Source Code
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These source-code files are part of a reconstructed copy of Comanche 051, the
original release of the Apollo 11 Command Module (CM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Comanche 055 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes related to the R-2 lunar potential model, using hints from program
comments and change-indicating asterisks in the Comanche 055 listing as a guide.
The reconstruction was verified by matching memory-bank checksums to those listed
in drawing 2021153D. Note that page numbers in the reconstructed code match those
on the Comanche 055 printout, although the added code would likely have changed page
numbers for a real Comanche 051 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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041702,000002: ## Copyright: Public domain.
041703,000003: ## Filename: TVCRESTARTS.agc
041704,000004: ## Purpose: A section of Comanche revision 051.
041705,000005: ## It is part of the reconstructed source code for the
041706,000006: ## original release of the flight software for the Command
041707,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
041708,000008: ## The code has been recreated from a copy of Comanche 055. It
041709,000009: ## has been adapted such that the resulting bugger words
041710,000010: ## exactly match those specified for Comanche 51 in NASA drawing
041711,000011: ## 2021153D, which gives relatively high confidence that the
041712,000012: ## reconstruction is correct.
041713,000013: ## Reference: pp. 956-960
041714,000014: ## Assembler: yaYUL
041715,000015: ## Contact: Ron Burkey <info@sandroid.org>.
041716,000016: ## Website: www.ibiblio.org/apollo/index.html
041717,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
041718,000018:
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Page 956
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041720,000020: # NAME....TVCRESTART PACKAGE, CONSISTING OF REDOTVC, ENABL1, 2, CMDSOUT, PHSCHK2, ETC.
041721,000021: # LOG SECTION...TVCRESTARTS SUBROUTINE...DAPCSM
041722,000022: # MODIFIED BY SCHLUNDT 21 OCTOBER 1968
041723,000023:
041724,000024: # FUNCTIONAL DESCRIPTION....
041725,000025:
041726,000026: # *RESTART-PROOFS THE TVC DAPS, INCLUDING PITCHDAP, YAWDAP,
041727,000027: # TVCEXECUTIVE, ROLLDAP, TVCINIT4, TVCDAPON, AND CSM/.M V46 SWTCHOVR.
041728,000028:
041729,000029: # *TVC RESTARTS DESERVE SPECIAL CONSIDERATION IN SEVERAL AREAS.
041730,000030: # RESTART DOWN-TIME IS IMPORTANT BECAUSE OF THE TRANSIENTS INTRODUCED
041731,000031: # BY THE THRUST VECTOR RETURN TO THE ACTUATOR MECHANICAL NULLS
041732,000032: # FOLLOWING TVC- AND OPTICS-ERROR-COUNTER-DISENABLES (CHANNEL 12).
041733,000033: # TVC USES A MIXTURE OF WAITLIST, T5, T6, AND JOB CALLS. THERE IS
041734,000034: # FILTER MEMORY (UP TO 6TH ORDER) TO BE PROTECTED IF WILD TRANSIENTS
041735,000035: # ARE TO BE AVOIDED. COUNTERS ARE INVOLVED FOR ONE-SHOT
041736,000036: # CORRECTIONS AND GAIN UPDATES. THE GIMBAL TRIM ESTIMATORS AND THE
041737,000037: # BODY AXIS ATTITUDE ERROR INTEGRATORS INVOLVE DIGITAL SUMMATION.
041738,000038: # DIGITAL DIFFERENTIATORS ARE INVOLVED IN THE BODY AXIS RATE ESTIMA-
041739,000039: # TIONS AND IN THE OUTPUTTING OF ACTUATOR COMMANDS. THERE IS AN
041740,000040: # OFFSET-TRACKER-FILTER TO PROTECT. ETC., ETC.
041741,000041:
041742,000042: # *THOSE QUANTITIES WHICH MUST BE PROTECTED ARE STORED IN TEMPORARY
041743,000043: # REGISTERS AS THEY ARE COMPUTED, FOR UPDATING THE REAL REGISTERS
041744,000044: # DURING COPYCYCLES.
