Source Code

This is the source-code for the Apollo 9 Command Module's Guidance Computer. These files were derived originally from the scan from MIT's Dibner Institute's now-discontinued website titled "History of Recent Science and Technology", which in turn was originally created by Gary Neff, though his high-quality scans were unfortunately reduced in legibility when presented online. The markings on the front of the printout imply that it was the original AGC developer Norm Brodeur's copy. A scan by Ron Burkey has superceded it, made from a more-legible copy from the collection of original AGC developer Fred Martin. The source code was transcribed from those images by Ron Burkey. Note that the page images presented online are of reduced quality, and that higher-quality images are available. Report any conversion errors or legibility problems in page images to info@sandroid.org. Notations on the program listing read, in part:

	ASSEMBLE REVISION 249 OF AGC PROGRAM COLOSSUS BY NASA 2021111-041
	20'35 OCT. 28,1968
Note that the date is the date of the printout, not the date of the program revision.

037284,000002:                                                                                                  ## Copyright:   Public domain.
037285,000003:                                                                                                  ## Filename:    CM_BODY_ATTITUDE.agc
037286,000004:                                                                                                  ## Purpose:     Part of the source code for Colossus, build 249.
037287,000005:                                                                                                  ##              It is part of the source code for the Command Module's (CM)
037288,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), for Apollo 9.
037289,000007:                                                                                                  ## Assembler:   yaYUL
037290,000008:                                                                                                  ## Reference:   pp. 836-842.
037291,000009:                                                                                                  ## Contact:     Ron Burkey <info@sandroid.org>.
037292,000010:                                                                                                  ## Website:     www.ibiblio.org/apollo.
037293,000011:                                                                                                  ## Mod history: 08/21/04 RSB.   Began transcribing.
037294,000012:                                                                                                  ##              2017-01-06 RSB  Page numbers now agree with those on the
037295,000013:                                                                                                  ##                              original harcopy, as opposed to the PDF page
037296,000014:                                                                                                  ##                              numbers in 1701.pdf.
037297,000015:                                                                                                  ##              2017-01-07 RSB  Cross-diff'd comment text (not whitespace)
037298,000016:                                                                                                  ##                              vs the already-proofed corresponding Colossus
037299,000017:                                                                                                  ##                              237 and Comanche 55 source-code files
037300,000018:                                                                                                  ##                              and corrected errors found.
037301,000019:                                                                                                  ##
037302,000020:                                                                                                  ## The contents of the "Colossus249" files, in general, are transcribed 
037303,000021:                                                                                                  ## from a scanned copy of the program listing.  Notations on this
037304,000022:                                                                                                  ## document read, in part:
037305,000023:                                                                                                  ##
037306,000024:                                                                                                  ##      Assemble revision 249 of AGC program Colossus by NASA
037307,000025:                                                                                                  ##      2021111-041.  October 28, 1968.  
037308,000026:                                                                                                  ##
037309,000027:                                                                                                  ##      This AGC program shall also be referred to as
037310,000028:                                                                                                  ##                              Colossus 1A
037311,000029:                                                                                                  ##
037312,000030:                                                                                                  ##      Prepared by
037313,000031:                                                                                                  ##                      Massachusetts Institute of Technology
037314,000032:                                                                                                  ##                      75 Cambridge Parkway
037315,000033:                                                                                                  ##                      Cambridge, Massachusetts
037316,000034:                                                                                                  ##      under NASA contract NAS 9-4065.
037317,000035:                                                                                                  ##
037318,000036:                                                                                                  ## Refer directly to the online document mentioned above for further information.
037319,000037:                                                                                                  ## Please report any errors (relative to the scanned pages) to info@sandroid.org.
037320,000038:                                                                                                  ##
037321,000039:                                                                                                  ## In some cases, where the source code for Luminary 131 overlaps that of 
037322,000040:                                                                                                  ## Colossus 249, this code is instead copied from the corresponding Luminary 131
037323,000041:                                                                                                  ## source file, and then is proofed to incorporate any changes.
037324,000042: 

