Source Code
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These source-code files are part of a reconstructed copy of Luminary 69/2,
the flown, final release of the Apollo 10 Lunar Module (LM) Apollo Guidance Computer (AGC) software.
The reconstruction is based on the source code of Luminary 69 — i.e., the
initial, unflown version, "revision 0" — of which
a contemporary listing was available. The code was then updated by incorporating the
differences between Luminary 69 and Luminary 69/2, known from other contemporary
documentation. The only such difference is the implementation in
Luminary 69/2 of the "R-2 Lunar Potential Model", the source code for which was taken
from program Luminary 99/1 (Apollo 11 LM), of which a contemporary listing was also available.
Finally, the now-reconstructed Luminary 69/2 was then validated by assembling it to
executable form and verifying that its memory banks had the correct checksums,
known from still other contemporary documentation.
Note that page numbers in the reconstructed code match those in the original Luminary 69
program listing, or in the ORBITAL INTEGRATION log section, in Luminary 99/1. Page numbers
would certainly differ somewhat in a contemporary Luminary 69/2 listing.
Moreover, annotations that were not present in the contemporary source code have been added
to the reconstructed code to justify each change in Luminary 69/2 relative to
Luminary 69. Here's a guide to the Apollo documentation referenced in those annotations:
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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008914,000002: ## Copyright: Public domain.
008915,000003: ## Filename: RCS_FAILURE_MONITOR.agc
008916,000004: ## Purpose: A section of LUM69 revision 2.
008917,000005: ## It is part of the reconstructed source code for the flown
008918,000006: ## version of the flight software for the Lunar Module's (LM)
008919,000007: ## Apollo Guidance Computer (AGC) for Apollo 10. The code has
008920,000008: ## been recreated from a copy of Luminary revsion 069, using
008921,000009: ## changes present in Luminary 099 which were described in
008922,000010: ## Luminary memos 75 and 78. The code has been adapted such
008923,000011: ## that the resulting bugger words exactly match those specified
008924,000012: ## for LUM69 revision 2 in NASA drawing 2021152B, which gives
008925,000013: ## relatively high confidence that the reconstruction is correct.
008926,000014: ## Reference: pp. 205-207
008927,000015: ## Assembler: yaYUL
008928,000016: ## Contact: Ron Burkey <info@sandroid.org>.
008929,000017: ## Website: www.ibiblio.org/apollo/index.html
008930,000018: ## Mod history: 2019-07-27 MAS Created from Luminary 69.
008931,000019:
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Page 205
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008933,000021: # PROGRAM DESCRIPTION
008934,000022:
008935,000023: # AUTHOR: J S MILLER
008936,000024:
008937,000025: # MODIFIED 6 MARCH 1968 BY P S WEISSMAN TO SET UP JOB FOR 1/ACCS WHEN THE MASKS ARE CHANGED.
008938,000026:
008939,000027: # THIS ROUTINE IS ATTACHED TO T4RUPT, AND IS ENTERED EVERY 480 MS. ITS FUNCTION IS TO EXAMINE THE LOW 8 BITS
008940,000028: # OF CHANNEL 32 TO SEE IF ANY ISOLATION-VALVE CLOSURE BITS HAVE APPEARED OR DISAPPEARED (THE CREW IS WARNED OF JET
008941,000029: # FAILURES BY LAMPS LIT BY THE GRUMMAN FAILURE-DETECTION CIRCUITRY; THEY MAY RESPOND BY OPERATING SWITCHES WHICH
008942,000030: # ISOLATE PAIRS OF JETS FROM THE PROPELLANT TANKS AND SET BITS IN CHANNEL 32). IN THE EVENT THAT CHANNEL 32 BITS
008943,000031: # DIFFER FROM 'PVALVEST', THE RECORD OF ACTIONS TAKEN BY THIS ROUTINE, THE APPROPRIATE BITS IN 'CH5MASK' &
008944,000032: # 'CH6MASK', USED BY THE DAP JET-SELECTION LOGIC, ARE UPDATED, AS IS 'PVALVEST'. TO SPEED UP & SHORTEN THE
008945,000033: # ROUTINE, NO MORE THAN ONE CHANGE IS ACCEPTED PER ENTRY. THE HIGHEST-NUMBERED BIT IN CHANNEL 32 WHICH REQUIRES
008946,000034: # ACTION IS THE ONE PROCESSED.
