Source Code
These source-code files are part of a reconstructed copy of Comanche 44, the
initial release (though not the final mission release) of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Subsequent releases
were Comanche 45 and Comanche 45/2 (the flown release on Apollo 10). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 44, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 51 (separately previously reconstructed from an Apollo-era listing of Comanche 55, flown on Apollo 11). Comanche 51 source code was then modified by undoing changes known to have been made between revisions 44 and 51. The now-reconstructed Comanche 44 source code was verified by assembling it and checking that the assembled code had the expected known-correct memory-bank checksums. Note that page numbers in the reconstructed code match those on the Comanche 55 printout, although the source code would likely have different page numbers in a contemporary Comanche 44 listing. Annotations that were not present in the contemporary source code have been added to the reconstructed code to justify each change relative to Comanche 51. Here's a guide to the Apollo documentation referenced in those annotations:
Comments expected to have been present in 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. |
038964,000002: ## Copyright: Public domain.
038965,000003: ## Filename: CM_BODY_ATTITUDE.agc
038966,000004: ## Purpose: A section of Comanche revision 044.
038967,000005: ## It is part of the reconstructed source code for the
038968,000006: ## original release of the flight software for the Command
038969,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
038970,000008: ## The code has been recreated from a copy of Comanche 055. It
038971,000009: ## has been adapted such that the resulting bugger words
038972,000010: ## exactly match those specified for Comanche 44 in NASA drawing
038973,000011: ## 2021153D, which gives relatively high confidence that the
038974,000012: ## reconstruction is correct.
038975,000013: ## Assembler: yaYUL
038976,000014: ## Contact: Ron Burkey <info@sandroid.org>.
038977,000015: ## Website: www.ibiblio.org/apollo/index.html
038978,000016: ## Mod history: 2020-12-03 MAS Created from Comanche 51.
038979,000017:
Page 883 |
038981,000019: 35,3504 BANK 35
038982,000020:
038983,000021: 37,2000 SETLOC BODYATT
038984,000022: 37,2000 BANK
038985,000023:
038986,000024: 37,3467 COUNT 37/CMBAT
038987,000025:
038988,000026: # PDL 12D - 15D SAFE.
038989,000027:
038990,000028: # VALUES OF GIMBAL AND BODY ANGLES VALID AT PIP TIME ARE SAVED DURING READACCS.
038991,000029:
038992,000030: 37,3467 E7,1451 EBANK= RTINIT # LET INTERPRETER SET EB
038993,000031:
038994,000032: 37,3467 06006 CM/POSE TC INTPRET # COME HERE VIA AVEGEXIT.
038995,000033:
038996,000034: 37,3470 77201 SETPD VLOAD
038997,000035: 37,3471 00001 0
038998,000036: 37,3472 01177 VN # KVSCALE = (12800/ .3048) /2VS
038999,000037: 37,3473 63361 VXSC PDVL
039000,000038: 37,3474 37766 -KVSCALE # KVSCALE = .81491944
039001,000039: 37,3475 01714 UNITW # FULL UNIT VECTOR
039002,000040: 37,3476 74235 VXV VXSC # VREL = V - WE*R
039003,000041: 37,3477 01760 UNITR
039004,000042: 37,3500 15245 KWE
039005,000043: 37,3501 45455 VAD STADR
039006,000044: 37,3502 74251 STORE -VREL # SAVE FOR ENTRY GUIDANCE. REF COORDS
039007,000045:
039008,000046: 37,3503 72056 UNIT LXA,1
039009,000047: 37,3504 00044 36D # ABVAL( -VREL) TO X1
039010,000048: 37,3505 03542 STORE UXA/2 # -UVREL REF COORDS
039011,000049:
039012,000050: 37,3506 57435 VXV VCOMP
039013,000051: 37,3507 01760 UNITR # .5 UNIT REF COORDS
039014,000052: 37,3510 66256 UNIT SSP # THE FOLLOWING IS TO PROVIDE A STABLE
039015,000053: 37,3511 00051 S1 # UN FOR THE END OF THE TERMINAL PHASE.
