Source Code
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These source-code files are part of a reconstructed copy of Comanche 72, the
first release of the Apollo Guidance Computer (AGC) Command Module (CM) software
for Apollo 13.
They have been adapted from sources files created from a listing of Comanche 55.
These source files were updated to match binary dumps of a set of Comanche 67 rope modules.
They were then further modified by applying known changes between Comanche 67 and Comanche 72.
A binary dump of module B2 of Comanche 72, part number 2010802-021, was also used
to validate changes made to banks 05-13. The resulting code assembles to have identical
memory-bank checksums as those specified in NASA drawing 2021153G; this gives reasonably
high confidence that the changes that have been made are correct. In places where
ambiguity exists, this ambiguity is discussed in "## Reconstruction:" comments.
Since no contemporary listings of Comanche 72 are available as source material,
all comments and labels are approximate.
They have been taken from other AGC programs where possible, or, in some places, written
from scratch to match what we believe would have been in the original listing.
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062970,000002: ## Copyright: Public domain.
062971,000003: ## Filename: RTB_OP_CODES.agc
062972,000004: ## Purpose: A section of Comanche revision 072.
062973,000005: ## It is part of the reconstructed source code for the first
062974,000006: ## release of the software for the Command Module's (CM) Apollo
062975,000007: ## Guidance Computer (AGC) for Apollo 13. No original listings
062976,000008: ## of this program are available; instead, this file was recreated
062977,000009: ## from a printout of Comanche 055, binary dumps of a set of
062978,000010: ## Comanche 067 rope modules, and changelogs between Comanche 067
062979,000011: ## and 072. It has been adapted such that the resulting bugger words
062980,000012: ## exactly match those specified for Comanche 072 in NASA drawing
062981,000013: ## 2021153G, which gives relatively high confidence that the
062982,000014: ## reconstruction is correct.
062983,000015: ## Assembler: yaYUL
062984,000016: ## Contact: Ron Burkey <info@sandroid.org>.
062985,000017: ## Website: www.ibiblio.org/apollo/index.html
062986,000018: ## Mod history: 2024-05-13 MAS Created from Comanche 067.
062987,000019:
062988,000020: 22,3510 BANK 22
062989,000021: 22,2000 SETLOC RTBCODES
062990,000022: 22,2000 BANK
062991,000023:
062992,000024: 22,3510 E5,1713 EBANK= XNB
062993,000025: 22,3510 COUNT* $$/RTB
062994,000026:
062995,000027: # LOAD TIME2, TIME1 INTO MPAC:
062996,000028:
062997,000029: 22,3510 00006 LOADTIME EXTEND
062998,000030: 22,3511 30025 DCA TIME2
062999,000031: 22,3512 16024 TCF SLOAD2
063000,000032:
063001,000033: # CONVERT THE SINGLE PRECISION 2'S COMPLEMENT NUMBER ARRIVING IN MPAC (SCALED IN HALF-REVOLUTIONS) TO A
063002,000034: # DP 1'S COMPLEMENT NUMBER SCALED IN REVOLUTIONS.
