Source Code

These source-code files are part of a reconstructed copy of Comanche 72/3 (AKA Manche72 revision 3), the final, flown mission release of the Apollo Guidance Computer (AGC) Command Module (CM) software for Apollo 13.

The starting point was the source code of Comanche 72 (itself previously reconstructed). Comanche 72 source code was then modified by incorporating changes known from contemporary documentation to have been made between revisions 72 and 72/3. The resulting code assembles to have identical memory-bank checksums as those specified in NASA drawing 2021153G; this gives reasonably high confidence that the changes that have been made are correct. In places where ambiguity exists, this ambiguity is discussed in "## Reconstruction:" comments.

Since no contemporary listings of Comanche 72/3 are available as source material, all comments and labels are approximate. They have been taken from other AGC programs where possible, or, in some places, written from scratch to match what we believe would have been in the original listing.

041046,000002:                                                                                                  ## Copyright:   Public domain.
041047,000003:                                                                                                  ## Filename:    TVCRESTARTS.agc
041048,000004:                                                                                                  ## Purpose:     A section of Manche72 revision 3.
041049,000005:                                                                                                  ##              It is part of the reconstructed source code for the final, flown
041050,000006:                                                                                                  ##              release of the software for the Command Module's (CM) Apollo
041051,000007:                                                                                                  ##              Guidance Computer (AGC) for Apollo 13. No original listings
041052,000008:                                                                                                  ##              of this program are available; instead, this file was recreated
041053,000009:                                                                                                  ##              from a reconstructed copy of Comanche 072. It has been adapted
041054,000010:                                                                                                  ##              such that the resulting bugger words exactly match those
041055,000011:                                                                                                  ##              specified for Manche72 revision 3 in NASA drawing 2021153G,
041056,000012:                                                                                                  ##              which gives relatively high confidence that the reconstruction
041057,000013:                                                                                                  ##              is correct.
041058,000014:                                                                                                  ## Assembler:   yaYUL
041059,000015:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
041060,000016:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
041061,000017:                                                                                                  ## Mod history: 2024-05-19 MAS  Created from Comanche 072.
041062,000018: 
041063,000019:                                                                                                  #  NAME....TVCRESTART PACKAGE, CONSISTING OF REDOTVC, ENABL1, 2, CMDSOUT, PHSCHK2, ETC.
041064,000020:                                                                                                  #  LOG SECTION...TVCRESTARTS                     SUBROUTINE...DAPCSM
041065,000021:                                                                                                  #  MODIFIED BY SCHLUNDT                          21 OCTOBER 1968
041066,000022: 
041067,000023:                                                                                                  #  FUNCTIONAL DESCRIPTION....
041068,000024: 
041069,000025:                                                                                                  #       *RESTART-PROOFS THE TVC DAPS, INCLUDING PITCHDAP, YAWDAP,
041070,000026:                                                                                                  #        TVCEXECUTIVE, ROLLDAP, TVCINIT4, TVCDAPON, AND CSM/.M V46 SWTCHOVR.
041071,000027: 
041072,000028:                                                                                                  #       *TVC RESTARTS DESERVE SPECIAL CONSIDERATION IN SEVERAL AREAS.
041073,000029:                                                                                                  #        RESTART DOWN-TIME IS IMPORTANT BECAUSE OF THE TRANSIENTS INTRODUCED
041074,000030:                                                                                                  #        BY THE THRUST VECTOR RETURN TO THE ACTUATOR MECHANICAL NULLS
041075,000031:                                                                                                  #        FOLLOWING TVC- AND OPTICS-ERROR-COUNTER-DISENABLES (CHANNEL 12).
041076,000032:                                                                                                  #        TVC USES A MIXTURE OF WAITLIST, T5, T6, AND JOB CALLS.  THERE IS
041077,000033:                                                                                                  #        FILTER MEMORY (UP TO 6TH ORDER) TO BE PROTECTED IF WILD TRANSIENTS
041078,000034:                                                                                                  #        ARE TO BE AVOIDED.  COUNTERS ARE INVOLVED FOR ONE-SHOT
041079,000035:                                                                                                  #        CORRECTIONS AND GAIN UPDATES.  THE GIMBAL TRIM ESTIMATORS AND THE
041080,000036:                                                                                                  #        BODY AXIS ATTITUDE ERROR INTEGRATORS INVOLVE DIGITAL SUMMATION.
