Source Code
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These source-code files are part of a reconstructed copy of Comanche 45/2 (AKA Manche45 revision 2),
the final, flown mission release of the Apollo 10 Command Module (CM) Apollo Guidance
Computer (AGC) software. Comanche 45/2 was preceded by Comanche 44 and Comanche 45. The
reconstruction is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 45/2, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 45 (itself previously accurately
reconstructed). Comanche 45 source code was then modified by incorporating changes
known from contemporary documentation to have been made between revisions 45 and 45/2.
The now-reconstructed Comanche 45/2 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:
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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019553,000002: ## Copyright: Public domain.
019554,000003: ## Filename: GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc
019555,000004: ## Purpose: A section of Manche45 revision 2.
019556,000005: ## It is part of the reconstructed source code for the
019557,000006: ## final, flown release of the flight software for the Command
019558,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
019559,000008: ## The code has been recreated from a copy of Comanche 055. It
019560,000009: ## has been adapted such that the resulting bugger words
019561,000010: ## exactly match those specified for Manche 45/2 in NASA drawing
019562,000011: ## 2021153D, which gives relatively high confidence that the
019563,000012: ## reconstruction is correct.
019564,000013: ## Assembler: yaYUL
019565,000014: ## Contact: Ron Burkey <info@sandroid.org>.
019566,000015: ## Website: www.ibiblio.org/apollo/index.html
019567,000016: ## Mod history: 2020-12-24 MAS Created from Comanche 45.
019568,000017:
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Page 456
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019570,000019: # GROUND TRACKING DETERMINATION PROGRAM P21
019571,000020:
019572,000021: # PROGRAM DESCRIPTION
019573,000022: # MOD NO - 1
019574,000023: # MOD BY - N. M. NEVILLE
019575,000024: # FUNCTIONAL DECRIPTION-
019576,000025:
019577,000026: # TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
019578,000027: # THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
019579,000028: # CALLING SEQUENCE-
019580,000029:
019581,000030: # ASTRONAUT REQUEST THROUGH DSKY V37E21E
019582,000031: # SUBROUTINES CALLED-
019583,000032:
019584,000033: # GOPERF4
019585,000034: # GOFLASH
019586,000035: # THISPREC
019587,000036: # OTHPREC
019588,000037: # LAT-LONG
019589,000038: # NORMAL EXIT MODES-
019590,000039:
019591,000040: # ASTRONAUT REQUEST TROUGH DSKY TO TERMINATE PROGRAM V34E
019592,000041: # ALARM OR ABORT EXIT MODES-
019593,000042:
019594,000043: # NONE
019595,000044: # OUTPUT-
019596,000045:
019597,000046: # OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
019598,000047: # COMPUTED
019599,000048: # OPTION CODE 00002
019600,000049: # THIS 00001
019601,000050: # OTHER 00002
019602,000051: # DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS , MINUTES , SECONDS
019603,000052: # DECIMAL DISPLAY OF LAT,LONG,ALT
019604,000053: # ERASABLE INITIALIZATION REQUIRED
019605,000054:
019606,000055: # AX0 2DEC 4.652459653 E-5 RADIANS %68-69 CONSTANTS"
019607,000056:
019608,000057: # -AY0 2DEC 2.147535898 E-5 RADIANS
019609,000058:
019610,000059: # AZ0 2DEC .7753206164 REVOLUTIONS
019611,000060: # FOR LUNAR ORBITS 504LM VECTOR IS NEEDED
019612,000061:
019613,000062: # 504LM 2DEC -2.700340600 E-5 RADIANS
019614,000063:
019615,000064: # 504LM _2 2DEC -7.514128400 E-4 RADIANS
019616,000065:
019617,000066: # 504LM _4 2DEC _2.553198641 E-4 RADIANS
019618,000067:
019619,000068: # NONE
019620,000069: # DEBRIS
019621,000070:
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Page 457
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019623,000072: # CENTRALS-A,Q,L
019624,000073: # OTHER-THOSE USED BY THE ABOVE LISTED SUBROUTINES
019625,000074: # SEE LEMPREC, LAT-LONG
019626,000075:
019627,000076: 33,3776 30,2000 SBANK= LOWSUPER # FOR LOW 2CADR'S.
