Source Code
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These source-code files are part of a reconstructed copy of Comanche 45, the
second release, though not the final mission release, of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Comanche 45 was
preceded by Comanche 44 and followed by Comanche 45/2 (the flown release). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 45, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 44 (itself previously accurately
reconstructed). Comanche 44 source code was then modified
by incorporating changes known from contemporary documentation to have been
made between revisions 44 and 45. The now-reconstructed Comanche 45 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 tend to match those in the Comanche 55, the
most-similar revision of Comanche for which we have access to an actual non-reconstructed hardcopy;
the source code would likely have different page numbers in a contemporary
Comanche 45 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 44. Here's a guide to the Apollo documentation referenced
in those annotations:
There is also
a detailed 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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041555,000002: ## Copyright: Public domain.
041556,000003: ## Filename: TVCMASSPROP.agc
041557,000004: ## Purpose: A section of Comanche revision 045.
041558,000005: ## It is part of the reconstructed source code for the
041559,000006: ## second release of the flight software for the Command
041560,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
041561,000008: ## The code has been recreated from a copy of Comanche 055. It
041562,000009: ## has been adapted such that the resulting bugger words
041563,000010: ## exactly match those specified for Comanche 45 in NASA drawing
041564,000011: ## 2021153D, which gives relatively high confidence that the
041565,000012: ## reconstruction is correct.
041566,000013: ## Assembler: yaYUL
041567,000014: ## Contact: Ron Burkey <info@sandroid.org>.
041568,000015: ## Website: www.ibiblio.org/apollo/index.html
041569,000016: ## Mod history: 2020-12-06 MAS Created from Comanche 44.
041570,000017:
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Page 951
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041572,000019: # PROGRAM NAME....MASSPROP
041573,000020: # LOG SECTION....TVCMASSPROP PROGRAMMER...MELANSON (ENGEL, SCHLUNDT)
041574,000021:
041575,000022: # FUNCTIONAL DESCRIPTION:
041576,000023:
041577,000024: # MASSPROP OPERATES IN TWO MODES: (1) IF LEM MASS OR CONFIGURATION ARE UPDATED (MASSPROP DOES NOT TEST
041578,000025: # FOR THIS) THE ENTIRE PROGRAM MUST BE RUN THROUGH, BREAKPOINT VALUES AND DERIVATIVES OF THE OUTPUTS WITH
041579,000026: # RESPECT TO CSM MASS BEING CALCULATED PRIOR TO CALCULATION OF THE OUTPUTS. (2) OTHERWISE, THE OUTPUTS CAN BE
041580,000027: # CALCULATED USING PREVIOUSLY COMPUTED BREAKPOINT VALUES AND DERIVATIVES.
041581,000028:
041582,000029: # CALLING SEQUENCES
041583,000030:
041584,000031: # IF LEM MASS OR CONFIGURATION HAS BEEN UPDATED, TRANSFER TO MASSPROP, OTHERWISE TRANSFER TO FIXCW.
041585,000032: # L TC BANKCALL OR IBNKCALL
041586,000033: # L+1 CADR MASSPROP
041587,000034: # OR
041588,000035: # L+1 CADR FIXCW
041589,000036: # L+2 RETURNS VIA Q
041590,000037:
041591,000038: # CALLED IN PARTICULAR BY DONOUN47 (JOB) AND TVCEXECUTIVE (TASK)
041592,000039:
041593,000040: # JOBS OR TASKS INITIATED - NONE
041594,000041:
041595,000042: # SUBROUTINES CALLED - NONE
041596,000043:
041597,000044: # ERASABLE INITIALIZATION REQUIRED
041598,000045:
041599,000046: # LEMMASS MUST CONTAIN LEM MASS SCALED AT B+16 IN KILOGRAMS
041600,000047: # CSMMASS MUST CONTAIN CSM MASS SCALED AT B+16 IN KILOGRAMS
041601,000048: # DAPDATR1 MUST BE SET TO INDICATE VEHICLE CONFIGURATION.
