Source Code

These source-code files were transcribed from a printout in Don Eyles's personal collection, scanned by archive.org, and financially sponsored by Linden Sims. A team of volunteers performed the transcription and proof-reading. The scanned page images are available at the Virtual AGC Project website, as well as higher-quality (but much larger) images at the Virtual AGC Project's collection in the Internet Archive. Report any problems by creating "issues" at the Virtual AGC Project's GitHub Repository.

Notations on the program listing read, in part:

	GAP:  ASSEMBLE REVISION 56 OF AGC PROGRAM ZERLINA BY ZOROASTER
	9:12 OCT. 21,1970
Note that the date is the date of the printout, not the date of the program revision.

016357,000002:                                                                                                  ## Copyright:   Public domain.
016358,000003:                                                                                                  ## Filename:    GIMBAL_LOCK_AVOIDANCE.agc
016359,000004:                                                                                                  ## Purpose:     A log section of Zerlina 56, the final revision of
016360,000005:                                                                                                  ##              Don Eyles's offline development program for the variable 
016361,000006:                                                                                                  ##              guidance period servicer. It also includes a new P66 with LPD 
016362,000007:                                                                                                  ##              (Landing Point Designator) capability, based on an idea of John 
016363,000008:                                                                                                  ##              Young's. Neither of these advanced features were actually flown,
016364,000009:                                                                                                  ##              but Zerlina was also the birthplace of other big improvements to
016365,000010:                                                                                                  ##              Luminary including the terrain model and new (Luminary 1E)
016366,000011:                                                                                                  ##              analog display programs. Zerlina was branched off of Luminary 145,
016367,000012:                                                                                                  ##              and revision 56 includes all changes up to and including Luminary
016368,000013:                                                                                                  ##              183. It is therefore quite close to the Apollo 14 program,
016369,000014:                                                                                                  ##              Luminary 178, where not modified with new features.
016370,000015:                                                                                                  ## Reference:   p.  369
016371,000016:                                                                                                  ## Assembler:   yaYUL
016372,000017:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
016373,000018:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
016374,000019:                                                                                                  ## Mod history: 2017-07-28 MAS  Created from Luminary 210.
016375,000020:                                                                                                  ##              2017-08-22 RSB  Transcribed.
016376,000021: 

Page 369

016378,000023: 15,2050                                           BANK     15                                    
016379,000024: 
016380,000025: 22,2000                                           SETLOC   KALCMON1                              
016381,000026: 22,2000                                           BANK                                           
016382,000027: 
016383,000028: 
016384,000029:                                                                                                  #  DETECTING GIMBAL LOCK
016385,000030: 22,2744  22,2744               LOCSKIRT           EQUALS   NOGIMLOC                              
016386,000031: 
016387,000032: 22,2744           77614        NOGIMLOC           SET                                            
016388,000033: 22,2745           01074                                    CALCMAN3                              
016389,000034: 22,2746           70740        WCALC              LXC,1    DLOAD*                                
016390,000035: 22,2747           01322                                    RATEINDX                              #  CHOOSE THE DESIRED MANEUVER RATE
016391,000036: 22,2750           04772                                    ARATE,1                               #  FROM A LIST OF FOUR
016392,000037: 22,2751           45002                           SR4      CALL                                  #  COMPUTE THE INCREMENTAL ROTATION MATRIX
016393,000038: 22,2752           44527                                    DELCOMP                               #  DEL CORRESPONDING TO A 1 SEC ROTATION
016394,000039:                                                                                                  #  ABOUT COF
016395,000040: 22,2753           74343                           DLOAD*   VXSC                                  
016396,000041: 22,2754           04772                                    ARATE,1                               
016397,000042: 22,2755           03270                                    COF                                   
016398,000043: 22,2756           17325                           STODL    BRATE                                 #  COMPONENT MANEUVER RATES 45 DEG/SEC
016399,000044: 22,2757           03335                                    AM                                    
016400,000045: 22,2760           55605                           DMP      DDV*                                  
016401,000046: 22,2761           05002                                    ANGLTIME                              
016402,000047: 22,2762           04772                                    ARATE,1                               
016403,000048: 22,2763           77661                           SR                                             
016404,000049: 22,2764           20606                                    5                                     
016405,000050: 22,2765           03333                           STORE    TM                                    #  MANEUVER EXECUTION TIME SCALED AS T2
016406,000051: 22,2766           77614                           SETGO                                          
016407,000052: 22,2767           01035                                    CALCMAN2                              #  0(OFF) = CONTINUE MANEUVER
016408,000053: 22,2770           45010                                    NEWANGL    +1                         #  1(ON) = START MANEUVER
016409,000054:                                                                                                  #           THE FOUR SELECTABLE FREE FALL MANEUVER RATES SELECTED BY
016410,000055:                                                                                                  #           LOADING RATEINDX WITH 0,2,4,6, RESPECTIVELY
016411,000056: 
016412,000057: 
016413,000058: 22,2771           00221 24255  ARATE              2DEC     .0088888888                            #  = 0.2 DEG/SEC       $ 22.5 DEG/SEC
016414,000059: 22,2773           00554 02660                     2DEC     .0222222222                            #  = 0.5 DEG/SEC       $ 22.5 DEG/SEC
016415,000060: 22,2775           02660 13301                     2DEC     .0888888888                            #  = 2.0 DEG/SEC       $ 22.5 DEG/SEC
016416,000061: 22,2777           16161 30707                     2DEC     .4444444444                            #  = 10.0 DEG/SEC      $ 22.5 DEG/SEC
016417,000062: 
016418,000063: 22,3001           00003 04000  ANGLTIME           2DEC     .0001907349                            #  = 100B-19     FUDGE FACTOR TO CONVERT
016419,000064:                                                                                                  #  MANEUVER ANGLE TO MANEUVER TIME

End of include-file GIMBAL_LOCK_AVOIDANCE.agc.  Parent file is MAIN.agc