Source Code
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These source-code files are part of a reconstructed copy of Luminary 178, the
final release of the Apollo 14 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Zerlina 56, Luminary 210, and
Luminary 131, previously transcribed from digitized copies of those programs.
The code was created by combining the three, using Zerlina 56 as a base, since
it was based off of Luminary 183. The differences between the three were
carefully merged using the Luminary memos as a guide, with all changes made
after Luminary 178 being backed out. The reconstruction was verified by matching
memory-bank checksums to those listed in drawing 2021152N. Note that page numbers
in the reconstructed code match those for the baseline log section mentioned in
each file's changelog; the page numbers for a real Luminary 178 listing would
be different.
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.
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015771,000002: ## Copyright: Public domain.
015772,000003: ## Filename: GIMBAL_LOCK_AVOIDANCE.agc
015773,000004: ## Purpose: A section of Luminary revision 178.
015774,000005: ## It is part of the reconstructed source code for the final
015775,000006: ## release of the flight software for the Lunar Module's
015776,000007: ## (LM) Apollo Guidance Computer (AGC) for Apollo 14. The
015777,000008: ## code has been recreated from copies of Zerlina 56, Luminary
015778,000009: ## 210, and Luminary 131, as well as many Luminary memos.
015779,000010: ## It has been adapted such that the resulting bugger words
015780,000011: ## exactly match those specified for Luminary 178 in NASA
015781,000012: ## drawing 2021152N, which gives relatively high confidence
015782,000013: ## that the reconstruction is correct.
015783,000014: ## Reference: p. 369
015784,000015: ## Assembler: yaYUL
015785,000016: ## Contact: Ron Burkey <info@sandroid.org>.
015786,000017: ## Website: www.ibiblio.org/apollo/index.html
015787,000018: ## Mod history: 2019-08-14 MAS Created from Zerlina 56.
015788,000019:
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Page 369
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015790,000021: 15,2050 BANK 15
015791,000022:
015792,000023: 22,2000 SETLOC KALCMON1
015793,000024: 22,2000 BANK
015794,000025:
015795,000026:
015796,000027: # DETECTING GIMBAL LOCK
015797,000028: 22,2744 22,2744 LOCSKIRT EQUALS NOGIMLOC
015798,000029:
015799,000030: 22,2744 77614 NOGIMLOC SET
015800,000031: 22,2745 01074 CALCMAN3
015801,000032: 22,2746 70740 WCALC LXC,1 DLOAD*
015802,000033: 22,2747 01322 RATEINDX # CHOOSE THE DESIRED MANEUVER RATE
015803,000034: 22,2750 04772 ARATE,1 # FROM A LIST OF FOUR
015804,000035: 22,2751 45002 SR4 CALL # COMPUTE THE INCREMENTAL ROTATION MATRIX
015805,000036: 22,2752 44527 DELCOMP # DEL CORRESPONDING TO A 1 SEC ROTATION
015806,000037: # ABOUT COF
015807,000038: 22,2753 74343 DLOAD* VXSC
015808,000039: 22,2754 04772 ARATE,1
015809,000040: 22,2755 03270 COF
015810,000041: 22,2756 17325 STODL BRATE # COMPONENT MANEUVER RATES 45 DEG/SEC
015811,000042: 22,2757 03335 AM
015812,000043: 22,2760 55605 DMP DDV*
015813,000044: 22,2761 05002 ANGLTIME
015814,000045: 22,2762 04772 ARATE,1
015815,000046: 22,2763 77661 SR
015816,000047: 22,2764 20606 5
015817,000048: 22,2765 03333 STORE TM # MANEUVER EXECUTION TIME SCALED AS T2
015818,000049: 22,2766 77614 SETGO
015819,000050: 22,2767 01035 CALCMAN2 # 0(OFF) = CONTINUE MANEUVER
015820,000051: 22,2770 45010 NEWANGL +1 # 1(ON) = START MANEUVER
015821,000052: # THE FOUR SELECTABLE FREE FALL MANEUVER RATES SELECTED BY
015822,000053: # LOADING RATEINDX WITH 0,2,4,6, RESPECTIVELY
015823,000054:
015824,000055:
015825,000056: 22,2771 00221 24255 ARATE 2DEC .0088888888 # = 0.2 DEG/SEC $ 22.5 DEG/SEC
015826,000057: 22,2773 00554 02660 2DEC .0222222222 # = 0.5 DEG/SEC $ 22.5 DEG/SEC
015827,000058: 22,2775 02660 13301 2DEC .0888888888 # = 2.0 DEG/SEC $ 22.5 DEG/SEC
015828,000059: 22,2777 16161 30707 2DEC .4444444444 # = 10.0 DEG/SEC $ 22.5 DEG/SEC
015829,000060:
015830,000061: 22,3001 00003 04000 ANGLTIME 2DEC .0001907349 # = 100B-19 FUDGE FACTOR TO CONVERT
015831,000062: # MANEUVER ANGLE TO MANEUVER TIME
End of include-file GIMBAL_LOCK_AVOIDANCE.agc. Parent file is MAIN.agc