page 488

020729,000548: 26,2411           03070 34344  VECANG2            2DEC     .09722222222                            #  = 35 DEGREES                          $360
020730,000549: 
020731,000550: 26,2413           00000        1BITDP             OCT      0                                     #  KEEP THIS BEFORE DPB(-14)     *********
020732,000551: 26,2414           00001        DPB-14             OCT      00001                                 
020733,000552: 26,2415           00000                           OCT      00000                                 
020734,000553: 

Page 489

020736,000555:                                                                                                  #  ROUTINE FOR INITIATING AUTOMATIC MANEUVER VIA KEYBOARD (V49)
020737,000556: 
020738,000557: 34,2000                                           BANK     34                                    
020739,000558: 23,2000                                           SETLOC   R62                                   
020740,000559: 23,2000                                           BANK                                           
020741,000560: 23,2103  E6,1675                                  EBANK=   BCDU                                  
020742,000561: 
020743,000562: 23,2103                                           COUNT*   $$/R62                                
020744,000563: 
020745,000564: 23,2103  23,2103               R62DISP            EQUALS   R62FLASH                              
020746,000565: 
020747,000566: 23,2103           35010        R62FLASH           CAF      V06N22                                #  FLASH V06N22 AND
020748,000567: 23,2104           04616                           TC       BANKCALL                              #  ICDU ANGLES
020749,000568: 23,2105           20477                           CADR     GOFLASH                               
020750,000569: 23,2106           15472                           TCF      ENDEXT                                #  TERMINATE
020751,000570: 23,2107           12111                           TCF      GOMOVE                                #  PROCEED
020752,000571: 23,2110           12103                           TCF      R62FLASH                              #  ENTER
020753,000572: 
020754,000573:                                                                                                  #  ASTRONAUT MAY LOAD NEW ICDUS AT THIS
020755,000574:                                                                                                  #  POINT
020756,000575: 23,2111           05504        GOMOVE             TC       UPFLAG                                #  SET FOR 3-AXIS MANEUVER
020757,000576: 23,2112           00124                           ADRES    3AXISFLG                              
020758,000577: 
020759,000578: 23,2113           04616                           TC       BANKCALL                              
020760,000579: 23,2114           54123                           CADR     R60LEM                                
020761,000580: 23,2115           15472                           TCF      ENDEXT                                #  END R62
020762,000581: 

End of include-file R60,R62.agc.  Parent file is MAIN.agc