Source Code
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This is the source-code for the Apollo 9 Command Module's Guidance Computer.
These files were derived originally from the scan from MIT's Dibner Institute's
now-discontinued website titled "History of Recent Science and Technology", which
in turn was originally created by Gary Neff, though his high-quality scans were
unfortunately reduced in legibility when presented online.
The markings on the front of the
printout imply that it was the original AGC developer Norm Brodeur's copy.
A scan by Ron Burkey has superceded it, made from a more-legible copy from the collection of original
AGC developer Fred Martin. The source code was transcribed from
those images by Ron Burkey. Note that the page images
presented online are of reduced quality, and that higher-quality images
are available. Report any conversion errors or legibility
problems in page images to info@sandroid.org.
Notations on the program listing read, in part:ASSEMBLE REVISION 249 OF AGC PROGRAM COLOSSUS BY NASA 2021111-041 20'35 OCT. 28,1968Note that the date is the date of the printout, not the date of the program revision. |
017858,000002: ## Copyright: Public domain.
017859,000003: ## Filename: GIMBAL_LOCK_AVOIDANCE.agc
017860,000004: ## Purpose: Part of the source code for Colossus, build 249.
017861,000005: ## It is part of the source code for the Command Module's (CM)
017862,000006: ## Apollo Guidance Computer (AGC), for Apollo 9.
017863,000007: ## Assembler: yaYUL
017864,000008: ## Reference: pp. 405-406.
017865,000009: ## Contact: Ron Burkey <info@sandroid.org>.
017866,000010: ## Website: www.ibiblio.org/apollo.
017867,000011: ## Mod history: 08/10/04 RSB. Began transcribing.
017868,000012: ## 2017-01-06 RSB Page numbers now agree with those on the
017869,000013: ## original harcopy, as opposed to the PDF page
017870,000014: ## numbers in 1701.pdf.
017871,000015: ## 2017-01-14 RSB Cross-diff'd comment text (not whitespace)
017872,000016: ## vs the already-proofed corresponding Colossus
017873,000017: ## 237 and Comanche 55 source-code files
017874,000018: ## and corrected errors found.
017875,000019: ##
017876,000020: ## The contents of the "Colossus249" files, in general, are transcribed
017877,000021: ## from a scanned copy of the program listing. Notations on this
017878,000022: ## document read, in part:
017879,000023: ##
017880,000024: ## Assemble revision 249 of AGC program Colossus by NASA
017881,000025: ## 2021111-041. October 28, 1968.
017882,000026: ##
017883,000027: ## This AGC program shall also be referred to as
017884,000028: ## Colossus 1A
017885,000029: ##
017886,000030: ## Prepared by
017887,000031: ## Massachusetts Institute of Technology
017888,000032: ## 75 Cambridge Parkway
017889,000033: ## Cambridge, Massachusetts
017890,000034: ## under NASA contract NAS 9-4065.
017891,000035: ##
017892,000036: ## Refer directly to the online document mentioned above for further information.
017893,000037: ## Please report any errors (relative to the scanned pages) to info@sandroid.org.
017894,000038: ##
017895,000039: ## In some cases, where the source code for Luminary 131 overlaps that of
017896,000040: ## Colossus 249, this code is instead copied from the corresponding Luminary 131
017897,000041: ## source file, and then is proofed to incorporate any changes.
017898,000042:
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Page 405 |
017900,000044: 15,2000 BANK 15
017901,000045:
017902,000046: 22,2000 SETLOC KALCMON1
017903,000047: 22,2000 BANK
017904,000048:
017905,000049: 22,2736 E6,1661 EBANK= BCDU
017906,000050:
017907,000051: # DETECTING GIMBAL LOCK
017908,000052: 22,2736 22,2736 LOCSKIRT EQUALS NOGIMLOC
017909,000053:
017910,000054: 22,2736 77614 NOGIMLOC SET
017911,000055: 22,2737 01074 CALCMAN3
017912,000056: 22,2740 70740 WCALC LXC,1 DLOAD*
017913,000057: 22,2741 01130 RATEINDX
017914,000058: 22,2742 04772 ARATE,1
017915,000059: 22,2743 45002 SR4 CALL # COMPUTE THE INCREMENTAL ROTATION MATRIX
017916,000060: 22,2744 44530 DELCOMP # DEL CORRESPONDING TO A 1 SEC ROTATION
017917,000061: # ABOUT COF
017918,000062: 22,2745 74343 DLOAD* VXSC
017919,000063: 22,2746 04772 ARATE,1
017920,000064: 22,2747 03343 COF
017921,000065: 22,2750 77721 MXV
017922,000066: 22,2751 05004 QUADROT
017923,000067:
017924,000068: 22,2752 17311 STODL BRATE
017925,000069: 22,2753 03365 AM
017926,000070: 22,2754 55605 DMP DDV*
017927,000071: 22,2755 05002 ANGLTIME
017928,000072: 22,2756 04772 ARATE,1
017929,000073: 22,2757 77661 SR
017930,000074: 22,2760 20606 5
017931,000075: 22,2761 27317 STOVL TM
017932,000076: 22,2762 03311 BRATE
017933,000077: 22,2763 77761 VXSC
017934,000078: 22,2764 05026 BIASCALE
017935,000079: 22,2765 03275 STORE BIASTEMP # ATTITUDE ERROR BIAS TO PREVENT OVERSHOOT
017936,000080: # IN SYSTEM
017937,000081: 22,2766 77614 SETGO # STATE SWITCH CALCMAN2 (43D)
017938,000082: 22,2767 01035 CALCMAN2 # 0(OFF) = BYPASS STARTING PROCEDURE
017939,000083: 22,2770 45033 NEWANGL +1 # 1(ON) = START MANEUVER
017940,000084:
017941,000085: 22,2771 00044 15053 ARATE 2DEC .0022222222 # = .05 DEG/SEC
017942,000086: 22,2773 00221 24255 2DEC .0088888889 # = .2 DEG/SEC
017943,000087: 22,2775 00554 02660 2DEC .0222222222 # = .5 DEG/SEC
017944,000088: 22,2777 05540 26603 2DEC .1777777777 # = 4 DEG/SEC $ 22.5 DEG/SEC
017945,000089:
017946,000090: 22,3001 00003 04000 ANGLTIME 2DEC .000190735 # = 100B-19
017947,000091: # MANEUVER ANGLE TO MANEUVER TIME
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Page 406 |
017949,000093: 22,3003 03146 14632 QUADROT 2DEC .1 # ROTATION MATRIX FROM S/C AXES TO CONTROL
017950,000094: 22,3005 00000 00000 2DEC 0 B-28 # AXES (X ROT = -7.25 DEG)
017951,000095: 22,3007 00000 00000 2DEC 0 B-28
017952,000096: 22,3011 00000 00000 2DEC 0 B-28
017953,000097: 22,3013 03131 11275 2DEC .099200 # = (.1)COS7.25
017954,000098: 22,3015 77461 47370 2DEC -.012620 # =-(.1)SIN7.25
017955,000099: 22,3017 00000 00000 2DEC 0 B-28
017956,000100: 22,3021 00316 30407 2DEC .012620 # (.1)SIN7.25
017957,000101: 22,3023 03131 11275 2DEC .099200 # (.1)COS7.25
017958,000102: 22,3025 00004 05253 BIASCALE 2DEC .0002543132 # = (450/180)(1/0.6)(1/16384)
017959,000103:
017960,000104:
End of include-file GIMBAL_LOCK_AVOIDANCE.agc. Parent file is MAIN.agc