Source Code
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These source-code files are part of a reconstructed copy of Comanche 45, the
second release, though not the final mission release, of the Apollo 10
Command Module (CM) Apollo Guidance Computer (AGC) software. Comanche 45 was
preceded by Comanche 44 and followed by Comanche 45/2 (the flown release). The reconstruction
is believed to be exactly accurate, but in the absence of an actual Apollo-era
listing of Comanche 45, some explanation of the reconstruction process is needed
to insure confidence in that accuracy.
The starting point was the source code of Comanche 44 (itself previously accurately
reconstructed). Comanche 44 source code was then modified
by incorporating changes known from contemporary documentation to have been
made between revisions 44 and 45. The now-reconstructed Comanche 45 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 tend to match those in the Comanche 55, the
most-similar revision of Comanche for which we have access to an actual non-reconstructed hardcopy;
the source code would likely have different page numbers in a contemporary
Comanche 45 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 44. Here's a guide to the Apollo documentation referenced
in those annotations:
There is also
a detailed commentary about the reconstruction process.
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.
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038499,000002: ## Copyright: Public domain.
038500,000003: ## Filename: CM_BODY_ATTITUDE.agc
038501,000004: ## Purpose: A section of Comanche revision 045.
038502,000005: ## It is part of the reconstructed source code for the
038503,000006: ## second release of the flight software for the Command
038504,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
038505,000008: ## The code has been recreated from a copy of Comanche 055. It
038506,000009: ## has been adapted such that the resulting bugger words
038507,000010: ## exactly match those specified for Comanche 45 in NASA drawing
038508,000011: ## 2021153D, which gives relatively high confidence that the
038509,000012: ## reconstruction is correct.
038510,000013: ## Assembler: yaYUL
038511,000014: ## Contact: Ron Burkey <info@sandroid.org>.
038512,000015: ## Website: www.ibiblio.org/apollo/index.html
038513,000016: ## Mod history: 2020-12-06 MAS Created from Comanche 44.
038514,000017:
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Page 883
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038516,000019: 35,3504 BANK 35
038517,000020:
038518,000021: 37,2000 SETLOC BODYATT
038519,000022: 37,2000 BANK
038520,000023:
038521,000024: 37,3467 COUNT 37/CMBAT
038522,000025:
038523,000026: # PDL 12D - 15D SAFE.
038524,000027:
038525,000028: # VALUES OF GIMBAL AND BODY ANGLES VALID AT PIP TIME ARE SAVED DURING READACCS.
038526,000029:
038527,000030: 37,3467 E7,1451 EBANK= RTINIT # LET INTERPRETER SET EB
038528,000031:
038529,000032: 37,3467 06006 CM/POSE TC INTPRET # COME HERE VIA AVEGEXIT.
038530,000033:
038531,000034: 37,3470 77201 SETPD VLOAD
038532,000035: 37,3471 00001 0
038533,000036: 37,3472 01177 VN # KVSCALE = (12800/ .3048) /2VS
038534,000037: 37,3473 63361 VXSC PDVL
038535,000038: 37,3474 37766 -KVSCALE # KVSCALE = .81491944
038536,000039: 37,3475 01714 UNITW # FULL UNIT VECTOR
038537,000040: 37,3476 74235 VXV VXSC # VREL = V - WE*R
038538,000041: 37,3477 01760 UNITR
038539,000042: 37,3500 15245 KWE
038540,000043: 37,3501 45455 VAD STADR
038541,000044: 37,3502 74251 STORE -VREL # SAVE FOR ENTRY GUIDANCE. REF COORDS
038542,000045:
038543,000046: 37,3503 72056 UNIT LXA,1
038544,000047: 37,3504 00044 36D # ABVAL( -VREL) TO X1
038545,000048: 37,3505 03542 STORE UXA/2 # -UVREL REF COORDS
038546,000049:
038547,000050: 37,3506 57435 VXV VCOMP
038548,000051: 37,3507 01760 UNITR # .5 UNIT REF COORDS
038549,000052: 37,3510 66256 UNIT SSP # THE FOLLOWING IS TO PROVIDE A STABLE
038550,000053: 37,3511 00051 S1 # UN FOR THE END OF THE TERMINAL PHASE.
