Source Code
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These source-code files are part of a reconstructed copy of Comanche 051, the
original release of the Apollo 11 Command Module (CM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Comanche 055 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes related to the R-2 lunar potential model, using hints from program
comments and change-indicating asterisks in the Comanche 055 listing as a guide.
The reconstruction was verified by matching memory-bank checksums to those listed
in drawing 2021153D. Note that page numbers in the reconstructed code match those
on the Comanche 055 printout, although the added code would likely have changed page
numbers for a real Comanche 051 listing.
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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064035,000002: ## Copyright: Public domain.
064036,000003: ## Filename: RTB_OP_CODES.agc
064037,000004: ## Purpose: A section of Comanche revision 051.
064038,000005: ## It is part of the reconstructed source code for the
064039,000006: ## original release of the flight software for the Command
064040,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
064041,000008: ## The code has been recreated from a copy of Comanche 055. It
064042,000009: ## has been adapted such that the resulting bugger words
064043,000010: ## exactly match those specified for Comanche 51 in NASA drawing
064044,000011: ## 2021153D, which gives relatively high confidence that the
064045,000012: ## reconstruction is correct.
064046,000013: ## Reference: pp. 1508-1516
064047,000014: ## Assembler: yaYUL
064048,000015: ## Contact: Ron Burkey <info@sandroid.org>.
064049,000016: ## Website: www.ibiblio.org/apollo/index.html
064050,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55, and removed R-2
064051,000018: ## lunar potential model code.
064052,000019:
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Page 1508
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064054,000021: 22,3510 BANK 22
064055,000022: 22,2000 SETLOC RTBCODES
064056,000023: 22,2000 BANK
064057,000024:
064058,000025: 22,3510 E5,1713 EBANK= XNB
064059,000026: 22,3510 COUNT* $$/RTB
064060,000027:
064061,000028: # LOAD TIME2, TIME1 INTO MPAC:
064062,000029:
064063,000030: 22,3510 00006 LOADTIME EXTEND
064064,000031: 22,3511 30025 DCA TIME2
064065,000032: 22,3512 16024 TCF SLOAD2
064066,000033:
064067,000034: # CONVERT THE SINGLE PRECISION 2'S COMPLEMENT NUMBER ARRIVING IN MPAC (SCALED IN HALF-REVOLUTIONS) TO A
064068,000035: # DP 1'S COMPLEMENT NUMBER SCALED IN REVOLUTIONS.
064069,000036:
064070,000037: 22,3513 10154 CDULOGIC CCS MPAC
064071,000038: 22,3514 35021 CAF ZERO
064072,000039: 22,3515 13520 TCF +3
064073,000040: 22,3516 13517 NOOP
064074,000041: 22,3517 45002 CS HALF
064075,000042:
064076,000043: 22,3520 54155 TS MPAC +1
064077,000044: 22,3521 35021 CAF ZERO
064078,000045: 22,3522 56154 XCH MPAC
064079,000046: 22,3523 00006 EXTEND
064080,000047: 22,3524 75002 MP HALF
064081,000048: 22,3525 20155 DAS MPAC
064082,000049: 22,3526 16030 TCF DANZIG # MODE IS ALREADY AT DOUBLE-PRECISION
064083,000050:
064084,000051: # READ THE PIPS INTO MPAC WITHOUT CHANGING THEM:
064085,000052:
064086,000053: 22,3527 00004 READPIPS INHINT
064087,000054: 22,3530 30037 CA PIPAX
064088,000055: 22,3531 54154 TS MPAC
064089,000056: 22,3532 30040 CA PIPAY
064090,000057: 22,3533 54157 TS MPAC +3
064091,000058: 22,3534 30041 CA PIPAZ
064092,000059: 22,3535 00003 RELINT
064093,000060: 22,3536 54161 TS MPAC +5
064094,000061:
064095,000062: 22,3537 35021 CAF ZERO
064096,000063: 22,3540 54155 TS MPAC +1
064097,000064: 22,3541 54160 TS MPAC +4
064098,000065: 22,3542 54162 TS MPAC +6
064099,000066: 22,3543 16470 VECMODE TCF VMODE
064100,000067:
064101,000068: # FORCE TP SIGN AGREEMENT IN MPAC:
064102,000069:
064103,000070: 22,3544 07226 SGNAGREE TC TPAGREE
064104,000071:
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Page 1509
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064106,000073:
064107,000074: 22,3545 16030 TCF DANZIG
064108,000075:
064109,000076: # CONVERT THE DP 1'S COMPLEMENT ANGLE SCALED IN REVOLUTIONS TO A SINGLE PRECISION 2'S COMPLEMENT ANGLE
064110,000077: # SCALED IN HALF-REVOLUTIONS.