041745,000045:
041746,000046: # *THE SEVERAL COPYCYCLES ARE EACH PROTECTED BY PHASE POINTS AT THEIR
041747,000047: # BEGINNING AND AT THEIR TERMINATION. THE PHASE POINTS ARE SIMPLY
041748,000048: # ..INCR.. INSTRUCTIONS, EITHER ..INCR TVCEXPHS.. FOR COPYCYCLES
041749,000049: # IN THE TVCEXECUTIVE, OR ..INCR TVCPHASE.. FOR THE PITCH AND YAW
041750,000050: # COPYCYCLES. INDEXING ON EACH OF THESE POINTERS THEN PERMITS A
041751,000051: # RETURN TO THE APPROPRIATE RESTART POINTS.
041752,000052:
041753,000053: # *IF A RESTART OCCURS DURING EITHER COPYCYCLE, THAT COPYCYCLE IS
041754,000054: # COMPLETED. THEN THE NORMAL TVCINIT4....DAPINIT....PITCHDAP STARTUP
041755,000055: # SEQUENCE IS CALLED UPON TO GET THINGS GOING AGAIN.
041756,000056:
041757,000057: # *TVC-ENABLE AND OPTICS-ERROR-COUNTER ENABLE MUST BE SET ASAP
041758,000058: # (ALLOWING FOR PROCEDURAL DELAYS). THEN THE ENGINES ARE COMMANDED
041759,000059: # TO THE P,YACTOFF TRIM VALUES. THE DAPS ARE THEN READY TO GO ON THE
041760,000060: # AIR, WITH THE REGULAR STARTUP SEQUENCE, EITHER AT MRCLEAN FOR A
041761,000061: # COMPLETE INITIALIZATION OR AT TVCINIT4 FOR A PARTIAL INITIALIZATION
041762,000062:
041763,000063: # *FOR RESTARTS PRIOR TO THE SETTING OF THE T5 BITS AT DOTVCON THE
041764,000064: # PRE40.6 SECTION OF S40.6 TAKES CARE OF RE-ESTABLISHING TRIMS.
041765,000065:
041766,000066: # *IF A RESTART OCCURS DURING THE TVCEXEC....TVCEXFIN SEQUENCE THE
041767,000067: # COMPUTATIONS WILL BE COMPLETED, STARTING AT THE APPROPRIATE RESTART
041768,000068: # POINT, AFTER THE DAPS ARE READY TO GO ON THE AIR.
041769,000069:
041770,000070: # *IF A RESTART OCCURS PRIOR TO TVCINIT4 (TVCPHASE = -1) E.G. DURING
041771,000071: # THE EARLY DAP INITIALIZATION PHASE, THE DAP STARTUP SEQUENCE IS
041772,000072: # ENTERED AT MRCLEAN FOR A FULL INITIALIZATION.
041773,000073:
041774,000074: # *FOR RESTARTS DURING CSM/LM V46 SWITCH-OVER, TVCPHASE IS SET TO -2.
041775,000075: # AND THE RESTART LOGIC GOES BACK TO REDO SWITCH-OVER (AFTER THE
041776,000076: # NORMAL DAP RESTART SEQUENCE IS FOLLOWED).
041777,000077:
041778,000078: # *RESTARTS ARE NOT CRITICAL TO THE ROLL DAP PERFORMANCES HENCE THE
041779,000079: # THE ROLL DAP IS MERELY RESTARTED.
041780,000080:
041781,000081: # *RESTARTS DURING A STROKE TEST (STROKER IS NON-ZERO) WILL CAUSE THE
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Page 957
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041783,000083: # STROKE TEST TO BE TERMINATED. A NEW V68 ENTRY WILL BE REQUIRED
041784,000084: # TO GET IT GOING AGAIN (NO AUTOMATIC RESTART).
041785,000085: #
041786,000086: # *REDOTVC IS REACHED FOLLOWING ANY RESTART WHICH FINDS THE T5 BITS
041787,000087: # (BITS 15,14 OF FLAGWRD6) SET FOR TVC. DOTVCON SETS TVCPHASE = -1
041788,000088: # AND TVC EXPHS = 0 JUST BEFORE SETTING THESE BITS, JUST BEFORE
041789,000089: # MAKING THE T5 CALL TO TVCDAPON. ON A NORMAL SHUTDOWN DOTVCRCS
041790,000090: # CALLS RCSDAPON, WHICH RESETS THE T5 BITS FOR RCS.