041081,000037:                                                                                                  #        DIGITAL DIFFERENTIATORS ARE INVOLVED IN THE BODY AXIS RATE ESTIMA-
041082,000038:                                                                                                  #        TIONS AND IN THE OUTPUTTING OF ACTUATOR COMMANDS.  THERE IS AN
041083,000039:                                                                                                  #        OFFSET-TRACKER-FILTER TO PROTECT.  ETC., ETC.
041084,000040: 
041085,000041:                                                                                                  #       *THOSE QUANTITIES WHICH MUST BE PROTECTED ARE STORED IN TEMPORARY
041086,000042:                                                                                                  #        REGISTERS AS THEY ARE COMPUTED, FOR UPDATING THE REAL REGISTERS
041087,000043:                                                                                                  #        DURING COPYCYCLES.
041088,000044: 
041089,000045:                                                                                                  #       *THE SEVERAL COPYCYCLES ARE EACH PROTECTED BY PHASE POINTS AT THEIR
041090,000046:                                                                                                  #        BEGINNING AND AT THEIR TERMINATION.  THE PHASE POINTS ARE SIMPLY
041091,000047:                                                                                                  #        ..INCR.. INSTRUCTIONS, EITHER ..INCR TVCEXPHS.. FOR COPYCYCLES
041092,000048:                                                                                                  #        IN THE TVCEXECUTIVE, OR ..INCR TVCPHASE.. FOR THE PITCH AND YAW
041093,000049:                                                                                                  #        COPYCYCLES.  INDEXING ON EACH OF THESE POINTERS THEN PERMITS A
041094,000050:                                                                                                  #        RETURN TO THE APPROPRIATE RESTART POINTS.
041095,000051: 
041096,000052:                                                                                                  #       *IF A RESTART OCCURS DURING EITHER COPYCYCLE, THAT COPYCYCLE IS
041097,000053:                                                                                                  #        COMPLETED.  THEN THE NORMAL TVCINIT4....DAPINIT....PITCHDAP STARTUP
041098,000054:                                                                                                  #        SEQUENCE IS CALLED UPON TO GET THINGS GOING AGAIN.
041099,000055: 
041100,000056:                                                                                                  #       *TVC-ENABLE AND OPTICS-ERROR-COUNTER ENABLE MUST BE SET ASAP
041101,000057:                                                                                                  #        (ALLOWING FOR PROCEDURAL DELAYS).  THEN THE ENGINES ARE COMMANDED
041102,000058:                                                                                                  #        TO THE P,YACTOFF TRIM VALUES.  THE DAPS ARE THEN READY TO GO ON THE
041103,000059:                                                                                                  #        AIR, WITH THE REGULAR STARTUP SEQUENCE, EITHER AT MRCLEAN FOR A
041104,000060:                                                                                                  #        COMPLETE INITIALIZATION OR AT TVCINIT4 FOR A PARTIAL INITIALIZATION
041105,000061: 
041106,000062:                                                                                                  #       *FOR RESTARTS PRIOR TO THE SETTING OF THE T5 BITS AT DOTVCON THE
041107,000063:                                                                                                  #        PRE40.6 SECTION OF S40.6 TAKES CARE OF RE-ESTABLISHING TRIMS.
041108,000064: 
041109,000065:                                                                                                  #       *IF A RESTART OCCURS DURING THE TVCEXEC....TVCEXFIN SEQUENCE THE
041110,000066:                                                                                                  #        COMPUTATIONS WILL BE COMPLETED, STARTING AT THE APPROPRIATE RESTART
041111,000067:                                                                                                  #        POINT, AFTER THE DAPS ARE READY TO GO ON THE AIR.
041112,000068: 
041113,000069:                                                                                                  #       *IF A RESTART OCCURS PRIOR TO TVCINIT4 (TVCPHASE = -1) E.G. DURING
041114,000070:                                                                                                  #        THE EARLY DAP INITIALIZATION PHASE, THE DAP STARTUP SEQUENCE IS
041115,000071:                                                                                                  #        ENTERED AT MRCLEAN FOR A FULL INITIALIZATION.