064111,000078:
064112,000079: 22,3546 03576 1STO2S TC 1TO2SUB
064113,000080: 22,3547 35021 CAF ZERO
064114,000081: 22,3550 54155 TS MPAC +1
064115,000082: 22,3551 16027 TCF NEWMODE
064116,000083:
064117,000084: # DO 1STO2S ON A VECTOR OF ANGLES:
064118,000085:
064119,000086: 22,3552 03576 V1STO2S TC 1TO2SUB # ANSWER ARRIVES IN A AND MPAC.
064120,000087:
064121,000088: 22,3553 52162 DXCH MPAC +5
064122,000089: 22,3554 52155 DXCH MPAC
064123,000090: 22,3555 03576 TC 1TO2SUB
064124,000091: 22,3556 54156 TS MPAC +2
064125,000092:
064126,000093: 22,3557 52160 DXCH MPAC +3
064127,000094: 22,3560 52155 DXCH MPAC
064128,000095: 22,3561 03576 TC 1TO2SUB
064129,000096: 22,3562 54155 TS MPAC +1
064130,000097:
064131,000098: 22,3563 30161 CA MPAC +5
064132,000099: 22,3564 54154 TS MPAC
064133,000100:
064134,000101: 22,3565 35017 TPMODE CAF ONE # MODE IS TP.
064135,000102: 22,3566 16027 TCF NEWMODE
064136,000103:
064137,000104: # V1STO2S FOR 2 COMPONENT VECTOR. USED BY RR.
064138,000105:
064139,000106: 22,3567 03576 2V1STO2S TC 1TO2SUB
064140,000107: 22,3570 52160 DXCH MPAC +3
064141,000108: 22,3571 52155 DXCH MPAC
064142,000109: 22,3572 03576 TC 1TO2SUB
064143,000110: 22,3573 54001 TS L
064144,000111: 22,3574 30157 CA MPAC +3
064145,000112: 22,3575 16024 TCF SLOAD2
064146,000113:
064147,000114: # SUBROUTINE TO DO DOUBLING AND 1'S TO 2'S CONVERSION:
064148,000115:
064149,000116: 22,3576 52155 1TO2SUB DXCH MPAC # FINAL MPAC +1 UNSPECIFIED.
064150,000117: 22,3577 20001 DDOUBL
064151,000118: 22,3600 10000 CCS A
064152,000119: 22,3601 65017 AD ONE
064153,000120: 22,3602 13604 TCF +2
064154,000121: 22,3603 40000 COM # THIS WAS REVERSE OF MSU.
064155,000122:
064156,000123: 22,3604 54154 TS MPAC # AND SKIP ON OVERFLOW.
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Page 1510
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064158,000125: 22,3605 00002 TC Q
064159,000126:
064160,000127: 22,3606 50000 INDEX A # OVERFLOW UNCORRECT AND IN MSU.
064161,000128: 22,3607 35000 CAF LIMITS
064162,000129: 22,3610 26154 ADS MPAC
064163,000130: 22,3611 00002 TC Q
064164,000131:
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Page 1511
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064166,000133: # SUBROUTINE TO INCREMENT CDUS
064167,000134:
064168,000135: 22,3612 33625 INCRCDUS CAF LOCTHETA
064169,000136: 22,3613 54130 TS BUF # PLACE ADRES(THETA) IN BUF.
064170,000137: 22,3614 30154 CAE MPAC # INCREMENT IN 1S COMPL.
