Source Code
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These source-code files are part of a reconstructed copy of Corona 261, the
final, flown release of the Block I Command Module (CM) Apollo Guidance Computer
(AGC) software for the AS-202 mission.
They have been created via disassembly of binary dumps of the original core rope
memory modules actually flown on the mission, part numbers 1003733-171, 1003733-241,
1003733-191, 1003733-211, 1003733-221, and 1003733-241. The source code for the Apollo
4 and 6 software, Solarium 55, was used as a starting point, since it was directly
derived from Corona and (at least in theory) only minimally modified.
Since only binary dumps (rather than listings) of Corona 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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030138,000002: ## Copyright: Public domain.
030139,000003: ## Filename: AVERAGE_G_INTEGRATOR.agc
030140,000004: ## Purpose: A section of Corona revision 261.
030141,000005: ## It is part of the source code for the Apollo Guidance Computer
030142,000006: ## (AGC) for AS-202. No original listings of this software are
030143,000007: ## available; instead, this file was created via disassembly of
030144,000008: ## the core rope modules actually flown on the mission.
030145,000009: ## Assembler: yaYUL
030146,000010: ## Contact: Ron Burkey <info@sandroid.org>.
030147,000011: ## Website: www.ibiblio.org/apollo/index.html
030148,000012: ## Mod history: 2023-05-27 MAS Created from Solarium 55.
030149,000013: ## 2023-06-17 MAS Updated for Corona.
030150,000014:
030151,000015:
030152,000016: # ROUTINE CALCRVG INTEGRATES THE EQUATIONS OF MOTION BY AVERAGING THE THRUST AND GRAVITATIONAL ACCELERA-
030153,000017: # TIONS OVER A TIME INTERVAL, DELTAT
030154,000018: # FOR THE EARTH-CENTERED GRAVITATIONAL FIELD THE PERTURBATION DUE TO OBLATENESS IS COMPUTED TO THE FIRST
030155,000019: # HARMONIC COEFFICIENT J
030156,000020: # ROUTINE NORMLISE MUST BE CALLED PRIOR TO THE FIRST ENTRY INTO CALCRVG. IT REQUIRES RN SCALED TO 2(+29)M
030157,000021: # IT LEAVES RN NORMALISED, SO THAT THE SCALED MAGNITUDE OF THE VECTOR CONTAINS ONE LEADING ZERO, BY SHIFTING THE
030158,000022: # VECTOR LEFT N BINARY PLACES
030159,000023: # ROUTINE CALCRVG REQUIRES
030160,000024: # 1) THRUST ACCELERATION INCREMENTS IN DELV SCALED SAME AS PIPAX,Y,Z
030161,000025: # 2) VN SCALED AT 2(+7) M/CS
030162,000026: # 3) ADDRESS OF CALCGLUN OR CALCGEAR IN CALCG
030163,000027: # 4) DELTAT SCALED AT 2(+9) CS
030164,000028: # 5) PUSH-DOWN COUNTER SET TO ZERO
030165,000029: # IT LEAVES UPDATED RN, SCALED AT 2(29-N) M, VN, AND GRAVITY SCALED AT 2(-5) M/CS/CS
030166,000030:
030167,000031:
030168,000032: # CONTINUE ON IN BANK 30.
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RSB — The original source code did not have the following BANK pseudo-op,
but for some reason I haven't tracked down yet, yaYUL can't resolve the addresses
without it. Perhaps a bug in yaYUL.
