Source Code
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These source-code files are part of a reconstructed copy of Artemis 071, the
first release of the Apollo 15 through 17 Command Module (CM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with source code of Artemis 072 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes between the two versions. The reconstruction was verified by matching
memory-bank checksums to those listed in drawing 2021154-. Note that page
numbers in the reconstructed code match those on the Artemis 072 printout,
although the changed code would likely have changed page numbers for a real
Artemis 071 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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039085,000002: ## Copyright: Public domain.
039086,000003: ## Filename: CM_BODY_ATTITUDE.agc
039087,000004: ## Purpose: A section of Artemis revision 071.
039088,000005: ## It is part of the reconstructed source code for the first
039089,000006: ## release of the flight software for the Command Module's
039090,000007: ## (CM) Apollo Guidance Computer (AGC) for Apollo 15 through
039091,000008: ## 17. The code has been recreated from a copy of Artemis 072.
039092,000009: ## It has been adapted such that the resulting bugger words
039093,000010: ## exactly match those specified for Artemis 071 in NASA
039094,000011: ## drawing 2021154-, which gives relatively high confidence
039095,000012: ## that the reconstruction is correct.
039096,000013: ## Reference: 890
039097,000014: ## Assembler: yaYUL
039098,000015: ## Contact: Ron Burkey <info@sandroid.org>.
039099,000016: ## Website: www.ibiblio.org/apollo/index.html
039100,000017: ## Mod history: 2019-08-14 MAS Created from Artemis 072.
039101,000018:
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Page 890
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039103,000020: 37,2000 SETLOC BODYATT
039104,000021: 37,2000 BANK
039105,000022:
039106,000023: 37,3404 COUNT* $$/CMBAT
039107,000024: # PDL 12D - 15D SAFE.
039108,000025:
039109,000026: # VALUES OF GIMBAL AND BODY ANGLES VALID AT PIP TIME ARE SAVED DURING READACCS.
039110,000027:
039111,000028: 37,3404 E7,1451 EBANK= RTINIT # LET INTERPRETER SET EB
039112,000029:
039113,000030: 37,3404 06006 CM/POSE TC INTPRET # COME HERE VIA AVEGEXIT.
039114,000031:
039115,000032: 37,3405 77201 SETPD VLOAD
039116,000033: 37,3406 00001 0
039117,000034: 37,3407 01036 VN # KVSCALE = (12800/ .3048) /2VS
039118,000035: 37,3410 63361 VXSC PDVL
039119,000036: 37,3411 37700 -KVSCALE # KVSCALE = .81491944
039120,000037: 37,3412 01712 UNITW # FULL UNIT VECTOR
039121,000038: 37,3413 74235 VXV VXSC # VREL = V - WE*R
039122,000039: 37,3414 01756 UNITR
039123,000040: 37,3415 15246 KWE
039124,000041: 37,3416 45455 VAD STADR
039125,000042: 37,3417 74251 STORE -VREL # SAVE FOR ENTRY GUIDANCE. REF COORDS
039126,000043:
039127,000044: 37,3420 72056 UNIT LXA,1
039128,000045: 37,3421 00044 36D # ABVAL( -VREL) TO X1
039129,000046: 37,3422 03542 STORE UXA/2 # -UVREL REF COORDS
039130,000047:
039131,000048: 37,3423 57435 VXV VCOMP
039132,000049: 37,3424 01756 UNITR # .5 UNIT REF COORDS
039133,000050: 37,3425 66256 UNIT SSP # THE FOLLOWING IS TO PROVIDE A STABLE
039134,000051: 37,3426 00051 S1 # UN FOR THE END OF THE TERMINAL PHASE.
039135,000052: 37,3427 00476 SPVQUIT DEC .019405 # 1000/ 2 VS
039136,000053: 37,3430 77300 TIX,1 VLOAD # IF V-VQUIT POS, BRANCH.
039137,000054: 37,3431 77433 CM/POSE2 # SAVE UYA IN OLDUYA
039138,000055: 37,3432 03534 OLDUYA # OTHERWISE CONTINUE TO USE OLDUYA.