041116,000072: 
041117,000073:                                                                                                  #       *FOR RESTARTS DURING CSM/LM V46 SWITCH-OVER, TVCPHASE IS SET TO -2.
041118,000074:                                                                                                  #        AND THE RESTART LOGIC GOES BACK TO REDO SWITCH-OVER (AFTER THE
041119,000075:                                                                                                  #        NORMAL DAP RESTART SEQUENCE IS FOLLOWED).
041120,000076: 
041121,000077:                                                                                                  #       *RESTARTS ARE NOT CRITICAL TO THE ROLL DAP PERFORMANCES HENCE THE
041122,000078:                                                                                                  #        THE ROLL DAP IS MERELY RESTARTED.
041123,000079: 
041124,000080:                                                                                                  #       *RESTARTS DURING A STROKE TEST (STROKER IS NON-ZERO) WILL CAUSE THE
041125,000081:                                                                                                  #        STROKE TEST TO BE TERMINATED.  A NEW V68 ENTRY WILL BE REQUIRED
041126,000082:                                                                                                  #        TO GET IT GOING AGAIN (NO AUTOMATIC RESTART).
041127,000083:                                                                                                  #   
041128,000084:                                                                                                  #       *REDOTVC IS REACHED FOLLOWING ANY RESTART WHICH FINDS THE T5 BITS
041129,000085:                                                                                                  #        (BITS 15,14 OF FLAGWRD6) SET FOR TVC.  DOTVCON SETS TVCPHASE = -1
041130,000086:                                                                                                  #        AND TVC EXPHS = 0 JUST BEFORE SETTING THESE BITS, JUST BEFORE
041131,000087:                                                                                                  #        MAKING THE T5 CALL TO TVCDAPON.  ON A NORMAL SHUTDOWN DOTVCRCS
041132,000088:                                                                                                  #        CALLS RCSDAPON, WHICH RESETS THE T5 BITS FOR RCS.
041133,000089: 
041134,000090:                                                                                                  #  CALLING SEQUENCE....T5, IN PARTICULAR BY ELRSKIP OF FRESH START/RESTART
041135,000091: 
041136,000092:                                                                                                  #  NORMAL EXIT MODES....RESUME, NOQRSM, POSTJUMP (TO TVCINIT4 OR MRCLEAN)
041137,000093: 
041138,000094:                                                                                                  #  ALARM OR ABORT EXIT MODES....NONE
041139,000095: 
041140,000096:                                                                                                  #  SUBROUTINES CALLED....
041141,000097: 
041142,000098:                                                                                                  #       *PCOPY+1, YCOPY+1 (PITCH AND YAW COPYCYCLES)
041143,000099:                                                                                                  #       *ENABLE1,2, CMDSOUT (RE-ESTABLISH ACTUATOR TRIMS)
041144,000100:                                                                                                  #       *MRCLEAN OR TVCINIT4 (TVCDAP INITIALIZATIONS)
041145,000101:                                                                                                  #       *SWICHOVR +5 (CSM/LM V46 SWITCH-OVER)
041146,000102:                                                                                                  #       *EXRSTRT AND TVCEXECUTIVE PHASE POINTS 1 THRU 6
041147,000103:                                                                                                  #       *WAITLIST, IBNKCALL, POSTJUMP, ISWCALL
041148,000104: 
041149,000105:                                                                                                  #  OTHER INTERFACES....DOTVCON AND RCSDAPON (T5 BITS), ELRSKIP (CALLS IT)
041150,000106: 
041151,000107:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED....
041152,000108: 
041153,000109:                                                                                                  #       *T5 BITS (1,0), TVCPHASE (-2,-1,0,1,2,3), TVCEXPHS (1 THRU 6)
041154,000110:                                                                                                  #       *TVC DAP VARIABLES
041155,000111:                                                                                                  #       *OPERATIONS PERFORMED BY REDOTVC ARE BASED ON THE ASSUMPTION THAT
041156,000112:                                                                                                  #        THE TVC DAPS ARE RUNNING NORMALLY
041157,000113: 
041158,000114:                                                                                                  #  OUTPUT....
