Source Code
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These source-code files are part of a reconstructed copy of Artemis 071, the
first release of the Apollo 15 through 17 Command Module (CM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with source code of Artemis 072 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes between the two versions. The reconstruction was verified by matching
memory-bank checksums to those listed in drawing 2021154-. Note that page
numbers in the reconstructed code match those on the Artemis 072 printout,
although the changed code would likely have changed page numbers for a real
Artemis 071 listing.
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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042234,000002: ## Copyright: Public domain.
042235,000003: ## Filename: TVCRESTARTS.agc
042236,000004: ## Purpose: A section of Artemis revision 071.
042237,000005: ## It is part of the reconstructed source code for the first
042238,000006: ## release of the flight software for the Command Module's
042239,000007: ## (CM) Apollo Guidance Computer (AGC) for Apollo 15 through
042240,000008: ## 17. The code has been recreated from a copy of Artemis 072.
042241,000009: ## It has been adapted such that the resulting bugger words
042242,000010: ## exactly match those specified for Artemis 071 in NASA
042243,000011: ## drawing 2021154-, which gives relatively high confidence
042244,000012: ## that the reconstruction is correct.
042245,000013: ## Reference: 959
042246,000014: ## Assembler: yaYUL
042247,000015: ## Contact: Ron Burkey <info@sandroid.org>.
042248,000016: ## Website: www.ibiblio.org/apollo/index.html
042249,000017: ## Mod history: 2019-08-14 MAS Created from Artemis 072.
042250,000018:
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Page 959
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042252,000020:
042253,000021: # NAME....TVCRESTART PACKAGE, CONSISTING OF REDOTVC, ENABL1, 2, CMDSOUT, PHSCHK2, ETC.
042254,000022: # LOG SECTION...TVCRESTARTS SUBROUTINE...DAPCSM
042255,000023: # MODIFIED BY SCHLUNDT 21 OCTOBER 1968
042256,000024: # MODIFIED BY BEALS TO ELIMINATE CSMMASS UPDATE LOGIC (NOW DONE IN S40.8)
042257,000025: # FUNCTIONAL DESCRIPTION....
042258,000026:
042259,000027: # *RESTART-PROOFS THE TVC DAPS, INCLUDING PITCHDAP, YAWDAP,
042260,000028: # TVCEXECUTIVE, ROLLDAP, TVCINIT4, TVCDAPON, AND CSM/.M V46 SWTCHOVR.
042261,000029: # *TVC RESTARTS DESERVE SPECIAL CONSIDERATION IN SEVERAL AREAS.
042262,000030: # RESTART DOWN-TIME IS IMPORTANT BECAUSE OF THE TRANSIENTS INTRODUCED
042263,000031: # BY THE THRUST VECTOR RETURN TO THE ACTUATOR MECHANICAL NULLS
042264,000032: # FOLLOWING TVC- AND OPTICS-ERROR-COUNTER-DISENABLES (CHANNEL 12).
042265,000033: # TVC USES A MIXTURE OF WAITLIST, T5, T6, AND JOB CALLS. THERE IS
042266,000034: # FILTER MEMORY (UP TO 6TH ORDER) TO BE PROTECTED IF WILD TRANSIENTS
042267,000035: # ARE TO BE AVOIDED. COUNTERS ARE INVOLVED FOR ONE-SHOT
042268,000036: # CORRECTIONS AND GAIN UPDATES. THE GIMBAL TRIM ESTIMATORS AND THE
042269,000037: # BODY AXIS ATTITUDE ERROR INTEGRATORS INVOLVE DIGITAL SUMMATION.
042270,000038: # DIGITAL DIFFERENTIATORS ARE INVOLVED IN THE BODY AXIS RATE ESTIMA-
042271,000039: # TIONS AND IN THE OUTPUTTING OF ACTUATOR COMMANDS. THERE IS AN
042272,000040: # OFFSET-TRACKER-FILTER TO PROTECT. ETC., ETC.