039139,000056: 37,3433 03550 CM/POSE2 STORE UYA/2 # REF COORDS
039140,000057:
039141,000058: 37,3434 03534 STORE OLDUYA # RESTORE, OR SAVE AS CASE MAY BE.
039142,000059:
039143,000060: 37,3435 57435 VXV VCOMP
039144,000061: 37,3436 03542 UXA/2 # FINISH OBTAINING TRAJECTORY TRIAD.
039145,000062: 37,3437 77772 VSL1
039146,000063: 37,3440 03556 STORE UZA/2 # REF COORDS
039147,000064:
039148,000065: 37,3441 77751 TLOAD # PICK UP CDUX, CDUY, CDUZ CORRESPONDING
039149,000066: 37,3442 03270 AOG/PIP # TO PIPUP TIME IN 2S,C AND SAVE.
039150,000067: 37,3443 14031 CM/TRIO STODL 24D
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Page 891
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039152,000069: 37,3444 00032 25D # AIG/PIP
039153,000070:
039154,000071: 37,3445 41434 RTB PUSH # TO PDL0
039155,000072: 37,3446 51754 CDULOGIC
039156,000073: 37,3447 77746 COS
039157,000074: 37,3450 17564 STODL UBX/2 # CI /2
039158,000075: # AIG/PIP FROM PDL 0
039159,000076: 37,3451 57556 SIN DCOMP
039160,000077: 37,3452 17570 STODL UBX/2 +4 # -SI /2
039161,000078: 37,3453 00033 26D # AMG/PIP
039162,000079: 37,3454 41434 RTB PUSH # TO PDL 0
039163,000080: 37,3455 51754 CDULOGIC
039164,000081: 37,3456 65356 SIN PDDL # XCH PDL 0. SAVE SM /2
039165,000082: 37,3457 65346 COS PDDL # CM /2 TO PDL 2
039166,000083: 37,3460 00001 0 # SM /2
039167,000084: 37,3461 74276 DCOMP VXSC
039168,000085: 37,3462 03564 UBX/2
039169,000086: 37,3463 77772 VSL1 # NOISE WONT OVFL.
039170,000087: 37,3464 17572 STODL UBY/2 # =(-SMCI, NOISE, SMSI)/2
039171,000088: 37,3465 00003 2 # CM /2 REPLACES NOISE
039172,000089: 37,3466 17574 STODL UBY/2 +2 # UBY/2=(-SMCI, CM, SMSI)/2
039173,000090: 37,3467 00031 24D # AOG/PIP
039174,000091: 37,3470 41434 RTB PUSH # TO PDL 4
039175,000092: 37,3471 51754 CDULOGIC
039176,000093: 37,3472 65356 SIN PDDL # XCH PDL 4. SAVE SO /2
039177,000094: 37,3473 74346 COS VXSC # CO /2
039178,000095: 37,3474 03572 UBY/2
039179,000096: 37,3475 17572 STODL UBY/2 # UBY/2=(-COSMCI, COCM, COSMSI)/4
039180,000097: 37,3476 00005 4D # SO /2
039181,000098: 37,3477 57405 DMP DCOMP
039182,000099: 37,3500 03570 UBX/2 +4 # -SI /2
039183,000100: 37,3501 77615 DAD
039184,000101: 37,3502 03572 UBY/2 # INCREMENT BY (SOSI /4)
039185,000102: 37,3503 17572 STODL UBY/2
039186,000103: # SO /2 FROM PDL 4
039187,000104: 37,3504 43205 DMP DAD
039188,000105: 37,3505 03564 UBX/2 # CI /2
039189,000106: 37,3506 03576 UBY/2 +4
039190,000107: 37,3507 27576 STOVL UBY/2 +4 # YB/4 PLATFORM COORDS
039191,000108:
039192,000109: # YB = (-COSMCI + SOSI , COCM , COSMSI + SOCI )
039193,000110:
039194,000111: 37,3510 03572 UBY/2
039195,000112: 37,3511 72505 VXM VSL2
039196,000113: 37,3512 01734 REFSMMAT # .5 UNIT
039197,000114: 37,3513 17572 STODL UBY/2 # YB/2 DONE REF COORDS
039198,000115:
039199,000116: # CM /2 FROM PDL 2
039200,000117: 37,3514 76561 VXSC VSL1
039201,000118: 37,3515 03564 UBX/2
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Page 892
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039203,000120: 37,3516 17564 STODL UBX/2 # =( CMCI, NOISE, -CMSI)/2
039204,000121: 37,3517 77626 STADR # SM /2 FROM PDL 0
039205,000122: 37,3520 50211 STOVL UBX/2 +2 # SM /2 REPLACES NOISE
039206,000123: 37,3521 03564 UBX/2 # XB/2 PLATFORM COORDS
039207,000124:
039208,000125: # XB = ( CMCI , SM , -CMSI )
039209,000126:
039210,000127: 37,3522 76505 VXM VSL1
039211,000128: 37,3523 01734 REFSMMAT # .5 UNIT
039212,000129: 37,3524 03564 STORE UBX/2 # XB/2 DONE REF COORDS
039213,000130:
039214,000131: 37,3525 76435 VXV VSL1
039215,000132: 37,3526 03572 UBY/2
039216,000133: 37,3527 27600 STOVL UBZ/2 # ZB/2 DONE REF COORDS
039217,000134:
039218,000135: # EQUIVALENT TO
039219,000136: # ZB = ( SOSMCI + COSI , -SOCM , -SOSMSI + COCI)
039220,000137:
039221,000138: 37,3530 03542 UXA/2 # -UVREL/2 = -UVA/2
039222,000139: 37,3531 53435 VXV UNIT # GET UNIT(-UVREL*UBY)/2 = UL/2
039223,000140: 37,3532 03572 UBY/2 # YB/2
039224,000141: 37,3533 50206 PUSH DOT # UL/2 TO PDL 0,5
039225,000142: 37,3534 03556 UZA/2 # UNA/2
039226,000143: 37,3535 24021 STOVL COSTH # COS(ROLL)/4
039227,000144: 37,3536 00001 0 # UL/2
039228,000145:
039229,000146: 37,3537 77641 DOT
039230,000147: 37,3540 03550 UYA/2
039231,000148: 37,3541 34023 STCALL SINTH # -SIN(ROLL)/4
039232,000149: 37,3542 47311 ARCTRIG
039233,000150: 37,3543 24007 STOVL 6D # -(ROLL/180) /2
039234,000151: 37,3544 03572 UBY/2
039235,000152: 37,3545 72441 DOT SL1 # -UVA.UBY = -SIN(BETA)
039236,000153: 37,3546 03542 UXA/2 # -UVREL/2
039237,000154: 37,3547 77736 ARCSIN
039238,000155: 37,3550 24010 STOVL 7D # -(BETA/180) /2
039239,000156: 37,3551 03564 UBX/2 # XB/2
039240,000157: 37,3552 77641 DOT # UL.UBX = -SIN(ALFA)
039241,000158: 37,3553 00001 0 # UL/2
039242,000159: 37,3554 24023 STOVL SINTH # -SIN(ALFA)/4
039243,000160: 37,3555 77641 DOT # UL/2 FROM PDL 0
039244,000161: 37,3556 03600 UBZ/2
039245,000162: 37,3557 34021 STCALL COSTH # COS(ALFA)/4
039246,000163: 37,3560 47311 ARCTRIG
039247,000164: 37,3561 24011 STOVL 8D # -(ALFA/180) /2
039248,000165: 37,3562 01756 UNITR # UR/2 REF COORDS
039249,000166: 37,3563 72441 DOT SL1
039250,000167: 37,3564 03556 UZA/2 # MORE ACCURATE AT LARGE ARG.
