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.

058963,000002:                                                                                                  ## Copyright:   Public domain.
058964,000003:                                                                                                  ## Filename:    RTB_OP_CODES.agc
058965,000004:                                                                                                  ## Purpose:     A section of Luminary revision 116.
058966,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM) 
058967,000006:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 12.
058968,000007:                                                                                                  ##              This file is intended to be a faithful transcription, except
058969,000008:                                                                                                  ##              that the code format has been changed to conform to the
058970,000009:                                                                                                  ##              requirements of the yaYUL assembler rather than the
058971,000010:                                                                                                  ##              original YUL assembler.
058972,000011:                                                                                                  ## Reference:   pp. 1387-1392
058973,000012:                                                                                                  ## Assembler:   yaYUL
058974,000013:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
058975,000014:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
058976,000015:                                                                                                  ## Mod history: 2017-01-22 MAS  Created from Luminary 99.
058977,000016:                                                                                                  ##              2017-02-09 RRB  Updated for Luminary 116.
058978,000017:                                                                                                  ##              2017-03-14 RSB  Proofed comment text via 3-way diff vs
058979,000018:                                                                                                  ##                              Luminary 99 and 131 ... no problems found.
058980,000019: 

Page 1387

058982,000021: 22,3773                                           BANK     22                                    
058983,000022: 10,2000                                           SETLOC   RTBCODES                              
058984,000023: 10,2000                                           BANK                                           
058985,000024: 
058986,000025: 10,3574  E5,1664                                  EBANK=   XNB                                   
058987,000026: 10,3574                                           COUNT*   $$/RTB                                
058988,000027: 
058989,000028:                                                                                                  #  LOAD TIME2, TIME1 INTO MPAC:
058990,000029: 
058991,000030: 10,3574           00006        LOADTIME           EXTEND                                         
058992,000031: 10,3575           30025                           DCA      TIME2                                 
058993,000032: 10,3576           16060                           TCF      SLOAD2                                
058994,000033: 
058995,000034:                                                                                                  #           CONVERT THE SINGLE PRECISION 2'S COMPLEMENT NUMBER ARRIVING IN MPAC (SCALED IN HALF-REVOLUTIONS) TO A
058996,000035:                                                                                                  #  DP 1'S COMPLEMENT NUMBER SCALED IN REVOLUTIONS.
058997,000036: 
058998,000037: 10,3577           10154        CDULOGIC           CCS      MPAC                                  
058999,000038: 10,3600           34755                           CAF      ZERO                                  
059000,000039: 10,3601           13604                           TCF      +3                                    
059001,000040: 10,3602           13603                           NOOP                                           
059002,000041: 10,3603           44736                           CS       HALF                                  
059003,000042: 
059004,000043: 10,3604           54155                           TS       MPAC       +1                         
059005,000044: 10,3605           34755                           CAF      ZERO                                  
059006,000045: 10,3606           56154                           XCH      MPAC                                  
059007,000046: 10,3607           00006                           EXTEND                                         
059008,000047: 10,3610           74736                           MP       HALF                                  
059009,000048: 10,3611           20155                           DAS      MPAC                                  
059010,000049: 10,3612           16064                           TCF      DANZIG                                #  MODE IS ALREADY AT DOUBLE-PRECISION
059011,000050: 
059012,000051:                                                                                                  #  FORCE TP SIGN AGREEMENT IN MPAC:
059013,000052: 
059014,000053: 10,3613           07262        SGNAGREE           TC       TPAGREE                               
059015,000054: 10,3614           16064                           TCF      DANZIG                                
059016,000055: 
059017,000056:                                                                                                  #           CONVERT THE DP 1'S COMPLEMENT ANGLE SCALED IN REVOLUTIONS TO A SINGLE PRECISION 2'S COMPLEMENT ANGLE
059018,000057:                                                                                                  #  SCALED IN HALF-REVOLUTIONS.
059019,000058: 
059020,000059: 10,3615           03645        1STO2S             TC       1TO2SUB                               
059021,000060: 10,3616           34755                           CAF      ZERO                                  
059022,000061: 10,3617           54155                           TS       MPAC       +1                         
059023,000062: 10,3620           16063                           TCF      NEWMODE                               
059024,000063: 
059025,000064:                                                                                                  #  DO 1STO2S ON A VECTOR OF ANGLES:
059026,000065: 
059027,000066: 10,3621           03645        V1STO2S            TC       1TO2SUB                               #  ANSWER ARRIVES IN A AND MPAC.
059028,000067: 
059029,000068: 10,3622           52162                           DXCH     MPAC       +5                         
059030,000069: 10,3623           52155                           DXCH     MPAC                                  
059031,000070: 10,3624           03645                           TC       1TO2SUB                               