042273,000041: # *THOSE QUANTITIES WHICH MUST BE PROTECTED ARE STORED IN TEMPORARY
042274,000042: # REGISTERS AS THEY ARE COMPUTED, FOR UPDATING THE REAL REGISTERS
042275,000043: # DURING COPYCYCLES.
042276,000044: # *THE SEVERAL COPYCYCLES ARE EACH PROTECTED BY PHASE POINTS AT THEIR
042277,000045: # BEGINNING AND AT THEIR TERMINATION. THE PHASE POINTS ARE SIMPLY
042278,000046: # ..INCR.. INSTRUCTIONS, EITHER ..INCR TVCEXPHS.. FOR COPYCYCLES
042279,000047: # IN THE TVCEXECUTIVE, OR ..INCR TVCPHASE.. FOR THE PITCH AND YAW
042280,000048: # COPYCYCLES. INDEXING ON EACH OF THESE POINTERS THEN PERMITS A
042281,000049: # RETURN TO THE APPROPRIATE RESTART POINTS.
042282,000050: # *IF A RESTART OCCURS DURING EITHER COPYCYCLE, THAT COPYCYCLE IS
042283,000051: # COMPLETED. THEN THE NORMAL TVCINIT4....DAPINIT....PITCHDAP STARTUP
042284,000052: # SEQUENCE IS CALLED UPON TO GET THINGS GOING AGAIN.
042285,000053: # *TVC-ENABLE AND OPTICS-ERROR-COUNTER ENABLE MUST BE SET ASAP
042286,000054: # (ALLOWING FOR PROCEDURAL DELAYS). THEN THE ENGINES ARE COMMANDED
042287,000055: # TO THE P,YACTOFF TRIM VALUES. THE DAPS ARE THEN READY TO GO ON THE
042288,000056: # AIR, WITH THE REGULAR STARTUP SEQUENCE, EITHER AT MRCLEAN FOR A
042289,000057: # COMPLETE INITIALIZATION OR AT TVCINIT4 FOR A PARTIAL INITIALIZATION
042290,000058: # *FOR RESTARTS PRIOR TO THE SETTING OF THE T5 BITS AT DOTVCON THE
042291,000059: # PRE40.6 SECTION OF S40.6 TAKES CARE OF RE-ESTABLISHING TRIMS.
042292,000060: # *IF A RESTART OCCURS DURING THE TVCEXEC....TVCEXFIN SEQUENCE THE
042293,000061: # COMPUTATIONS WILL BE COMPLETED, STARTING AT THE APPROPRIATE RESTART
042294,000062: # POINT, AFTER THE DAPS ARE READY TO GO ON THE AIR.
042295,000063: # *IF A RESTART OCCURS PRIOR TO TVCINIT4 (TVCPHASE = -1) E.G. DURING
042296,000064: # THE EARLY DAP INITIALIZATION PHASE, THE DAP STARTUP SEQUENCE IS
042297,000065: # ENTERED AT MRCLEAN FOR A FULL INITIALIZATION.
042298,000066: # *FOR RESTARTS DURING CSM/LM V46 SWITCH-OVER, TVCPHASE IS SET TO -2.
042299,000067: # AND THE RESTART LOGIC GOES BACK TO REDO SWITCH-OVER (AFTER THE
042300,000068: # NORMAL DAP RESTART SEQUENCE IS FOLLOWED).
042301,000069: # *RESTARTS ARE NOT CRITICAL TO THE ROLL DAP PERFORMANCES HENCE THE
042302,000070: # THE ROLL DAP IS MERELY RESTARTED.
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Page 960
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042304,000072: # *REDOTVC IS REACHED FOLLOWING ANY RESTART WHICH FINDS THE T5 BITS
042305,000073: # (BITS 15,14 OF FLAGWRD6) SET FOR TVC. DOTVCON SETS TVCPHASE = -1
042306,000074: # AND TVC EXPHS = 0 JUST BEFORE SETTING THESE BITS, JUST BEFORE
042307,000075: # MAKING THE T5 CALL TO TVCDAPON. ON A NORMAL SHUTDOWN DOTVCRCS
042308,000076: # CALLS RCSDAPON, WHICH RESETS THE T5 BITS FOR RCS.
