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.

058959,000002:                                                                                                  ## Copyright:   Public domain.
058960,000003:                                                                                                  ## Filename:    RTB_OP_CODES.agc
058961,000004:                                                                                                  ## Purpose:     A section of Luminary revision 116.
058962,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM) 
058963,000006:                                                                                                  ##              Apollo Guidance Computer (AGC) for Apollo 12.
058964,000007:                                                                                                  ##              This file is intended to be a faithful transcription, except
058965,000008:                                                                                                  ##              that the code format has been changed to conform to the
058966,000009:                                                                                                  ##              requirements of the yaYUL assembler rather than the
058967,000010:                                                                                                  ##              original YUL assembler.
058968,000011:                                                                                                  ## Reference:   pp. 1387-1392
058969,000012:                                                                                                  ## Assembler:   yaYUL
058970,000013:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
058971,000014:                                                                                                  ## Website:     www.ibiblio.org/apollo/index.html
058972,000015:                                                                                                  ## Mod history: 2017-01-22 MAS  Created from Luminary 99.
058973,000016:                                                                                                  ##              2017-02-09 RRB  Updated for Luminary 116.
058974,000017:                                                                                                  ##              2017-03-14 RSB  Proofed comment text via 3-way diff vs
058975,000018:                                                                                                  ##                              Luminary 99 and 131 ... no problems found.
058976,000019: 

Page 1387

058978,000021: 22,3773                                           BANK     22                                    
058979,000022: 10,2000                                           SETLOC   RTBCODES                              
058980,000023: 10,2000                                           BANK                                           
058981,000024: 
058982,000025: 10,3574  E5,1664                                  EBANK=   XNB                                   
058983,000026: 10,3574                                           COUNT*   $$/RTB                                
058984,000027: 
058985,000028:                                                                                                  #  LOAD TIME2, TIME1 INTO MPAC:
058986,000029: 
058987,000030: 10,3574           00006        LOADTIME           EXTEND                                         
058988,000031: 10,3575           30025                           DCA      TIME2                                 
058989,000032: 10,3576           16060                           TCF      SLOAD2                                
058990,000033: 
058991,000034:                                                                                                  #           CONVERT THE SINGLE PRECISION 2'S COMPLEMENT NUMBER ARRIVING IN MPAC (SCALED IN HALF-REVOLUTIONS) TO A
058992,000035:                                                                                                  #  DP 1'S COMPLEMENT NUMBER SCALED IN REVOLUTIONS.
058993,000036: 
058994,000037: 10,3577           10154        CDULOGIC           CCS      MPAC                                  
058995,000038: 10,3600           34755                           CAF      ZERO                                  
058996,000039: 10,3601           13604                           TCF      +3                                    
058997,000040: 10,3602           13603                           NOOP                                           
058998,000041: 10,3603           44736                           CS       HALF                                  
058999,000042: 
059000,000043: 10,3604           54155                           TS       MPAC       +1                         
059001,000044: 10,3605           34755                           CAF      ZERO                                  
059002,000045: 10,3606           56154                           XCH      MPAC                                  
059003,000046: 10,3607           00006                           EXTEND                                         
059004,000047: 10,3610           74736                           MP       HALF                                  
059005,000048: 10,3611           20155                           DAS      MPAC                                  
059006,000049: 10,3612           16064                           TCF      DANZIG                                #  MODE IS ALREADY AT DOUBLE-PRECISION
059007,000050: 
059008,000051:                                                                                                  #  FORCE TP SIGN AGREEMENT IN MPAC:
059009,000052: 
059010,000053: 10,3613           07262        SGNAGREE           TC       TPAGREE                               
059011,000054: 10,3614           16064                           TCF      DANZIG                                
059012,000055: 
059013,000056:                                                                                                  #           CONVERT THE DP 1'S COMPLEMENT ANGLE SCALED IN REVOLUTIONS TO A SINGLE PRECISION 2'S COMPLEMENT ANGLE
059014,000057:                                                                                                  #  SCALED IN HALF-REVOLUTIONS.
059015,000058: 
059016,000059: 10,3615           03645        1STO2S             TC       1TO2SUB                               
059017,000060: 10,3616           34755                           CAF      ZERO                                  
059018,000061: 10,3617           54155                           TS       MPAC       +1                         
059019,000062: 10,3620           16063                           TCF      NEWMODE                               
059020,000063: 
059021,000064:                                                                                                  #  DO 1STO2S ON A VECTOR OF ANGLES:
059022,000065: 
059023,000066: 10,3621           03645        V1STO2S            TC       1TO2SUB                               #  ANSWER ARRIVES IN A AND MPAC.
059024,000067: 
059025,000068: 10,3622           52162                           DXCH     MPAC       +5                         
059026,000069: 10,3623           52155                           DXCH     MPAC                                  
059027,000070: 10,3624           03645                           TC       1TO2SUB                               