039016,000054: 37,3512 00476 SPVQUIT DEC .019405 # 1000/ 2 VS
039017,000055: 37,3513 77300 TIX,1 VLOAD # IF V-VQUIT POS, BRANCH.
039018,000056: 37,3514 77516 CM/POSE2 # SAVE UYA IN OLDUYA
039019,000057: 37,3515 03534 OLDUYA # OTHERWISE CONTINUE TO USE OLDUYA.
039020,000058: 37,3516 03550 CM/POSE2 STORE UYA/2 # REF COORDS
039021,000059:
039022,000060: 37,3517 03534 STORE OLDUYA # RESTORE, OR SAVE AS CASE MAY BE.
039023,000061:
039024,000062: 37,3520 57435 VXV VCOMP
039025,000063: 37,3521 03542 UXA/2 # FINISH OBTAINING TRAJECTORY TRIAD.
039026,000064: 37,3522 77772 VSL1
039027,000065: 37,3523 03556 STORE UZA/2 # REF COORDS
Page 884 |
039029,000067: 37,3524 77751 TLOAD # PICK UP CDUX, CDUY, CDUZ CORRESPONDING
039030,000068: 37,3525 03270 AOG/PIP # TO PIPUP TIME IN 2S,C AND SAVE.
039031,000069: 37,3526 14031 CM/TRIO STODL 24D
039032,000070: 37,3527 00032 25D # AIG/PIP
039033,000071:
039034,000072: 37,3530 41434 RTB PUSH # TO PDL0
039035,000073: 37,3531 45513 CDULOGIC
039036,000074: 37,3532 77746 COS
039037,000075: 37,3533 17564 STODL UBX/2 # CI /2
039038,000076: # AIG/PIP FROM PDL 0
039039,000077: 37,3534 57556 SIN DCOMP
039040,000078: 37,3535 17570 STODL UBX/2 +4 # -SI /2
039041,000079: 37,3536 00033 26D # AMG/PIP
039042,000080: 37,3537 41434 RTB PUSH # TO PDL 0
039043,000081: 37,3540 45513 CDULOGIC
039044,000082: 37,3541 65356 SIN PDDL # XCH PDL 0. SAVE SM /2
039045,000083: 37,3542 65346 COS PDDL # CM /2 TO PDL 2
039046,000084: 37,3543 00001 0 # SM /2
039047,000085: 37,3544 74276 DCOMP VXSC
039048,000086: 37,3545 03564 UBX/2
039049,000087: 37,3546 77772 VSL1 # NOISE WONT OVFL.
039050,000088: 37,3547 17572 STODL UBY/2 # =(-SMCI, NOISE, SMSI)/2
039051,000089: 37,3550 00003 2 # CM /2 REPLACES NOISE
039052,000090: 37,3551 17574 STODL UBY/2 +2 # UBY/2=(-SMCI, CM, SMSI)/2
039053,000091: 37,3552 00031 24D # AOG/PIP
039054,000092: 37,3553 41434 RTB PUSH # TO PDL 4
039055,000093: 37,3554 45513 CDULOGIC
039056,000094: 37,3555 65356 SIN PDDL # XCH PDL 4. SAVE SO /2
039057,000095: 37,3556 74346 COS VXSC # CO /2
039058,000096: 37,3557 03572 UBY/2
039059,000097: 37,3560 17572 STODL UBY/2 # UBY/2=(-COSMCI, COCM, COSMSI)/4
039060,000098: 37,3561 00005 4D # SO /2
039061,000099: 37,3562 57405 DMP DCOMP
039062,000100: 37,3563 03570 UBX/2 +4 # -SI /2
039063,000101: 37,3564 77615 DAD
039064,000102: 37,3565 03572 UBY/2 # INCREMENT BY (SOSI /4)
039065,000103: 37,3566 17572 STODL UBY/2
039066,000104: # SO /2 FROM PDL 4
039067,000105: 37,3567 43205 DMP DAD
039068,000106: 37,3570 03564 UBX/2 # CI /2
039069,000107: 37,3571 03576 UBY/2 +4
039070,000108: 37,3572 27576 STOVL UBY/2 +4 # YB/4 PLATFORM COORDS