041602,000049: # BITS (15,14,13) = ( 0 , 0 , 1 ) LEM OFF
041603,000050: # ( 0 , 1 , 0 ) LEM ON (ASCNT,DSCNT)
041604,000051: # ( 1 , 1 , 0 ) LEM ON (ASCNT ONLY)
041605,000052:
041606,000053: # ALARMS - NONE
041607,000054:
041608,000055: # EXIT - TC Q
041609,000056:
041610,000057: # OUTPUTS:
041611,000058:
041612,000059: # (1) IXX, SINGLE PRECISION SCALED AT B+20 IN KG-M SQ.
041613,000060: # (2) IAVG, SINGLE PRECISION SCALED AT B+20 IN KG-M SQ.
041614,000061: # (3) IAVG/TLX, SINGLE PRECISION, SCALED AT B+2 SEC-SQD
041615,000062: #
041616,000063: # THEY ARE STORED IN CONSECUTIVE REGISTERS IXX0, IXX1, IXX2
041617,000064: # CONVERSION FACTOR: (SLUG-FTSQ) = 0.737562 (KG-MSQ)
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Page 952
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041619,000066:
041620,000067: # OUTPUTS ARE CALCULATED AS FOLLOWS:
041621,000068:
041622,000069: # (1) IF LEM DOCKED, LEMMASS IS FIRST ELIMINATED AS A PARAMETER
041623,000070:
041624,000071: # VARST0 = INTVALUE0 + LEMMASS(SLOPEVAL0) IXX BREAKPOINT VALUE
041625,000072: # VARST1 = INTVALUE1 + LEMMASS(SLOPEVAL1) IAVG BREAKPOINT VALUE
041626,000073: # VARST2 = INTVALUE2 + LEMMASS(SLOPEVAL2) IAVG/TLX BREAKPOINT VALUE
041627,000074:
041628,000075: # VARST3 = INTVALUE3 + LEMMASS(SLOPEVAL3) IAVG/TLX SLOPE FOR CSMMASS > 33956 LBS (SPS > 10000 LBS)
041629,000076: # VARST4 = INTVALUE4 + LEMMASS(SLOPEVAL4) IAVG SLOPE FOR CSMMASS > 33956 LBS (SPS > 10000 LBS)
041630,000077:
041631,000078: # VARST5 = INTVALUE5 + LEMMASS(SLOPEVAL5) IXX SLOPE FOR ALL VALUES OF CSMMASS
041632,000079:
041633,000080: # VARST6 = INTVALUE6 + LEMMASS(SLOPEVAL6) IAVG SLOPE FOR CSMMASS < 33956 LBS (SPS < 10000 LBS)
041634,000081: # VARST7 = INTVALUE7 + LEMMASS(SLOPEVAL7) IAVG/TLX SLOPE FOR CSMMASS < 33956 LBS (SPS < 10000 LBS)
041635,000082:
041636,000083: # VARST8 = INTVALUE8 + LEMMASS(SLOPEVAL8) IAVG DECREMENT TO BRKPT VALUE WHEN LEM DSCNT STAGE OFF
041637,000084: # VARST9 = INTVALUE9 + LEMMASS(SLOPEVAL9) IAVG/TLX DECREMENT TO BRKPT VALUE WHEN LEM DSCNT STAGE OFF
041638,000085:
041639,000086: # (2) IF LEM NOT DOCKED
041640,000087:
041641,000088: # VARST0 = NOLEMVAL0 WHERE THE MEANING AND SCALING OF VARST0
041642,000089: # . . TO VARST9 ARE THE SAME AS GIVEN ABOVE
041643,000090: # . .
041644,000091: # . . NOTE... FOR THIS CASE, VARST8,9 HAVE NO
041645,000092: # VARST9 = NOLEMVAL9 MEANING (THEY ARE COMPUTED BUT NOT USED)
041646,000093:
041647,000094: # (3) THE FINAL OUTPUT CALCULATIONS ARE THEN DONE
041648,000095:
041649,000096: # IXX0 = VARST0 + (CSMMASS + NEGBPW)VARST5 IXX
041650,000097:
041651,000098: # IXX1 = VARST1 + (CSMMASS + NEGBPW)VARST(4 OR 6) IAVG
041652,000099:
041653,000100: # IXX2 = VARST2 + (CSMMASS + NEGBPW)VARST(3 OR 7) IAVG/TLX
041654,000101:
041655,000102: # THE DATA USED CAME FROM CSM/LM SPACECRAFT OPERATIONAL DATA BOOK.