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030172,000036: 30,7513 BANK 30
030173,000037:
030174,000038: 30,7513 71173 NORMLISE ABVAL 3 # COUNT NUMBER OF LEADING ZEROS IN
030175,000039: 30,7514 57715 TSLC INCR,1 # ABVAL (RN) AND STORE -N(=2-M) IN NSHIFT
030176,000040: 30,7515 67515 SXA,1 INCR,1 # RN MUST BE SCALED AT 2(+29)M
030177,000041: 30,7516 67425 SXA,1 ITA
030178,000042: 30,7517 00766 RN
030179,000043: 30,7520 00047 X1
030180,000044: 30,7521 00003 2
030181,000045: 30,7522 01041 NSHIFT # SAVE C(X1)=-N
030182,000046: 30,7523 00017 14D
030183,000047: 30,7524 01042 XSHIFT # SAVE C(X1) =14-N
030184,000048: 30,7525 00052 S2
030185,000049:
030186,000050: 30,7526 75175 VMOVE 1
030187,000051: 30,7527 44376 VSLT*
030188,000052: 30,7530 00766 RN
030189,000053: 30,7531 00035 14D,1
030190,000054: 30,7532 32766 STORE RN # RN SCALED AT 2(29-N)METRES
030191,000055:
030192,000056: 30,7533 76776 ITC 0
030193,000057: 30,7534 21634 CALCGRV1
030194,000058:
030195,000059: 30,7535 44576 ITCI 0
030196,000060: 30,7536 00052 S2
030197,000061:
030198,000062:
030199,000063: 30,7537 75776 CALCRVG VXSC 0
030200,000064: 30,7540 01002 DELV
030201,000065: 30,7541 21730 KPIP # DV TO PD SCALED AT 2(+4)M/CS
030202,000066:
030203,000067: 30,7542 75775 VXSC 1
030204,000068: 30,7543 73432 LXA,1 BVSU
030205,000069: 30,7544 01010 GRAVITY
030206,000070: 30,7545 01030 DELTAT
030207,000071: 30,7546 01042 XSHIFT
030208,000072: 30,7547 00001 0 # (DV-(OLD GDT))/2 TO PD SCALED 2(+3)M/CS
030209,000073:
030210,000074: 30,7550 47573 NOLOD 3
030211,000075: 30,7551 45642 VSRT VAD
030212,000076: 30,7552 75620 VXSC VSLT*
030213,000077: 30,7553 50625 VAD ITA
030214,000078: 30,7554 00005 4
030215,000079: 30,7555 00774 VN
030216,000080: 30,7556 01030 DELTAT
030217,000081: 30,7557 00003 1,1
030218,000082: 30,7560 00766 RN
030219,000083: 30,7561 00052 S2
030220,000084: 30,7562 33300 STORE RN1 # SCALED AT 2(29-N) METERS
030221,000085:
030222,000086: 30,7563 76776 ITC 0
030223,000087: 30,7564 21634 CALCGRV1
030224,000088:
030225,000089: 30,7565 47573 NOLOD 3
030226,000090: 30,7566 75632 VXSC BVSU
030227,000091: 30,7567 50626 VAD VSRT
030228,000092: 30,7570 50776 VAD
030229,000093: 30,7571 01030 DELTAT
030230,000094: 30,7572 77777 - # (DV-(OLD GDT))/2
030231,000095: 30,7573 77777 - # DV/2
030232,000096: 30,7574 00005 4
030233,000097: 30,7575 00774 VN
030234,000098: 30,7576 33306 STORE VN1 # SCALED AT 2(+7) MET/CS
030235,000099:
030236,000100: # IN AVERAGE G, UP THE PHASE BITS BY 2 OF ACTIVE PROG BEFORE COPY CYCLE.
030237,000101:
030238,000102: 30,7577 77576 EXIT 0
030239,000103:
030240,000104: 30,7600 20067 INDEX FIXLOC
030241,000105: 30,7601 40051 CS S2 # SAVE NEG RETURN ADDRESS IN NON-VAC AREA.
030242,000106: 30,7602 51313 CALCRVG2 TS AVGRETRN # SAVE NEGATIVE OF RETURN ADDRESS.
030243,000107:
030244,000108: 30,7603 40662 CS -PHASE1 +4 # PICK UP PHASES.
030245,000109: 30,7604 64516 AD ONE # INCREMENT BY 1.
030246,000110: 30,7605 02312 TC NEWPHASE # AND CALL ROUTINE TO CHANGE PHASE.
030247,000111: 30,7606 00005 OCT 00005
030248,000112: 30,7607 20017 REFAZE6 INHINT
030249,000113: 30,7610 37630 CAF ELEVEND
030250,000114: 30,7611 50115 TS MPAC # USE MPAC FOR LOOP COUNTER.
030251,000115: 30,7612 20115 INDEX MPAC
030252,000116: 30,7613 41277 CS RN1 # RN1 AND VN1 MUST BE IN ORDER.
030253,000117: 30,7614 40000 COM # LEAVE RN1 ALONE IN CASE OF RESTARTS.
030254,000118: 30,7615 20115 INDEX MPAC # SELECT THE RIGHT TERM.
030255,000119: 30,7616 50765 TS RN # ...AND GO THRU COPY CYCLE.
030256,000120:
030257,000121: 30,7617 10115 CCS MPAC # ARE WE DONE..
030258,000122: 30,7620 07611 TC REFAZE6 +2 # NO, NOT YET.
030259,000123: 30,7621 44515 CS BIT2 # YES, MPAC = 0.
030260,000124: 30,7622 70675 MASK TMMARKER
030261,000125: 30,7623 64515 AD BIT2 # SET BIT 2 TO ONE IN TMMARKER.
030262,000126: 30,7624 50675 TS TMMARKER
030263,000127: # WHAT ABOUT GRAVITY FOR RESTART..
030264,000128: 30,7625 20016 RELINT
030265,000129: 30,7626 41313 CS AVGRETRN # NEG OF ADDRESS WAS STORED.
030266,000130: 30,7627 05723 TC BANKJUMP
030267,000131:
030268,000132:
030269,000133:
030270,000134: 30,7630 00013 ELEVEND DEC 11 B-14 # 11D (ELEVEN DECIMAL, OF COURSE.)
