Source Code
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This is a reconstruction of the AGC program Luminary 99 Rev 0. It was the third release
of the Lunar Module flight software targeted for use in Apollo 11, after Luminary 96 and 97.
A bug (which had been around since at least Apollo 10, Luminary 69) was
discovered in Rev 0 shortly before the Apollo 11 flight, resulting in a last minute
revision into Rev 1,
which is what actually flew rather than
the Rev 0 presented here. A hardcopy of Rev 0 is known to
exist — it belonged to AGC developer Allan Klumpp for many years — but
unfortunately the Virtual AGC Project has not had access to that hardcopy. Thus
the code you see here had been reconstructed (we believe accurately) rather than
transcribed. The first step of the reconstruction of the Rev 0 source code was
the transcription of the Rev 1 source code from a hardcopy in the MIT Museum collection.
The process of reverting the active portion of the source code (i.e., other than
program comments) from Rev 1 to Rev 0 was very minor, consisting
only of moving the position of the STARTSB1 label in
FRESH START AND RESTART. Allan had previously given
us the checksums of the memory banks of Rev 0, and we have verified the program presented here has checksums
identical to all banks of Allan's listing of Rev 0. The notations on Allan's Rev 0 program listing read,
in part:GAP: ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-051 A single program comment is known to differ between Rev 0 and Rev 1, but these are harder to reconstruct and verify than changes to the active portion of the code. Thus it is possible that there are additional differences between the program comments in Rev 0 and Rev 1 that are unknown to us, and therefore are not reflected in the code presented here. |
007819,000002: ## Copyright: Public domain.
007820,000003: ## Filename: RCS_FAILURE_MONITOR.agc
007821,000004: ## Purpose: Part of the reconstructed source code for LMY99 Rev 0,
007822,000005: ## otherwise known as Luminary Rev 99, the third release
007823,000006: ## of the Apollo Guidance Computer (AGC) software for Apollo 11.
007824,000007: ## It differs from LMY99 Rev 1 (the flown version) only in the
007825,000008: ## placement of a single label. The corrections shown here have
007826,000009: ## been verified to have the same bank checksums as AGC developer
007827,000010: ## Allan Klumpp's copy of Luminary Rev 99, and so are believed
007828,000011: ## to be accurate. This file is intended to be a faithful
007829,000012: ## recreation, except that the code format has been changed to
007830,000013: ## conform to the requirements of the yaYUL assembler rather than
007831,000014: ## the original YUL assembler.
007832,000015: ##
007833,000016: ## Assembler: yaYUL
007834,000017: ## Contact: Hartmuth Gutsche <hgutsche@xplornet.com>.
007835,000018: ## Website: www.ibiblio.org/apollo.
007836,000019: ## Pages: 190-192
007837,000020: ## Mod history: 2009-05-19 HG Transcribed from page images.
007838,000021: ## 2016-12-13 RSB Proofed text comments with octopus/ProoferComments
007839,000022: ## and corrected the errors found.
007840,000023: ## 2017-03-14 RSB Comment-text fixes noted in proofing Luminary 116.
007841,000024: ## 2017-08-01 MAS Created from LMY99 Rev 1.
007842,000025: ## 2017-08-18 RSB Comment-text bug identified in ZERLINA 56.
007843,000026:
007844,000027: ## This source code has been transcribed or otherwise adapted from
007845,000028: ## digitized images of a hardcopy from the MIT Museum. The digitization
007846,000029: ## was performed by Paul Fjeld, and arranged for by Deborah Douglas of
007847,000030: ## the Museum. Many thanks to both. The images (with suitable reduction
007848,000031: ## in storage size and consequent reduction in image quality as well) are
007849,000032: ## available online at www.ibiblio.org/apollo. If for some reason you
007850,000033: ## find that the images are illegible, contact me at info@sandroid.org
007851,000034: ## about getting access to the (much) higher-quality images which Paul
007852,000035: ## actually created.