041159,000115: 
041160,000116:                                                                                                  #       *PITCH AND YAW TVC DAP COPYCYCLES COMPLETED IF INTERUPTED
041161,000117:                                                                                                  #       *TVCEXECUTIVE COMPLETED IF INTERUPTED
041162,000118:                                                                                                  #       *STROKE TEST TERMINATED IF INTERRUPTED
041163,000119:                                                                                                  #       *CSM/LM V46 SWITCH-OVER REPEATED IF INTERRUPTED
041164,000120:                                                                                                  #       *ACTUATOR TRIMS RE-ESTABLISHED (ACTUATORS BACK ON THE AIR)
041165,000121:                                                                                                  #       *TVC DAP INITIALIZATION AS REQUIRED
041166,000122:                                                                                                  #       *ALL TVC DAP OPERATIONS ON THE AIR
041167,000123: 
041168,000124:                                                                                                  #  DEBRIS....TVC TEMPORARIES IN EBANK6
041169,000125: 
041170,000126: 
041171,000127: 16,3212                                           BANK     16                                    
041172,000128: 16,2000                                           SETLOC   DAPROLL                               
041173,000129: 16,2000                                           BANK                                           
041174,000130: 16,3212  E6,1644                                  EBANK=   TVCPHASE                              
041175,000131: 16,3212                                           COUNT*   $$/RSRT                               
041176,000132: 
041177,000133: 16,3212           22016        REDOTVC            LXCH     BANKRUPT                              #  TVC RESTART PACKAGE
041178,000134: 16,3213           00006                           EXTEND                                         
041179,000135: 16,3214           22012                           QXCH     QRUPT                                 #  (..TCR.. IN ..FINCOPY..)
041180,000136: 
041181,000137: 16,3215           11653        EXECPHS            CCS      TVCEXPHS                              #  CHECK TVCEXECUTIVE PHASE
041182,000138: 16,3216           13220                           TCF      +2                                    #        MUST RESTART TVCEXECUTIVE
041183,000139: 16,3217           13224                           TCF      TVCDAPHS                              #        NO NEED TO RESTART TVCEXECUTIVE
041184,000140: 
041185,000141: 16,3220           34334                           CAF      NINE                                  #  9CS DELAY TO FORCE EXRSTRT TO OCCUR
041186,000142: 16,3221           05261                           TC       WAITLIST                              #        BEFORE PITCHDAP, AFTER CMDSOUT
041187,000143: 16,3222  E6,1653                                  EBANK=   TVCEXPHS                              
041188,000144: 16,3222           03325 34066                     2CADR    EXRSTRT                               
041189,000145: 
041190,000146: 16,3224           47700        TVCDAPHS           CS       OCT37776                              #  CHECK BITS 15 AND 1 OF TVCPHASE TO SEE
041191,000147: 16,3225           71644                           MASK     TVCPHASE                              #        DAP RESTART LOCATION (-1,1,2,3)
041192,000148: 16,3226           10000                           CCS      A                                     
041193,000149: 16,3227           13312                           TCF      FINCOPY                               #        FINISH THE COPYCYCLE FIRST
041194,000150: 16,3230           13235                           TCF      ENABL1                                #        JUST PREPARE THE OUTCOUNTERS AND GO
041195,000151: 
041196,000152: 16,3231           41644                           CS       TVCPHASE                              #  TEST FOR TVCPHASE = -2
041197,000153: 16,3232           75032                           MASK     BIT2                                  #        (THIS INDICATES RESTART OCCURRED
041198,000154: 16,3233           00006                           EXTEND                                         #         DURING CSM/LM V46 SWITCH-OVER)
041199,000155: 16,3234           13316                           BZF      TRIM/CMD                              #  NO, TVCPHASE = -1, RSTRT WAS IN TVCINIT
041200,000156: 
041201,000157: 16,3235           35024        ENABL1             CAF      BIT8                                  #  TVC ENABLE, FOLLOWED BY 40 MS (MIN) WAIT
041202,000158: 16,3236           65021                           AD       BIT11                                 #        SET BIT FOR OPTICS-DAC-ENABLE ALSO