063003,000035:
063004,000036: 22,3513 10154 CDULOGIC CCS MPAC
063005,000037: 22,3514 35035 CAF ZERO
063006,000038: 22,3515 13520 TCF +3
063007,000039: 22,3516 13517 NOOP
063008,000040: 22,3517 45016 CS HALF
063009,000041:
063010,000042: 22,3520 54155 TS MPAC +1
063011,000043: 22,3521 35035 CAF ZERO
063012,000044: 22,3522 56154 XCH MPAC
063013,000045: 22,3523 00006 EXTEND
063014,000046: 22,3524 75016 MP HALF
063015,000047: 22,3525 20155 DAS MPAC
063016,000048: 22,3526 16030 TCF DANZIG # MODE IS ALREADY AT DOUBLE-PRECISION
063017,000049:
063018,000050: # READ THE PIPS INTO MPAC WITHOUT CHANGING THEM:
063019,000051:
063020,000052: 22,3527 00004 READPIPS INHINT
063021,000053: 22,3530 30037 CA PIPAX
063022,000054: 22,3531 54154 TS MPAC
063023,000055: 22,3532 30040 CA PIPAY
063024,000056: 22,3533 54157 TS MPAC +3
063025,000057: 22,3534 30041 CA PIPAZ
063026,000058: 22,3535 00003 RELINT
063027,000059: 22,3536 54161 TS MPAC +5
063028,000060:
063029,000061: 22,3537 35035 CAF ZERO
063030,000062: 22,3540 54155 TS MPAC +1
063031,000063: 22,3541 54160 TS MPAC +4
063032,000064: 22,3542 54162 TS MPAC +6
063033,000065: 22,3543 16470 VECMODE TCF VMODE
063034,000066:
063035,000067: # FORCE TP SIGN AGREEMENT IN MPAC:
063036,000068:
063037,000069: 22,3544 07226 SGNAGREE TC TPAGREE
063038,000070:
063039,000071:
063040,000072: 22,3545 16030 TCF DANZIG
063041,000073:
063042,000074: # CONVERT THE DP 1'S COMPLEMENT ANGLE SCALED IN REVOLUTIONS TO A SINGLE PRECISION 2'S COMPLEMENT ANGLE
063043,000075: # SCALED IN HALF-REVOLUTIONS.
063044,000076:
063045,000077: 22,3546 03576 1STO2S TC 1TO2SUB
063046,000078: 22,3547 35035 CAF ZERO
063047,000079: 22,3550 54155 TS MPAC +1
063048,000080: 22,3551 16027 TCF NEWMODE
063049,000081:
063050,000082: # DO 1STO2S ON A VECTOR OF ANGLES:
063051,000083:
063052,000084: 22,3552 03576 V1STO2S TC 1TO2SUB # ANSWER ARRIVES IN A AND MPAC.
063053,000085:
063054,000086: 22,3553 52162 DXCH MPAC +5
063055,000087: 22,3554 52155 DXCH MPAC
063056,000088: 22,3555 03576 TC 1TO2SUB
063057,000089: 22,3556 54156 TS MPAC +2
063058,000090:
063059,000091: 22,3557 52160 DXCH MPAC +3
063060,000092: 22,3560 52155 DXCH MPAC
063061,000093: 22,3561 03576 TC 1TO2SUB
063062,000094: 22,3562 54155 TS MPAC +1
063063,000095:
063064,000096: 22,3563 30161 CA MPAC +5
063065,000097: 22,3564 54154 TS MPAC
063066,000098:
063067,000099: 22,3565 35033 TPMODE CAF ONE # MODE IS TP.
063068,000100: 22,3566 16027 TCF NEWMODE
063069,000101:
063070,000102: # V1STO2S FOR 2 COMPONENT VECTOR. USED BY RR.
063071,000103:
063072,000104: 22,3567 03576 2V1STO2S TC 1TO2SUB
063073,000105: 22,3570 52160 DXCH MPAC +3
063074,000106: 22,3571 52155 DXCH MPAC
063075,000107: 22,3572 03576 TC 1TO2SUB
063076,000108: 22,3573 54001 TS L
063077,000109: 22,3574 30157 CA MPAC +3
063078,000110: 22,3575 16024 TCF SLOAD2
063079,000111:
063080,000112: # SUBROUTINE TO DO DOUBLING AND 1'S TO 2'S CONVERSION:
063081,000113:
063082,000114: 22,3576 52155 1TO2SUB DXCH MPAC # FINAL MPAC +1 UNSPECIFIED.
063083,000115: 22,3577 20001 DDOUBL
063084,000116: 22,3600 10000 CCS A
063085,000117: 22,3601 65033 AD ONE
063086,000118: 22,3602 13604 TCF +2
063087,000119: 22,3603 40000 COM # THIS WAS REVERSE OF MSU.
063088,000120:
063089,000121: 22,3604 54154 TS MPAC # AND SKIP ON OVERFLOW.
063090,000122: 22,3605 00002 TC Q
063091,000123:
063092,000124: 22,3606 50000 INDEX A # OVERFLOW UNCORRECT AND IN MSU.