041656,000103: # VOL. 3, NASA DOCUMENT SNA-8-D-027 (MARCH 1968)
041657,000104:
041658,000105: # PERTINENT MASS DATA: CSM WEIGHT (FULL) 64100 LBS
041659,000106: # (EMPTY) 23956 LBS
041660,000107: # LEM WEIGHT (FULL) 32000 LBS
041661,000108: # (EMPTY) 14116 LBS
041662,000109:
041663,000110: # (WEIGHTS ARE FROM AMENDMENT #1 (APRIL 24, 1968) TO ABOVE DATA BOOK)
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Page 953
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041665,000112:
041666,000113: 25,3774 BANK 25
041667,000114: 05,2000 SETLOC DAPMASS
041668,000115: 05,2000 BANK
041669,000116: 05,3366 E6,1702 EBANK= BZERO
041670,000117: 05,3366 COUNT* $$/MASP
041671,000118:
041672,000119: 05,3366 34334 MASSPROP CAF NINE # MASSPROP USES TVC/RCS INTERUPT TEMPS
041673,000120: 05,3367 55506 TS PHI333 # SET UP TEN PASSES
041674,000121:
041675,000122: 05,3370 31466 LEMTEST CAE DAPDATR1 # DETERMINE LEM STATUS
041676,000123: 05,3371 75003 MASK BIT13
041677,000124: 05,3372 00006 EXTEND
041678,000125: 05,3373 13377 BZF LEMYES
041679,000126:
041680,000127: 05,3374 51506 LEMNO INDEX PHI333 # LEM NOT ATTACHED
041681,000128: 05,3375 33463 CAF NOLEMVAL
041682,000129: 05,3376 13407 TCF STOINST
041683,000130:
041684,000131: 05,3377 31473 LEMYES CAE LEMMASS # LEM IS ATTACHED
041685,000132: 05,3400 60000 DOUBLE
041686,000133: 05,3401 00006 EXTEND
041687,000134: 05,3402 51506 INDEX PHI333
041688,000135: 05,3403 73505 MP SLOPEVAL
041689,000136: 05,3404 20001 DDOUBL
041690,000137: 05,3405 51506 INDEX PHI333
041691,000138: 05,3406 63473 AD INTVALUE
041692,000139:
041693,000140: 05,3407 51506 STOINST INDEX PHI333 # STORAGE INST BEGIN HERE
041694,000141: 05,3410 55511 TS VARST0
041695,000142: 05,3411 11506 CCS PHI333 # ARE ALL TEN PASSES COMPLETED
041696,000143: 05,3412 13367 TCF MASSPROP +1 # NO - GO DECREMENT PHI333
041697,000144:
041698,000145: 05,3413 11466 DXTEST CCS DAPDATR1 # IF NEG, BIT15 IS 1, LEM DSCNT STAGE OFF
041699,000146: 05,3414 13422 TCF FIXCW
041700,000147: 05,3415 13422 TCF FIXCW
041701,000148: 05,3416 53522 DXCH VARST0 +8D
041702,000149: 05,3417 21513 DAS VARST0 +1
041703,000150: 05,3420 33520 CA DXITFIX
041704,000151: 05,3421 27520 ADS VARST0 +7
041705,000152:
041706,000153: 05,3422 35016 FIXCW CAF BIT2 # COMPUTATION PHASE BEGINS HERE. SET UP
041707,000154: 05,3423 55506 TS PHI333 # THREE PASSES
041708,000155: 05,3424 55507 TS PSI333
041709,000156:
041710,000157: 05,3425 31474 CAE CSMMASS # GET DELTA CSM WEIGHT - SIGN DETERMINES
041711,000158: 05,3426 63517 AD NEGBPW # SLOPE LOCATIONS.