064171,000138: 22,3615 03626 TC CDUINC
064172,000139:
064173,000140: 22,3616 24130 INCR BUF
064174,000141: 22,3617 30157 CAE MPAC +3
064175,000142: 22,3620 03626 TC CDUINC
064176,000143:
064177,000144: 22,3621 24130 INCR BUF
064178,000145: 22,3622 30161 CAE MPAC +5
064179,000146: 22,3623 03626 TC CDUINC
064180,000147:
064181,000148: 22,3624 13543 TCF VECMODE
064182,000149:
064183,000150: 22,3625 01155 LOCTHETA ADRES THETAD
064184,000151:
064185,000152: # THE FOLLOWING ROUTINE INCREMENTS IN 2S COMPLEMENT THE REGISTER WHOSE ADDRESS IS IN BUF BY THE 1S COMPL.
064186,000153: # QUANTITY FOUND IN TEM2. THIS MAY BE USED TO INCREMENT DESIRED IMU AND OPTICS CDU ANGLES OR ANY OTHER 2S COMPL.
064187,000154: # (+0 UNEQUAL TO -0) QUANTITY. MAY BE CALLED BY BANKCALL/SWCALL.
064188,000155:
064189,000156: 22,3626 54142 CDUINC TS TEM2 # 1S COMPL. QUANT. ARRIVES IN ACC. STORE IT
064190,000157: 22,3627 50130 INDEX BUF
064191,000158: 22,3630 10000 CCS 0 # CHANGE 2S COMPL. ANGLE (IN BUF) INTO 1S
064192,000159: 22,3631 65017 AD ONE
064193,000160: 22,3632 13636 TCF +4
064194,000161: 22,3633 65017 AD ONE
064195,000162: 22,3634 65017 AD ONE # OVERFLOW HERE IF 2S COMPL. IS 180 DEG.
064196,000163: 22,3635 40000 COM
064197,000164:
064198,000165: 22,3636 60142 AD TEM2 # SULT MOVES FROM 2ND TO 3D QUAD. (OR BACK)
064199,000166: 22,3637 10000 CCS A # BACK TO 2S COMPL.
064200,000167: 22,3640 65017 AD ONE
064201,000168: 22,3641 13643 TCF +2
064202,000169: 22,3642 40000 COM
064203,000170: 22,3643 54142 TS TEM2 # STORE 14BIT QUANTITY WITH PRESENT SIGN
064204,000171: 22,3644 13650 TCF +4
064205,000172: 22,3645 50000 INDEX A # SIGN.
064206,000173: 22,3646 35000 CAF LIMITS # FIX IT, BY ADDING IN 37777 OR 40000
064207,000174: 22,3647 60142 AD TEM2
064208,000175:
064209,000176: 22,3650 50130 INDEX BUF
064210,000177: 22,3651 54000 TS 0 # STORE NEW ANGLE IN 2S COMPLEMENT.
064211,000178: 22,3652 00002 TC Q
064212,000179:
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Page 1512
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064214,000181: # RTB TO TORQUE GYROS, EXCEPT FOR THE CALL TO IMUSTALL. ECADR OF COMMANDS ARRIVES IN X1.
064215,000182:
064216,000183: 22,3653 50120 PULSEIMU INDEX FIXLOC # ADDRESS OF GYRO COMMANDS SHOULD BE IN X1
064217,000184: 22,3654 30046 CA X1
064218,000185: 22,3655 04662 TC BANKCALL
064219,000186: 22,3656 17206 CADR IMUPULSE
064220,000187: 22,3657 16030 TCF DANZIG
064221,000188:
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Page 1513
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064223,000190: # EACH ROUTINE TAKES A 3X3 MATRIX STORED IN DOUBLE PRECISION IN A FIXED AREA OF ERASABLE MEMORY AND REPLACES IT
064224,000191: # WITH THE TRANSPOSE MATRIX. TRANSP1 USES LOCATIONS XNB+0,+1 THROUGH XNB+16D, 17D AND TRANSP2 USES LOCATIONS
064225,000192: # XNB1+0,+1 THROUGH XNB1+16D, 17D. EACH MATRIX IS STORED BY ROWS.
