Source Code
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These source-code files are part of a reconstructed copy of Comanche 44, the
initial release (though not the final mission release) of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Subsequent releases
were Comanche 45 and Comanche 45/2 (the flown release on Apollo 10). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 44, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 51
(separately previously reconstructed from an Apollo-era listing of Comanche 55,
flown on Apollo 11). Comanche 51 source code was then modified
by undoing changes known to have been made between revisions 44 and 51. The now-reconstructed
Comanche 44 source code was verified by assembling it and checking that the assembled code had
the expected known-correct memory-bank checksums.
Note that page numbers in the reconstructed code match those on the Comanche 55 printout,
although the source code would likely have different page numbers in a contemporary
Comanche 44 listing.
Annotations that were not present in the contemporary source code have been added to the reconstructed
code to justify each change relative to Comanche 51. Here's a guide to the Apollo documentation referenced
in those annotations:
In most cases, only the titles (rather than the full texts) of PCRs are known. In addition to the
explanatory annotations, there is also
a step-by-step commentary about the reconstruction process.
Comments expected to have been present in 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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042031,000002: ## Copyright: Public domain.
042032,000003: ## Filename: TVCMASSPROP.agc
042033,000004: ## Purpose: A section of Comanche revision 044.
042034,000005: ## It is part of the reconstructed source code for the
042035,000006: ## original release of the flight software for the Command
042036,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
042037,000008: ## The code has been recreated from a copy of Comanche 055. It
042038,000009: ## has been adapted such that the resulting bugger words
042039,000010: ## exactly match those specified for Comanche 44 in NASA drawing
042040,000011: ## 2021153D, which gives relatively high confidence that the
042041,000012: ## reconstruction is correct.
042042,000013: ## Assembler: yaYUL
042043,000014: ## Contact: Ron Burkey <info@sandroid.org>.
042044,000015: ## Website: www.ibiblio.org/apollo/index.html
042045,000016: ## Mod history: 2020-12-03 MAS Created from Comanche 51.
042046,000017:
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Page 951
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042048,000019: # PROGRAM NAME....MASSPROP
042049,000020: # LOG SECTION....TVCMASSPROP PROGRAMMER...MELANSON (ENGEL, SCHLUNDT)
042050,000021:
042051,000022: # FUNCTIONAL DESCRIPTION:
042052,000023:
042053,000024: # MASSPROP OPERATES IN TWO MODES: (1) IF LEM MASS OR CONFIGURATION ARE UPDATED (MASSPROP DOES NOT TEST
042054,000025: # FOR THIS) THE ENTIRE PROGRAM MUST BE RUN THROUGH, BREAKPOINT VALUES AND DERIVATIVES OF THE OUTPUTS WITH
042055,000026: # RESPECT TO CSM MASS BEING CALCULATED PRIOR TO CALCULATION OF THE OUTPUTS. (2) OTHERWISE, THE OUTPUTS CAN BE
042056,000027: # CALCULATED USING PREVIOUSLY COMPUTED BREAKPOINT VALUES AND DERIVATIVES.
042057,000028:
042058,000029: # CALLING SEQUENCES
042059,000030:
042060,000031: # IF LEM MASS OR CONFIGURATION HAS BEEN UPDATED, TRANSFER TO MASSPROP, OTHERWISE TRANSFER TO FIXCW.
042061,000032: # L TC BANKCALL OR IBNKCALL
042062,000033: # L+1 CADR MASSPROP
042063,000034: # OR
042064,000035: # L+1 CADR FIXCW
042065,000036: # L+2 RETURNS VIA Q
042066,000037:
042067,000038: # CALLED IN PARTICULAR BY DONOUN47 (JOB) AND TVCEXECUTIVE (TASK)
042068,000039:
042069,000040: # JOBS OR TASKS INITIATED - NONE
042070,000041:
042071,000042: # SUBROUTINES CALLED - NONE
042072,000043:
042073,000044: # ERASABLE INITIALIZATION REQUIRED
042074,000045:
042075,000046: # LEMMASS MUST CONTAIN LEM MASS SCALED AT B+16 IN KILOGRAMS
042076,000047: # CSMMASS MUST CONTAIN CSM MASS SCALED AT B+16 IN KILOGRAMS
042077,000048: # DAPDATR1 MUST BE SET TO INDICATE VEHICLE CONFIGURATION.