Page 836

037326,000044: 35,3755                                           BANK     35                                    
037327,000045: 
037328,000046: 37,2000                                           SETLOC   BODYATT                               
037329,000047: 37,2000                                           BANK                                           
037330,000048: 
037331,000049: 37,3373                                           COUNT    37/CMBAT                              
037332,000050: 
037333,000051:                                                                                                  #  PDL 12D - 15D SAFE.
037334,000052: 
037335,000053:                                                                                                  #  VALUES OF GIMBAL AND BODY ANGLES VALID AT PIP TIME ARE SAVED DURING READACCS.
037336,000054: 
037337,000055: 37,3373  E7,1451                                  EBANK=   RTINIT                                #  LET INTERPRETER SET EB
037338,000056: 
037339,000057: 37,3373           06006        CM/POSE            TC       INTPRET                               #  COME HERE VIA AVEGEXIT.
037340,000058: 
037341,000059: 37,3374           77201                           SETPD    VLOAD                                 
037342,000060: 37,3375           00001                                    0                                     
037343,000061: 37,3376           01177                                    VN                                    #  KVSCALE = (12800/ .3048) /2VS
037344,000062: 37,3377           63361                           VXSC     PDVL                                  
037345,000063: 37,3400           37672                                    -KVSCALE                              #  KVSCALE = .81491944
037346,000064: 37,3401           01714                                    UNITW                                 #  FULL UNIT VECTOR
037347,000065: 37,3402           74235                           VXV      VXSC                                  #  VREL = V - WE*R
037348,000066: 37,3403           01760                                    UNITR                                 
037349,000067: 37,3404           15244                                    KWE                                   
037350,000068: 37,3405           45455                           VAD      STADR                                 
037351,000069: 37,3406           74251                           STORE    -VREL                                 #  SAVE FOR ENTRY GUIDANCE.      REF COORDS
037352,000070: 
037353,000071: 37,3407           72056                           UNIT     LXA,1                                 
037354,000072: 37,3410           00044                                    36D                                   #  ABVAL( -VREL) TO X1
037355,000073: 37,3411           03542                           STORE    UXA/2                                 #  -UVREL                        REF COORDS
037356,000074: 
037357,000075: 37,3412           57435                           VXV      VCOMP                                 
037358,000076: 37,3413           01760                                    UNITR                                 #  .5 UNIT                       REF COORDS
037359,000077: 37,3414           66256                           UNIT     SSP                                   #  THE FOLLOWING IS TO PROVIDE A STABLE
037360,000078: 37,3415           00051                                    S1                                    #  UN FOR THE END OF THE TERMINAL PHASE.
037361,000079: 37,3416           00476        SPVQUIT            DEC      .019405                               #  1000/ 2 VS
037362,000080: 37,3417           77300                           TIX,1    VLOAD                                 #  IF V-VQUIT POS, BRANCH.
037363,000081: 37,3420           77422                                    CM/POSE2                              #  SAVE UYA IN OLDUYA
037364,000082: 37,3421           03534                                    OLDUYA                                #  OTHERWISE CONTINUE TO USE OLDUYA.
037365,000083: 37,3422           03550        CM/POSE2           STORE    UYA/2                                 #                                REF COORDS
037366,000084: 
037367,000085: 37,3423           03534                           STORE    OLDUYA                                #  RESTORE, OR SAVE AS CASE MAY BE.
037368,000086: 
037369,000087: 37,3424           57435                           VXV      VCOMP                                 
037370,000088: 37,3425           03542                                    UXA/2                                 #  FINISH OBTAINING TRAJECTORY TRIAD.
037371,000089: 37,3426           77772                           VSL1                                           
037372,000090: 37,3427           03556                           STORE    UZA/2                                 #                                REF COORDS