039071,000109:
039072,000110: # YB = (-COSMCI + SOSI , COCM , COSMSI + SOCI )
039073,000111:
039074,000112: 37,3573 03572 UBY/2
039075,000113: 37,3574 72505 VXM VSL2
039076,000114: 37,3575 01736 REFSMMAT # .5 UNIT
039077,000115: 37,3576 17572 STODL UBY/2 # YB/2 DONE REF COORDS
Page 885 |
039079,000117: # CM /2 FROM PDL 2
039080,000118: 37,3577 76561 VXSC VSL1
039081,000119: 37,3600 03564 UBX/2
039082,000120: 37,3601 17564 STODL UBX/2 # =( CMCI, NOISE, -CMSI)/2
039083,000121: 37,3602 77626 STADR # SM /2 FROM PDL 0
039084,000122: 37,3603 50211 STOVL UBX/2 +2 # SM /2 REPLACES NOISE
039085,000123: 37,3604 03564 UBX/2 # XB/2 PLATFORM COORDS
039086,000124:
039087,000125: # XB = ( CMCI , SM , -CMSI )
039088,000126:
039089,000127: 37,3605 76505 VXM VSL1
039090,000128: 37,3606 01736 REFSMMAT # .5 UNIT
039091,000129: 37,3607 03564 STORE UBX/2 # XB/2 DONE REF COORDS
039092,000130:
039093,000131: 37,3610 76435 VXV VSL1
039094,000132: 37,3611 03572 UBY/2
039095,000133: 37,3612 27600 STOVL UBZ/2 # ZB/2 DONE REF COORDS
039096,000134:
039097,000135: # EQUIVALENT TO
039098,000136: # ZB = ( SOSMCI + COSI , -SOCM , -SOSMSI + COCI )
039099,000137:
039100,000138: 37,3613 03542 UXA/2 # -UVREL/2 = -UVA/2
039101,000139: 37,3614 53435 VXV UNIT # GET UNIT(-UVREL*UBY)/2 = UL/2
039102,000140: 37,3615 03572 UBY/2 # YB/2
039103,000141: 37,3616 50206 PUSH DOT # UL/2 TO PDL 0,5
039104,000142: 37,3617 03556 UZA/2 # UNA/2
039105,000143: 37,3620 24021 STOVL COSTH # COS(ROLL)/4
039106,000144: 37,3621 00001 0 # UL/2
039107,000145:
039108,000146: 37,3622 77641 DOT
039109,000147: 37,3623 03550 UYA/2
039110,000148: 37,3624 34023 STCALL SINTH # -SIN(ROLL)/4
039111,000149: 37,3625 47256 ARCTRIG
039112,000150: 37,3626 24007 STOVL 6D # -(ROLL/180) /2
039113,000151: 37,3627 03572 UBY/2
039114,000152: 37,3630 72441 DOT SL1 # -UVA.UBY = -SIN(BETA)
039115,000153: 37,3631 03542 UXA/2 # -UVREL/2
039116,000154: 37,3632 77736 ARCSIN
039117,000155: 37,3633 24010 STOVL 7D # -(BETA/180) /2
039118,000156: 37,3634 03564 UBX/2 # XB/2
039119,000157: 37,3635 77641 DOT # UL.UBX = -SIN(ALFA)
039120,000158: 37,3636 00001 0 # UL/2
039121,000159: 37,3637 24023 STOVL SINTH # -SIN(ALFA)/4
039122,000160: 37,3640 77641 DOT # UL/2 FROM PDL 0
039123,000161: 37,3641 03600 UBZ/2
039124,000162: 37,3642 34021 STCALL COSTH # COS(ALFA)/4
039125,000163: 37,3643 47256 ARCTRIG
039126,000164: 37,3644 24011 STOVL 8D # -(ALFA/180) /2
039127,000165: 37,3645 01760 UNITR # UR/2 REF COORDS
039128,000166: 37,3646 72441 DOT SL1
Page 886 |
039130,000168: 37,3647 03556 UZA/2 # MORE ACCURATE AT LARGE ARG.