042078,000049: # BITS (15,14,13) = ( 0 , 0 , 1 ) LEM OFF
042079,000050: # ( 0 , 1 , 0 ) LEM ON (ASCNT,DSCNT)
042080,000051: # ( 1 , 1 , 0 ) LEM ON (ASCNT ONLY)
042081,000052:
042082,000053: # ALARMS - NONE
042083,000054:
042084,000055: # EXIT - TC Q
042085,000056:
042086,000057: # OUTPUTS:
042087,000058:
042088,000059: # (1) IXX, SINGLE PRECISION SCALED AT B+20 IN KG-M SQ.
042089,000060: # (2) IAVG, SINGLE PRECISION SCALED AT B+20 IN KG-M SQ.
042090,000061: # (3) IAVG/TLX, SINGLE PRECISION, SCALED AT B+2 SEC-SQD
042091,000062: #
042092,000063: # THEY ARE STORED IN CONSECUTIVE REGISTERS IXX0, IXX1, IXX2
042093,000064: # CONVERSION FACTOR: (SLUG-FTSQ) = 0.737562 (KG-MSQ)
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Page 952
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042095,000066:
042096,000067: # OUTPUTS ARE CALCULATED AS FOLLOWS:
042097,000068:
042098,000069: # (1) IF LEM DOCKED, LEMMASS IS FIRST ELIMINATED AS A PARAMETER
042099,000070:
042100,000071: # VARST0 = INTVALUE0 + LEMMASS(SLOPEVAL0) IXX BREAKPOINT VALUE
042101,000072: # VARST1 = INTVALUE1 + LEMMASS(SLOPEVAL1) IAVG BREAKPOINT VALUE
042102,000073: # VARST2 = INTVALUE2 + LEMMASS(SLOPEVAL2) IAVG/TLX BREAKPOINT VALUE
042103,000074:
042104,000075: # VARST3 = INTVALUE3 + LEMMASS(SLOPEVAL3) IAVG/TLX SLOPE FOR CSMMASS > 33956 LBS (SPS > 10000 LBS)
042105,000076: # VARST4 = INTVALUE4 + LEMMASS(SLOPEVAL4) IAVG SLOPE FOR CSMMASS > 33956 LBS (SPS > 10000 LBS)
042106,000077:
042107,000078: # VARST5 = INTVALUE5 + LEMMASS(SLOPEVAL5) IXX SLOPE FOR ALL VALUES OF CSMMASS
042108,000079:
042109,000080: # VARST6 = INTVALUE6 + LEMMASS(SLOPEVAL6) IAVG SLOPE FOR CSMMASS < 33956 LBS (SPS < 10000 LBS)
042110,000081: # VARST7 = INTVALUE7 + LEMMASS(SLOPEVAL7) IAVG/TLX SLOPE FOR CSMMASS < 33956 LBS (SPS < 10000 LBS)
042111,000082:
042112,000083: # VARST8 = INTVALUE8 + LEMMASS(SLOPEVAL8) IAVG DECREMENT TO BRKPT VALUE WHEN LEM DSCNT STAGE OFF
042113,000084: # VARST9 = INTVALUE9 + LEMMASS(SLOPEVAL9) IAVG/TLX DECREMENT TO BRKPT VALUE WHEN LEM DSCNT STAGE OFF
042114,000085:
042115,000086: # (2) IF LEM NOT DOCKED
042116,000087:
042117,000088: # VARST0 = NOLEMVAL0 WHERE THE MEANING AND SCALING OF VARST0
042118,000089: # . . TO VARST9 ARE THE SAME AS GIVEN ABOVE
042119,000090: # . .
042120,000091: # . . NOTE... FOR THIS CASE, VARST8,9 HAVE NO
042121,000092: # VARST9 = NOLEMVAL9 MEANING (THEY ARE COMPUTED BUT NOT USED)
042122,000093:
042123,000094: # (3) THE FINAL OUTPUT CALCULATIONS ARE THEN DONE
042124,000095:
042125,000096: # IXX0 = VARST0 + (CSMMASS + NEGBPW)VARST5 IXX
042126,000097:
042127,000098: # IXX1 = VARST1 + (CSMMASS + NEGBPW)VARST(4 OR 6) IAVG
042128,000099:
042129,000100: # IXX2 = VARST2 + (CSMMASS + NEGBPW)VARST(3 OR 7) IAVG/TLX
042130,000101:
042131,000102: # THE DATA USED CAME FROM CSM/LM SPACECRAFT OPERATIONAL DATA BOOK.