Page 837

037374,000092: 37,3430           77751                           TLOAD                                          #  PICK UP CDUX, CDUY, CDUZ CORRESPONDING
037375,000093: 37,3431           03270                                    AOG/PIP                               #  TO PIPUP TIME IN 2S,C AND SAVE.
037376,000094: 37,3432           14031        CM/TRIO            STODL    24D                                   
037377,000095: 37,3433           00032                                    25D                                   #  AIG/PIP
037378,000096: 
037379,000097: 37,3434           41434                           RTB      PUSH                                  #  TO PDL0
037380,000098: 37,3435           45510                                    CDULOGIC                              
037381,000099: 37,3436           77746                           COS                                            
037382,000100: 37,3437           17564                           STODL    UBX/2                                 #  CI /2
037383,000101:                                                                                                  #  AIG/PIP FROM PDL 0
037384,000102: 37,3440           57556                           SIN      DCOMP                                 
037385,000103: 37,3441           17570                           STODL    UBX/2      +4                         #  -SI /2
037386,000104: 37,3442           00033                                    26D                                   #  AMG/PIP
037387,000105: 37,3443           41434                           RTB      PUSH                                  #  TO PDL 0
037388,000106: 37,3444           45510                                    CDULOGIC                              
037389,000107: 37,3445           65356                           SIN      PDDL                                  #  XCH PDL 0.  SAVE SM /2
037390,000108: 37,3446           65346                           COS      PDDL                                  #  CM /2 TO PDL 2
037391,000109: 37,3447           00001                                    0                                     #  SM /2
037392,000110: 37,3450           74276                           DCOMP    VXSC                                  
037393,000111: 37,3451           03564                                    UBX/2                                 
037394,000112: 37,3452           77772                           VSL1                                           #  NOISE WONT OVFL.
037395,000113: 37,3453           17572                           STODL    UBY/2                                 #  =(-SMCI, NOISE, SMSI)/2
037396,000114: 37,3454           00003                                    2                                     #  CM /2 REPLACES NOISE
037397,000115: 37,3455           17574                           STODL    UBY/2      +2                         #  UBY/2=(-SMCI, CM, SMSI)/2
037398,000116: 37,3456           00031                                    24D                                   #  AOG/PIP
037399,000117: 37,3457           41434                           RTB      PUSH                                  #  TO PDL 4
037400,000118: 37,3460           45510                                    CDULOGIC                              
037401,000119: 37,3461           65356                           SIN      PDDL                                  #  XCH PDL 4.  SAVE SO /2
037402,000120: 37,3462           74346                           COS      VXSC                                  #  CO /2
037403,000121: 37,3463           03572                                    UBY/2                                 
037404,000122: 37,3464           17572                           STODL    UBY/2                                 #  UBY/2=(-COSMCI, COCM, COSMSI)/4
037405,000123: 37,3465           00005                                    4D                                    #  SO /2
037406,000124: 37,3466           57405                           DMP      DCOMP                                 
037407,000125: 37,3467           03570                                    UBX/2      +4                         #  -SI /2
037408,000126: 37,3470           77615                           DAD                                            
037409,000127: 37,3471           03572                                    UBY/2                                 #  INCREMENT BY (SOSI /4)
037410,000128: 37,3472           17572                           STODL    UBY/2                                 
037411,000129:                                                                                                  #  SO /2 FROM PDL 4
037412,000130: 37,3473           43205                           DMP      DAD                                   
037413,000131: 37,3474           03564                                    UBX/2                                 #  CI /2
037414,000132: 37,3475           03576                                    UBY/2      +4                         
037415,000133: 37,3476           27576                           STOVL    UBY/2      +4                         #  YB/4                          PLATFORM COORDS
037416,000134: 
037417,000135:                                                                                                  #  YB = (-COSMCI + SOSI , COCM , COSMSI + SOCI )
037418,000136: 
037419,000137: 37,3477           03572                                    UBY/2                                 
037420,000138: 37,3500           72505                           VXM      VSL2                                  
037421,000139: 37,3501           01736                                    REFSMMAT                              #  .5 UNIT
037422,000140: 37,3502           17572                           STODL    UBY/2                                 #  YB/2 DONE                     REF COORDS

