Source Code
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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. |
015052,000002: ## Copyright: Public domain. 015053,000003: ## Filename: GIMBAL_LOCK_AVOIDANCE.agc 015054,000004: ## Purpose: A section of LM131 revision 1. 015055,000005: ## It is part of the reconstructed source code for the final 015056,000006: ## release of the flight software for the Lunar Module's (LM) 015057,000007: ## Apollo Guidance Computer (AGC) for Apollo 13. The code has 015058,000008: ## been reconstructed from a listing of Luminary 131 and a dump 015059,000009: ## of a core rope memory module B5, part number 2010802-171, 015060,000010: ## which is the only module different between LM131 revision 1 015061,000011: ## and Luminary 131. The executable generated from this source 015062,000012: ## has been verified against the module dump, so while the names, 015063,000013: ## comments, and ordering may not be exactly correct, the 015064,000014: ## resulting binary is. 015065,000015: ## Reference: p. 366 015066,000016: ## Assembler: yaYUL 015067,000017: ## Contact: Ron Burkey <info@sandroid.org>. 015068,000018: ## Website: www.ibiblio.org/apollo/index.html 015069,000019: ## Mod history: 2022-10-28 MAS Created from Luminary 131. 015070,000020:
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015072,000022: 15,2050 BANK 15 015073,000023: 015074,000024: 22,2000 SETLOC KALCMON1 015075,000025: 22,2000 BANK 015076,000026: 015077,000027: # DETECTING GIMBAL LOCK 015078,000028: 22,2744 22,2744 LOCSKIRT EQUALS NOGIMLOC 015079,000029: 015080,000030: 22,2744 77614 NOGIMLOC SET 015081,000031: 22,2745 01074 CALCMAN3 015082,000032: 22,2746 70740 WCALC LXC,1 DLOAD* 015083,000033: 22,2747 01322 RATEINDX # CHOOSE THE DESIRED MANEUVER RATE 015084,000034: 22,2750 04772 ARATE,1 # FROM A LIST OF FOUR 015085,000035: 22,2751 45002 SR4 CALL # COMPUTE THE INCREMENTAL ROTATION MATRIX 015086,000036: 22,2752 44527 DELCOMP # DEL CORRESPONDING TO A 1 SEC ROTATION 015087,000037: # ABOUT COF 015088,000038: 22,2753 74343 DLOAD* VXSC 015089,000039: 22,2754 04772 ARATE,1 015090,000040: 22,2755 03270 COF 015091,000041: 22,2756 17325 STODL BRATE # COMPONENT MANEUVER RATES 45 DEG/SEC 015092,000042: 22,2757 03335 AM 015093,000043: 22,2760 55605 DMP DDV* 015094,000044: 22,2761 05002 ANGLTIME 015095,000045: 22,2762 04772 ARATE,1 015096,000046: 22,2763 77661 SR 015097,000047: 22,2764 20606 5 015098,000048: 22,2765 03333 STORE TM # MANEUVER EXECUTION TIME SCALED AS T2 015099,000049: 22,2766 77614 SETGO 015100,000050: 22,2767 01035 CALCMAN2 # 0(OFF) = CONTINUE MANEUVER 015101,000051: 22,2770 45010 NEWANGL +1 # 1(ON) = START MANEUVER 015102,000052: 015103,000053: # THE FOUR SELECTABLE FREE FALL MANEUVER RATES SELECTED BY 015104,000054: # LOADING RATEINDX WITH 0, 2, 4, 6, RESPECTIVELY 015105,000055: 015106,000056: 22,2771 00221 24255 ARATE 2DEC .0088888888 # = 0.2 DEG/SEC $ 22.5 DEG/SEC 015107,000057: 22,2773 00554 02660 2DEC .0222222222 # = 0.5 DEG/SEC $ 22.5 DEG/SEC 015108,000058: 22,2775 02660 13301 2DEC .0888888888 # = 2.0 DEG/SEC $ 22.5 DEG/SEC 015109,000059: 22,2777 16161 30707 2DEC .4444444444 # = 10.0 DEG/SEC $ 22.5 DEG/SEC 015110,000060: 015111,000061: 22,3001 00003 04000 ANGLTIME 2DEC .0001907349 # = 100B-19 FUDGE FACTOR TO CONVERT 015112,000062: # MANEUVER ANGLE TO MANEUVER TIME 015113,000063: 015114,000064: End of include-file GIMBAL_LOCK_AVOIDANCE.agc. Parent file is MAIN.agc