Page 1388

059029,000072: 10,3625           54156                           TS       MPAC       +2                         
059030,000073: 
059031,000074: 10,3626           52160                           DXCH     MPAC       +3                         
059032,000075: 10,3627           52155                           DXCH     MPAC                                  
059033,000076: 10,3630           03645                           TC       1TO2SUB                               
059034,000077: 10,3631           54155                           TS       MPAC       +1                         
059035,000078: 
059036,000079: 10,3632           30161                           CA       MPAC       +5                         
059037,000080: 10,3633           54154                           TS       MPAC                                  
059038,000081: 
059039,000082: 10,3634           34753        TPMODE             CAF      ONE                                   #  MODE IS TP.
059040,000083: 10,3635           16063                           TCF      NEWMODE                               
059041,000084: 
059042,000085:                                                                                                  #  V1STO2S FOR 2 COMPONENT VECTOR. USED BY RR.
059043,000086: 
059044,000087: 10,3636           03645        2V1STO2S           TC       1TO2SUB                               
059045,000088: 10,3637           52160                           DXCH     MPAC       +3                         
059046,000089: 10,3640           52155                           DXCH     MPAC                                  
059047,000090: 10,3641           03645                           TC       1TO2SUB                               
059048,000091: 10,3642           54001                           TS       L                                     
059049,000092: 10,3643           30157                           CA       MPAC       +3                         
059050,000093: 10,3644           16060                           TCF      SLOAD2                                
059051,000094: 
059052,000095:                                                                                                  #  SUBROUTINE TO DO DOUBLING AND 1'S TO 2'S CONVERSION:
059053,000096: 
059054,000097: 10,3645           52155        1TO2SUB            DXCH     MPAC                                  #  FINAL MPAC +1 UNSPECIFIED.
059055,000098: 10,3646           20001                           DDOUBL                                         
059056,000099: 10,3647           10000                           CCS      A                                     
059057,000100: 10,3650           64753                           AD       ONE                                   
059058,000101: 10,3651           13653                           TCF      +2                                    
059059,000102: 10,3652           40000                           COM                                            #  THIS WAS REVERSE OF MSU.
059060,000103: 
059061,000104: 10,3653           54154                           TS       MPAC                                  #  AND SKIP ON OVERFLOW.
059062,000105: 10,3654           00002                           TC       Q                                     
059063,000106: 
059064,000107: 10,3655           50000                           INDEX    A                                     #  OVERFLOW UNCORRECT AND IN MSU.
059065,000108: 10,3656           34734                           CAF      LIMITS                                
059066,000109: 10,3657           26154                           ADS      MPAC                                  
059067,000110: 10,3660           00002                           TC       Q                                     
059068,000111: 
059069,000112:                                                                                                  #           THE FOLLOWING ROUTINE INCREMENTS IN 2S COMPLEMENT THE REGISTER WHOSE ADDRESS IS IN BUF BY THE 1S COMPL.
059070,000113:                                                                                                  #  QUANTITY FOUND IN TEM2. THIS MAY BE USED TO INCREMENT DESIRED IMU AND OPTICS CDU ANGLES OR ANY OTHER 2S COMPL.
059071,000114:                                                                                                  #  (+0 UNEQUAL TO -0) QUANTITY. MAY BE CALLED BY BANKCALL/SWCALL.
059072,000115: 
059073,000116: 10,3661           54142        CDUINC             TS       TEM2                                  #  1S COMPL.QUANT. ARRIVES IN ACC.  STORE IT
059074,000117: 10,3662           50130                           INDEX    BUF                                   
059075,000118: 10,3663           10000                           CCS      0                                     #  CHANGE 2S COMPL. ANGLE(IN BUF)INTO 1S
059076,000119: 10,3664           64753                           AD       ONE                                   
059077,000120: 10,3665           13671                           TCF      +4                                    
059078,000121: 10,3666           64753                           AD       ONE                                   