041712,000159: 05,3427 60000 DOUBLE
041713,000160: 05,3430 55510 TS TEMP333
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Page 954
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041715,000162: 05,3431 00006 EXTEND
041716,000163: 05,3432 63435 BZMF PEGGY # DETERMINE CORRECT SLOPE
041717,000164: 05,3433 37715 CAF NEG2
041718,000165: 05,3434 55506 TS PHI333
041719,000166:
041720,000167: 05,3435 51506 PEGGY INDEX PHI333 # ALL IS READY - CALCULATE OUTPUTS NOW
041721,000168: 05,3436 31516 CAE VARST5 # GET SLOPE
041722,000169: 05,3437 00006 EXTEND
041723,000170: 05,3440 71510 MP TEMP333 # MULT BY DELTA CSM WEIGHT
041724,000171: 05,3441 60000 DOUBLE
041725,000172: 05,3442 51507 INDEX PSI333
041726,000173: 05,3443 61511 AD VARST0 # ADD BREAKPOINT VALUE
041727,000174: 05,3444 51507 INDEX PSI333
041728,000175: 05,3445 55470 TS IXX # ****** OUTPUTS (IXX0, IXX1, IXX2) ******
041729,000176:
041730,000177: 05,3446 11507 CCS PSI333 # BOOKKEEPING - MASSPROP FINISHED OR NOT
041731,000178: 05,3447 13457 TCF BOKKEP2 # NO - GO TAKE CARE OF INDEXING REGISTERS
041732,000179:
041733,000180: 05,3450 31466 CAE DAPDATR1 # UPDATE WEIGHT/G
041734,000181: 05,3451 75002 MASK BIT14
041735,000182: 05,3452 10000 CCS A
041736,000183: 05,3453 31473 CA LEMMASS
041737,000184: 05,3454 61474 AD CSMMASS
041738,000185: 05,3455 55475 TS WEIGHT/G # SCALED AT B+16 IN KILOGRAMS
041739,000186: 05,3456 00002 ENDMASSP TC Q
041740,000187:
041741,000188: 05,3457 55507 BOKKEP2 TS PSI333 # REDUCE PSI BY ONE
041742,000189: 05,3460 00006 EXTEND
041743,000190: 05,3461 27506 DIM PHI333
041744,000191: 05,3462 13435 TCF PEGGY
041745,000192:
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Page 955
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041747,000194: 05,3463 00616 NOLEMVAL DEC 25445 B-20
041748,000195: 05,3464 02526 DEC 87450 B-20
041749,000196: 05,3465 02352 DEC .30715 B-2
041750,000197: 05,3466 01471 DEC 1.22877 E-5 B+12
041751,000198: 05,3467 00634 DEC 1.6096 B-6
041752,000199: 05,3470 00612 DEC 1.54 B-6
041753,000200: 05,3471 03706 DEC 7.77177 B-6
041754,000201: 05,3472 04425 DEC 3.46458 E-5 B+12
041755,000202:
041756,000203: 05,3473 00644 INTVALUE DEC 26850 B-20
041757,000204: 05,3474 03710 DEC 127518 B-20
041758,000205: 05,3475 04246 DEC .54059 B-2
041759,000206: 05,3476 02011 DEC .153964 E-4 B+12
041760,000207: 05,3477 77501 DEC -.742923 B-6
041761,000208: 05,3500 00612 DEC 1.5398 B-6
041762,000209: 05,3501 04656 DEC 9.68 B-6
041763,000210: 05,3502 10372 DEC .647625 E-4 B+12
041764,000211: 05,3503 77126 DEC -27228 B-20
041765,000212: 05,3504 76261 DEC -.206476 B-2
041766,000213:
041767,000214: 05,3505 00767 SLOPEVAL DEC 1.96307 B-6
041768,000215: 05,3506 15624 DEC 27.5774 B-6
041769,000216: 05,3507 03054 DEC 2.3548 E-5 B+12
041770,000217: 05,3510 04532 DEC 2.1777 E-9 B+26
041771,000218: 05,3511 10433 DEC 1.044 E-3 B+8
041772,000219: 05,3512 00000 DEC 0 B-14
041773,000220: 05,3513 22070 DEC 2.21068 E-3 B+8
041774,000221: 05,3514 03204 DEC 1.5166 E-9 B+26
041775,000222: 05,3515 77266 DEC -1.284 B-6
041776,000223: 05,3516 02476 DEC 2 E-5 B+12
041777,000224:
041778,000225: 05,3517 70364 NEGBPW DEC -15402.17 B-16
041779,000226: 05,3520 75420 DXITFIX DEC* -1.88275 E-5 B+12*
041780,000227:
End of include-file TVCMASSPROP.agc. Parent file is MAIN.agc