Source Code
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These source-code files are part of a reconstructed copy of Comanche 51, the
initial release (though not the final mission release) of the Apollo 11
Command Module (CM) Apollo Guidance Computer (AGC) software. The flown, final
release was Comanche 55. The reconstruction is believed to be exactly accurate,
but in the absence of an actual Apollo-era listing of Comanche 51, some
explanation of the reconstruction process is needed to insure confidence in
that accuracy.
The starting point was the source code of Comanche 55, whose original source code
is available. Comanche 55 source code was then modified by undoing changes known
to have been made between revisions 51 and 55. The most-significant steps involved
reverting changes related to the R-2 lunar potential model, the details of which
were known from the previous, separate, independent reconstruction of the Apollo 10
Lunar Module software Luminary 69/2. The now-reconstructed
Comanche 51 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 or Luminary 69 printouts, although
the source code would likely have different page numbers in a contemporary Comanche 51 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 55. Here's a guide
to some of the Apollo documentation relevant to those annotations:
Among documentation not actually referenced in the annotations, there is
a short writeup about the reconstruction process in our software repository
that may be helpful in understanding it from a different perspective. There's also
a handy table
that lists what the number of memory-words should be for each routine in Comanche 51,
which could make a nice double-check; however, we've not performed that double-check ourselves.
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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043617,000002: ## Copyright: Public domain.
043618,000003: ## Filename: MYSUBS.agc
043619,000004: ## Purpose: A section of Comanche revision 051.
043620,000005: ## It is part of the reconstructed source code for the
043621,000006: ## original release of the flight software for the Command
043622,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
043623,000008: ## The code has been recreated from a copy of Comanche 055. It
043624,000009: ## has been adapted such that the resulting bugger words
043625,000010: ## exactly match those specified for Comanche 51 in NASA drawing
043626,000011: ## 2021153D, which gives relatively high confidence that the
043627,000012: ## reconstruction is correct.
043628,000013: ## Reference: pp. 999-1001
043629,000014: ## Assembler: yaYUL
043630,000015: ## Contact: Ron Burkey <info@sandroid.org>.
043631,000016: ## Website: www.ibiblio.org/apollo/index.html
043632,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
043633,000018:
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Page 999
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043635,000020: 20,3612 BANK 20
043636,000021: 21,2000 SETLOC MYSUBS
043637,000022: 21,2000 BANK
043638,000023:
043639,000024: 21,2042 E6,1510 EBANK= KMPAC
043640,000025: 21,2042 5074 SPCOS1 EQUALS SPCOS
043641,000026: 21,2042 5075 SPSIN1 EQUALS SPSIN
043642,000027: 21,2042 5074 SPCOS2 EQUALS SPCOS
043643,000028: 21,2042 5075 SPSIN2 EQUALS SPSIN
043644,000029:
043645,000030: 21,2042 COUNT 21/DAPMS
043646,000031:
043647,000032: # ONE AND ONE HALF PRECISION MULTIPLICATION ROUTINE
043648,000033:
043649,000034: 21,2042 55512 SMALLMP TS KMPTEMP # A(X+Y)
043650,000035: 21,2043 00006 EXTEND
043651,000036: 21,2044 71511 MP KMPAC +1
043652,000037: 21,2045 55511 TS KMPAC +1 # AY
043653,000038: 21,2046 35021 CAF ZERO
043654,000039: 21,2047 57510 XCH KMPAC
043655,000040: 21,2050 00006 EXTEND
043656,000041: 21,2051 71512 MP KMPTEMP # AX
043657,000042: 21,2052 21511 DAS KMPAC # AX+AY
043658,000043: 21,2053 00002 TC Q
043659,000044:
043660,000045: # SUBROUTINE FOR DOUBLE PRECISION ADDITIONS OF ANGLES
043661,000046: # A AND L CONTAIN A DP(1S) ANGLE SCALED BY 180 DEGS TO BE ADDED TO KMPAC.
043662,000047: # RESULT IS PLACED IN KMPAC. TIMING = 6 MCT (22 MCT ON OVERFLOW)
043663,000048:
043664,000049: 21,2054 21511 DPADD DAS KMPAC
043665,000050: 21,2055 00006 EXTEND
043666,000051: 21,2056 12073 BZF TSK +1 # NO OVERFLOW
043667,000052: 21,2057 11510 CCS KMPAC
043668,000053: 21,2060 12074 TCF DPADD+ # + OVERFLOW
043669,000054: 21,2061 12063 TCF +2
043670,000055: 21,2062 12076 TCF DPADD- # - OVERFLOW
043671,000056: 21,2063 11511 CCS KMPAC +1
043672,000057: 21,2064 12101 TCF DPADD2+ # UPPER = 0, LOWER +
043673,000058: 21,2065 12067 TCF +2
043674,000059: 21,2066 40000 COM # UPPER = 0, LOWER -
043675,000060: 21,2067 64777 AD POSMAX # LOWER = 0, A = 0
043676,000061: 21,2070 55511 TS KMPAC +1 # CAN NOT OVERFLOW
043677,000062: 21,2071 34777 CA POSMAX # UPPER WAS = 0
043678,000063: 21,2072 55510 TSK TS KMPAC
043679,000064: 21,2073 00002 TC Q
043680,000065:
043681,000066: 21,2074 65001 DPADD+ AD NEGMAX # KMPAC GREATER THAN 0
043682,000067: 21,2075 12072 TCF TSK
043683,000068:
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Page 1000
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043685,000070: 21,2076 40000 DPADD- COM
043686,000071: 21,2077 64777 AD POSMAX # KMPAC LESS THAN 0
043687,000072: 21,2100 12072 TCF TSK
043688,000073:
043689,000074: 21,2101 65001 DPADD2+ AD NEGMAX # CAN NOT OVERFLOW
043690,000075: 21,2102 55511 TS KMPAC +1
043691,000076: 21,2103 35001 CA NEGMAX # UPPER WAS = 0
043692,000077: 21,2104 12072 TCF TSK
043693,000078:
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Page 1001
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043696,000081:
043697,000082:
End of include-file MYSUBS.agc. Parent file is MAIN.agc