042132,000103: # VOL. 3, NASA DOCUMENT SNA-8-D-027 (MARCH 1968)
042133,000104:
042134,000105: # PERTINENT MASS DATA: CSM WEIGHT (FULL) 64100 LBS
042135,000106: # (EMPTY) 23956 LBS
042136,000107: # LEM WEIGHT (FULL) 32000 LBS
042137,000108: # (EMPTY) 14116 LBS
042138,000109:
042139,000110: # (WEIGHTS ARE FROM AMENDMENT #1 (APRIL 24, 1968) TO ABOVE DATA BOOK)
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Page 953
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042141,000112:
042142,000113: 25,3774 BANK 25
042143,000114: 05,2000 SETLOC DAPMASS
042144,000115: 05,2000 BANK
042145,000116: 05,3366 E6,1702 EBANK= BZERO
042146,000117: 05,3366 COUNT* $$/MASP
042147,000118:
042148,000119: 05,3366 34334 MASSPROP CAF NINE # MASSPROP USES TVC/RCS INTERUPT TEMPS
042149,000120: 05,3367 55506 TS PHI333 # SET UP TEN PASSES
042150,000121:
042151,000122: 05,3370 31466 LEMTEST CAE DAPDATR1 # DETERMINE LEM STATUS
042152,000123: 05,3371 75003 MASK BIT13
042153,000124: 05,3372 00006 EXTEND
042154,000125: 05,3373 13377 BZF LEMYES
042155,000126:
042156,000127: 05,3374 51506 LEMNO INDEX PHI333 # LEM NOT ATTACHED
042157,000128: 05,3375 33463 CAF NOLEMVAL
042158,000129: 05,3376 13407 TCF STOINST
042159,000130:
042160,000131: 05,3377 31473 LEMYES CAE LEMMASS # LEM IS ATTACHED
042161,000132: 05,3400 60000 DOUBLE
042162,000133: 05,3401 00006 EXTEND
042163,000134: 05,3402 51506 INDEX PHI333
042164,000135: 05,3403 73505 MP SLOPEVAL
042165,000136: 05,3404 20001 DDOUBL
042166,000137: 05,3405 51506 INDEX PHI333
042167,000138: 05,3406 63473 AD INTVALUE
042168,000139:
042169,000140: 05,3407 51506 STOINST INDEX PHI333 # STORAGE INST BEGIN HERE
042170,000141: 05,3410 55511 TS VARST0
042171,000142: 05,3411 11506 CCS PHI333 # ARE ALL TEN PASSES COMPLETED
042172,000143: 05,3412 13367 TCF MASSPROP +1 # NO - GO DECREMENT PHI333
042173,000144:
042174,000145: 05,3413 11466 DXTEST CCS DAPDATR1 # IF NEG, BIT15 IS 1, LEM DSCNT STAGE OFF
042175,000146: 05,3414 13422 TCF FIXCW
042176,000147: 05,3415 13422 TCF FIXCW
042177,000148: 05,3416 53522 DXCH VARST0 +8D
042178,000149: 05,3417 21513 DAS VARST0 +1
042179,000150: 05,3420 33520 CA DXITFIX
042180,000151: 05,3421 27520 ADS VARST0 +7
042181,000152:
042182,000153: 05,3422 35016 FIXCW CAF BIT2 # COMPUTATION PHASE BEGINS HERE. SET UP
042183,000154: 05,3423 55506 TS PHI333 # THREE PASSES
042184,000155: 05,3424 55507 TS PSI333
042185,000156:
042186,000157: 05,3425 31474 CAE CSMMASS # GET DELTA CSM WEIGHT - SIGN DETERMINES
042187,000158: 05,3426 63517 AD NEGBPW # SLOPE LOCATIONS.