Page 1388

059033,000072: 10,3625           54156                           TS       MPAC       +2                         
059034,000073: 
059035,000074: 10,3626           52160                           DXCH     MPAC       +3                         
059036,000075: 10,3627           52155                           DXCH     MPAC                                  
059037,000076: 10,3630           03645                           TC       1TO2SUB                               
059038,000077: 10,3631           54155                           TS       MPAC       +1                         
059039,000078: 
059040,000079: 10,3632           30161                           CA       MPAC       +5                         
059041,000080: 10,3633           54154                           TS       MPAC                                  
059042,000081: 
059043,000082: 10,3634           34753        TPMODE             CAF      ONE                                   #  MODE IS TP.
059044,000083: 10,3635           16063                           TCF      NEWMODE                               
059045,000084: 
059046,000085:                                                                                                  #  V1STO2S FOR 2 COMPONENT VECTOR. USED BY RR.
059047,000086: 
059048,000087: 10,3636           03645        2V1STO2S           TC       1TO2SUB                               
059049,000088: 10,3637           52160                           DXCH     MPAC       +3                         
059050,000089: 10,3640           52155                           DXCH     MPAC                                  
059051,000090: 10,3641           03645                           TC       1TO2SUB                               
059052,000091: 10,3642           54001                           TS       L                                     
059053,000092: 10,3643           30157                           CA       MPAC       +3                         
059054,000093: 10,3644           16060                           TCF      SLOAD2                                
059055,000094: 
059056,000095:                                                                                                  #  SUBROUTINE TO DO DOUBLING AND 1'S TO 2'S CONVERSION:
059057,000096: 
059058,000097: 10,3645           52155        1TO2SUB            DXCH     MPAC                                  #  FINAL MPAC +1 UNSPECIFIED.
059059,000098: 10,3646           20001                           DDOUBL                                         
059060,000099: 10,3647           10000                           CCS      A                                     
059061,000100: 10,3650           64753                           AD       ONE                                   
059062,000101: 10,3651           13653                           TCF      +2                                    
059063,000102: 10,3652           40000                           COM                                            #  THIS WAS REVERSE OF MSU.
059064,000103: 
059065,000104: 10,3653           54154                           TS       MPAC                                  #  AND SKIP ON OVERFLOW.
059066,000105: 10,3654           00002                           TC       Q                                     
059067,000106: 
059068,000107: 10,3655           50000                           INDEX    A                                     #  OVERFLOW UNCORRECT AND IN MSU.
059069,000108: 10,3656           34734                           CAF      LIMITS                                
059070,000109: 10,3657           26154                           ADS      MPAC                                  
059071,000110: 10,3660           00002                           TC       Q                                     
059072,000111: 
059073,000112:                                                                                                  #           THE FOLLOWING ROUTINE INCREMENTS IN 2S COMPLEMENT THE REGISTER WHOSE ADDRESS IS IN BUF BY THE 1S COMPL.
059074,000113:                                                                                                  #  QUANTITY FOUND IN TEM2. THIS MAY BE USED TO INCREMENT DESIRED IMU AND OPTICS CDU ANGLES OR ANY OTHER 2S COMPL.
059075,000114:                                                                                                  #  (+0 UNEQUAL TO -0) QUANTITY. MAY BE CALLED BY BANKCALL/SWCALL.
059076,000115: 
059077,000116: 10,3661           54142        CDUINC             TS       TEM2                                  #  1S COMPL.QUANT. ARRIVES IN ACC.  STORE IT
059078,000117: 10,3662           50130                           INDEX    BUF                                   
059079,000118: 10,3663           10000                           CCS      0                                     #  CHANGE 2S COMPL. ANGLE(IN BUF)INTO 1S
059080,000119: 10,3664           64753                           AD       ONE                                   
059081,000120: 10,3665           13671                           TCF      +4                                    
059082,000121: 10,3666           64753                           AD       ONE                                   