063093,000125: 22,3607 35014 CAF LIMITS
063094,000126: 22,3610 26154 ADS MPAC
063095,000127: 22,3611 00002 TC Q
063096,000128:
063097,000129: # SUBROUTINE TO INCREMENT CDUS
063098,000130:
063099,000131: 22,3612 33625 INCRCDUS CAF LOCTHETA
063100,000132: 22,3613 54130 TS BUF # PLACE ADRES(THETA) IN BUF.
063101,000133: 22,3614 30154 CAE MPAC # INCREMENT IN 1S COMPL.
063102,000134: 22,3615 03626 TC CDUINC
063103,000135:
063104,000136: 22,3616 24130 INCR BUF
063105,000137: 22,3617 30157 CAE MPAC +3
063106,000138: 22,3620 03626 TC CDUINC
063107,000139:
063108,000140: 22,3621 24130 INCR BUF
063109,000141: 22,3622 30161 CAE MPAC +5
063110,000142: 22,3623 03626 TC CDUINC
063111,000143:
063112,000144: 22,3624 13543 TCF VECMODE
063113,000145:
063114,000146: 22,3625 01155 LOCTHETA ADRES THETAD
063115,000147:
063116,000148: # THE FOLLOWING ROUTINE INCREMENTS IN 2S COMPLEMENT THE REGISTER WHOSE ADDRESS IS IN BUF BY THE 1S COMPL.
063117,000149: # QUANTITY FOUND IN TEM2. THIS MAY BE USED TO INCREMENT DESIRED IMU AND OPTICS CDU ANGLES OR ANY OTHER 2S COMPL.
063118,000150: # (+0 UNEQUAL TO -0) QUANTITY. MAY BE CALLED BY BANKCALL/SWCALL.
063119,000151:
063120,000152: 22,3626 54142 CDUINC TS TEM2 # 1S COMPL. QUANT. ARRIVES IN ACC. STORE IT
063121,000153: 22,3627 50130 INDEX BUF
063122,000154: 22,3630 10000 CCS 0 # CHANGE 2S COMPL. ANGLE (IN BUF) INTO 1S
063123,000155: 22,3631 65033 AD ONE
063124,000156: 22,3632 13636 TCF +4
063125,000157: 22,3633 65033 AD ONE
063126,000158: 22,3634 65033 AD ONE # OVERFLOW HERE IF 2S COMPL. IS 180 DEG.
063127,000159: 22,3635 40000 COM
063128,000160:
063129,000161: 22,3636 60142 AD TEM2 # SULT MOVES FROM 2ND TO 3D QUAD. (OR BACK)
063130,000162: 22,3637 10000 CCS A # BACK TO 2S COMPL.
063131,000163: 22,3640 65033 AD ONE
063132,000164: 22,3641 13643 TCF +2
063133,000165: 22,3642 40000 COM
063134,000166: 22,3643 54142 TS TEM2 # STORE 14BIT QUANTITY WITH PRESENT SIGN
063135,000167: 22,3644 13650 TCF +4
063136,000168: 22,3645 50000 INDEX A # SIGN.
063137,000169: 22,3646 35014 CAF LIMITS # FIX IT, BY ADDING IN 37777 OR 40000
063138,000170: 22,3647 60142 AD TEM2
063139,000171:
063140,000172: 22,3650 50130 INDEX BUF
063141,000173: 22,3651 54000 TS 0 # STORE NEW ANGLE IN 2S COMPLEMENT.
063142,000174: 22,3652 00002 TC Q
063143,000175:
063144,000176: # RTB TO TORQUE GYROS, EXCEPT FOR THE CALL TO IMUSTALL. ECADR OF COMMANDS ARRIVES IN X1.
