Source Code

These source-code files derive from a printout of Luminary 116 (the Apollo 12 Lunar Module guidance computer program), from the personal library of original AGC developer Don Eyles, digitally photographed at archive.org, financially sponsored by Ron Burkey, and transcribed to source code by a team of volunteers. This colorized, syntax-highlighted form was created by assembling that transcribed source code. Note that the full page images are available on the Virtual AGC project page at archive.org, while reduced-size images are presented at the VirtualAGC project website. Report or fix any transcription errors at the Virtual AGC project code repository.

Notations on the program listing read, in part:

	GAP:  ASSEMBLE REVISION 116 OF AGC PROGRAM LUMINARY BY NASA 2021112-071
	19:09 AUG. 11,1969
Note that the date is the date of the printout, not the date of the program revision.

052570,000002:                                                                                                  ## Copyright:   Public domain.

052571,000003:                                                                                                  ## Filename:    INFLIGHT_ALIGNMENT_ROUTINES.agc

052572,000004:                                                                                                  ## Purpose:     A section of Luminary revision 116.

052573,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM) 

052574,000006:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 12.

052575,000007:                                                                                                  ##              This file is intended to be a faithful transcription, except

052576,000008:                                                                                                  ##              that the code format has been changed to conform to the

052577,000009:                                                                                                  ##              requirements of the yaYUL assembler rather than the

052578,000010:                                                                                                  ##              original YUL assembler.

052579,000011:                                                                                                  ## Reference:   pp. 1239-1248

052580,000012:                                                                                                  ## Assembler:   yaYUL

052581,000013:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.

052582,000014:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html

052583,000015:                                                                                                  ## Mod history: 2017-01-22 MAS  Created from Luminary 99.

052584,000016:                                                                                                  ##              2017-01-26 RRB  Updated for Luminary 116.

052585,000017:                                                                                                  ##              2017-03-13 RSB  Proofed comment text via 3-way diff vs

052586,000018:                                                                                                  ##                              Luminary 99 and 131, but no changes were needed.

052587,000019:                                                                                                  ##              2017-03-17 RSB  Comment-text fixes identified in diff'ing

052588,000020:                                                                                                  ##                              Luminary 99 vs Comanche 55.

052589,000021: 

Page 1239

052591,000023: 22,3773                                           BANK     22                                    
052592,000024: 23,2000                                           SETLOC   INFLIGHT                              
052593,000025: 23,2000                                           BANK                                           
052594,000026: 
052595,000027: 23,3251  E5,1642                                  EBANK=   XSM                                   
052596,000028: 
052597,000029:                                                                                                  #  CALCGTA COMPUTES THE GYRO TORQUE ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.

052598,000030: 
052599,000031:                                                                                                  #  THE INPUT IS THE DESIRED STABLE MEMBER COORDINATES REFERRED TO PRESENT STABLE MEMBER COORDINATES. THE THREE

052600,000032:                                                                                                  #  HALF-UNIT VECTORS ARE STORED AT XDC, YDC, AND ZDC.

052601,000033: 
052602,000034:                                                                                                  #  THE OUTPUTS ARE THE THREE GYRO TORQUING ANGLES TO BE APPLIED TO THE Y, Z, AND X GYROS AND ARE STORED DP AT IGC,

052603,000035:                                                                                                  #  MGC, AND OGC RESPECTIVELY.

052604,000036: 
052605,000037: 23,3251                                           COUNT*   $$/INFLT                              
052606,000038: 23,3251           71220        CALCGTA            ITA      DLOAD                                 #  PUSHDOWN  00-03, 16D-27D, 34D-37D

052607,000039: 23,3252           00051                                    S2                                    #  XDC = (XD1 XD2 XD3)

052608,000040: 23,3253           02665                                    XDC                                   #  YDC = (YD1 YD2 YD3)

052609,000041: 23,3254           65325                           PDDL     PDDL                                  #  ZDC = (ZD1 ZD2 ZD3)

052610,000042: 23,3255           06524                                    HI6ZEROS                              
052611,000043: 23,3256           02671                                    XDC        +4                         
052612,000044: 23,3257           55476                           DCOMP    VDEF                                  
052613,000045: 23,3260           77656                           UNIT                                           
052614,000046: 23,3261           14027                           STODL    ZPRIME                                #  ZP = UNIT(-XD3 0 XD1) = (ZP1 ZP2 ZP3)

052615,000047: 23,3262           00027                                    ZPRIME                                
052616,000048: 
052617,000049: 23,3263           77742                           SR1                                            
052618,000050: 23,3264           14023                           STODL    SINTH                                 #  SIN(IGC) = ZP1

052619,000051: 23,3265           00033                                    ZPRIME     +4                         
052620,000052: 23,3266           77742                           SR1                                            
052621,000053: 23,3267           34021                           STCALL   COSTH                                 #  COS(IGC) = ZP3

052622,000054: 23,3270           47322                                    ARCTRIG                               
052623,000055: 
052624,000056: 23,3271           16742                           STODL    IGC                                   #  Y GYRO TORQUING ANGLE   FRACTION OF REV.