019628,000077:
019629,000078: 33,3776 BANK 33
019630,000079: 37,2000 SETLOC P20S
019631,000080: 37,2000 BANK
019632,000081:
019633,000082: 37,2001 E4,1715 EBANK= P21TIME
019634,000083: 37,2001 COUNT 24/P21
019635,000084:
019636,000085: 37,2001 35017 PROG21 CAF ONE
019637,000086: 37,2002 55132 TS OPTION2 # ASSUMED VEHICLE IS LM, R2 = 00001
019638,000087: 37,2003 35016 CAF BIT2 # OPTION 2
019639,000088: 37,2004 04662 TC BANKCALL
019640,000089: 37,2005 21055 CADR GOPERF4
019641,000090: 37,2006 04106 TC GOTOPOOH # TERMINATE
019642,000091: 37,2007 02011 TC +2 # PROCEED VALUE OF ASSUMED VEHICLE OK
019643,000092: 37,2010 02003 TC -5 # R2 LOADED THROUGH DSKY
019644,000093: 37,2011 32151 P21PROG1 CAF V6N34 # LOAD DESIRED TIME OF LAT-LONG.
019645,000094: 37,2012 04662 TC BANKCALL
019646,000095: 37,2013 20720 CADR GOFLASH
019647,000096: 37,2014 04106 TC GOTOPOOH # TERM
019648,000097: 37,2015 02017 TC +2 # PROCEED VALUES OK
019649,000098: 37,2016 02011 TC -5 # TIME LOADED THROUGH DSKY
019650,000099: 37,2017 06006 TC INTPRET
019651,000100: 37,2020 77745 DLOAD
019652,000101: 37,2021 01046 DSPTEM1
019653,000102: 37,2022 34041 STCALL TDEC1 # INTEG TO TIME SPECIFIED IN TDEC
019654,000103: 37,2023 27442 INTSTALL
019655,000104: 37,2024 43014 BON SET
019656,000105: 37,2025 01303 P21FLAG
019657,000106: 37,2026 76044 P21CONT # ON...RECYCLE USING BASE VECTOR
019658,000107: 37,2027 01474 VINTFLAG # OFF..1ST PASS CALC BASE VECTOR
019659,000108: 37,2030 70535 SLOAD SR1
019660,000109: 37,2031 01133 OPTION2
019661,000110: 37,2032 43030 BHIZ CLEAR
019662,000111: 37,2033 76035 +2 # ZERO..THIS VEHICLE (CM)
019663,000112: 37,2034 01674 VINTFLAG # ONE...OTHER VEHICLE(LM)
019664,000113: 37,2035 43014 CLEAR CLEAR
019665,000114: 37,2036 01676 DIM0FLAG
019666,000115: 37,2037 01673 INTYPFLG # PRECISION
019667,000116: 37,2040 77624 CALL
019668,000117: 37,2041 27162 INTEGRV # CALCULATE
019669,000118: 37,2042 77650 GOTO # .AND
019670,000119: 37,2043 76065 P21VSAVE # ..SAVE BASE VECTOR
019671,000120: 37,2044 77775 P21CONT VLOAD # RECYCLE..INTEG FROM BASE VECTOR
019672,000121: 37,2045 03605 P21BASER
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Page 458
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019674,000123: 37,2046 25535 STOVL RCV # ..POS
019675,000124: 37,2047 03613 P21BASEV
019676,000125: 37,2050 15543 STODL VCV # ..VEL
019677,000126: 37,2051 02316 P21TIME
019678,000127: 37,2052 01517 STORE TET # ..TIME
019679,000128: 37,2053 43014 CLEAR CLEAR
019680,000129: 37,2054 01676 DIM0FLAG
019681,000130: 37,2055 00263 MOONFLAG
019682,000131: 37,2056 53135 SLOAD BZE
019683,000132: 37,2057 03604 P21ORIG
019684,000133: 37,2060 76063 +3 # ZERO = EARTH
019685,000134: 37,2061 77614 SET # ...2 = MOON
019686,000135: 37,2062 00063 MOONFLAG
019687,000136: 37,2063 77624 CALL