038551,000054: 37,3512 00476 SPVQUIT DEC .019405 # 1000/ 2 VS
038552,000055: 37,3513 77300 TIX,1 VLOAD # IF V-VQUIT POS, BRANCH.
038553,000056: 37,3514 77516 CM/POSE2 # SAVE UYA IN OLDUYA
038554,000057: 37,3515 03534 OLDUYA # OTHERWISE CONTINUE TO USE OLDUYA.
038555,000058: 37,3516 03550 CM/POSE2 STORE UYA/2 # REF COORDS
038556,000059:
038557,000060: 37,3517 03534 STORE OLDUYA # RESTORE, OR SAVE AS CASE MAY BE.
038558,000061:
038559,000062: 37,3520 57435 VXV VCOMP
038560,000063: 37,3521 03542 UXA/2 # FINISH OBTAINING TRAJECTORY TRIAD.
038561,000064: 37,3522 77772 VSL1
038562,000065: 37,3523 03556 STORE UZA/2 # REF COORDS
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Page 884
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038564,000067: 37,3524 77751 TLOAD # PICK UP CDUX, CDUY, CDUZ CORRESPONDING
038565,000068: 37,3525 03270 AOG/PIP # TO PIPUP TIME IN 2S,C AND SAVE.
038566,000069: 37,3526 14031 CM/TRIO STODL 24D
038567,000070: 37,3527 00032 25D # AIG/PIP
038568,000071:
038569,000072: 37,3530 41434 RTB PUSH # TO PDL0
038570,000073: 37,3531 45513 CDULOGIC
038571,000074: 37,3532 77746 COS
038572,000075: 37,3533 17564 STODL UBX/2 # CI /2
038573,000076: # AIG/PIP FROM PDL 0
038574,000077: 37,3534 57556 SIN DCOMP
038575,000078: 37,3535 17570 STODL UBX/2 +4 # -SI /2
038576,000079: 37,3536 00033 26D # AMG/PIP
038577,000080: 37,3537 41434 RTB PUSH # TO PDL 0
038578,000081: 37,3540 45513 CDULOGIC
038579,000082: 37,3541 65356 SIN PDDL # XCH PDL 0. SAVE SM /2
038580,000083: 37,3542 65346 COS PDDL # CM /2 TO PDL 2
038581,000084: 37,3543 00001 0 # SM /2
038582,000085: 37,3544 74276 DCOMP VXSC
038583,000086: 37,3545 03564 UBX/2
038584,000087: 37,3546 77772 VSL1 # NOISE WONT OVFL.
038585,000088: 37,3547 17572 STODL UBY/2 # =(-SMCI, NOISE, SMSI)/2
038586,000089: 37,3550 00003 2 # CM /2 REPLACES NOISE
038587,000090: 37,3551 17574 STODL UBY/2 +2 # UBY/2=(-SMCI, CM, SMSI)/2
038588,000091: 37,3552 00031 24D # AOG/PIP
038589,000092: 37,3553 41434 RTB PUSH # TO PDL 4
038590,000093: 37,3554 45513 CDULOGIC
038591,000094: 37,3555 65356 SIN PDDL # XCH PDL 4. SAVE SO /2
038592,000095: 37,3556 74346 COS VXSC # CO /2
038593,000096: 37,3557 03572 UBY/2
038594,000097: 37,3560 17572 STODL UBY/2 # UBY/2=(-COSMCI, COCM, COSMSI)/4
038595,000098: 37,3561 00005 4D # SO /2
038596,000099: 37,3562 57405 DMP DCOMP
038597,000100: 37,3563 03570 UBX/2 +4 # -SI /2
038598,000101: 37,3564 77615 DAD
038599,000102: 37,3565 03572 UBY/2 # INCREMENT BY (SOSI /4)
038600,000103: 37,3566 17572 STODL UBY/2
038601,000104: # SO /2 FROM PDL 4
038602,000105: 37,3567 43205 DMP DAD
038603,000106: 37,3570 03564 UBX/2 # CI /2
038604,000107: 37,3571 03576 UBY/2 +4
038605,000108: 37,3572 27576 STOVL UBY/2 +4 # YB/4 PLATFORM COORDS
038606,000109:
038607,000110: # YB = (-COSMCI + SOSI , COCM , COSMSI + SOCI )
038608,000111:
038609,000112: 37,3573 03572 UBY/2
038610,000113: 37,3574 72505 VXM VSL2
038611,000114: 37,3575 01736 REFSMMAT # .5 UNIT
038612,000115: 37,3576 17572 STODL UBY/2 # YB/2 DONE REF COORDS
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Page 885
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038614,000117: # CM /2 FROM PDL 2
038615,000118: 37,3577 76561 VXSC VSL1
038616,000119: 37,3600 03564 UBX/2
038617,000120: 37,3601 17564 STODL UBX/2 # =( CMCI, NOISE, -CMSI)/2
038618,000121: 37,3602 77626 STADR # SM /2 FROM PDL 0
038619,000122: 37,3603 50211 STOVL UBX/2 +2 # SM /2 REPLACES NOISE
038620,000123: 37,3604 03564 UBX/2 # XB/2 PLATFORM COORDS
038621,000124:
038622,000125: # XB = ( CMCI , SM , -CMSI )
038623,000126:
038624,000127: 37,3605 76505 VXM VSL1
038625,000128: 37,3606 01736 REFSMMAT # .5 UNIT
038626,000129: 37,3607 03564 STORE UBX/2 # XB/2 DONE REF COORDS
038627,000130:
038628,000131: 37,3610 76435 VXV VSL1
038629,000132: 37,3611 03572 UBY/2
038630,000133: 37,3612 27600 STOVL UBZ/2 # ZB/2 DONE REF COORDS
038631,000134:
038632,000135: # EQUIVALENT TO
038633,000136: # ZB = ( SOSMCI + COSI , -SOCM , -SOSMSI + COCI )
038634,000137:
038635,000138: 37,3613 03542 UXA/2 # -UVREL/2 = -UVA/2
038636,000139: 37,3614 53435 VXV UNIT # GET UNIT(-UVREL*UBY)/2 = UL/2
038637,000140: 37,3615 03572 UBY/2 # YB/2
038638,000141: 37,3616 50206 PUSH DOT # UL/2 TO PDL 0,5
038639,000142: 37,3617 03556 UZA/2 # UNA/2
038640,000143: 37,3620 24021 STOVL COSTH # COS(ROLL)/4
038641,000144: 37,3621 00001 0 # UL/2
038642,000145:
038643,000146: 37,3622 77641 DOT
038644,000147: 37,3623 03550 UYA/2
038645,000148: 37,3624 34023 STCALL SINTH # -SIN(ROLL)/4
038646,000149: 37,3625 47256 ARCTRIG
038647,000150: 37,3626 24007 STOVL 6D # -(ROLL/180) /2
038648,000151: 37,3627 03572 UBY/2
038649,000152: 37,3630 72441 DOT SL1 # -UVA.UBY = -SIN(BETA)
038650,000153: 37,3631 03542 UXA/2 # -UVREL/2
038651,000154: 37,3632 77736 ARCSIN
038652,000155: 37,3633 24010 STOVL 7D # -(BETA/180) /2
038653,000156: 37,3634 03564 UBX/2 # XB/2
038654,000157: 37,3635 77641 DOT # UL.UBX = -SIN(ALFA)
038655,000158: 37,3636 00001 0 # UL/2
038656,000159: 37,3637 24023 STOVL SINTH # -SIN(ALFA)/4
038657,000160: 37,3640 77641 DOT # UL/2 FROM PDL 0
038658,000161: 37,3641 03600 UBZ/2
038659,000162: 37,3642 34021 STCALL COSTH # COS(ALFA)/4
038660,000163: 37,3643 47256 ARCTRIG
038661,000164: 37,3644 24011 STOVL 8D # -(ALFA/180) /2
038662,000165: 37,3645 01760 UNITR # UR/2 REF COORDS
038663,000166: 37,3646 72441 DOT SL1
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Page 886
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038665,000168: 37,3647 03556 UZA/2 # MORE ACCURATE AT LARGE ARG.