042188,000159: 05,3427 60000 DOUBLE
042189,000160: 05,3430 55510 TS TEMP333
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Page 954
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042191,000162: 05,3431 00006 EXTEND
042192,000163: 05,3432 63435 BZMF PEGGY # DETERMINE CORRECT SLOPE
042193,000164: 05,3433 37715 CAF NEG2
042194,000165: 05,3434 55506 TS PHI333
042195,000166:
042196,000167: 05,3435 51506 PEGGY INDEX PHI333 # ALL IS READY - CALCULATE OUTPUTS NOW
042197,000168: 05,3436 31516 CAE VARST5 # GET SLOPE
042198,000169: 05,3437 00006 EXTEND
042199,000170: 05,3440 71510 MP TEMP333 # MULT BY DELTA CSM WEIGHT
042200,000171: 05,3441 60000 DOUBLE
042201,000172: 05,3442 51507 INDEX PSI333
042202,000173: 05,3443 61511 AD VARST0 # ADD BREAKPOINT VALUE
042203,000174: 05,3444 51507 INDEX PSI333
042204,000175: 05,3445 55470 TS IXX # ****** OUTPUTS (IXX0, IXX1, IXX2) ******
042205,000176:
042206,000177: 05,3446 11507 CCS PSI333 # BOOKKEEPING - MASSPROP FINISHED OR NOT
042207,000178: 05,3447 13457 TCF BOKKEP2 # NO - GO TAKE CARE OF INDEXING REGISTERS
042208,000179:
042209,000180: 05,3450 31466 CAE DAPDATR1 # UPDATE WEIGHT/G
042210,000181: 05,3451 75002 MASK BIT14
042211,000182: 05,3452 10000 CCS A
042212,000183: 05,3453 31473 CA LEMMASS
042213,000184: 05,3454 61474 AD CSMMASS
042214,000185: 05,3455 55475 TS WEIGHT/G # SCALED AT B+16 IN KILOGRAMS
042215,000186: 05,3456 00002 ENDMASSP TC Q
042216,000187:
042217,000188: 05,3457 55507 BOKKEP2 TS PSI333 # REDUCE PSI BY ONE
042218,000189: 05,3460 00006 EXTEND
042219,000190: 05,3461 27506 DIM PHI333
042220,000191: 05,3462 13435 TCF PEGGY
042221,000192:
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Page 955
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042223,000194: 05,3463 00616 NOLEMVAL DEC 25445 B-20
042224,000195: 05,3464 02526 DEC 87450 B-20
042225,000196: 05,3465 02352 DEC .30715 B-2
042226,000197: 05,3466 01471 DEC 1.22877 E-5 B+12
042227,000198: 05,3467 00634 DEC 1.6096 B-6
042228,000199: 05,3470 00612 DEC 1.54 B-6
042229,000200: 05,3471 03706 DEC 7.77177 B-6
042230,000201: 05,3472 04425 DEC 3.46458 E-5 B+12
042231,000202:
042232,000203: 05,3473 00644 INTVALUE DEC 26850 B-20
042233,000204: 05,3474 03710 DEC 127518 B-20
042234,000205: 05,3475 04246 DEC .54059 B-2
042235,000206: 05,3476 02011 DEC .153964 E-4 B+12
042236,000207: 05,3477 77501 DEC -.742923 B-6
042237,000208: 05,3500 00612 DEC 1.5398 B-6
042238,000209: 05,3501 04656 DEC 9.68 B-6
042239,000210: 05,3502 10372 DEC .647625 E-4 B+12
042240,000211: 05,3503 77126 DEC -27228 B-20
042241,000212: 05,3504 76261 DEC -.206476 B-2
042242,000213:
042243,000214: 05,3505 00767 SLOPEVAL DEC 1.96307 B-6
042244,000215: 05,3506 15624 DEC 27.5774 B-6
042245,000216: 05,3507 03054 DEC 2.3548 E-5 B+12
042246,000217: 05,3510 04532 DEC 2.1777 E-9 B+26
042247,000218: 05,3511 10433 DEC 1.044 E-3 B+8
042248,000219: 05,3512 00000 DEC 0 B-14
042249,000220: 05,3513 22070 DEC 2.21068 E-3 B+8
042250,000221: 05,3514 03204 DEC 1.5166 E-9 B+26
042251,000222: 05,3515 77266 DEC -1.284 B-6
042252,000223: 05,3516 02476 DEC 2 E-5 B+12
042253,000224:
042254,000225: 05,3517 70364 NEGBPW DEC -15402.17 B-16
042255,000226: 05,3520 75420 DXITFIX DEC* -1.88275 E-5 B+12*
042256,000227:
End of include-file TVCMASSPROP.agc. Parent file is MAIN.agc