052625,000057: 23,3272           02667                                    XDC        +2                         
052626,000058: 23,3273           77742                           SR1                                            
052627,000059: 23,3274           14023                           STODL    SINTH                                 #  SIN(MGC) = XD2

052628,000060: 23,3275           00027                                    ZPRIME                                
052629,000061: 
052630,000062: 23,3276           65205                           DMP      PDDL                                  
052631,000063: 23,3277           02671                                    XDC        +4                         #  PD00 = (ZP1)(XD3)

052632,000064: 23,3300           00033                                    ZPRIME     +4                         
052633,000065: 
052634,000066: 23,3301           45205                           DMP      DSU                                   
052635,000067: 23,3302           02665                                    XDC                                   #  MPAC = (ZP3)(XD1)

052636,000068: 23,3303           77626                           STADR                                          
052637,000069: 23,3304           43756                           STCALL   COSTH                                 #  COS(MGC) = MPAC - PD00

052638,000070: 23,3305           47322                                    ARCTRIG                               

Page 1240

052640,000072: 23,3306           26744                           STOVL    MGC                                   #  Z GYRO TORQUING ANGLE   FRACTION OF REV.

052641,000073: 23,3307           00027                                    ZPRIME                                
052642,000074: 23,3310           77641                           DOT                                            
052643,000075: 23,3311           02701                                    ZDC                                   
052644,000076: 23,3312           24021                           STOVL    COSTH                                 #  COS(OGC) = ZP . ZDC

052645,000077: 23,3313           00027                                    ZPRIME                                
052646,000078: 23,3314           77641                           DOT                                            
052647,000079: 23,3315           02673                                    YDC                                   
052648,000080: 23,3316           34023                           STCALL   SINTH                                 #  SIN(OGC) = ZP . YDC

052649,000081: 23,3317           47322                                    ARCTRIG                               
052650,000082: 
052651,000083: 23,3320           36740                           STCALL   OGC                                   #  X GYRO TORQUING ANGLE   FRACTION OF REV.

052652,000084: 23,3321           00051                                    S2                                    
052653,000085: 

Page 1241

052655,000087:                                                                                                  #  ARCTRIG COMPUTES AN ANGLE GIVEN THE SINE AND COSINE OF THIS ANGLE.

052656,000088: 
052657,000089:                                                                                                  #  THE INPUTS ARE SIN/4 AND COS/4 STORED DP AT SINTH AND COSTH.

052658,000090: 
052659,000091:                                                                                                  #  THE OUTPUT IS THE CALCULATED ANGLE BETWEEN +.5 AND -.5 REVOLUTIONS AND STORED AT THETA. THE OUTPUT IS ALSO

052660,000092:                                                                                                  #  AVAILABLE AT MPAC.

052661,000093: 
052662,000094: 23,3322           51545        ARCTRIG            DLOAD    ABS                                   #  PUSHDOWN  16D-21D

052663,000095: 23,3323           00023                                    SINTH                                 
052664,000096: 23,3324           50025                           DSU      BMN                                   
052665,000097: 23,3325           07536                                    QTSN45                                #  ABS(SIN/4) - SIN(45)/4

052666,000098: 23,3326           47335                                    TRIG1                                 #  IF (-45,45) OR (135,-135)

052667,000099: 
052668,000100: 23,3327           72545                           DLOAD    SL1                                   #  (45,135) OR (-135,-45)

052669,000101: 23,3330           00021                                    COSTH                                 
052670,000102: 23,3331           75326                           ACOS     SIGN                                  
052671,000103: 23,3332           00023                                    SINTH                                 
052672,000104: 23,3333           00025                           STORE    THETA                                 #  X = ARCCOS(COS) WITH SIGN(SIN)

052673,000105: 23,3334           77616                           RVQ                                            
052674,000106: 
052675,000107: 23,3335           72545        TRIG1              DLOAD    SL1                                   #  (-45,45) OR (135,-135)