064226,000193:
064227,000194: 22,3660 02713 XNBEB ECADR XNB
064228,000195: 22,3661 02554 XNB1EB ECADR XNB1
064229,000196:
064230,000197: 22,3662 E5,1713 EBANK= XNB
064231,000198:
064232,000199: 22,3662 33660 TRANSP1 CAF XNBEB
064233,000200: 22,3663 54003 TS EBANK
064234,000201: 22,3664 53716 DXCH XNB +2
064235,000202: 22,3665 53722 DXCH XNB +6
064236,000203: 22,3666 53716 DXCH XNB +2
064237,000204:
064238,000205: 22,3667 53720 DXCH XNB +4
064239,000206: 22,3670 53730 DXCH XNB +12D
064240,000207: 22,3671 53720 DXCH XNB +4
064241,000208:
064242,000209: 22,3672 53726 DXCH XNB +10D
064243,000210: 22,3673 53732 DXCH XNB +14D
064244,000211: 22,3674 53726 DXCH XNB +10D
064245,000212: 22,3675 16030 TCF DANZIG
064246,000213: 22,3676 E5,1554 EBANK= XNB1
064247,000214:
064248,000215: 22,3676 33661 TRANSP2 CAF XNB1EB
064249,000216: 22,3677 54003 TS EBANK
064250,000217: 22,3700 53557 DXCH XNB1 +2
064251,000218: 22,3701 53563 DXCH XNB1 +6
064252,000219: 22,3702 53557 DXCH XNB1 +2
064253,000220:
064254,000221: 22,3703 53561 DXCH XNB1 +4
064255,000222: 22,3704 53571 DXCH XNB1 +12D
064256,000223: 22,3705 53561 DXCH XNB1 +4
064257,000224:
064258,000225: 22,3706 53567 DXCH XNB1 +10D
064259,000226: 22,3707 53573 DXCH XNB1 +14D
064260,000227: 22,3710 53567 DXCH XNB1 +10D
064261,000228: 22,3711 16030 TCF DANZIG
064262,000229:
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Page 1514
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064264,000231: # THE SUBROUTINE SIGNMPAC SETS C(MPAC, MPAC +1) TO SIGN(MPAC).
064265,000232: # FOR THIS, ONLY THE CONTENTS OF MPAC ARE EXAMINED. ALSO +0 YIELDS POSMAX AND -0 YIELDS NEGMAX.
064266,000233:
064267,000234: # ENTRY MAY BE BY EITHER OF THE FOLLOWING:
064268,000235: # 1. LIMIT THE SIZE OF MPAC ON INTERPRETIVE OVERFLOW:
064269,000236: # ENTRY: BOVB
064270,000237: # SIGNMPAC
064271,000238: # 2. GENERATE IN MPAC THE SIGNUM FUNCTION OF MPAC:
064272,000239: # ENTRY: RTB
064273,000240: # SIGNMPAC
064274,000241: # IN EITHER CASE, RETURN IS TO THE NEXT INTERPRETIVE INSTRUCTION IN THE CALLING SEQUENCE.
064275,000242:
064276,000243: 22,3712 00006 SIGNMPAC EXTEND
064277,000244: 22,3713 34777 DCA DPOSMAX
064278,000245: 22,3714 52155 DXCH MPAC
064279,000246: 22,3715 10000 CCS A
064280,000247: 22,3716 35021 DPMODE CAF ZERO # SETS MPAC +2 TO ZERO IN THE PROCESS
064281,000248: 22,3717 16026 TCF SLOAD2 +2
064282,000249: 22,3720 13721 TCF +1
064283,000250: 22,3721 00006 EXTEND
064284,000251: 22,3722 44777 DCS DPOSMAX
064285,000252: 22,3723 16024 TCF SLOAD2
064286,000253:
064287,000254: # RTB OP CODE NORMUNIT IS LIKE INTERPRETIVE INSTRUCTION UNIT, EXCEPT THAT IT CAN BE DEPENDED ON NOT TO BLOW
064288,000255: # UP WHEN THE VECTOR BEING UNITIZED IS VERY SMALL -- IT WILL BLOW UP WHEN ALL COMPONENTS ARE ZERO. IF NORMUNIT
064289,000256: # IS USED AND THE UPPER ORDER HALVES OF ALL COMPONENTS ARE ZERO, THE MAGNITUDE RETURNED IN 36D WILL BE TOO LARGE
064290,000257: # BY A FACTOR OF 2(13) AND THE SQUARED MAGNITUDE RETURNED AT 34D WILL BE TOO BIG BY A FACTOR OF 2(26).