Page 838

037424,000142:                                                                                                  #  CM /2 FROM PDL 2
037425,000143: 37,3503           76561                           VXSC     VSL1                                  
037426,000144: 37,3504           03564                                    UBX/2                                 
037427,000145: 37,3505           17564                           STODL    UBX/2                                 #  =( CMCI, NOISE, -CMSI)/2
037428,000146: 37,3506           77626                           STADR                                          #  SM /2 FROM PDL 0
037429,000147: 37,3507           50211                           STOVL    UBX/2      +2                         #  SM /2 REPLACES NOISE
037430,000148: 37,3510           03564                                    UBX/2                                 #  XB/2                          PLATFORM COORDS
037431,000149: 
037432,000150:                                                                                                  #  XB = ( CMCI , SM , -CMSI )
037433,000151: 
037434,000152: 37,3511           76505                           VXM      VSL1                                  
037435,000153: 37,3512           01736                                    REFSMMAT                              #  .5 UNIT
037436,000154: 37,3513           03564                           STORE    UBX/2                                 #  XB/2 DONE                     REF COORDS
037437,000155: 
037438,000156: 37,3514           76435                           VXV      VSL1                                  
037439,000157: 37,3515           03572                                    UBY/2                                 
037440,000158: 37,3516           27600                           STOVL    UBZ/2                                 #  ZB/2 DONE                     REF COORDS
037441,000159: 
037442,000160:                                                                                                  #  EQUIVALENT TO
037443,000161:                                                                                                  #  ZB = ( SOSMCI + COSI , -SOCM , -SOSMSI + COCI )
037444,000162: 
037445,000163: 37,3517           03542                                    UXA/2                                 #  -UVREL/2 = -UVA/2
037446,000164: 37,3520           53435                           VXV      UNIT                                  #  GET UNIT(-UVREL*UBY)/2 = UL/2
037447,000165: 37,3521           03572                                    UBY/2                                 #  YB/2
037448,000166: 37,3522           50206                           PUSH     DOT                                   #  UL/2 TO PDL 0,5
037449,000167: 37,3523           03556                                    UZA/2                                 #  UNA/2
037450,000168: 37,3524           24021                           STOVL    COSTH                                 #  COS(ROLL)/4
037451,000169: 37,3525           00001                                    0                                     #  UL/2
037452,000170: 
037453,000171: 37,3526           77641                           DOT                                            
037454,000172: 37,3527           03550                                    UYA/2                                 
037455,000173: 37,3530           34023                           STCALL   SINTH                                 #  -SIN(ROLL)/4
037456,000174: 37,3531           47211                                    ARCTRIG                               
037457,000175: 37,3532           24007                           STOVL    6D                                    #  -(ROLL/180) /2
037458,000176: 37,3533           03572                                    UBY/2                                 
037459,000177: 37,3534           72441                           DOT      SL1                                   #  -UVA.UBY = -SIN(BETA)
037460,000178: 37,3535           03542                                    UXA/2                                 #  -UVREL/2
037461,000179: 37,3536           77736                           ARCSIN                                         
037462,000180: 37,3537           24010                           STOVL    7D                                    #  -(BETA/180) /2
037463,000181: 37,3540           03564                                    UBX/2                                 #  XB/2
037464,000182: 37,3541           77641                           DOT                                            #  UL.UBX = -SIN(ALFA)
037465,000183: 37,3542           00001                                    0                                     #  UL/2
037466,000184: 37,3543           24023                           STOVL    SINTH                                 #  -SIN(ALFA)/4
037467,000185: 37,3544           77641                           DOT                                            #  UL/2 FROM PDL 0
037468,000186: 37,3545           03600                                    UBZ/2                                 
037469,000187: 37,3546           34021                           STCALL   COSTH                                 #  COS(ALFA)/4
037470,000188: 37,3547           47211                                    ARCTRIG                               
037471,000189: 37,3550           24011                           STOVL    8D                                    #  -(ALFA/180) /2
037472,000190: 37,3551           01760                                    UNITR                                 #  UR/2                          REF COORDS
037473,000191: 37,3552           72441                           DOT      SL1                                   

Page 839

037475,000193: 37,3553           03556                                    UZA/2                                 #  MORE ACCURATE AT LARGE ARG.
037476,000194: 37,3554           77726                           ARCCOS                                         
037477,000195: 37,3555           00013                           STORE    10D                                   #  (-GAMA/180)/2
037478,000196: 
037479,000197: 37,3556           77551                           TLOAD    EXIT                                  #  ANGLES IN MPAC IN THE ORDER
037480,000198:                                                                                                  #  -( (ROLL, BETA, ALFA) /180)/2
037481,000199: 37,3557           00007                                    6D                                    #  THESE VALUES CORRECT AT PIPUP TIME.
037482,000200: 
037483,000201:                                                                                                  #  SPACER