041203,000159: 16,3237           00006                           EXTEND                                         #        (ENABL1 ENTERED FROM TVCDAPHS / FINCOPY)
041204,000160: 16,3240           05012                           WOR      CHAN12                                
041205,000161: 16,3241           33331                           CAF      TVCADDR                               #  WAIT, CALLING ENABL2 (BBCON THERE)
041206,000162: 16,3242           55312                           TS       T5LOC                                 
041207,000163: 16,3243           33335                           CAF      TVCADDR    +4                         #        60 MS (TVCEXADR)
041208,000164: 16,3244           54030                           TS       TIME5                                 
041209,000165: 
041210,000166: 16,3245           15347                           TCF      RESUME                                
041211,000167: 
041212,000168: 16,3246           22016        ENABL2             LXCH     BANKRUPT                              #  CONTINUE PREPARATION OF OUTCOUNTERS
041213,000169: 
041214,000170: 16,3247           35032                           CAF      BIT2                                  #  OPTICS ERROR CNTR ENABLE, 4MS MIN WAIT
041215,000171: 16,3250           00006                           EXTEND                                         
041216,000172: 16,3251           05012                           WOR      CHAN12                                
041217,000173: 16,3252           33333                           CAF      TVCADDR    +2                         #  WAIT, CALLING CMDSOUT (BBCON THERE)
041218,000174: 16,3253           55312                           TS       T5LOC                                 
041219,000175: 16,3254           37700                           CAF      OCT37776                              #        20MS
041220,000176: 16,3255           54030                           TS       TIME5                                 
041221,000177: 
041222,000178: 16,3256           15351                           TCF      NOQRSM                                
041223,000179: 
041224,000180: 16,3257           22016        CMDSOUT            LXCH     BANKRUPT                              #  CONTINUE PREPARATION OF OUTCOUNTERS
041225,000181: 16,3260           00006                           EXTEND                                         
041226,000182: 16,3261           22012                           QXCH     QRUPT                                 
041227,000183: 
041228,000184: 16,3262           45035                           CS       ZERO                                  #  MOST RECENT ACTUATOR COMMANDS
041229,000185: 16,3263           61623                           AD       PCMD                                  #        (AVOID +0)
041230,000186: 16,3264           54054                           TS       TVCPITCH                              
041231,000187: 16,3265           45035                           CS       ZERO                                  
041232,000188: 16,3266           61624                           AD       YCMD                                  
041233,000189: 16,3267           54053                           TS       TVCYAW                                
041234,000190: 
041235,000191: 16,3270           35076                           CAF      PRIO6                                 #  RELEASE THE COUNTERS (BITS 11,12)
041236,000192: 16,3271           00006                           EXTEND                                         
041237,000193: 16,3272           05014                           WOR      CHAN14                                
041238,000194: 
041239,000195: 16,3273           11644        PHSCHK2            CCS      TVCPHASE                              #  CHECK TVCPHASE AGAIN
041240,000196: 16,3274           13304                           TCF      CHKSTRK                               
041241,000197: 16,3275           13304                           TCF      CHKSTRK                               
041242,000198: 16,3276           10000                           CCS      A                                     #  A CONTAINS THE DIMINISHED ABSOLUTE OF
041243,000199: 16,3277           03302                           TC       +3                                    #  TVCPHASE (-2 BECOMES +1. -1 BECOMES +0)
041244,000200: 
041245,000201: 16,3300           04715                           TC       POSTJUMP                              #        REPEAT TVC INITIALIZATION
041246,000202: 16,3301           36210                           CADR     MRCLEAN                               #        (DO NOT RETURN)
041247,000203: 
041248,000204: 16,3302           04754                 +3        TC       IBNKCALL                              #        REPEAT CSM/LM V46 SWITCH-OVER
041249,000205: 16,3303           36417                           CADR     SWICHOVR   +5                         #        (RETURN TO CHECK FOR STROKE TEST)
041250,000206: 