042309,000077: # CALLING SEQUENCE....T5, IN PARTICULAR BY ELRSKIP OF FRESH START/RESTART
042310,000078:
042311,000079: # NORMAL EXIT MODES....RESUME, NOQRSM, POSTJUMP (TO TVCINIT4 OR MRCLEAN)
042312,000080:
042313,000081: # ALARM OR ABORT EXIT MODES....NONE
042314,000082:
042315,000083: # SUBROUTINES CALLED....
042316,000084:
042317,000085: # *PCOPY+1, YCOPY+1 (PITCH AND YAW COPYCYCLES)
042318,000086: # *ENABLE1,2, CMDSOUT (RE-ESTABLISH ACTUATOR TRIMS)
042319,000087: # *MRCLEAN OR TVCINIT4 (TVCDAP INITIALIZATIONS)
042320,000088: # *SWICHOVR +5 (CSM/LM V46 SWITCH-OVER)
042321,000089: # *EXRSTRT AND TVCEXECUTIVE PHASE POINTS 1 THRU 6
042322,000090: # *WAITLIST, IBNKCALL, POSTJUMP, ISWCALL
042323,000091:
042324,000092: # OTHER INTERFACES....DOTVCON AND RCSDAPON (T5 BITS), ELRSKIP (CALLS IT)
042325,000093: # ERASABLE INITIALIZATION REQUIRED....
042326,000094:
042327,000095: # *T5 BITS (1,0), TVCPHASE (-2,-1,0,1,2,3), TVCEXPHS (1 THRU 6)
042328,000096: # *TVC DAP VARIABLES
042329,000097: # *OPERATIONS PERFORMED BY REDOTVC ARE BASED ON THE ASSUMPTION THAT
042330,000098: # THE TVC DAPS ARE RUNNING NORMALLY
042331,000099:
042332,000100: # OUTPUT....
042333,000101:
042334,000102: # *PITCH AND YAW TVC DAP COPYCYCLES COMPLETED IF INTERUPTED
042335,000103: # *TVCEXECUTIVE COMPLETED IF INTERUPTED
042336,000104: # *CSM/LM V46 SWITCH-OVER REPEATED IF INTERRUPTED
042337,000105: # *ACTUATOR TRIMS RE-ESTABLISHED (ACTUATORS BACK ON THE AIR)
042338,000106: # *TVC DAP INITIALIZATION AS REQUIRED
042339,000107: # *ALL TVC DAP OPERATIONS ON THE AIR
042340,000108:
042341,000109: # DEBRIS....TVC TEMPORARIES IN EBANK6
042342,000110:
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Page 961
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042344,000112: 16,2000 SETLOC DAPROLL
042345,000113: 16,2000 BANK
042346,000114: 16,3222 E6,1635 EBANK= TVCPHASE
042347,000115: 16,3222 COUNT* $$/RSRT
042348,000116:
042349,000117: 16,3222 22016 REDOTVC LXCH BANKRUPT # TVC RESTART PACKAGE
042350,000118: 16,3223 00006 EXTEND
042351,000119: 16,3224 22012 QXCH QRUPT # ( ..TCR.. IN ..FINCOPY.. )
042352,000120:
042353,000121: 16,3225 11644 EXECPHS CCS TVCEXPHS # CHECK TVCEXECUTIVE PHASE
042354,000122: 16,3226 13230 TCF +2 # MUST RESTART TVCEXECUTIVE
042355,000123: 16,3227 13233 TCF TVCDAPHS # NO NEED TO RESTART TVCEXECUTIVE
042356,000124:
042357,000125: 16,3230 34322 CAF NINE # 9CS DELAY TO FORCE EXRSTRT TO OCCUR
042358,000126: 16,3231 05223 TC TWIDDLE # BEFORE PITCHDAP, AFTER CMDSOUT
042359,000127: 16,3232 03325 ADRES EXRSTRT
042360,000128: 16,3233 47663 TVCDAPHS CS OCT37776 # CHECK BITS 15 AND 1 OF TVCPHASE TO SEE