063145,000177:
063146,000178: 22,3653 50120 PULSEIMU INDEX FIXLOC # ADDRESS OF GYRO COMMANDS SHOULD BE IN X1
063147,000179: 22,3654 30046 CA X1
063148,000180: 22,3655 04676 TC BANKCALL
063149,000181: 22,3656 17206 CADR IMUPULSE
063150,000182: 22,3657 16030 TCF DANZIG
063151,000183:
063152,000184: # EACH ROUTINE TAKES A 3X3 MATRIX STORED IN DOUBLE PRECISION IN A FIXED AREA OF ERASABLE MEMORY AND REPLACES IT
063153,000185: # WITH THE TRANSPOSE MATRIX. TRANSP1 USES LOCATIONS XNB+0,+1 THROUGH XNB+16D, 17D AND TRANSP2 USES LOCATIONS
063154,000186: # XNB1+0,+1 THROUGH XNB1+16D, 17D. EACH MATRIX IS STORED BY ROWS.
063155,000187:
063156,000188: 22,3660 02713 XNBEB ECADR XNB
063157,000189: 22,3661 02554 XNB1EB ECADR XNB1
063158,000190:
063159,000191: 22,3662 E5,1713 EBANK= XNB
063160,000192:
063161,000193: 22,3662 33660 TRANSP1 CAF XNBEB
063162,000194: 22,3663 54003 TS EBANK
063163,000195: 22,3664 53716 DXCH XNB +2
063164,000196: 22,3665 53722 DXCH XNB +6
063165,000197: 22,3666 53716 DXCH XNB +2
063166,000198:
063167,000199: 22,3667 53720 DXCH XNB +4
063168,000200: 22,3670 53730 DXCH XNB +12D
063169,000201: 22,3671 53720 DXCH XNB +4
063170,000202:
063171,000203: 22,3672 53726 DXCH XNB +10D
063172,000204: 22,3673 53732 DXCH XNB +14D
063173,000205: 22,3674 53726 DXCH XNB +10D
063174,000206: 22,3675 16030 TCF DANZIG
063175,000207: 22,3676 E5,1554 EBANK= XNB1
063176,000208:
063177,000209: 22,3676 33661 TRANSP2 CAF XNB1EB
063178,000210: 22,3677 54003 TS EBANK
063179,000211: 22,3700 53557 DXCH XNB1 +2
063180,000212: 22,3701 53563 DXCH XNB1 +6
063181,000213: 22,3702 53557 DXCH XNB1 +2
063182,000214:
063183,000215: 22,3703 53561 DXCH XNB1 +4
063184,000216: 22,3704 53571 DXCH XNB1 +12D
063185,000217: 22,3705 53561 DXCH XNB1 +4
063186,000218:
063187,000219: 22,3706 53567 DXCH XNB1 +10D
063188,000220: 22,3707 53573 DXCH XNB1 +14D
063189,000221: 22,3710 53567 DXCH XNB1 +10D
063190,000222: 22,3711 16030 TCF DANZIG
063191,000223:
063192,000224: # THE SUBROUTINE SIGNMPAC SETS C(MPAC, MPAC +1) TO SIGN(MPAC).
063193,000225: # FOR THIS, ONLY THE CONTENTS OF MPAC ARE EXAMINED. ALSO +0 YIELDS POSMAX AND -0 YIELDS NEGMAX.
063194,000226:
063195,000227: # ENTRY MAY BE BY EITHER OF THE FOLLOWING:
063196,000228: # 1. LIMIT THE SIZE OF MPAC ON INTERPRETIVE OVERFLOW:
063197,000229: # ENTRY: BOVB
063198,000230: # SIGNMPAC
063199,000231: # 2. GENERATE IN MPAC THE SIGNUM FUNCTION OF MPAC:
063200,000232: # ENTRY: RTB
063201,000233: # SIGNMPAC
063202,000234: # IN EITHER CASE, RETURN IS TO THE NEXT INTERPRETIVE INSTRUCTION IN THE CALLING SEQUENCE.