038666,000169: 37,3650 77726 ARCCOS
038667,000170: 37,3651 00013 STORE 10D # (-GAMA/180)/2
038668,000171:
038669,000172: 37,3652 77551 TLOAD EXIT # ANGLES IN MPAC IN THE ORDER
038670,000173: # -( (ROLL, BETA, ALFA) /180)/2
038671,000174: 37,3653 00007 6D # THESE VALUES CORRECT AT PIPUP TIME.
038672,000175:
038673,000176: # SPACER
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Page 887
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038675,000178: # BASIC SUBROUTINE TO UPDATE ATTITUDE ANGLES
038676,000179:
038677,000180: 37,3654 E6,1661 EBANK= AOG
038678,000181:
038679,000182: 37,3654 35057 CM/ATUP CA EBAOG
038680,000183: 37,3655 54003 TS EBANK
038681,000184: 37,3656 50120 CMTR1 INDEX FIXLOC
038682,000185: 37,3657 40012 CS 10D # (GAMA/180)/2
038683,000186: 37,3660 57722 XCH GAMA
038684,000187: 37,3661 54001 TS L
038685,000188:
038686,000189: 37,3662 00004 INHINT
038687,000190: # MUST REMAIN INHINTED UNTIL UPDATE OF BODY
038688,000191: # ANGLES, SO THAT GAMDIFSW IS VALID FIRST PASS
038689,000192: # INDICATOR.
038690,000193:
038691,000194: 37,3663 40102 CS CM/FLAGS
038692,000195: 37,3664 75005 MASK BIT11 # GAMDIFSW=94D BIT11 INITLY=0
038693,000196: 37,3665 00006 EXTEND # DONT CALC GAMA DOT UNTIL HAVE FORMD
038694,000197: # ONE DIFFERENCE.
038695,000198: 37,3666 13671 BZF DOGAMDOT # IS OK, GO ON.
038696,000199: 37,3667 26102 ADS CM/FLAGS # KNOW BIT IS 0
038697,000200: 37,3670 03704 TC NOGAMDOT # SET GAMDOT = 0
038698,000201:
038699,000202: 37,3671 40001 DOGAMDOT CS L
038700,000203: 37,3672 61722 AD GAMA # DEL GAMA/360= T GAMDOT/360
038701,000204: 37,3673 00006 EXTEND
038702,000205: 37,3674 73767 MP TCDU # TCDU = .1 SEC, T = 2 SEC.
038703,000206: 37,3675 55723 TS GAMDOT # GAMA DOT TCDU / 180
038704,000207:
038705,000208: 37,3676 00006 EXTEND # IGNORE GAMDOT IF LEQ .5 DEG/SEC
038706,000209: 37,3677 63701 BZMF +2
038707,000210: 37,3700 40000 COM
038708,000211: 37,3701 65022 AD FIVE
038709,000212: 37,3702 00006 EXTEND
038710,000213: 37,3703 63706 BZMF +3 # SET GAMDOT=+0 AS TAG IF TOO SMALL.
038711,000214:
038712,000215: 37,3704 35021 NOGAMDOT CA ZERO # COME HERE INHINTED.