Page 840

037485,000203:                                                                                                  #  BASIC SUBROUTINE TO UPDATE ATTITUDE ANGLES
037486,000204: 
037487,000205: 37,3560  E6,1661                                  EBANK=   AOG                                   
037488,000206: 
037489,000207: 37,3560           34752        CM/ATUP            CA       EBAOG                                 
037490,000208: 37,3561           54003                           TS       EBANK                                 
037491,000209: 37,3562           50120        CMTR1              INDEX    FIXLOC                                
037492,000210: 37,3563           40012                           CS       10D                                   #  (GAMA/180)/2
037493,000211: 37,3564           57722                           XCH      GAMA                                  
037494,000212: 37,3565           54001                           TS       L                                     
037495,000213: 
037496,000214: 37,3566           00004                           INHINT                                         
037497,000215:                                                                                                  #  MUST REMAIN INHINTED UNTIL UPDATE OF BODY
037498,000216:                                                                                                  #  ANGLES, SO THAT GAMDIFSW IS VALID FIRST PASS
037499,000217:                                                                                                  #  INDICATOR.
037500,000218: 
037501,000219: 37,3567           40102                           CS       CM/FLAGS                              
037502,000220: 37,3570           74700                           MASK     BIT11                                 #  GAMDIFSW=94D BIT11    INITLY=0
037503,000221: 37,3571           00006                           EXTEND                                         #  DONT CALC GAMA DOT UNTIL HAVE FORMD
037504,000222:                                                                                                  #  ONE DIFFERENCE.
037505,000223: 37,3572           13575                           BZF      DOGAMDOT                              #  IS OK, GO ON.
037506,000224: 37,3573           26102                           ADS      CM/FLAGS                              #  KNOW BIT IS 0
037507,000225: 37,3574           03610                           TC       NOGAMDOT                              #  SET GAMDOT = 0
037508,000226: 
037509,000227: 37,3575           40001        DOGAMDOT           CS       L                                     
037510,000228: 37,3576           61722                           AD       GAMA                                  #  DEL GAMA/360= T GAMDOT/360
037511,000229: 37,3577           00006                           EXTEND                                         
037512,000230: 37,3600           73673                           MP       TCDU                                  #  TCDU = .1 SEC, T = 2 SEC.
037513,000231: 37,3601           55723                           TS       GAMDOT                                #  GAMA DOT TCDU / 180
037514,000232: 
037515,000233: 37,3602           00006                           EXTEND                                         #  IGNORE GAMDOT IF LEQ .5 DEG/SEC
037516,000234: 37,3603           63605                           BZMF     +2                                    
037517,000235: 37,3604           40000                           COM                                            
037518,000236: 37,3605           64715                           AD       FIVE                                  
037519,000237: 37,3606           00006                           EXTEND                                         
037520,000238: 37,3607           63612                           BZMF     +3                                    #  SET GAMDOT=+0 AS TAG IF TOO SMALL.
037521,000239: 
037522,000240: 37,3610           34714        NOGAMDOT           CA       ZERO                                  #  COME HERE INHINTED.
037523,000241: 37,3611           55723                           TS       GAMDOT                                
037524,000242:                                                                                                  #  FOR NOW LEAVE IN 2S,C
037525,000243:                                                                                                  #  UPDATE ANGLES BY CORRECTING EUILER ANG
037526,000244:                                                                                                  #  FOR ACCRUED INCREMENT SINCE PIPUP
037527,000245:                                                                                                  #  R = R EUIL + R(NOW) - R(PIPUP)
037528,000246: 37,3612           40154                           CS       MPAC                                  #  GET (R EUL/180) /2
037529,000247: 37,3613           60000                           DOUBLE                                         #  POSSIBLE OVERFLOW
037530,000248: 37,3614           03663                           TC       CORANGOV                              #  CORRECT FOR OVFL IF ANY
037531,000249: 37,3615           00006                           EXTEND                                         
037532,000250: 37,3616           61672                           SU       ROLL/PIP                              #  GET INCR SINCE PIPUP
037533,000251: 37,3617           61664                           AD       ROLL/180                              #  ONLY SINGLE OVFL POSSIBLE.
037534,000252: 37,3620           03663                           TC       CORANGOV                              #  CORRECT FOR OVFL IF ANY