052676,000108: 23,3336           00023                                    SINTH                                 
052677,000109: 23,3337           77736                           ASIN                                           
052678,000110: 23,3340           14025                           STODL    THETA                                 #  X = ARCSIN(SIN) WITH SIGN(SIN)

052679,000111: 23,3341           00021                                    COSTH                                 
052680,000112: 23,3342           77640                           BMN                                            
052681,000113: 23,3343           47346                                    TRIG2                                 #  IF (135,-135)

052682,000114: 
052683,000115: 23,3344           43545                           DLOAD    RVQ                                   
052684,000116: 23,3345           00025                                    THETA                                 #  X = ARCSIN(SIN)   (-45,45)

052685,000117: 
052686,000118: 23,3346           75345        TRIG2              DLOAD    SIGN                                  #  (135,-135)

052687,000119: 23,3347           06522                                    HIDPHALF                              
052688,000120: 23,3350           00023                                    SINTH                                 
052689,000121: 23,3351           77625                           DSU                                            
052690,000122: 23,3352           00025                                    THETA                                 
052691,000123: 23,3353           00025                           STORE    THETA                                 #  X = .5 WITH SIGN(SIN) - ARCSIN(SIN)

052692,000124: 23,3354           77616                           RVQ                                            #                   (+) - (+) OR (-) - (-)

052693,000125: 

Page 1242

052695,000127:                                                                                                  #      SMNB, NBSM, AND AXISROT, WHICH USED TO APPEAR HERE, HAVE BEEN

052696,000128:                                                                                                  #  COMBINED IN A ROUTINE CALLED AX*SR*T, WHICH APPEARS AMONG THE POWERED

052697,000129:                                                                                                  #  FLIGHT SUBROUTINES.

052698,000130: 

Page 1243

052700,000132:                                                                                                  #  CALCGA COMPUTES THE CDU DRIVING ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.

052701,000133: 
052702,000134:                                                                                                  #  THE INPUTS ARE  1) THE NAVIGATION BASE COORDINATES REFERRED TO ANY COORDINATE SYSTEM.  THE THREE HALF-UNIT

052703,000135:                                                                                                  #  VECTORS ARE STORED AT XNB,YNB, AND ZNB.  2) THE DESIRED STABLE MEMBER COORDINATES REFERRED TO THE SAME

052704,000136:                                                                                                  #  COORDINATE SYSTEM ARE STORED AT XSM, YSM, AND ZSM.

052705,000137: 
052706,000138:                                                                                                  #  THE OUTPUTS ARE THE THREE CDU DRIVING ANGLES AND ARE STORED SP AT THETAD, THETAD +1, AND THETAD +2.

052707,000139: 
052708,000140: 23,3355           77601        CALCGA             SETPD                                          #  PUSHDOWN 00-05, 16D-21D, 34D-37D

052709,000141: 23,3356           00001                                    0                                     
052710,000142: 23,3357           47375                           VLOAD    VXV                                   
052711,000143: 23,3360           02665                                    XNB                                   #  XNB = OGA (OUTER GIMBAL AXIS)

052712,000144: 23,3361           02651                                    YSM                                   #  YSM = IGA (INNER GIMBAL AXIS)

052713,000145: 23,3362           41456                           UNIT     PUSH                                  #  PD0 = UNIT(OGA X IGA) = MGA

052714,000146: 
052715,000147: 23,3363           44041                           DOT      ITA                                   
052716,000148: 23,3364           02701                                    ZNB                                   
052717,000149: 23,3365           00051                                    S2                                    
052718,000150: 23,3366           24021                           STOVL    COSTH                                 #  COS(OG) = MGA . ZNB

052719,000151: 23,3367           00001                                    0                                     
052720,000152: 23,3370           77641                           DOT                                            
052721,000153: 23,3371           02673                                    YNB                                   
052722,000154: 23,3372           34023                           STCALL   SINTH                                 #  SIN(OG) = MGA . YNB

052723,000155: 23,3373           47322                                    ARCTRIG                               
052724,000156: 23,3374           26740                           STOVL    OGC                                   
052725,000157: 23,3375           00001                                    0                                     
052726,000158: 
052727,000159: 23,3376           50235                           VXV      DOT                                   #  PROVISION FOR MG ANGLE OF 90 DEGREES

052728,000160: 23,3377           02665                                    XNB                                   
052729,000161: 23,3400           02651                                    YSM                                   
052730,000162: 23,3401           77752                           SL1                                            
052731,000163: 23,3402           24021                           STOVL    COSTH                                 #  COS(MG) = IGA . (MGA X OGA)