041791,000091:
041792,000092: # CALLING SEQUENCE....T5, IN PARTICULAR BY ELRSKIP OF FRESH START/RESTART
041793,000093:
041794,000094: # NORMAL EXIT MODES....RESUME, NOQRSM, POSTJUMP (TO TVCINIT4 OR MRCLEAN)
041795,000095:
041796,000096: # ALARM OR ABORT EXIT MODES....NONE
041797,000097:
041798,000098: # SUBROUTINES CALLED....
041799,000099:
041800,000100: # *PCOPY+1, YCOPY+1 (PITCH AND YAW COPYCYCLES)
041801,000101: # *ENABLE1,2, CMDSOUT (RE-ESTABLISH ACTUATOR TRIMS)
041802,000102: # *MRCLEAN OR TVCINIT4 (TVCDAP INITIALIZATIONS)
041803,000103: # *SWICHOVR +5 (CSM/LM V46 SWITCH-OVER)
041804,000104: # *EXRSTRT AND TVCEXECUTIVE PHASE POINTS 1 THRU 6
041805,000105: # *WAITLIST, IBNKCALL, POSTJUMP, ISWCALL
041806,000106:
041807,000107: # OTHER INTERFACES....DOTVCON AND RCSDAPON (T5 BITS), ELRSKIP (CALLS IT)
041808,000108:
041809,000109: # ERASABLE INITIALIZATION REQUIRED....
041810,000110:
041811,000111: # *T5 BITS (1,0), TVCPHASE (-2,-1,0,1,2,3), TVCEXPHS (1 THRU 6)
041812,000112: # *TVC DAP VARIABLES
041813,000113: # *OPERATIONS PERFORMED BY REDOTVC ARE BASED ON THE ASSUMPTION THAT
041814,000114: # THE TVC DAPS ARE RUNNING NORMALLY
041815,000115:
041816,000116: # OUTPUT....
041817,000117:
041818,000118: # *PITCH AND YAW TVC DAP COPYCYCLES COMPLETED IF INTERUPTED
041819,000119: # *TVCEXECUTIVE COMPLETED IF INTERUPTED
041820,000120: # *STROKE TEST TERMINATED IF INTERRUPTED
041821,000121: # *CSM/LM V46 SWITCH-OVER REPEATED IF INTERRUPTED
041822,000122: # *ACTUATOR TRIMS RE-ESTABLISHED (ACTUATORS BACK ON THE AIR)
041823,000123: # *TVC DAP INITIALIZATION AS REQUIRED
041824,000124: # *ALL TVC DAP OPERATIONS ON THE AIR
041825,000125:
041826,000126: # DEBRIS....TVC TEMPORARIES IN EBANK6
041827,000127:
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Page 958
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041829,000129:
041830,000130: 16,3140 BANK 16
041831,000131: 16,2000 SETLOC DAPROLL
041832,000132: 16,2000 BANK
041833,000133: 16,3140 E6,1644 EBANK= TVCPHASE
041834,000134: 16,3140 COUNT* $$/RSRT
041835,000135:
041836,000136: 16,3140 22016 REDOTVC LXCH BANKRUPT # TVC RESTART PACKAGE
041837,000137: 16,3141 00006 EXTEND
041838,000138: 16,3142 22012 QXCH QRUPT # (..TCR.. IN ..FINCOPY..)