008947,000035:
008948,000036: # THE CODING IN THE FAILURE MONITOR HAS BEEN WRITTEN SO AS TO HAVE ALMOST COMPLETE RESTART PROTECTION. FOR
008949,000037: # EXAMPLE, NO ASSUMPTION IS MADE WHEN SETTING A 'CH5MASK' BIT TO 1 THAT THE PREVIOUS STATE IS 0, ALTHOUGH IT OF
008950,000038: # COURSE SHOULD BE. ONE CASE WHICH MAY BE SEEN TO EVADE PROTECTION IS THE OCCURRENCE OF A RESTART AFTER UPDATING
008951,000039: # ONE OR BOTH DAP MASK-WORDS BUT BEFORE UPDATING 'PVALVEST', COUPLED WITH A CHANGE IN THE VALVE-BIT BACK TO ITS
008952,000040: # FORMER STATE. THE CONSEQUENCE OF THIS IS THAT THE NEXT ENTRY WOULD NOT SEE THE CHANGE INCOMPLETELY INCORP-
008953,000041: # ORATED BY THE LAST PASS (BECAUSE IT WENT AWAY AT JUST THE RIGHT TIME), BUT THE DAP MASK-WORDS WILL BE INCORRECT.
008954,000042: # THIS COMBINATION OF EVENTS SEEMS QUITE REMOTE, BUT NOT IMPOSSIBLE UNLESS THE CREW OPERATES THE SWITCHES AT HALF-
008955,000043: # SECOND INTERVALS OR LONGER. IN ANY EVENT, A DISAGREEMENT BETWEEN REALITY AND THE DAP MASKS WILL BE CURED IF
008956,000044: # THE MISINTERPRETED SWITCH IS REVERSED AND THEN RESTORED TO ITS CORRECT POSITION (SLOWLY).
008957,000045:
008958,000046: # CALLING SEQUENCE:
008959,000047:
008960,000048: # TCF RCSMONIT (IN INTERRUPT MODE, EVERY 480 MS.)
008961,000049:
008962,000050: # EXIT: TCF RCSMONEX (ALL PATHS EXIT VIA SUCH AN INSTRUCTION)
008963,000051: 06,3156 5270 RCSMONEX EQUALS RESUME
008964,000052:
008965,000053: # ERASABLE INITIALIZATION REQUIRED:
008966,000054:
008967,000055: # VIA FRESH START: PVALVEST = +0 (ALL JETS ENABLED)
008968,000056: # CH5MASK, CH6MASK = +0 (ALL JETS OK)
008969,000057:
008970,000058: # OUTPUT: CH5MASK & CH6MASK UPDATED (1'S WHERE JETS NOT TO BE USED, IN CHANNEL 5 & 6 FORMAT)
008971,000059: # PVALTEST UPDATED (1,S WHEN VALVE CLOSURES HAVE BEEN TRANSLATED INTO CH5MASK & CH6MASK; CHAN 32 FORMAT)
008972,000060: # JOB TO DO 1/ACCS.
008973,000061:
008974,000062: # DEBRIS: A, L, Q AND DEBRIS OF NOVAC.
008975,000063:
008976,000064: # SUBROUTINE CALLED: NOVAC.
008977,000065:
008978,000066: 06,3156 1262 EBANK= CH5MASK
008979,000067:
008980,000068: 23,2000 BANK 23
008981,000069: 06,2000 SETLOC RCSMONT
008982,000070: 06,2000 BANK
008983,000071:
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Page 206
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008985,000073: 06,3156 COUNT* $$/T4RCS
008986,000074:
008987,000075: 06,3156 06,3156 RCSMONIT EQUALS RCSMON
008988,000076:
008989,000077: 06,3156 44755 RCSMON CS ZERO
008990,000078: 06,3157 00006 EXTEND
008991,000079: 06,3160 06032 RXOR CHAN32 # PICK UP + INVERT INVERTED CHANNEL 32.
008992,000080: 06,3161 74357 MASK LOW8 # KEEP JET-FAIL BITS ONLY.
008993,000081: 06,3162 54002 TS Q
008994,000082:
008995,000083: 06,3163 41276 CS PVALVEST # - -
008996,000084: 06,3164 70002 MASK Q # FORM PC + PC.
008997,000085: 06,3165 54001 TS L # (P = PREVIOUS ISOLATION VALVE STATE,
008998,000086: 06,3166 40002 CS Q # C = CURRENT VALVE STATE (CH32)).
008999,000087: 06,3167 71276 MASK PVALVEST
009000,000088: 06,3170 26001 ADS L # RESULT NZ INDICATES ACTION REQUIRED.
009001,000089:
009002,000090: 06,3171 00006 EXTEND
009003,000091: 06,3172 15270 BZF RCSMONEX # QUIT IF NO ACTION REQUIRED.
009004,000092:
009005,000093: 06,3173 00006 EXTEND
009006,000094: 06,3174 74745 MP BIT7 # MOVE BITS 8 - 1 OF A TO 14 - 7 OF L.
009007,000095: 06,3175 56001 XCH L # ZERO TO L IN THE PROCESS.