052732,000164: 23,3403           02651                                    YSM                                   
052733,000165: 23,3404           77641                           DOT                                            
052734,000166: 23,3405           02665                                    XNB                                   
052735,000167: 23,3406           34023                           STCALL   SINTH                                 #  SIN(MG) = IGA . OGA

052736,000168: 23,3407           47322                                    ARCTRIG                               
052737,000169: 23,3410           02744                           STORE    MGC                                   
052738,000170: 
052739,000171: 23,3411           45246                           ABS      DSU                                   
052740,000172: 23,3412           07540                                    .166...                               
052741,000173: 23,3413           77644                           BPL                                            
052742,000174: 23,3414           47433                                    GIMLOCK1                              #  IF ANGLE GREATER THAN 60 DEGREES

052743,000175: 
052744,000176: 23,3415           50375        CALCGA1            VLOAD    DOT                                   
052745,000177: 23,3416           02657                                    ZSM                                   
052746,000178: 23,3417           00001                                    0                                     
052747,000179: 23,3420           24021                           STOVL    COSTH                                 #  COS(IG) = ZSM . MGA

052748,000180: 23,3421           02643                                    XSM                                   

Page 1244

052750,000182: 23,3422           45441                           DOT      STADR                                 
052751,000183: 23,3423           43754                           STCALL   SINTH                                 #  SIN(IG) = XSM . MGA

052752,000184: 23,3424           47322                                    ARCTRIG                               
052753,000185: 
052754,000186: 23,3425           26742                           STOVL    IGC                                   
052755,000187: 23,3426           02740                                    OGC                                   
052756,000188: 23,3427           77634                           RTB                                            
052757,000189: 23,3430           21621                                    V1STO2S                               
052758,000190: 23,3431           34322                           STCALL   THETAD                                
052759,000191: 23,3432           00051                                    S2                                    
052760,000192: 
052761,000193: 23,3433           77776        GIMLOCK1           EXIT                                           
052762,000194: 23,3434           05567                           TC       ALARM                                 
052763,000195: 23,3435           00401                           OCT      00401                                 
052764,000196: 23,3436           05504                           TC       UPFLAG                                #  GIMBAL LOCK HAS OCCURED

052765,000197: 23,3437           00056                           ADRES    GLOKFAIL                              
052766,000198: 
052767,000199: 23,3440           06042                           TC       INTPRET                               
052768,000200: 23,3441           77650                           GOTO                                           
052769,000201: 23,3442           47415                                    CALCGA1                               
052770,000202: 

Page 1245

052772,000204:                                                                                                  #  AXISGEN COMPUTES THE COORDINATES OF ONE COORDINATE SYSTEM REFERRED TO ANOTHER COORDINATE SYSTEM.

052773,000205: 
052774,000206:                                                                                                  #  THE INPUTS ARE  1) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM A STORED AT STARAD.  2) THE STAR2 VECTOR

052775,000207:                                                                                                  #  REFERRED TO COORDINATE SYSTEM A STORED AT STARAD +6.  3) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM B STORED

052776,000208:                                                                                                  #  AT LOCATION 6 OF THE VAC AREA.  4) THE STAR2 VECTOR REFERRED TO COORDINATE SYSTEM B STORED AT LOCATION 12D OF

052777,000209:                                                                                                  #  THE VAC AREA.

052778,000210: 
052779,000211:                                                                                                  #  THE OUTPUT DEFINES COORDINATE SYSTEM A REFERRED TO COORDINATE SYSTEM B. THE THREE HALF-UNIT VECTORS ARE STORED

052780,000212:                                                                                                  #  AT LOCATIONS XDC, XDC +6, XDC +12D, AND STARAD, STARAD +6, STARAD +12D.

052781,000213: 
052782,000214: 23,3443           66370        AXISGEN            AXT,1    SSP                                   #  PUSHDOWN 00-30D, 34D-37D

052783,000215: 23,3444           02714                                    STARAD     +6                         
052784,000216: 23,3445           00051                                    S1                                    
052785,000217: 23,3446           02700                                    STARAD     -6                         
052786,000218: 
052787,000219: 23,3447           77601                           SETPD                                          
052788,000220: 23,3450           00001                                    0                                     
052789,000221: 23,3451           46773        AXISGEN1           VLOAD*   VXV*                                  #  06D   UA = S1

052790,000222: 23,3452           02723                                    STARAD     +12D,1                     #         STARAD +00D    UB = S1