Page 1389

059084,000123: 10,3667           64753                           AD       ONE                                   #  OVERFLOW HERE IF 2S COMPL. IS 180 DEG.
059085,000124: 10,3670           40000                           COM                                            
059086,000125: 
059087,000126: 10,3671           60142                           AD       TEM2                                  #  SULT MOVES FROM 2ND TO 3D QUAD. (OR BACK)
059088,000127: 10,3672           10000                           CCS      A                                     #  BACK TO 2S COMPL.
059089,000128: 10,3673           64753                           AD       ONE                                   
059090,000129: 10,3674           13676                           TCF      +2                                    
059091,000130: 10,3675           40000                           COM                                            
059092,000131: 10,3676           54142                           TS       TEM2                                  #  STORE 14BIT QUANTITY WITH PRESENT SIGN
059093,000132: 10,3677           13703                           TCF      +4                                    
059094,000133: 10,3700           50000                           INDEX    A                                     #   SIGN.
059095,000134: 10,3701           34734                           CAF      LIMITS                                #  FIX IT, BY ADDING IN 37777 OR 40000
059096,000135: 10,3702           60142                           AD       TEM2                                  
059097,000136: 
059098,000137: 10,3703           50130                           INDEX    BUF                                   
059099,000138: 10,3704           54000                           TS       0                                     #  STORE NEW ANGLE IN 2S COMPLEMENT.
059100,000139: 10,3705           00002                           TC       Q                                     
059101,000140: 

Page 1390

059103,000142:                                                                                                  #  RTB TO TORQUE GYROS, EXCEPT FOR THE CALL TO IMUSTALL. ECADR OF COMMANDS ARRIVES IN X1.
059104,000143: 
059105,000144: 10,3706           50120        PULSEIMU           INDEX    FIXLOC                                #  ADDRESS OF GYRO COMMANDS SHOULD BE IN X1
059106,000145: 10,3707           30046                           CA       X1                                    
059107,000146: 10,3710           04616                           TC       BANKCALL                              
059108,000147: 10,3711           17315                           CADR     IMUPULSE                              
059109,000148: 10,3712           16064                           TCF      DANZIG                                
059110,000149: 