042361,000129: 16,3234 71635 MASK TVCPHASE # DAP RESTART LOCATION (-1,1,2,3)
042362,000130: 16,3235 10000 CCS A
042363,000131: 16,3236 13315 TCF FINCOPY # FINISH THE COPYCYCLE FIRST
042364,000132: 16,3237 13244 TCF ENABL1 # JUST PREPARE THE OUTCOUNTERS AND GO
042365,000133:
042366,000134: 16,3240 41635 CS TVCPHASE # TEST FOR TVCPHASE = -2
042367,000135: 16,3241 74767 MASK BIT2 # (THIS INDICATES RESTART OCCURRED
042368,000136: 16,3242 00006 EXTEND # DURING CSM/LM V46 SWITCH-OVER)
042369,000137: 16,3243 13321 BZF TRIM/CMD # NO, TVCPHASE = -1, RSTRT WAS IN TVCINIT
042370,000138:
042371,000139: 16,3244 34761 ENABL1 CAF BIT8 # TVC ENABLE, FOLLOWED BY 40 MS (MIN) WAIT
042372,000140: 16,3245 64756 AD BIT11 # SET BIT FOR OPTICS-DAC-ENABLE ALSO
042373,000141: 16,3246 00006 EXTEND # (ENABL1 ENTERED FROM TVCDAPHS / FINCOPY)
042374,000142: 16,3247 05012 WOR CHAN12
042375,000143: 16,3250 33331 CAF TVCADDR # WAIT, CALLING ENABL2 (BBCON THERE)
042376,000144: 16,3251 54112 TS T5LOC
042377,000145: 16,3252 33335 CAF TVCADDR +4 # 60 MS (TVCEXADR)
042378,000146: 16,3253 54030 TS TIME5
042379,000147:
042380,000148: 16,3254 15323 TCF RESUME
042381,000149:
042382,000150: 16,3255 22016 ENABL2 LXCH BANKRUPT # CONTINUE PREPARATION OF OUTCOUNTERS
042383,000151:
042384,000152: 16,3256 34767 CAF BIT2 # OPTICS ERROR CNTR ENABLE, 4MS MIN WAIT
042385,000153: 16,3257 00006 EXTEND
042386,000154: 16,3260 05012 WOR CHAN12
042387,000155: 16,3261 33333 CAF TVCADDR +2 # WAIT, CALLING CMDSOUT (BBCON THERE)
042388,000156: 16,3262 54112 TS T5LOC
042389,000157: 16,3263 37663 CAF OCT37776 # 20MS
042390,000158: 16,3264 54030 TS TIME5
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Page 962
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042392,000160: 16,3265 15325 TCF NOQRSM
042393,000161:
042394,000162: 16,3266 22016 CMDSOUT LXCH BANKRUPT # CONTINUE PREPARATION OF OUTCOUNTERS
042395,000163: 16,3267 00006 EXTEND
042396,000164: 16,3270 22012 QXCH QRUPT
042397,000165:
042398,000166: 16,3271 44772 CS ZERO # MOST RECENT ACTUATOR COMMANDS
042399,000167: 16,3272 61623 AD PCMD # (AVOID +0)
042400,000168: 16,3273 54054 TS TVCPITCH
042401,000169: 16,3274 44772 CS ZERO
042402,000170: 16,3275 61624 AD YCMD
042403,000171: 16,3276 54053 TS TVCYAW
042404,000172:
042405,000173: 16,3277 35050 CAF PRIO6 # RELEASE THE COUNTERS (BITS 11,12)
042406,000174: 16,3300 00006 EXTEND
042407,000175: 16,3301 05014 WOR CHAN14
042408,000176:
042409,000177: 16,3302 11635 PHSCHK2 CCS TVCPHASE # CHECK TVCPHASE AGAIN
042410,000178: 16,3303 13313 TCF JUMPTVC4
042411,000179: 16,3304 13313 TCF JUMPTVC4