007853,000036: ##
007854,000037: ## The code has been modified to match LMY99 Revision 0, otherwise
007855,000038: ## known as Luminary Revision 99, the Apollo 11 software release preceeding
007856,000039: ## the listing from which it was transcribed. It has been verified to
007857,000040: ## contain the same bank checksums as AGC developer Allan Klumpp's listing
007858,000041: ## of Luminary Revision 99 (for which we do not have scans).
007859,000042: ##
007860,000043: ## Notations on Allan Klumpp's listing read, in part:
007861,000044: ##
007862,000045: ## ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-51
007863,000046:
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Page 190 |
007865,000048: # PROGRAM DESCRIPTION
007866,000049:
007867,000050: # AUTHOR: J S MILLER
007868,000051:
007869,000052: # MODIFIED 6 MARCH 1968 BY P S WEISSMAN TO SET UP JOB FOR 1/ACCS WHEN THE MASKS ARE CHANGED.
007870,000053:
007871,000054: # THIS ROUTINE IS ATTACHED TO T4RUPT, AND IS ENTERED EVERY 480 MS. ITS FUNCTION IS TO EXAMINE THE LOW 8 BITS
007872,000055: # OF CHANNEL 32 TO SEE IF ANY ISOLATION-VALVE CLOSURE BITS HAVE APPEARED OR DISAPPEARED (THE CREW IS WARNED OF JET
007873,000056: # FAILURES BY LAMPS LIT BY THE GRUMMAN FAILURE-DETECTION CIRCUITRY; THEY MAY RESPOND BY OPERATING SWITCHES WHICH
007874,000057: # ISOLATE PAIRS OF JETS FROM THE PROPELLANT TANKS AND SET BITS IN CHANNEL 32). IN THE EVENT THAT CHANNEL 32 BITS
007875,000058: # DIFFER FROM 'PVALVEST', THE RECORD OF ACTIONS TAKEN BY THIS ROUTINE, THE APPROPRIATE BITS IN 'CH5MASK' &
007876,000059: # 'CH6MASK', USED BY THE DAP JET-SELECTION LOGIC, ARE UPDATED, AS IS 'PVALVEST'. TO SPEED UP & SHORTEN THE
007877,000060: # ROUTINE, NO MORE THAN ONE CHANGE IS ACCEPTED PER ENTRY. THE HIGHEST-NUMBERED BIT IN CHANNEL 32 WHICH REQUIRES
007878,000061: # ACTION IS THE ONE PROCESSED.
007879,000062:
007880,000063: # THE CODING IN THE FAILURE MONITOR HAS BEEN WRITTEN SO AS TO HAVE ALMOST COMPLETE RESTART PROTECTION. FOR
007881,000064: # EXAMPLE, NO ASSUMPTION IS MADE WHEN SETTING A 'CH5MASK' BIT TO 1 THAT THE PREVIOUS STATE IS 0, ALTHOUGH IT OF
007882,000065: # COURSE SHOULD BE. ONE CASE WHICH MAY BE SEEN TO EVADE PROTECTION IS THE OCCURRENCE OF A RESTART AFTER UPDATING
007883,000066: # ONE OR BOTH DAP MASK-WORDS BUT BEFORE UPDATING 'PVALVEST', COUPLED WITH A CHANGE IN THE VALVE-BIT BACK TO ITS
007884,000067: # FORMER STATE. THE CONSEQUENCE OF THIS IS THAT THE NEXT ENTRY WOULD NOT SEE THE CHANGE INCOMPLETELY INCORP-
007885,000068: # ORATED BY THE LAST PASS (BECAUSE IT WENT AWAY AT JUST THE RIGHT TIME), BUT THE DAP MASK-WORDS WILL BE INCORRECT.
007886,000069: # THIS COMBINATION OF EVENTS SEEMS QUITE REMOTE, BUT NOT IMPOSSIBLE UNLESS THE CREW OPERATES THE SWITCHES AT HALF-
007887,000070: # SECOND INTERVALS OR LONGER. IN ANY EVENT, A DISAGREEMENT BETWEEN REALITY AND THE DAP MASKS WILL BE CURED IF
007888,000071: # THE MISINTERPRETED SWITCH IS REVERSED AND THEN RESTORED TO ITS CORRECT POSITION (SLOWLY).