039131,000169: 37,3650 77726 ARCCOS
039132,000170: 37,3651 00013 STORE 10D # (-GAMA/180)/2
039133,000171:
039134,000172: 37,3652 77551 TLOAD EXIT # ANGLES IN MPAC IN THE ORDER
039135,000173: # -( (ROLL, BETA, ALFA) /180)/2
039136,000174: 37,3653 00007 6D # THESE VALUES CORRECT AT PIPUP TIME.
039137,000175:
039138,000176: # SPACER
Page 887 |
039140,000178: # BASIC SUBROUTINE TO UPDATE ATTITUDE ANGLES
039141,000179:
039142,000180: 37,3654 E6,1661 EBANK= AOG
039143,000181:
039144,000182: 37,3654 35057 CM/ATUP CA EBAOG
039145,000183: 37,3655 54003 TS EBANK
039146,000184: 37,3656 50120 CMTR1 INDEX FIXLOC
039147,000185: 37,3657 40012 CS 10D # (GAMA/180)/2
039148,000186: 37,3660 57722 XCH GAMA
039149,000187: 37,3661 54001 TS L
039150,000188:
039151,000189: 37,3662 00004 INHINT
039152,000190: # MUST REMAIN INHINTED UNTIL UPDATE OF BODY
039153,000191: # ANGLES, SO THAT GAMDIFSW IS VALID FIRST PASS
039154,000192: # INDICATOR.
039155,000193:
039156,000194: 37,3663 40102 CS CM/FLAGS
039157,000195: 37,3664 75005 MASK BIT11 # GAMDIFSW=94D BIT11 INITLY=0
039158,000196: 37,3665 00006 EXTEND # DONT CALC GAMA DOT UNTIL HAVE FORMD
039159,000197: # ONE DIFFERENCE.
039160,000198: 37,3666 13671 BZF DOGAMDOT # IS OK, GO ON.
039161,000199: 37,3667 26102 ADS CM/FLAGS # KNOW BIT IS 0
039162,000200: 37,3670 03704 TC NOGAMDOT # SET GAMDOT = 0
039163,000201:
039164,000202: 37,3671 40001 DOGAMDOT CS L
039165,000203: 37,3672 61722 AD GAMA # DEL GAMA/360= T GAMDOT/360
039166,000204: 37,3673 00006 EXTEND
039167,000205: 37,3674 73767 MP TCDU # TCDU = .1 SEC, T = 2 SEC.
039168,000206: 37,3675 55723 TS GAMDOT # GAMA DOT TCDU / 180
039169,000207:
039170,000208: 37,3676 00006 EXTEND # IGNORE GAMDOT IF LEQ .5 DEG/SEC
039171,000209: 37,3677 63701 BZMF +2
039172,000210: 37,3700 40000 COM
039173,000211: 37,3701 65022 AD FIVE
039174,000212: 37,3702 00006 EXTEND
039175,000213: 37,3703 63706 BZMF +3 # SET GAMDOT=+0 AS TAG IF TOO SMALL.
039176,000214:
039177,000215: 37,3704 35021 NOGAMDOT CA ZERO # COME HERE INHINTED.
039178,000216: 37,3705 55723 TS GAMDOT
039179,000217: # FOR NOW LEAVE IN 2S,C
039180,000218: # UPDATE ANGLES BY CORRECTING EUILER ANG
039181,000219: # FOR ACCRUED INCREMENT SINCE PIPUP
039182,000220: # R = R EUIL + R(NOW) - R(PIPUP)
039183,000221: 37,3706 40154 CS MPAC # GET (R EUL/180) /2
039184,000222: 37,3707 60000 DOUBLE # POSSIBLE OVERFLOW
039185,000223: 37,3710 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
039186,000224: 37,3711 00006 EXTEND
039187,000225: 37,3712 61672 SU ROLL/PIP # GET INCR SINCE PIPUP
039188,000226: 37,3713 61664 AD ROLL/180 # ONLY SINGLE OVFL POSSIBLE.