041839,000139:
041840,000140: 16,3143 11651 EXECPHS CCS TVCEXPHS # CHECK TVCEXECUTIVE PHASE
041841,000141: 16,3144 13146 TCF +2 # MUST RESTART TVCEXECUTIVE
041842,000142: 16,3145 13152 TCF TVCDAPHS # NO NEED TO RESTART TVCEXECUTIVE
041843,000143:
041844,000144: 16,3146 34334 CAF NINE # 9CS DELAY TO FORCE EXRSTRT TO OCCUR
041845,000145: 16,3147 05245 TC WAITLIST # BEFORE PITCHDAP, AFTER CMDSOUT
041846,000146: 16,3150 E6,1651 EBANK= TVCEXPHS
041847,000147: 16,3150 03253 34066 2CADR EXRSTRT
041848,000148:
041849,000149: 16,3152 47700 TVCDAPHS CS OCT37776 # CHECK BITS 15 AND 1 OF TVCPHASE TO SEE
041850,000150: 16,3153 71644 MASK TVCPHASE # DAP RESTART LOCATION (-1,1,2,3)
041851,000151: 16,3154 10000 CCS A
041852,000152: 16,3155 13240 TCF FINCOPY # FINISH THE COPYCYCLE FIRST
041853,000153: 16,3156 13163 TCF ENABL1 # JUST PREPARE THE OUTCOUNTERS AND GO
041854,000154:
041855,000155: 16,3157 41644 CS TVCPHASE # TEST FOR TVCPHASE = -2
041856,000156: 16,3160 75016 MASK BIT2 # (THIS INDICATES RESTART OCCURRED
041857,000157: 16,3161 00006 EXTEND # DURING CSM/LM V46 SWITCH-OVER)
041858,000158: 16,3162 13244 BZF TRIM/CMD # NO, TVCPHASE = -1, RSTRT WAS IN TVCINIT
041859,000159:
041860,000160: 16,3163 35010 ENABL1 CAF BIT8 # TVC ENABLE, FOLLOWED BY 40 MS (MIN) WAIT
041861,000161: 16,3164 65005 AD BIT11 # SET BIT FOR OPTICS-DAC-ENABLE ALSO
041862,000162: 16,3165 00006 EXTEND # (ENABL1 ENTERED FROM TVCDAPHS / FINCOPY)
041863,000163: 16,3166 05012 WOR CHAN12
041864,000164: 16,3167 33257 CAF TVCADDR # WAIT, CALLING ENABL2 (BBCON THERE)
041865,000165: 16,3170 55312 TS T5LOC
041866,000166: 16,3171 33263 CAF TVCADDR +4 # 60 MS (TVCEXADR)
041867,000167: 16,3172 54030 TS TIME5
041868,000168:
041869,000169: 16,3173 15333 TCF RESUME
041870,000170:
041871,000171: 16,3174 22016 ENABL2 LXCH BANKRUPT # CONTINUE PREPARATION OF OUTCOUNTERS
041872,000172:
041873,000173: 16,3175 35016 CAF BIT2 # OPTICS ERROR CNTR ENABLE, 4MS MIN WAIT
041874,000174: 16,3176 00006 EXTEND
041875,000175: 16,3177 05012 WOR CHAN12
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Page 959
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041877,000177: 16,3200 33261 CAF TVCADDR +2 # WAIT, CALLING CMDSOUT (BBCON THERE)
041878,000178: 16,3201 55312 TS T5LOC
041879,000179: 16,3202 37700 CAF OCT37776 # 20MS
041880,000180: 16,3203 54030 TS TIME5
041881,000181:
041882,000182: 16,3204 15335 TCF NOQRSM
041883,000183:
041884,000184: 16,3205 22016 CMDSOUT LXCH BANKRUPT # CONTINUE PREPARATION OF OUTCOUNTERS
041885,000185: 16,3206 00006 EXTEND
041886,000186: 16,3207 22012 QXCH QRUPT
041887,000187:
041888,000188: 16,3210 45021 CS ZERO # MOST RECENT ACTUATOR COMMANDS
041889,000189: 16,3211 61623 AD PCMD # (AVOID +0)
041890,000190: 16,3212 54054 TS TVCPITCH
041891,000191: 16,3213 45021 CS ZERO
041892,000192: 16,3214 61624 AD YCMD
041893,000193: 16,3215 54053 TS TVCYAW
041894,000194:
041895,000195: 16,3216 35062 CAF PRIO6 # RELEASE THE COUNTERS (BITS 11,12)
041896,000196: 16,3217 00006 EXTEND
041897,000197: 16,3220 05014 WOR CHAN14
041898,000198:
041899,000199: 16,3221 11644 PHSCHK2 CCS TVCPHASE # CHECK TVCPHASE AGAIN
041900,000200: 16,3222 13232 TCF CHKSTRK