007889,000072:
007890,000073: # CALLING SEQUENCE:
007891,000074:
007892,000075: # TCF RCSMONIT (IN INTERRUPT MODE, EVERY 480 MS.)
007893,000076:
007894,000077: # EXIT: TCF RCSMONEX (ALL PATHS EXIT VIA SUCH AN INSTRUCTION)
007895,000078:
007896,000079: 06,3156 5270 RCSMONEX EQUALS RESUME
007897,000080:
007898,000081: # ERASABLE INITIALIZATION REQUIRED:
007899,000082:
007900,000083: # VIA FRESH START: PVALVEST = +0 (ALL JETS ENABLED)
007901,000084: # CH5MASK,CH6MASK = +0 (ALL JETS OK)
007902,000085:
007903,000086: # OUTPUT: CH5MASK & CH6MASK UPDATED (1'S WHERE JETS NOT TO BE USED, IN CHANNEL 5 & 6 FORMAT)
007904,000087: # PVALTEST UPDATED (1,S WHEN VALVE CLOSURES HAVE BEEN TRANSLATED INTO CH5MASK & CH6MASK; CHAN 32 FORMAT)
007905,000088: # JOB TO DO 1/ACCS.
007906,000089:
007907,000090: # DEBRIS: A, L, Q AND DEBRIS OF NOVAC.
007908,000091:
007909,000092: # SUBROUTINE CALLED: NOVAC.
007910,000093:
007911,000094: 06,3156 1262 EBANK= CH5MASK
007912,000095:
007913,000096: 23,2000 BANK 23
007914,000097: 06,2000 SETLOC RCSMONT
007915,000098: 06,2000 BANK
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007917,000100: 06,3156 COUNT* $$/T4RCS
007918,000101:
007919,000102: 06,3156 06,3156 RCSMONIT EQUALS RCSMON
007920,000103:
007921,000104: 06,3156 44755 RCSMON CS ZERO
007922,000105: 06,3157 00006 EXTEND
007923,000106: 06,3160 06032 RXOR CHAN32 # PICK UP + INVERT INVERTED CHANNEL 32.
007924,000107: 06,3161 74357 MASK LOW8 # KEEP JET-FAIL BITS ONLY.
007925,000108: 06,3162 54002 TS Q
007926,000109:
007927,000110: 06,3163 41276 CS PVALVEST # - -
007928,000111: 06,3164 70002 MASK Q # FORM PC + PC.
007929,000112: 06,3165 54001 TS L # (P = PREVIOUS ISOLATION VALVE STATE,
007930,000113: 06,3166 40002 CS Q # C = CURRENT VALVE STATE (CH32)).
007931,000114: 06,3167 71276 MASK PVALVEST
007932,000115: 06,3170 26001 ADS L # RESULT NZ INDICATES ACTION REQUIRED.
007933,000116:
007934,000117: 06,3171 00006 EXTEND
007935,000118: 06,3172 15270 BZF RCSMONEX # QUIT IF NO ACTION REQUIRED.
007936,000119:
007937,000120: 06,3173 00006 EXTEND
007938,000121: 06,3174 74745 MP BIT7 # MOVE BITS 8-1 OF A TO 14-7 OF L.
007939,000122: 06,3175 56001 XCH L # ZERO TO L IN THE PROCESS.
007940,000123:
007941,000124: 06,3176 24001 -3 INCR L
007942,000125: 06,3177 60000 DOUBLE # BOUND TO GET OVERFLOW IN THIS LOOP,
007943,000126: 06,3200 54000 OVSK # SINCE WE ASSURED INITIAL NZ IN A.
007944,000127: 06,3201 13176 TCF -3
007945,000128:
007946,000129: 06,3202 50001 INDEX L
007947,000130: 06,3203 34743 CA BIT8 -1 # SAVE THE RELEVANT BIT (8-1).
007948,000131: 06,3204 54002 TS Q
007949,000132: 06,3205 71276 MASK PVALVEST # LOOK AT PREVIOUS VALVE STATE BIT.
007950,000133: 06,3206 10000 CCS A
007951,000134: 06,3207 13223 TCF VOPENED # THE VALVE HAS JUST BEEN OPENED.
