These source-code files are part of a reconstructed copy of LM131 revision 1, the final release of the Apollo 13 Lunar Module (LM) Apollo Guidance Computer (AGC) software. The source reconstruction began with source code of Luminary 131 previously transcribed from a digitized copy of that program. A dump of the flight spare core rope memory module B5, part number 2010802-171, serial number RAY 411, was obtained. This module is the only module different between Luminary 131 and LM131 revision 1. The dump was disassembled and all changes were incorporated into these source files. Note that page numbers in the reconstructed code match those on the Luminary 131 printout, although the changed code would likely have changed page numbers for a real LM131 revision 1 listing. Comments from 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.