Page 841

037536,000254: 37,3621           55770                           TS       TEMPROLL                              
037537,000255: 
037538,000256: 37,3622           40156                           CS       MPAC       +2                         #  GET (ALFA EUL/180) /2
037539,000257: 37,3623           60000                           DOUBLE                                         #  SAME AS FOR ROLL.  NEEDED FOR EXT ATM DAP
037540,000258: 37,3624           03663                           TC       CORANGOV                              #  CORRECT FOR OVFL IF ANY
037541,000259: 37,3625           00006                           EXTEND                                         
037542,000260: 37,3626           61673                           SU       ALFA/PIP                              
037543,000261: 37,3627           61665                           AD       ALFA/180                              
037544,000262: 37,3630           03663                           TC       CORANGOV                              #  CORRECT FOR OVFL IF ANY
037545,000263: 37,3631           55771                           TS       TEMPALFA                              
037546,000264: 
037547,000265: 37,3632           40155                           CS       MPAC       +1                         #  GET (BETA EUL/180) /2
037548,000266: 37,3633           60000        CMTR2              DOUBLE                                         
037549,000267: 37,3634           00006                           EXTEND                                         
037550,000268: 37,3635           61674                           SU       BETA/PIP                              
037551,000269: 37,3636           61666                           AD       BETA/180                              
037552,000270: 37,3637           57772                           XCH      TEMPBETA                              #  OVFL NOT EXPECTED.
037553,000271: 
037554,000272: 37,3640           34744                           CA       EBANK3                                
037555,000273: 37,3641           54003                           TS       EBANK                                 
037556,000274: 
037557,000275: 37,3642  E3,1446                                  EBANK=   PHSNAME5                              
037558,000276: 37,3642           00006                           EXTEND                                         
037559,000277: 37,3643           33675                           DCA      REPOSADR                              #  THIS ASSUMES THAT THE         TC  PHASCHNG
037560,000278: 37,3644           53447                           DXCH     PHSNAME5                              #  IS NOT CHANGED IN             OCT 10035
037561,000279:                                                                                                  #  SERVICER.
037562,000280: 
037563,000281: 37,3645           34752                           CA       EBAOG                                 
037564,000282: 37,3646           54003                           TS       EBANK                                 
037565,000283: 
037566,000284: 37,3647  E6,1661                                  EBANK=   AOG                                   
037567,000285: 37,3647           00006        REDOPOSE           EXTEND                                         #  RE-STARTS COME HERE
037568,000286: 37,3650           31771                           DCA      TEMPROLL                              
037569,000287: 37,3651           53665                           DXCH     ROLL/180                              
037570,000288: 37,3652           31772                           CA       TEMPBETA                              
037571,000289: 37,3653           55666                           TS       BETA/180                              
037572,000290: 
037573,000291: 37,3654           00003                           RELINT                                         
037574,000292: 
037575,000293: 37,3655           06006                           TC       INTPRET                               #  CANT TC DANZIG AFTER PHASCHNG.
037576,000294: 37,3656           51575        CM/POSE3           VLOAD    ABVAL                                 #  RETURN FROM CM/ATUP.  (RESTART)
037577,000295: 37,3657           01177                                    VN                                    #  2(-7) M/CS
037578,000296: 37,3660           03723                           STORE    VMAGI                                 #  FOR DISPLAY ON CALL.
037579,000297: 
037580,000298: 37,3661           77650                           GOTO                                           
037581,000299: 37,3662           03324                                    POSEXIT                               #  ENDEXIT, STARTENT, OR SCALEPOP.
037582,000300: 
037583,000301: 37,3663           54001        CORANGOV           TS       L                                     
037584,000302: 37,3664           00002                           TC       Q                                     
037585,000303: 37,3665           50000                           INDEX    A                                     

Page 842

037587,000305: 37,3666           34673                           CA       LIMITS                                
037588,000306: 37,3667           26001                           ADS      L                                     
037589,000307: 37,3670           00002                           TC       Q                                     #  COSTS 2 MCT TO USE.  SEE ANGOVCOR.
037590,000308: 
037591,000309: 37,3671           45730 53410  -KVSCALE           2DEC     -.81491944                            #  -12800/(2 VS .3048)
037592,000310: 
037593,000311: 37,3673           03146        TCDU               DEC      .1                                    #  TCDU = .1 SEC.
037594,000312: 
037595,000313: 37,3674  E6,1661                                  EBANK=   AOG                                   
037596,000314: 37,3674           03647 76066  REPOSADR           2CADR    REDOPOSE                              
037597,000315: 

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