007952,000135:
007953,000136: 06,3210 41262 CS CH5MASK # THE VALVE HAS JUST BEEN CLOSED.
007954,000137: 06,3211 50001 INDEX L
007955,000138: 06,3212 73242 MASK 5FAILTAB
007956,000139: 06,3213 27262 ADS CH5MASK # SET INHIBIT BIT FOR CHANNEL 5 JET.
007957,000140:
007958,000141: 06,3214 41263 CS CH6MASK
007959,000142: 06,3215 50001 INDEX L
007960,000143: 06,3216 73252 MASK 6FAILTAB
007961,000144: 06,3217 27263 ADS CH6MASK # SET INGIBIT BIT FOR CHANNEL 6 JET.
007962,000145:
007963,000146: 06,3220 30002 CA Q
007964,000147: 06,3221 27276 ADS PVALVEST # RECORD ACTION TAKEN.
007965,000148:
007966,000149: 06,3222 13236 TCF 1/ACCFIX # SET UP 1/ACCJOB AND EXIT.
007967,000150:
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007969,000152: 06,3223 50001 VOPENED INDEX L # A VALVE HAS JUST BEEN OPENED.
007970,000153: 06,3224 43242 CS 5FAILTAB
007971,000154: 06,3225 71262 MASK CH5MASK
007972,000155: 06,3226 55262 TS CH5MASK # REMOVE INHIBIT BIT FOR CHANNEL 5 JET.
007973,000156:
007974,000157: 06,3227 50001 INDEX L
007975,000158: 06,3230 43252 CS 6FAILTAB
007976,000159: 06,3231 71263 MASK CH6MASK
007977,000160: 06,3232 55263 TS CH6MASK # REMOVE INHIBIT BIT FOR CHANNEL 6 JET.
007978,000161:
007979,000162: 06,3233 40002 CS Q
007980,000163: 06,3234 71276 MASK PVALVEST
007981,000164: 06,3235 55276 TS PVALVEST # RECORD ACTION TAKEN.
007982,000165:
007983,000166: 06,3236 37715 1/ACCFIX CAF PRIO27 # SET UP 1/ACCS SO THAT THE SWITCH CURVES
007984,000167: 06,3237 05072 TC NOVAC # FOR TJETLAW CAN BE MODIFIED IF CH5MASK
007985,000168: 06,3240 E6,1537 EBANK= AOSQ # HAS BEEN ALTERED.
007986,000169: 06,3240 02454 40106 2CADR 1/ACCJOB
007987,000170:
007988,000171: 06,3242 15270 TCF RCSMONEX # EXIT.
007989,000172:
007990,000173: 06,3243 5FAILTAB EQUALS -1 # CH 5 JET BIT CORRESPONDING TO CH 32 BIT:
007991,000174: 06,3243 00040 OCT 00040 # 8
007992,000175: 06,3244 00020 OCT 00020 # 7
007993,000176: 06,3245 00100 OCT 00100 # 6
007994,000177: 06,3246 00200 OCT 00200 # 5
007995,000178: 06,3247 00010 OCT 00010 # 4
007996,000179: 06,3250 00001 OCT 00001 # 3
007997,000180: 06,3251 00004 OCT 00004 # 2
007998,000181: 06,3252 00002 OCT 00002 # 1
007999,000182:
008000,000183: 06,3253 6FAILTAB EQUALS -1 # CH 6 JET BIT CORRESPONDING TO CH 32 BIT:
008001,000184: 06,3253 00010 OCT 00010 # 8
008002,000185: 06,3254 00020 OCT 00020 # 7
008003,000186: 06,3255 00004 OCT 00004 # 6
008004,000187: 06,3256 00200 OCT 00200 # 5
008005,000188: 06,3257 00001 OCT 00001 # 4
008006,000189: 06,3260 00002 OCT 00002 # 3
008007,000190: 06,3261 00040 OCT 00040 # 2
008008,000191: 06,3262 00100 OCT 00100 # 1
008009,000192:
008010,000193:
End of include-file RCS_FAILURE_MONITOR.agc. Parent file is MAIN.agc