Page 1389

059080,000123: 10,3667           64753                           AD       ONE                                   #  OVERFLOW HERE IF 2S COMPL. IS 180 DEG.
059081,000124: 10,3670           40000                           COM                                            
059082,000125: 
059083,000126: 10,3671           60142                           AD       TEM2                                  #  SULT MOVES FROM 2ND TO 3D QUAD. (OR BACK)
059084,000127: 10,3672           10000                           CCS      A                                     #  BACK TO 2S COMPL.
059085,000128: 10,3673           64753                           AD       ONE                                   
059086,000129: 10,3674           13676                           TCF      +2                                    
059087,000130: 10,3675           40000                           COM                                            
059088,000131: 10,3676           54142                           TS       TEM2                                  #  STORE 14BIT QUANTITY WITH PRESENT SIGN
059089,000132: 10,3677           13703                           TCF      +4                                    
059090,000133: 10,3700           50000                           INDEX    A                                     #   SIGN.
059091,000134: 10,3701           34734                           CAF      LIMITS                                #  FIX IT, BY ADDING IN 37777 OR 40000
059092,000135: 10,3702           60142                           AD       TEM2                                  
059093,000136: 
059094,000137: 10,3703           50130                           INDEX    BUF                                   
059095,000138: 10,3704           54000                           TS       0                                     #  STORE NEW ANGLE IN 2S COMPLEMENT.
059096,000139: 10,3705           00002                           TC       Q                                     
059097,000140: 

Page 1390

059099,000142:                                                                                                  #  RTB TO TORQUE GYROS, EXCEPT FOR THE CALL TO IMUSTALL. ECADR OF COMMANDS ARRIVES IN X1.
059100,000143: 
059101,000144: 10,3706           50120        PULSEIMU           INDEX    FIXLOC                                #  ADDRESS OF GYRO COMMANDS SHOULD BE IN X1
059102,000145: 10,3707           30046                           CA       X1                                    
059103,000146: 10,3710           04616                           TC       BANKCALL                              
059104,000147: 10,3711           17315                           CADR     IMUPULSE                              
059105,000148: 10,3712           16064                           TCF      DANZIG                                
059106,000149: 