Page 1391

059112,000151:                                                                                                  #           THE SUBROUTINE  SIGNMPAC  SETS C(MPAC, MPAC +1) TO SIGN(MPAC).
059113,000152:                                                                                                  #  FOR THIS, ONLY THE CONTENTS OF MPAC ARE EXAMINED.    ALSO +0 YIELDS POSMAX AND -0 YIELDS NEGMAX.
059114,000153: 
059115,000154:                                                                                                  #  ENTRY MAY BE BY EITHER OF THE FOLLOWING:
059116,000155: 
059117,000156:                                                                                                  #  1.       LIMIT THE SIZE OF MPAC ON INTERPRETIVE OVERFLOW:
059118,000157:                                                                                                  #  ENTRY:          BOVB
059119,000158:                                                                                                  #                         SIGNMPAC
059120,000159: 
059121,000160:                                                                                                  #  2.       GENERATE IN MPAC THE SIGNUM FUNCTION OF MPAC:
059122,000161:                                                                                                  #  ENTRY:          RTB
059123,000162:                                                                                                  #                         SIGNMPAC
059124,000163: 
059125,000164:                                                                                                  #  IN EITHER CASE, RETURN IS TO THE NEXT INTERPRETIVE INSTRUCTION IN THE CALLING SEQUENCE.
059126,000165: 
059127,000166: 10,3713           00006        SIGNMPAC           EXTEND                                         
059128,000167: 10,3714           34733                           DCA      DPOSMAX                               
059129,000168: 10,3715           52155                           DXCH     MPAC                                  
059130,000169: 10,3716           10000                           CCS      A                                     
059131,000170: 10,3717           34755        DPMODE             CAF      ZERO                                  #  SETS MPAC +2 TO ZERO IN THE PROCESS
059132,000171: 10,3720           16062                           TCF      SLOAD2     +2                         
059133,000172: 10,3721           13722                           TCF      +1                                    
059134,000173: 10,3722           00006                           EXTEND                                         
059135,000174: 10,3723           44733                           DCS      DPOSMAX                               
059136,000175: 10,3724           16060                           TCF      SLOAD2                                
059137,000176: 
059138,000177:                                                                                                  #      RTB OP CODE NORMUNIT IS LIKE INTERPRETIVE INSTRUCTION UNIT, EXCEPT THAT IT CAN BE DEPENDED ON NOT TO BLOW
059139,000178:                                                                                                  #  UP WHEN THE VECTOR BEING UNITIZED IS VERY SMALL -- IT WILL BLOW UP WHEN ALL COMPONENTS ARE ZERO.  IF NORMUNIT
059140,000179:                                                                                                  #  IS USED AND THE UPPER ORDER HALVES OF ALL COMPONENTS ARE ZERO, THE MAGNITUDE RETURNED IN 36D WILL BE TOO LARGE
059141,000180:                                                                                                  #  BY A FACTOR OF 2(13) AND THE SQUARED MAGNITUDE RETURNED AT 34D WILL BE TOO BIG BY A FACTOR OF 2(26).
059142,000181: 
059143,000182: 10,3725           34753        NORMUNX1           CAF      ONE                                   
059144,000183: 10,3726           13730                           TCF      NORMUNIT   +1                         
059145,000184: 10,3727           34755        NORMUNIT           CAF      ZERO                                  
059146,000185: 10,3730           60120                           AD       FIXLOC                                
059147,000186: 10,3731           54156                           TS       MPAC       +2                         
059148,000187: 10,3732           04616                           TC       BANKCALL                              #  GET SIGN AGREEMENT IN ALL COMPONENTS
059149,000188: 10,3733           01010                           CADR     VECAGREE                              
059150,000189: 10,3734           10154                           CCS      MPAC                                  
059151,000190: 10,3735           13771                           TCF      NOSHIFT                               
059152,000191: 10,3736           13740                           TCF      +2                                    
059153,000192: 10,3737           13771                           TCF      NOSHIFT                               
059154,000193: 10,3740           10157                           CCS      MPAC       +3                         
059155,000194: 10,3741           13771                           TCF      NOSHIFT                               
059156,000195: 10,3742           13744                           TCF      +2                                    
059157,000196: 10,3743           13771                           TCF      NOSHIFT                               
059158,000197: 10,3744           10161                           CCS      MPAC       +5                         
059159,000198: 10,3745           13771                           TCF      NOSHIFT                               
059160,000199: 10,3746           13750                           TCF      +2                                    
059161,000200: 10,3747           13771                           TCF      NOSHIFT                               

Page 1392

059163,000202: 10,3750           30155                           CA       MPAC       +1                         #  SHIFT ALL COMPONENTS LEFT 13
059164,000203: 10,3751           00006                           EXTEND                                         
059165,000204: 10,3752           74736                           MP       BIT14                                 
059166,000205: 10,3753           20155                           DAS      MPAC                                  #  DAS GAINS A LITTLE ACCURACY
059167,000206: 10,3754           30160                           CA       MPAC       +4                         
059168,000207: 10,3755           00006                           EXTEND                                         
059169,000208: 10,3756           74736                           MP       BIT14                                 
059170,000209: 10,3757           20160                           DAS      MPAC       +3                         
059171,000210: 10,3760           30162                           CA       MPAC       +6                         
059172,000211: 10,3761           00006                           EXTEND                                         
059173,000212: 10,3762           74736                           MP       BIT14                                 
059174,000213: 10,3763           20162                           DAS      MPAC       +5                         
059175,000214: 10,3764           34761                           CAF      THIRTEEN                              
059176,000215: 10,3765           50156                           INDEX    MPAC       +2                         
059177,000216: 10,3766           54045                           TS       37D                                   
059178,000217: 10,3767           04635        OFFTUNIT           TC       POSTJUMP                              
059179,000218: 10,3770           01024                           CADR     UNIT       +1                         #  SKIP THE "TC VECAGREE" DONE AT UNIT
059180,000219: 
059181,000220: 10,3771           34755        NOSHIFT            CAF      ZERO                                  
059182,000221: 10,3772           13765                           TCF      OFFTUNIT   -2                         
059183,000222: 
059184,000223:                                                                                                  #  RTB VECSGNAG ... FORCES SIGN AGREEMENT OF VECTOR IN MPAC.
059185,000224: 
059186,000225: 10,3773           04616        VECSGNAG           TC       BANKCALL                              
059187,000226: 10,3774           01010                           CADR     VECAGREE                              
059188,000227: 10,3775           06064                           TC       DANZIG                                
059189,000228: 
059190,000229: 

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