Source Code

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: MIT/IL engineering drawing 2021153D, sheet 3. Listing of the memory-bank checksums for Comanche 44. Comanche 55 (Apollo 11 CM final release) assembly listing. Reconstructed Comanche 51 (Apollo 11 CM initial release) assembly listing. Colossus 249 (Apollo 9 CM final release) assembly listing. Guidance System Operations Plan for Colossus 3, Section 5, p. xiii. Table listing some Program Request Changes (PCRs) incorporated between Comanche 45/2 and Comanche 55. Guidance System Operations Plan for Colossus 2E, Section 3, pp. ix-x. Tables listing some Program Change Requests (PCRs) incorporated between Comanche 44 and Comanche 55. Programmed Guidance Equations for Colossus 2, Based on Comanche 55. Provides a pseudocode representation of portions of Comanche 55, showing change bars. The software revisions from which and to which the changes occurred are indicated by the markings next to the document page number: "Rev. 0" pages: change bars are from Colossus 249 to Comanche 45 "Rev. 1" pages: change bars are from Comanche 45 to Comanche 45/2 "Rev. 2" pages: change bars are from Comanche 45/2 to Comanche 55 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.

041305,000002:                                                                                                  ## Copyright:   Public domain.
041306,000003:                                                                                                  ## Filename:    LUNAR_LANDMARK_SELECTION_FOR_CM.agc
041307,000004:                                                                                                  ## Purpose:     A section of Comanche revision 044.
041308,000005:                                                                                                  ##              It is part of the reconstructed source code for the
041309,000006:                                                                                                  ##              original release of the flight software for the Command
041310,000007:                                                                                                  ##              Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
041311,000008:                                                                                                  ##              The code has been recreated from a copy of Comanche 055. It
041312,000009:                                                                                                  ##              has been adapted such that the resulting bugger words
041313,000010:                                                                                                  ##              exactly match those specified for Comanche 44 in NASA drawing
041314,000011:                                                                                                  ##              2021153D, which gives relatively high confidence that the
041315,000012:                                                                                                  ##              reconstruction is correct.
041316,000013:                                                                                                  ## Assembler:   yaYUL
041317,000014:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
041318,000015:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
041319,000016:                                                                                                  ## Mod history: 2020-12-03 MAS  Created from Comanche 51.
041320,000017: 

Page 936 This page (and this entire section) contains only assembler-generated messages.

End of include-file LUNAR_LANDMARK_SELECTION_FOR_CM.agc.  Parent file is MAIN.agc