064291,000258:
064292,000259: 22,3724 35017 NORMUNX1 CAF ONE
064293,000260: 22,3725 13727 TCF NORMUNIT +1
064294,000261: 22,3726 35021 NORMUNIT CAF ZERO
064295,000262: 22,3727 60120 AD FIXLOC
064296,000263: 22,3730 54156 TS MPAC +2
064297,000264: 22,3731 04662 TC BANKCALL # GET SIGN AGREEMENT IN ALL COMPONENTS
064298,000265: 22,3732 01010 CADR VECAGREE
064299,000266: 22,3733 10154 CCS MPAC
064300,000267: 22,3734 13770 TCF NOSHIFT
064301,000268: 22,3735 13737 TCF +2
064302,000269: 22,3736 13770 TCF NOSHIFT
064303,000270: 22,3737 10157 CCS MPAC +3
064304,000271: 22,3740 13770 TCF NOSHIFT
064305,000272: 22,3741 13743 TCF +2
064306,000273: 22,3742 13770 TCF NOSHIFT
064307,000274: 22,3743 10161 CCS MPAC +5
064308,000275: 22,3744 13770 TCF NOSHIFT
064309,000276: 22,3745 13747 TCF +2
064310,000277: 22,3746 13770 TCF NOSHIFT
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Page 1515
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064312,000279: 22,3747 30155 CA MPAC +1 # SHIFT ALL COMPONENTS LEFT 13
064313,000280: 22,3750 00006 EXTEND
064314,000281: 22,3751 75002 MP BIT14
064315,000282: 22,3752 20155 DAS MPAC # DAS GAINS A LITTLE ACCURACY
064316,000283: 22,3753 30160 CA MPAC +4
064317,000284: 22,3754 00006 EXTEND
064318,000285: 22,3755 75002 MP BIT14
064319,000286: 22,3756 20160 DAS MPAC +3
064320,000287: 22,3757 30162 CA MPAC +6
064321,000288: 22,3760 00006 EXTEND
064322,000289: 22,3761 75002 MP BIT14
064323,000290: 22,3762 20162 DAS MPAC +5
064324,000291: 22,3763 35025 CAF THIRTEEN
064325,000292: 22,3764 50156 INDEX MPAC +2
064326,000293: 22,3765 54045 TS 37D
064327,000294: 22,3766 04701 OFFTUNIT TC POSTJUMP
064328,000295: 22,3767 01024 CADR UNIT +1 # SKIP THE "TC VECAGREE" DONE AT UNIT
064329,000296:
064330,000297: 22,3770 35021 NOSHIFT CAF ZERO
064331,000298: 22,3771 13764 TCF OFFTUNIT -2
064332,000299:
064333,000300: # RTB VECSGNAG ... FORCES SIGN AGREEMENT OF VECTOR IN MPAC.
064334,000301:
064335,000302: 22,3772 04662 VECSGNAG TC BANKCALL
064336,000303: 22,3773 01010 CADR VECAGREE
064337,000304: 22,3774 06030 TC DANZIG
064338,000305:
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Page 1516
Between Comanche 51 and 55, two new functions, QUALITY1 and QUALITY2, were inserted
here. They are part of the R-2 lunar potential model. They belong in ORBITAL INTEGRATION,
but were placed here to simplify making the changes such that only a single module (B2)
had to be remanufactured.
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End of include-file RTB_OP_CODES.agc. Parent file is MAIN.agc