009008,000096:
009009,000097: 06,3176 24001 -3 INCR L
009010,000098: 06,3177 60000 DOUBLE # BOUND TO GET OVERFLOW IN THIS LOOP,
009011,000099: 06,3200 54000 OVSK # SINCE WE ASSURED INITIAL NZ IN A.
009012,000100: 06,3201 13176 TCF -3
009013,000101:
009014,000102: 06,3202 50001 INDEX L
009015,000103: 06,3203 34743 CA BIT8 -1 # SAVE THE RELEVANT BIT (8 - 1).
009016,000104: 06,3204 54002 TS Q
009017,000105: 06,3205 71276 MASK PVALVEST # LOOK AT PREVIOUS VALVE STATE BIT.
009018,000106: 06,3206 10000 CCS A
009019,000107: 06,3207 13223 TCF VOPENED # THE VALVE HAS JUST BEEN OPENED.
009020,000108:
009021,000109: 06,3210 41262 CS CH5MASK # THE VALVE HAS JUST BEEN CLOSED.
009022,000110: 06,3211 50001 INDEX L
009023,000111: 06,3212 73242 MASK 5FAILTAB
009024,000112: 06,3213 27262 ADS CH5MASK # SET INHIBIT BIT FOR CHANNEL 5 JET.
009025,000113:
009026,000114: 06,3214 41263 CS CH6MASK
009027,000115: 06,3215 50001 INDEX L
009028,000116: 06,3216 73252 MASK 6FAILTAB
009029,000117: 06,3217 27263 ADS CH6MASK # SET INGIBIT BIT FOR CHANNEL 6 JET.
009030,000118:
009031,000119: 06,3220 30002 CA Q
009032,000120: 06,3221 27276 ADS PVALVEST # RECORD ACTION TAKEN.
009033,000121:
009034,000122: 06,3222 13236 TCF 1/ACCFIX # SET UP 1/ACCJOB AND EXIT.
009035,000123:
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Page 207
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009037,000125: 06,3223 50001 VOPENED INDEX L # A VALVE HAS JUST BEEN OPENED.
009038,000126: 06,3224 43242 CS 5FAILTAB
009039,000127: 06,3225 71262 MASK CH5MASK
009040,000128: 06,3226 55262 TS CH5MASK # REMOVE INHIBIT BIT FOR CHANNEL 5 JET.
009041,000129:
009042,000130: 06,3227 50001 INDEX L
009043,000131: 06,3230 43252 CS 6FAILTAB
009044,000132: 06,3231 71263 MASK CH6MASK
009045,000133: 06,3232 55263 TS CH6MASK # REMOVE INHIBIT BIT FOR CHANNEL 6 JET.
009046,000134:
009047,000135: 06,3233 40002 CS Q
009048,000136: 06,3234 71276 MASK PVALVEST
009049,000137: 06,3235 55276 TS PVALVEST # RECORD ACTION TAKEN.
009050,000138:
009051,000139: 06,3236 37714 1/ACCFIX CAF PRIO27 # SET UP 1/ACCS SO THAT THE SWITCH CURVES
009052,000140: 06,3237 05072 TC NOVAC # FOR TJETLAW CAN BE MODIFIED IF CH5MASK
009053,000141: 06,3240 E6,1537 EBANK= AOSQ # HAS BEEN ALTERED.
009054,000142: 06,3240 02454 40106 2CADR 1/ACCJOB
009055,000143:
009056,000144: 06,3242 15270 TCF RCSMONEX # EXIT.
009057,000145:
009058,000146: 06,3243 5FAILTAB EQUALS -1 # CH 5 JET BIT CORRESPONDING TO CH 32 BIT:
009059,000147: 06,3243 00040 OCT 00040 # 8
009060,000148: 06,3244 00020 OCT 00020 # 7
009061,000149: 06,3245 00100 OCT 00100 # 6
009062,000150: 06,3246 00200 OCT 00200 # 5
009063,000151: 06,3247 00010 OCT 00010 # 4
009064,000152: 06,3250 00001 OCT 00001 # 3
009065,000153: 06,3251 00004 OCT 00004 # 2
009066,000154: 06,3252 00002 OCT 00002 # 1
009067,000155:
009068,000156: 06,3253 6FAILTAB EQUALS -1 # CH 6 JET BIT CORRESPONDING TO CH 32 BIT:
009069,000157: 06,3253 00010 OCT 00010 # 8
009070,000158: 06,3254 00020 OCT 00020 # 7
009071,000159: 06,3255 00004 OCT 00004 # 6
009072,000160: 06,3256 00200 OCT 00200 # 5
009073,000161: 06,3257 00001 OCT 00001 # 4
009074,000162: 06,3260 00002 OCT 00002 # 3
009075,000163: 06,3261 00040 OCT 00040 # 2
009076,000164: 06,3262 00100 OCT 00100 # 1
End of include-file RCS_FAILURE_MONITOR.agc. Parent file is MAIN.agc