042412,000180: 16,3305 10000 CCS A # A CONTAINS THE DIMINISHED ABSOLUTE OF
042413,000181: 16,3306 03311 TC +3 # TVCPHASE (-2 BECOMES +1. -1 BECOMES +0)
042414,000182:
042415,000183: 16,3307 04655 TC POSTJUMP # REPEAT TVC INITIALIZATION
042416,000184: 16,3310 36166 CADR MRCLEAN # (DO NOT RETURN)
042417,000185:
042418,000186: 16,3311 04714 +3 TC IBNKCALL # REPEAT CSM/LM V46 SWITCH-OVER
042419,000187: 16,3312 36351 CADR SWICHOVR +5 # (RETURN TO CHECK FOR STROKE TEST)
042420,000188:
042421,000189: 16,3313 04655 JUMPTVC4 TC POSTJUMP # IF POSITIVE OR ZERO, RESTART AT
042422,000190: 16,3314 36326 CADR TVCINIT4 # TVCINIT4 (ZEROS TVCPHASE, AND
042423,000191: # CALLS TVC DAPS VIA DAPINIT)
042424,000192: 16,3315 51635 FINCOPY INDEX TVCPHASE # PICK UP THE APPROPRIATE COPYCYCLE
042425,000193: 16,3316 33331 CAF TVCCADR
042426,000194: 16,3317 04720 TCR ISWCALL # RE-ENTER THE COPYCYCLE, RETURN AT END
042427,000195: 16,3320 13244 TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
042428,000196:
042429,000197:
042430,000198: 16,3321 00006 TRIM/CMD EXTEND # TVCDAPON INITIALIZATION NOT COMPLETED,
042431,000199: 16,3322 31424 DCA PACTOFF # EG. P,YCMD MAY NOT BE SET. SET...
042432,000200: 16,3323 53624 DXCH PCMD
042433,000201: 16,3324 13244 TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
042434,000202:
042435,000203:
042436,000204: 16,3325 51644 EXRSTRT INDEX TVCEXPHS # TVCEXECUTIVE RESTARTS....GO TO
042437,000205: 16,3326 33335 CAF TVCEXADR # APPROPRIATE RESTART POINT
042438,000206: 16,3327 50000 INDEX A
042439,000207: 16,3330 10000 TCF 0
042440,000208:
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Page 963
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042442,000210:
042443,000211: # TVC RESTART TABLES.... ORDER IS REQUIRED. HI-ORDER WORDS ONLY, OF 2CADRS, SINCE BBCON IS ALREADY THERE.
042444,000212:
042445,000213: 16,3331 16,3331 TVCADDR = TVCCADR # TABLE OF CADRS, UNUSED LOCS FOR GENADRS
042446,000214: 16,3331 03255 TVCCADR GENADR ENABL2 # (FOR T5 CALL, UNUSED TABLE LOC)
042447,000215: 16,3332 41005 +1 CADR PCOPY +1 # PITCH COPYCYCLE
042448,000216: 16,3333 03266 +2 GENADR CMDSOUT # (FOR T5 CALL, UNUSED TABLE LOC)
042449,000217: 16,3334 41171 +3 CADR YCOPY +1 # YAW COPYCYCLE
042450,000218: 16,3335 37772 TVCEXADR OCT 37772 # (UNUSED TABLE LOC, FILL WITH 60MS, T5)
042451,000219: 16,3336 03123 +1 GENADR TEMPSET # TVCEXECUTIVE RESTART POINTS (ORDERED)
042452,000220: 16,3337 03126 +2 GENADR CORSETUP
042453,000221: 16,3340 03204 +3 GENADR CORCOPY +1
042454,000222: 16,3341 03215 +4 GENADR CNTRCOPY
End of include-file TVCRESTARTS.agc. Parent file is MAIN.agc