041251,000207: 16,3304           11574        CHKSTRK            CCS      STROKER                               #  CHECK FOR STROKE TEST IN PROGRESS
041252,000208: 16,3305           13322                           TCF      TSTINITJ                              #  YES, KILL IT
041253,000209: 16,3306           13310                           TCF      +2                                    #  NO, PROCEED
041254,000210: 16,3307           13322                           TCF      TSTINITJ                              #  YES, KILL IT
041255,000211: 
041256,000212: 16,3310           04715                 +4        TC       POSTJUMP                              #        IF POSITIVE OR ZERO, RESTART AT
041257,000213: 16,3311           36362                           CADR     TVCINIT4                              #                TVCINIT4 (ZEROS TVCPHASE, AND
041258,000214:                                                                                                  #                CALLS TVC DAPS VIA DAPINIT)
041259,000215: 16,3312           51644        FINCOPY            INDEX    TVCPHASE                              #  PICK UP THE APPROPRIATE COPYCYCLE
041260,000216: 16,3313           33331                           CAF      TVCCADR                               
041261,000217: 16,3314           04760                           TCR      ISWCALL                               #  RE-ENTER THE COPYCYCLE, RETURN AT END
041262,000218: 16,3315           13235                           TCF      ENABL1                                #  NOW PREPARE THE OUTCOUNTERS
041263,000219: 
041264,000220: 16,3316           00006        TRIM/CMD           EXTEND                                         #  TVCDAPON INITIALIZATION NOT COMPLETED,
041265,000221: 16,3317           31424                           DCA      PACTOFF                               #        EG. P,YCMD MAY NOT BE SET.  SET...
041266,000222: 16,3320           53624                           DXCH     PCMD                                  
041267,000223: 16,3321           13235                           TCF      ENABL1                                #  NOW PREPARE THE OUTCOUNTERS
041268,000224: 
041269,000225: 16,3322           35035        TSTINITJ           CAF      ZERO                                  #  DISABLE STROKE TEST (-0 SHOWS PRIOR V68)
041270,000226: 16,3323           55574                           TS       STROKER                               #  (+0 MEANS NEW V68 REQUIRED FOR STARTUP)
041271,000227: 
041272,000228: 16,3324           13310                           TCF      CHKSTRK    +4                         
041273,000229: 
041274,000230: 16,3325           51653        EXRSTRT            INDEX    TVCEXPHS                              #  TVCEXECUTIVE RESTARTS....GO TO
041275,000231: 16,3326           33335                           CAF      TVCEXADR                              #        APPROPRIATE RESTART POINT
041276,000232: 16,3327           50000                           INDEX    A                                     
041277,000233: 16,3330           10000                           TCF      0                                     
041278,000234: 
041279,000235:                                                                                                  #  TVC RESTART TABLES.... ORDER IS REQUIRED.  HI-ORDER WORDS ONLY, OF 2CADRS, SINCE BBCON IS ALREADY THERE.
041280,000236: 
041281,000237: 16,3331  16,3331               TVCADDR            =        TVCCADR                               #  TABLE OF CADRS, UNUSED LOCS FOR GENADRS
041282,000238: 16,3331           03246        TVCCADR            GENADR   ENABL2                                #  (FOR T5 CALL, UNUSED TABLE LOC)
041283,000239: 16,3332           40714                 +1        CADR     PCOPY      +1                         #  PITCH COPYCYCLE
041284,000240: 16,3333           03257                 +2        GENADR   CMDSOUT                               #  (FOR T5 CALL, UNUSED TABLE LOC)
041285,000241: 16,3334           41104                 +3        CADR     YCOPY      +1                         #  YAW COPYCYCLE
041286,000242: 16,3335           37772        TVCEXADR           OCT      37772                                 #  (UNUSED TABLE LOC, FILL WITH 60MS, T5)
041287,000243: 16,3336           03055                 +1        GENADR   EXECCOPY   +1                         #  TVCEXECUTIVE RESTART POINTS (ORDERED)
041288,000244: 16,3337           03063                 +2        GENADR   1SHOTCHK                              
041289,000245: 16,3340           03112                 +3        GENADR   TEMPSET                               
041290,000246: 16,3341           03115                 +4        GENADR   CORSETUP                              
041291,000247: 16,3342           03173                 +5        GENADR   CORCOPY    +1                         
041292,000248: 16,3343           03204                 +6        GENADR   CNTRCOPY                              

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