Source Code
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These source-code files are part of a reconstructed copy of Luminary 173, the
second (unflown) release of the Apollo 14 Lunar Module (LM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with reconstructed source code for Luminary 178. Changes
between revision 173 and 178 were backed out, as described by Luminary memo 167
(revision 1). 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 173 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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015724,000002: ## Copyright: Public domain.
015725,000003: ## Filename: GIMBAL_LOCK_AVOIDANCE.agc
015726,000004: ## Purpose: A section of Luminary revision 173.
015727,000005: ## It is part of the reconstructed source code for the second
015728,000006: ## (unflown) release of the flight software for the Lunar
015729,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 14.
015730,000008: ## The code has been recreated from a reconstructed copy of
015731,000009: ## Luminary 178, as well as Luminary memo 167 (revision 1).
015732,000010: ## It has been adapted such that the resulting bugger words
015733,000011: ## exactly match those specified for Luminary 173 in NASA
015734,000012: ## drawing 2021152N, which gives relatively high confidence
015735,000013: ## that the reconstruction is correct.
015736,000014: ## Reference: p. 369
015737,000015: ## Assembler: yaYUL
015738,000016: ## Contact: Ron Burkey <info@sandroid.org>.
015739,000017: ## Website: www.ibiblio.org/apollo/index.html
015740,000018: ## Mod history: 2019-09-18 MAS Created from Luminary 178.
015741,000019:
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Page 369
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015743,000021: 15,2050 BANK 15
015744,000022:
015745,000023: 22,2000 SETLOC KALCMON1
015746,000024: 22,2000 BANK
015747,000025:
015748,000026:
015749,000027: # DETECTING GIMBAL LOCK
015750,000028: 22,2744 22,2744 LOCSKIRT EQUALS NOGIMLOC
015751,000029:
015752,000030: 22,2744 77614 NOGIMLOC SET
015753,000031: 22,2745 01074 CALCMAN3
015754,000032: 22,2746 70740 WCALC LXC,1 DLOAD*
015755,000033: 22,2747 01322 RATEINDX # CHOOSE THE DESIRED MANEUVER RATE
015756,000034: 22,2750 04772 ARATE,1 # FROM A LIST OF FOUR
015757,000035: 22,2751 45002 SR4 CALL # COMPUTE THE INCREMENTAL ROTATION MATRIX
015758,000036: 22,2752 44527 DELCOMP # DEL CORRESPONDING TO A 1 SEC ROTATION
015759,000037: # ABOUT COF
015760,000038: 22,2753 74343 DLOAD* VXSC
015761,000039: 22,2754 04772 ARATE,1
015762,000040: 22,2755 03270 COF
015763,000041: 22,2756 17325 STODL BRATE # COMPONENT MANEUVER RATES 45 DEG/SEC
015764,000042: 22,2757 03335 AM
015765,000043: 22,2760 55605 DMP DDV*
015766,000044: 22,2761 05002 ANGLTIME
015767,000045: 22,2762 04772 ARATE,1
015768,000046: 22,2763 77661 SR
015769,000047: 22,2764 20606 5
015770,000048: 22,2765 03333 STORE TM # MANEUVER EXECUTION TIME SCALED AS T2
015771,000049: 22,2766 77614 SETGO
015772,000050: 22,2767 01035 CALCMAN2 # 0(OFF) = CONTINUE MANEUVER
015773,000051: 22,2770 45010 NEWANGL +1 # 1(ON) = START MANEUVER
015774,000052: # THE FOUR SELECTABLE FREE FALL MANEUVER RATES SELECTED BY
015775,000053: # LOADING RATEINDX WITH 0,2,4,6, RESPECTIVELY
015776,000054:
015777,000055:
015778,000056: 22,2771 00221 24255 ARATE 2DEC .0088888888 # = 0.2 DEG/SEC $ 22.5 DEG/SEC
015779,000057: 22,2773 00554 02660 2DEC .0222222222 # = 0.5 DEG/SEC $ 22.5 DEG/SEC
015780,000058: 22,2775 02660 13301 2DEC .0888888888 # = 2.0 DEG/SEC $ 22.5 DEG/SEC
015781,000059: 22,2777 16161 30707 2DEC .4444444444 # = 10.0 DEG/SEC $ 22.5 DEG/SEC
015782,000060:
015783,000061: 22,3001 00003 04000 ANGLTIME 2DEC .0001907349 # = 100B-19 FUDGE FACTOR TO CONVERT
015784,000062: # MANEUVER ANGLE TO MANEUVER TIME
End of include-file GIMBAL_LOCK_AVOIDANCE.agc. Parent file is MAIN.agc