052791,000223: 23,3453           02731                                    STARAD     +18D,1                     
052792,000224: 23,3454           77656                           UNIT                                           #  12D   VA = UNIT(S1 X S2)

052793,000225: 23,3455           06731                           STORE    STARAD     +18D,1                     #        STARAD +06D    VB = UNIT(S1 X S2)

052794,000226: 23,3456           77773                           VLOAD*                                         
052795,000227: 23,3457           02723                                    STARAD     +12D,1                     
052796,000228: 
052797,000229: 23,3460           76433                           VXV*     VSL1                                  
052798,000230: 23,3461           02731                                    STARAD     +18D,1                     #  18D   WA = UA X VA

052799,000231: 23,3462           06737                           STORE    STARAD     +24D,1                     #         STARAD +12D    WB = UB X VB

052800,000232: 
052801,000233: 23,3463           77700                           TIX,1                                          
052802,000234: 23,3464           47451                                    AXISGEN1                              
052803,000235: 
052804,000236: 23,3465           66160                           AXC,1    SXA,1                                 
052805,000237: 23,3466           00006                                    6                                     
052806,000238: 23,3467           00036                                    30D                                   
052807,000239: 
052808,000240: 23,3470           66370                           AXT,1    SSP                                   
052809,000241: 23,3471           00022                                    18D                                   
052810,000242: 23,3472           00051                                    S1                                    
052811,000243: 23,3473           00006                                    6                                     
052812,000244: 
052813,000245: 23,3474           66374                           AXT,2    SSP                                   
052814,000246: 23,3475           00006                                    6                                     
052815,000247: 23,3476           00052                                    S2                                    
052816,000248: 23,3477           00002                                    2                                     
052817,000249: 
052818,000250: 23,3500           76720        AXISGEN2           XCHX,1   VLOAD*                                
052819,000251: 23,3501           00036                                    30D                                   #  X1=-6 X2=+6   X1=-6 X2=+4     X1=-6 X2=+2

052820,000252: 23,3502           00001                                    0,1                                   
052821,000253: 

Page 1246

052823,000255: 23,3503           62757                           VXSC*    PDVL*                                 #  J=(UA)(UB1)   J=(UA)(UB2)     J=(UA)(UB3)

052824,000256: 23,3504           75062                                    STARAD     +6,2                       
052825,000257: 23,3505           00007                                    6,1                                   
052826,000258: 23,3506           77757                           VXSC*                                          
052827,000259: 23,3507           75054                                    STARAD     +12D,2                     
052828,000260: 23,3510           30031                           STOVL*   24D                                   #  K=(VA)(VB1)   J=(VA)(VB2)     J=(VA)(VB3)

052829,000261: 23,3511           00015                                    12D,1                                 
052830,000262: 
052831,000263: 23,3512           53357                           VXSC*    VAD                                   
052832,000264: 23,3513           75046                                    STARAD     +18D,2                     #  L=(WA)(WB1)   J=(WA)(WB2)     J=(WA)(WB3)

052833,000265: 23,3514           76455                           VAD      VSL1                                  
052834,000266: 23,3515           00031                                    24D                                   
052835,000267: 23,3516           53520                           XCHX,1   UNIT                                  
052836,000268: 23,3517           00036                                    30D                                   
052837,000269: 23,3520           06707                           STORE    XDC        +18D,1                     #  XDC = L+J+K   YDC = L+J+K     ZDC = L+J+K

052838,000270: 
052839,000271: 23,3521           77700                           TIX,1                                          
052840,000272: 23,3522           47523                                    AXISGEN3                              
052841,000273: 
052842,000274: 23,3523           77704        AXISGEN3           TIX,2                                          
052843,000275: 23,3524           47500                                    AXISGEN2                              
052844,000276: 
052845,000277: 23,3525           77775                           VLOAD                                          
052846,000278: 23,3526           02665                                    XDC                                   
052847,000279: 23,3527           26707                           STOVL    STARAD                                
052848,000280: 23,3530           02673                                    YDC                                   
052849,000281: 23,3531           26715                           STOVL    STARAD     +6                         
052850,000282: 23,3532           02701                                    ZDC                                   
052851,000283: 23,3533           02723                           STORE    STARAD     +12D                       
052852,000284: 
052853,000285: 23,3534           77616                           RVQ                                            
052854,000286: 

Page 1247

052856,000288: 23,3535           05520 26075  QTSN45             2DEC     .1768                                 
052857,000289: 
052858,000290: 23,3537           05252 25253  .166...            2DEC     .1666666667                            
052859,000291: 

Page 1248
Empty page


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