039251,000168: 37,3565 77726 ARCCOS
039252,000169: 37,3566 00013 STORE 10D # (-GAMA/180)/2
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Page 893
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039254,000171: 37,3567 77551 TLOAD EXIT # ANGLES IN MPAC IN THE ORDER
039255,000172: # -( (ROLL, BETA, ALFA) /180)/2
039256,000173: 37,3570 00007 6D # THESE VALUES CORRECT AT PIPUP TIME.
039257,000174: # SPACER
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Page 894
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039259,000176:
039260,000177: # BASIC SUBROUTINE TO UPDATE ATTITUDE ANGLES
039261,000178:
039262,000179: 37,3571 E6,1661 EBANK= AOG
039263,000180:
039264,000181: 37,3571 04611 CM/ATUP TC E6SETTER
039265,000182:
039266,000183: 37,3572 50120 CMTR1 INDEX FIXLOC
039267,000184: 37,3573 40012 CS 10D # (GAMA/180)/2
039268,000185: 37,3574 57722 XCH GAMA
039269,000186: 37,3575 54001 TS L
039270,000187:
039271,000188: 37,3576 00004 INHINT
039272,000189: # MUST REMAIN INHINTED UNTIL UPDATE OF BODY
039273,000190: # ANGLES, SO THAT GAMDIFSW IS VALID FIRST PASS
039274,000191: # INDICATOR.
039275,000192:
039276,000193: 37,3577 40102 CS CM/FLAGS
039277,000194: 37,3600 74756 MASK GMDIFBIT # GAMDIFSW = 94D BIT11 INITLY=
039278,000195: 37,3601 00006 EXTEND # DONT CALC GAMA DOT UNTIL HAVE FORMD
039279,000196: # ONE DIFFERENCE.
039280,000197: 37,3602 13605 BZF DOGAMDOT # IS OK, GO ON.
039281,000198: 37,3603 26102 ADS CM/FLAGS # KNOW BIT IS 0
039282,000199: 37,3604 03620 TC NOGAMDOT # SET GAMDOT = 0
039283,000200:
039284,000201: 37,3605 40001 DOGAMDOT CS L
039285,000202: 37,3606 61722 AD GAMA # DEL GAMA/360= T GAMDOT/360
039286,000203: 37,3607 00006 EXTEND
039287,000204: 37,3610 73701 MP TCDU # TCDU = .1 SEC, T = 2 SEC.
039288,000205: 37,3611 55723 TS GAMDOT # GAMA DOT TCDU / 180
039289,000206:
039290,000207: 37,3612 00006 EXTEND # IGNORE GAMDOT IF LEQ .5 DEG/SEC
039291,000208: 37,3613 63615 BZMF +2
039292,000209: 37,3614 40000 COM
039293,000210: 37,3615 64773 AD FIVE
039294,000211: 37,3616 00006 EXTEND
039295,000212: 37,3617 63622 BZMF +3 # SET GAMDOT=+0 AS TAG IF TOO SMALL.
039296,000213:
039297,000214: 37,3620 34772 NOGAMDOT CA ZERO # COME HERE INHINTED.
039298,000215: 37,3621 55723 TS GAMDOT
039299,000216: # FOR NOW LEAVE IN 2S,C
039300,000217: # UPDATE ANGLES BY CORRECTING EUILER ANG
039301,000218: # FOR ACCRUED INCREMENT SINCE PIPUP
039302,000219: # R = R EUIL + R(NOW) -R(PIPUP)
039303,000220: 37,3622 40154 CS MPAC # GET (R EUL/180) /2
039304,000221: 37,3623 60000 DOUBLE # POSSIBLE OVERFLOW
039305,000222: 37,3624 03671 TC CORANGOV # CORRECT FOR OVFL IF ANY
039306,000223: 37,3625 00006 EXTEND
039307,000224: 37,3626 61672 SU ROLL/PIP # GET INCR SINCE PIPUP
039308,000225: 37,3627 61664 AD ROLL/180 # ONLY SINGLE OVFL POSSIBLE.