063203,000235:
063204,000236: 22,3712 00006 SIGNMPAC EXTEND
063205,000237: 22,3713 35013 DCA DPOSMAX
063206,000238: 22,3714 52155 DXCH MPAC
063207,000239: 22,3715 10000 CCS A
063208,000240: 22,3716 35035 DPMODE CAF ZERO # SETS MPAC +2 TO ZERO IN THE PROCESS
063209,000241: 22,3717 16026 TCF SLOAD2 +2
063210,000242: 22,3720 13721 TCF +1
063211,000243: 22,3721 00006 EXTEND
063212,000244: 22,3722 45013 DCS DPOSMAX
063213,000245: 22,3723 16024 TCF SLOAD2
063214,000246:
063215,000247: # RTB OP CODE NORMUNIT IS LIKE INTERPRETIVE INSTRUCTION UNIT, EXCEPT THAT IT CAN BE DEPENDED ON NOT TO BLOW
063216,000248: # UP WHEN THE VECTOR BEING UNITIZED IS VERY SMALL -- IT WILL BLOW UP WHEN ALL COMPONENTS ARE ZERO. IF NORMUNIT
063217,000249: # IS USED AND THE UPPER ORDER HALVES OF ALL COMPONENTS ARE ZERO, THE MAGNITUDE RETURNED IN 36D WILL BE TOO LARGE
063218,000250: # BY A FACTOR OF 2(13) AND THE SQUARED MAGNITUDE RETURNED AT 34D WILL BE TOO BIG BY A FACTOR OF 2(26).
063219,000251:
063220,000252: 22,3724 35033 NORMUNX1 CAF ONE
063221,000253: 22,3725 13727 TCF NORMUNIT +1
063222,000254: 22,3726 35035 NORMUNIT CAF ZERO
063223,000255: 22,3727 60120 AD FIXLOC
063224,000256: 22,3730 54156 TS MPAC +2
063225,000257: 22,3731 04676 TC BANKCALL # GET SIGN AGREEMENT IN ALL COMPONENTS
063226,000258: 22,3732 01010 CADR VECAGREE
063227,000259: 22,3733 10154 CCS MPAC
063228,000260: 22,3734 13770 TCF NOSHIFT
063229,000261: 22,3735 13737 TCF +2
063230,000262: 22,3736 13770 TCF NOSHIFT
063231,000263: 22,3737 10157 CCS MPAC +3
063232,000264: 22,3740 13770 TCF NOSHIFT
063233,000265: 22,3741 13743 TCF +2
063234,000266: 22,3742 13770 TCF NOSHIFT
063235,000267: 22,3743 10161 CCS MPAC +5
063236,000268: 22,3744 13770 TCF NOSHIFT
063237,000269: 22,3745 13747 TCF +2
063238,000270: 22,3746 13770 TCF NOSHIFT
063239,000271: 22,3747 30155 CA MPAC +1 # SHIFT ALL COMPONENTS LEFT 13
063240,000272: 22,3750 00006 EXTEND
063241,000273: 22,3751 75016 MP BIT14
063242,000274: 22,3752 20155 DAS MPAC # DAS GAINS A LITTLE ACCURACY
063243,000275: 22,3753 30160 CA MPAC +4
063244,000276: 22,3754 00006 EXTEND
063245,000277: 22,3755 75016 MP BIT14
063246,000278: 22,3756 20160 DAS MPAC +3
063247,000279: 22,3757 30162 CA MPAC +6
063248,000280: 22,3760 00006 EXTEND
063249,000281: 22,3761 75016 MP BIT14
063250,000282: 22,3762 20162 DAS MPAC +5
063251,000283: 22,3763 35041 CAF THIRTEEN
063252,000284: 22,3764 50156 INDEX MPAC +2
063253,000285: 22,3765 54045 TS 37D
063254,000286: 22,3766 04715 OFFTUNIT TC POSTJUMP
063255,000287: 22,3767 01024 CADR UNIT +1 # SKIP THE "TC VECAGREE" DONE AT UNIT
063256,000288:
063257,000289: 22,3770 35035 NOSHIFT CAF ZERO
063258,000290: 22,3771 13764 TCF OFFTUNIT -2
063259,000291:
063260,000292: # RTB VECSGNAG ... FORCES SIGN AGREEMENT OF VECTOR IN MPAC.
063261,000293:
063262,000294: 22,3772 04676 VECSGNAG TC BANKCALL
063263,000295: 22,3773 01010 CADR VECAGREE
063264,000296: 22,3774 06030 TC DANZIG
End of include-file RTB_OP_CODES.agc. Parent file is MAIN.agc