030271,000135:
030272,000136:
030273,000137:
030274,000138: 30,7631 73576 CALCGRAV LXA,1 0
030275,000139: 30,7632 01042 XSHIFT
030276,000140:
030277,000141: 30,7633 47575 CALCGRV1 NOLOD 1
030278,000142: 30,7634 73176 UNIT
030279,000143: 30,7635 33016 STORE UNITR
030280,000144:
030281,000145: 30,7636 45176 DMOVE 0
030282,000146: 30,7637 00037 30D
030283,000147: 30,7640 33024 STORE RMAG # SCALED AT 2(30-N)M
030284,000148:
030285,000149: 30,7641 63776 TSLT 0
030286,000150: 30,7642 00035 28D
030287,000151: 30,7643 00004 3
030288,000152: 30,7644 33026 STORE RMAGSQ # SCALED AT 2(+50)M(+2)
030289,000153:
030290,000154: 30,7645 45575 ITA 1
030291,000155: 30,7646 61421 XAD,1 ITCI
030292,000156: 30,7647 00034 27D
030293,000157: 30,7650 01041 NSHIFT
030294,000158: 30,7651 01043 CALCG
030295,000159:
030296,000160: 30,7652 42776 CALCGEAR DOT 0
030297,000161: 30,7653 01016 UNITR
030298,000162: 30,7654 01044 UNITW
030299,000163: 30,7655 32032 STORE 25D
030300,000164:
030301,000165: 30,7656 47574 NOLOD 2
030302,000166: 30,7657 51122 DSQ DMP
030303,000167: 30,7660 63726 TSLT BDSU
030304,000168: 30,7661 21734 DP(5/8)
030305,000169: 30,7662 00005 4
030306,000170: 30,7663 21732 DP2(-3)
030307,000171:
030308,000172: 30,7664 62775 DDV 1
030309,000173: 30,7665 63376 TSLT*
030310,000174: 30,7666 21742 J(RE)SQ # SCALED AT 2(+40) M(+2)
030311,000175: 30,7667 01026 RMAGSQ
030312,000176: 30,7670 00001 0,1
030313,000177: 30,7671 32030 STORE 23D # J(RE/RN) SQ SCALED AT 2(-3)
030314,000178:
030315,000179: 30,7672 47574 NOLOD 2
030316,000180: 30,7673 64766 DMP VXSC
030317,000181: 30,7674 50776 VAD
030318,000182: 30,7675 77777 -
030319,000183: 30,7676 01016 UNITR
030320,000184: 30,7677 01016 UNITR
030321,000185:
030322,000186: 30,7700 64775 DMP 1
030323,000187: 30,7701 75642 VXSC VAD
030324,000188: 30,7702 00030 23D
030325,000189: 30,7703 00032 25D
030326,000190: 30,7704 01044 UNITW
030327,000191:
030328,000192: 30,7705 45175 DMOVE 1
030329,000193: 30,7706 76776 ITC
030330,000194: 30,7707 21736 MUEARTH
030331,000195: 30,7710 21720 MU/RSQ
030332,000196:
030333,000197: 30,7711 75176 CALCGLUN VMOVE 0
030334,000198: 30,7712 01016 UNITR
030335,000199:
030336,000200: 30,7713 45175 DMOVE 1
030337,000201: 30,7714 63576 INCR,1
030338,000202: 30,7715 21740 MUMOON
030339,000203: 30,7716 00007 6
030340,000204:
030341,000205: 30,7717 47574 MU/RSQ NOLOD 2
030342,000206: 30,7720 62714 DDV TSLT*
030343,000207: 30,7721 75776 VXSC
030344,000208: 30,7722 01026 RMAGSQ # C(X1)=14-2N (EARTH)
030345,000209: 30,7723 00013 5,1 # =20-2N (MOON)
030346,000210: 30,7724 33010 STORE GRAVITY # SCALED AT 2(-5) M/CS/CS
030347,000211:
030348,000212: 30,7725 44576 ITCI 0
030349,000213: 30,7726 00034 27D
030350,000214:
030351,000215: 30,7727 23126 25370 KPIP 2DEC 0.59904
030352,000216: 30,7731 04000 00000 DP2(-3) 2DEC 0.125
030353,000217: 30,7733 24000 00000 DP(5/8) 2DEC 0.625
030354,000218: 30,7735 00224 17561 MUEARTH 2DEC .009063188 # SCALED AT 2(+42)M(+3)/CS(+2)
030355,000219: 30,7737 00164 34414 MUMOON 2DEC 0.007134481 # 4.90277800 E12 2(+36)M(+3)/CS(+2)
030356,000220: 30,7741 01730 04155 J(RE)SQ 2DEC .06006663 # SCALED AT 2(+40)M(+2)
End of include-file AVERAGE_G_INTEGRATOR.agc. Parent file is MAIN.agc