019688,000137: 37,2064 27135 INTEGRVS
019689,000138: 37,2065 77745 P21VSAVE DLOAD # SAVE CURRENT BASE VECTOR
019690,000139: 37,2066 00015 TAT
019691,000140: 37,2067 26316 STOVL P21TIME # ..TIME
019692,000141: 37,2070 00017 RATT1
019693,000142: 37,2071 27605 STOVL P21BASER # ..POS B-29 OR B-27
019694,000143: 37,2072 00025 VATT1
019695,000144: 37,2073 03613 STORE P21BASEV # ..VEL B-7 OR B-5
019696,000145: 37,2074 77646 ABVAL
019697,000146: 37,2075 27623 STOVL P21VEL # /VEL/ FOR N73 DSP
019698,000147: 37,2076 00001 RATT
019699,000148: 37,2077 50256 UNIT DOT
019700,000149: 37,2100 00007 VATT # U(R).(V)
019701,000150: 37,2101 67471 DDV ASIN # U(R).U(V)
019702,000151: 37,2102 03623 P21VEL
019703,000152: 37,2103 03625 STORE P21GAM # SIN-1 U(R).U(V), -90 TO +90
019704,000153: 37,2104 43134 SXA,2 SET
019705,000154: 37,2105 03603 P21ORIG # 0 = EARTH 2 = MOON
019706,000155: 37,2106 01063 P21FLAG
019707,000156: 37,2107 67214 P21DSP CLEAR SLOAD # GENERATE DISPLAY DATA
019708,000157: 37,2110 01663 LUNAFLAG
019709,000158: 37,2111 00050 X2
019710,000159: 37,2112 43054 BZE SET
019711,000160: 37,2113 76115 +2 # 0 = EARTH
019712,000161: 37,2114 01463 LUNAFLAG
019713,000162: 37,2115 77775 VLOAD
019714,000163: 37,2116 00001 RATT
019715,000164: 37,2117 16152 STODL ALPHAV
019716,000165: 37,2120 00015 TAT
019717,000166: 37,2121 45014 CLEAR CALL
019718,000167: 37,2122 00662 ERADFLAG
019719,000168: 37,2123 26370 LAT-LONG
019720,000169: 37,2124 77605 DMP # MPAC = ALT, METERS B-29
019721,000170: 37,2125 36153 K.01
019722,000171: 37,2126 03621 STORE P21ALT # ALT/100 FOR N73 DSP
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019724,000173: 37,2127 77776 EXIT
019725,000174: 37,2130 32150 CAF V06N43 # DISPLAY LAT,LONG,ALT
019726,000175: 37,2131 04662 TC BANKCALL # LAT,LONG = REVS B0 BOTH EARTH/MOON
019727,000176: 37,2132 20720 CADR GOFLASH # ALT = METERS B-29 BOTH EARTH/MOON
019728,000177: 37,2133 04106 TC GOTOPOOH # TERM
019729,000178: 37,2134 04106 TC GOTOPOOH
019730,000179: 37,2135 06006 TC INTPRET # V32E RECYCLE
019731,000180: 37,2136 43345 DLOAD DAD
019732,000181: 37,2137 02316 P21TIME
019733,000182: 37,2140 36145 600SEC # 600 SECONDS OR 10 MIN
019734,000183: 37,2141 01046 STORE DSPTEM1
019735,000184: 37,2142 77634 RTB
019736,000185: 37,2143 76011 P21PROG1
019737,000186:
019738,000187: 37,2144 00003 25140 600SEC 2DEC 60000 B-28 # 10 MIN
019739,000188:
019740,000189: 37,2146 00001 P21ONENN OCT 00001 # NEEDED TO DETERMINE VEHICLE
019741,000190: 37,2147 00000 OCT 00000 # TO BE INTEGRATED
019742,000191: 37,2150 01453 V06N43 VN 00643
019743,000192: 37,2151 01442 V6N34 VN 00634
019744,000193: 37,2152 00243 32703 K.01 2DEC .01
019745,000194:
End of include-file GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc. Parent file is MAIN.agc