Page 1391

059108,000151:                                                                                                  #           THE SUBROUTINE  SIGNMPAC  SETS C(MPAC, MPAC +1) TO SIGN(MPAC).
059109,000152:                                                                                                  #  FOR THIS, ONLY THE CONTENTS OF MPAC ARE EXAMINED.    ALSO +0 YIELDS POSMAX AND -0 YIELDS NEGMAX.
059110,000153: 
059111,000154:                                                                                                  #  ENTRY MAY BE BY EITHER OF THE FOLLOWING:
059112,000155: 
059113,000156:                                                                                                  #  1.       LIMIT THE SIZE OF MPAC ON INTERPRETIVE OVERFLOW:
059114,000157:                                                                                                  #  ENTRY:          BOVB
059115,000158:                                                                                                  #                         SIGNMPAC
059116,000159: 
059117,000160:                                                                                                  #  2.       GENERATE IN MPAC THE SIGNUM FUNCTION OF MPAC:
059118,000161:                                                                                                  #  ENTRY:          RTB
059119,000162:                                                                                                  #                         SIGNMPAC
059120,000163: 
059121,000164:                                                                                                  #  IN EITHER CASE, RETURN IS TO THE NEXT INTERPRETIVE INSTRUCTION IN THE CALLING SEQUENCE.
059122,000165: 
059123,000166: 10,3713           00006        SIGNMPAC           EXTEND                                         
059124,000167: 10,3714           34733                           DCA      DPOSMAX                               
059125,000168: 10,3715           52155                           DXCH     MPAC                                  
059126,000169: 10,3716           10000                           CCS      A                                     
059127,000170: 10,3717           34755        DPMODE             CAF      ZERO                                  #  SETS MPAC +2 TO ZERO IN THE PROCESS
059128,000171: 10,3720           16062                           TCF      SLOAD2     +2                         
059129,000172: 10,3721           13722                           TCF      +1                                    
059130,000173: 10,3722           00006                           EXTEND                                         
059131,000174: 10,3723           44733                           DCS      DPOSMAX                               
059132,000175: 10,3724           16060                           TCF      SLOAD2                                
059133,000176: 
059134,000177:                                                                                                  #      RTB OP CODE NORMUNIT IS LIKE INTERPRETIVE INSTRUCTION UNIT, EXCEPT THAT IT CAN BE DEPENDED ON NOT TO BLOW
059135,000178:                                                                                                  #  UP WHEN THE VECTOR BEING UNITIZED IS VERY SMALL -- IT WILL BLOW UP WHEN ALL COMPONENTS ARE ZERO.  IF NORMUNIT
059136,000179:                                                                                                  #  IS USED AND THE UPPER ORDER HALVES OF ALL COMPONENTS ARE ZERO, THE MAGNITUDE RETURNED IN 36D WILL BE TOO LARGE
059137,000180:                                                                                                  #  BY A FACTOR OF 2(13) AND THE SQUARED MAGNITUDE RETURNED AT 34D WILL BE TOO BIG BY A FACTOR OF 2(26).
059138,000181: 
059139,000182: 10,3725           34753        NORMUNX1           CAF      ONE                                   
059140,000183: 10,3726           13730                           TCF      NORMUNIT   +1                         
059141,000184: 10,3727           34755        NORMUNIT           CAF      ZERO                                  
059142,000185: 10,3730           60120                           AD       FIXLOC                                
059143,000186: 10,3731           54156                           TS       MPAC       +2                         
059144,000187: 10,3732           04616                           TC       BANKCALL                              #  GET SIGN AGREEMENT IN ALL COMPONENTS
059145,000188: 10,3733           01010                           CADR     VECAGREE                              
059146,000189: 10,3734           10154                           CCS      MPAC                                  
059147,000190: 10,3735           13771                           TCF      NOSHIFT                               
059148,000191: 10,3736           13740                           TCF      +2                                    
059149,000192: 10,3737           13771                           TCF      NOSHIFT                               
059150,000193: 10,3740           10157                           CCS      MPAC       +3                         
059151,000194: 10,3741           13771                           TCF      NOSHIFT                               
059152,000195: 10,3742           13744                           TCF      +2                                    
059153,000196: 10,3743           13771                           TCF      NOSHIFT                               
059154,000197: 10,3744           10161                           CCS      MPAC       +5                         
059155,000198: 10,3745           13771                           TCF      NOSHIFT                               
059156,000199: 10,3746           13750                           TCF      +2                                    
059157,000200: 10,3747           13771                           TCF      NOSHIFT                               

Page 1392

059159,000202: 10,3750           30155                           CA       MPAC       +1                         #  SHIFT ALL COMPONENTS LEFT 13
059160,000203: 10,3751           00006                           EXTEND                                         
059161,000204: 10,3752           74736                           MP       BIT14                                 
059162,000205: 10,3753           20155                           DAS      MPAC                                  #  DAS GAINS A LITTLE ACCURACY
059163,000206: 10,3754           30160                           CA       MPAC       +4                         
059164,000207: 10,3755           00006                           EXTEND                                         
059165,000208: 10,3756           74736                           MP       BIT14                                 
059166,000209: 10,3757           20160                           DAS      MPAC       +3                         
059167,000210: 10,3760           30162                           CA       MPAC       +6                         
059168,000211: 10,3761           00006                           EXTEND                                         
059169,000212: 10,3762           74736                           MP       BIT14                                 
059170,000213: 10,3763           20162                           DAS      MPAC       +5                         
059171,000214: 10,3764           34761                           CAF      THIRTEEN                              
059172,000215: 10,3765           50156                           INDEX    MPAC       +2                         
059173,000216: 10,3766           54045                           TS       37D                                   
059174,000217: 10,3767           04635        OFFTUNIT           TC       POSTJUMP                              
059175,000218: 10,3770           01024                           CADR     UNIT       +1                         #  SKIP THE "TC VECAGREE" DONE AT UNIT
059176,000219: 
059177,000220: 10,3771           34755        NOSHIFT            CAF      ZERO                                  
059178,000221: 10,3772           13765                           TCF      OFFTUNIT   -2                         
059179,000222: 
059180,000223:                                                                                                  #  RTB VECSGNAG ... FORCES SIGN AGREEMENT OF VECTOR IN MPAC.
059181,000224: 
059182,000225: 10,3773           04616        VECSGNAG           TC       BANKCALL                              
059183,000226: 10,3774           01010                           CADR     VECAGREE                              
059184,000227: 10,3775           06064                           TC       DANZIG                                
059185,000228: 
059186,000229: 

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