039189,000227: 37,3714 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
Page 888 |
039191,000229: 37,3715 55770 TS TEMPROLL
039192,000230:
039193,000231: 37,3716 40156 CS MPAC +2 # GET (ALFA EUL/180) /2
039194,000232: 37,3717 60000 DOUBLE # SAME AS FOR ROLL. NEEDED FOR EXT ATM DAP
039195,000233: 37,3720 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
039196,000234: 37,3721 00006 EXTEND
039197,000235: 37,3722 61673 SU ALFA/PIP
039198,000236: 37,3723 61665 AD ALFA/180
039199,000237: 37,3724 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
039200,000238: 37,3725 55771 TS TEMPALFA
039201,000239:
039202,000240: 37,3726 40155 CS MPAC +1 # GET (BETA EUL/180) /2
039203,000241: 37,3727 60000 CMTR2 DOUBLE
039204,000242: 37,3730 00006 EXTEND
039205,000243: 37,3731 61674 SU BETA/PIP
039206,000244: 37,3732 61666 AD BETA/180
039207,000245: 37,3733 57772 XCH TEMPBETA # OVFL NOT EXPECTED.
039208,000246:
039209,000247: 37,3734 35051 CA EBANK3
039210,000248: 37,3735 54003 TS EBANK
039211,000249:
039212,000250: 37,3736 E3,1446 EBANK= PHSNAME5
039213,000251: 37,3736 00006 EXTEND
039214,000252: 37,3737 33771 DCA REPOSADR # THIS ASSUMES THAT THE TC PHASCHNG
039215,000253: 37,3740 53447 DXCH PHSNAME5 # IS NOT CHANGED IN OCT 10035
039216,000254: # SERVICER.
039217,000255:
039218,000256: 37,3741 35057 CA EBAOG
039219,000257: 37,3742 54003 TS EBANK
039220,000258:
039221,000259: 37,3743 E6,1661 EBANK= AOG
039222,000260: 37,3743 00006 REDOPOSE EXTEND # RE-STARTS COME HERE
039223,000261: 37,3744 31771 DCA TEMPROLL
039224,000262: 37,3745 53665 DXCH ROLL/180
039225,000263: 37,3746 31772 CA TEMPBETA
039226,000264: 37,3747 55666 TS BETA/180
039227,000265:
039228,000266: 37,3750 00003 RELINT
039229,000267:
039230,000268: 37,3751 06006 TC INTPRET # CANT TC DANZIG AFTER PHASCHNG.
039231,000269: 37,3752 51575 CM/POSE3 VLOAD ABVAL # RETURN FROM CM/ATUP. (RESTART)
039232,000270: 37,3753 01177 VN # 2(-7) M/CS
039233,000271: 37,3754 03723 STORE VMAGI # FOR DISPLAY ON CALL.
039234,000272:
039235,000273: 37,3755 77650 GOTO
039236,000274: 37,3756 03324 POSEXIT # ENDEXIT, STARTENT, OR SCALEPOP.
039237,000275:
039238,000276: 37,3757 54001 CORANGOV TS L
039239,000277: 37,3760 00002 TC Q
039240,000278: 37,3761 50000 INDEX A
Page 889 |
039242,000280: 37,3762 35000 CA LIMITS
039243,000281: 37,3763 26001 ADS L
039244,000282: 37,3764 00002 TC Q # COSTS 2 MCT TO USE. SEE ANGOVCOR.
039245,000283:
039246,000284: 37,3765 45730 53410 -KVSCALE 2DEC -.81491944 # -12800/(2 VS .3048)
039247,000285:
039248,000286: 37,3767 03146 TCDU DEC .1 # TCDU = .1 SEC.
039249,000287:
039250,000288: 37,3770 E6,1661 EBANK= AOG
039251,000289: 37,3770 03743 76066 REPOSADR 2CADR REDOPOSE
039252,000290:
End of include-file CM_BODY_ATTITUDE.agc. Parent file is MAIN.agc