041901,000201: 16,3223 13232 TCF CHKSTRK
041902,000202: 16,3224 10000 CCS A # A CONTAINS THE DIMINISHED ABSOLUTE OF
041903,000203: 16,3225 03230 TC +3 # TVCPHASE (-2 BECOMES +1. -1 BECOMES +0)
041904,000204:
041905,000205: 16,3226 04701 TC POSTJUMP # REPEAT TVC INITIALIZATION
041906,000206: 16,3227 36152 CADR MRCLEAN # (DO NOT RETURN)
041907,000207:
041908,000208: 16,3230 04740 +3 TC IBNKCALL # REPEAT CSM/LM V46 SWITCH-OVER
041909,000209: 16,3231 36361 CADR SWICHOVR +5 # (RETURN TO CHECK FOR STROKE TEST)
041910,000210:
041911,000211: 16,3232 11574 CHKSTRK CCS STROKER # CHECK FOR STROKE TEST IN PROGRESS
041912,000212: 16,3233 13250 TCF TSTINITJ # YES, KILL IT
041913,000213: 16,3234 13236 TCF +2 # NO, PROCEED
041914,000214: 16,3235 13250 TCF TSTINITJ # YES, KILL IT
041915,000215:
041916,000216: 16,3236 04701 +4 TC POSTJUMP # IF POSITIVE OR ZERO, RESTART AT
041917,000217: 16,3237 36324 CADR TVCINIT4 # TVCINIT4 (ZEROS TVCPHASE, AND
041918,000218: # CALLS TVC DAPS VIA DAPINIT)
041919,000219: 16,3240 51644 FINCOPY INDEX TVCPHASE # PICK UP THE APPROPRIATE COPYCYCLE
041920,000220: 16,3241 33257 CAF TVCCADR
041921,000221: 16,3242 04744 TCR ISWCALL # RE-ENTER THE COPYCYCLE, RETURN AT END
041922,000222: 16,3243 13163 TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
041923,000223:
041924,000224: 16,3244 00006 TRIM/CMD EXTEND # TVCDAPON INITIALIZATION NOT COMPLETED,
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Page 960
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041926,000226: 16,3245 31424 DCA PACTOFF # EG. P,YCMD MAY NOT BE SET. SET...
041927,000227: 16,3246 53624 DXCH PCMD
041928,000228: 16,3247 13163 TCF ENABL1 # NOW PREPARE THE OUTCOUNTERS
041929,000229:
041930,000230: 16,3250 35021 TSTINITJ CAF ZERO # DISABLE STROKE TEST (-0 SHOWS PRIOR V68)
041931,000231: 16,3251 55574 TS STROKER # (+0 MEANS NEW V68 REQUIRED FOR STARTUP)
041932,000232:
041933,000233: 16,3252 13236 TCF CHKSTRK +4
041934,000234:
041935,000235: 16,3253 51651 EXRSTRT INDEX TVCEXPHS # TVCEXECUTIVE RESTARTS....GO TO
041936,000236: 16,3254 33263 CAF TVCEXADR # APPROPRIATE RESTART POINT
041937,000237: 16,3255 50000 INDEX A
041938,000238: 16,3256 10000 TCF 0
041939,000239:
041940,000240: # TVC RESTART TABLES.... ORDER IS REQUIRED. HI-ORDER WORDS ONLY, OF 2CADRS, SINCE BBCON IS ALREADY THERE.
041941,000241:
041942,000242: 16,3257 16,3257 TVCADDR = TVCCADR # TABLE OF CADRS, UNUSED LOCS FOR GENADRS
041943,000243: 16,3257 03174 TVCCADR GENADR ENABL2 # (FOR T5 CALL, UNUSED TABLE LOC)
041944,000244: 16,3260 40675 +1 CADR PCOPY +1 # PITCH COPYCYCLE
041945,000245: 16,3261 03205 +2 GENADR CMDSOUT # (FOR T5 CALL, UNUSED TABLE LOC)
041946,000246: 16,3262 41051 +3 CADR YCOPY +1 # YAW COPYCYCLE
041947,000247: 16,3263 37772 TVCEXADR OCT 37772 # (UNUSED TABLE LOC, FILL WITH 60MS, T5)
041948,000248: 16,3264 03003 +1 GENADR EXECCOPY +1 # TVCEXECUTIVE RESTART POINTS (ORDERED)
041949,000249: 16,3265 03011 +2 GENADR 1SHOTCHK
041950,000250: 16,3266 03040 +3 GENADR TEMPSET
041951,000251: 16,3267 03043 +4 GENADR CORSETUP
041952,000252: 16,3270 03121 +5 GENADR CORCOPY +1
041953,000253: 16,3271 03132 +6 GENADR CNTRCOPY
End of include-file TVCRESTARTS.agc. Parent file is MAIN.agc