039309,000226: 37,3630 03671 TC CORANGOV # CORRECT FOR OVFL IF ANY
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Page 895
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039311,000228: 37,3631 55770 TS TEMPROLL
039312,000229:
039313,000230: 37,3632 40156 CS MPAC +2 # GET (ALFA EUL/180) /2
039314,000231: 37,3633 60000 DOUBLE # SAME AS FOR ROLL. NEEDED FOR EXT ATM DAP
039315,000232: 37,3634 03671 TC CORANGOV # CORRECT FOR OVFL IF ANY
039316,000233: 37,3635 00006 EXTEND
039317,000234: 37,3636 61673 SU ALFA/PIP
039318,000235: 37,3637 61665 AD ALFA/180
039319,000236: 37,3640 03671 TC CORANGOV # CORRECT FOR OVFL IF ANY
039320,000237: 37,3641 55771 TS TEMPALFA
039321,000238:
039322,000239: 37,3642 40155 CS MPAC +1 # GET (BETA EUL/180) /2
039323,000240: 37,3643 60000 CMTR2 DOUBLE
039324,000241: 37,3644 00006 EXTEND
039325,000242: 37,3645 61674 SU BETA/PIP
039326,000243: 37,3646 61666 AD BETA/180
039327,000244: 37,3647 57772 XCH TEMPBETA # OVFL NOT EXPECTED.
039328,000245:
039329,000246: 37,3650 35024 CA EBANK3
039330,000247: 37,3651 54003 TS EBANK
039331,000248:
039332,000249: 37,3652 E3,1446 EBANK= PHSNAME5
039333,000250: 37,3652 00006 EXTEND
039334,000251: 37,3653 33703 DCA REPOSADR # THIS ASSUMES THAT THE TC PHASCHNG
039335,000252: 37,3654 53447 DXCH PHSNAME5 # IS NOT CHANGED IN OCT 10035
039336,000253: # SERVICER.
039337,000254:
039338,000255: 37,3655 04611 TC E6SETTER
039339,000256:
039340,000257: 37,3656 E6,1661 EBANK= AOG
039341,000258: 37,3656 00006 REDOPOSE EXTEND # RE-STARTS COME HERE
039342,000259: 37,3657 31771 DCA TEMPROLL
039343,000260: 37,3660 53665 DXCH ROLL/180
039344,000261: 37,3661 31772 CA TEMPBETA
039345,000262: 37,3662 55666 TS BETA/180
039346,000263:
039347,000264: 37,3663 06006 TC INTPRET # CANT TC DANZIG AFTER PHASCHNG.
039348,000265: 37,3664 51575 CM/POSE3 VLOAD ABVAL # RETURN FROM CM/ATUP. (RESTART)
039349,000266: 37,3665 01036 VN # 2(-7) M/CS
039350,000267: 37,3666 03723 STORE VMAGI # FOR DISPLAY ON CALL.
039351,000268:
039352,000269: 37,3667 77650 GOTO
039353,000270: 37,3670 03324 POSEXIT # ENDEXIT, STARTENT, OR SCALEPOP.
039354,000271:
039355,000272: 37,3671 54001 CORANGOV TS L
039356,000273: 37,3672 00002 TC Q
039357,000274: 37,3673 50000 INDEX A
039358,000275: 37,3674 34751 CA LIMITS
039359,000276: 37,3675 26001 ADS L
039360,000277: 37,3676 00002 TC Q # COSTS 2 MCT TO USE. SEE ANGOVCOR.
039361,000278:
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Page 896
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039363,000280: 37,3677 45730 53410 -KVSCALE 2DEC -.81491944 # -12800/(2 VS .3048)
039364,000281: 37,3701 03146 TCDU DEC .1 # TCDU = .1 SEC.
039365,000282:
039366,000283: 37,3702 E6,1661 EBANK= AOG
039367,000284: 37,3702 03656 76066 REPOSADR 2CADR REDOPOSE
End of include-file CM_BODY_ATTITUDE.agc. Parent file is MAIN.agc