038713,000216: 37,3705 55723 TS GAMDOT
038714,000217: # FOR NOW LEAVE IN 2S,C
038715,000218: # UPDATE ANGLES BY CORRECTING EUILER ANG
038716,000219: # FOR ACCRUED INCREMENT SINCE PIPUP
038717,000220: # R = R EUIL + R(NOW) - R(PIPUP)
038718,000221: 37,3706 40154 CS MPAC # GET (R EUL/180) /2
038719,000222: 37,3707 60000 DOUBLE # POSSIBLE OVERFLOW
038720,000223: 37,3710 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
038721,000224: 37,3711 00006 EXTEND
038722,000225: 37,3712 61672 SU ROLL/PIP # GET INCR SINCE PIPUP
038723,000226: 37,3713 61664 AD ROLL/180 # ONLY SINGLE OVFL POSSIBLE.
038724,000227: 37,3714 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
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Page 888
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038726,000229: 37,3715 55770 TS TEMPROLL
038727,000230:
038728,000231: 37,3716 40156 CS MPAC +2 # GET (ALFA EUL/180) /2
038729,000232: 37,3717 60000 DOUBLE # SAME AS FOR ROLL. NEEDED FOR EXT ATM DAP
038730,000233: 37,3720 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
038731,000234: 37,3721 00006 EXTEND
038732,000235: 37,3722 61673 SU ALFA/PIP
038733,000236: 37,3723 61665 AD ALFA/180
038734,000237: 37,3724 03757 TC CORANGOV # CORRECT FOR OVFL IF ANY
038735,000238: 37,3725 55771 TS TEMPALFA
038736,000239:
038737,000240: 37,3726 40155 CS MPAC +1 # GET (BETA EUL/180) /2
038738,000241: 37,3727 60000 CMTR2 DOUBLE
038739,000242: 37,3730 00006 EXTEND
038740,000243: 37,3731 61674 SU BETA/PIP
038741,000244: 37,3732 61666 AD BETA/180
038742,000245: 37,3733 57772 XCH TEMPBETA # OVFL NOT EXPECTED.
038743,000246:
038744,000247: 37,3734 35051 CA EBANK3
038745,000248: 37,3735 54003 TS EBANK
038746,000249:
038747,000250: 37,3736 E3,1446 EBANK= PHSNAME5
038748,000251: 37,3736 00006 EXTEND
038749,000252: 37,3737 33771 DCA REPOSADR # THIS ASSUMES THAT THE TC PHASCHNG
038750,000253: 37,3740 53447 DXCH PHSNAME5 # IS NOT CHANGED IN OCT 10035
038751,000254: # SERVICER.
038752,000255:
038753,000256: 37,3741 35057 CA EBAOG
038754,000257: 37,3742 54003 TS EBANK
038755,000258:
038756,000259: 37,3743 E6,1661 EBANK= AOG
038757,000260: 37,3743 00006 REDOPOSE EXTEND # RE-STARTS COME HERE
038758,000261: 37,3744 31771 DCA TEMPROLL
038759,000262: 37,3745 53665 DXCH ROLL/180
038760,000263: 37,3746 31772 CA TEMPBETA
038761,000264: 37,3747 55666 TS BETA/180
038762,000265:
038763,000266: 37,3750 00003 RELINT
038764,000267:
038765,000268: 37,3751 06006 TC INTPRET # CANT TC DANZIG AFTER PHASCHNG.
038766,000269: 37,3752 51575 CM/POSE3 VLOAD ABVAL # RETURN FROM CM/ATUP. (RESTART)
038767,000270: 37,3753 01177 VN # 2(-7) M/CS
038768,000271: 37,3754 03723 STORE VMAGI # FOR DISPLAY ON CALL.
038769,000272:
038770,000273: 37,3755 77650 GOTO
038771,000274: 37,3756 03324 POSEXIT # ENDEXIT, STARTENT, OR SCALEPOP.
038772,000275:
038773,000276: 37,3757 54001 CORANGOV TS L
038774,000277: 37,3760 00002 TC Q
038775,000278: 37,3761 50000 INDEX A
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Page 889
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038777,000280: 37,3762 35000 CA LIMITS
038778,000281: 37,3763 26001 ADS L
038779,000282: 37,3764 00002 TC Q # COSTS 2 MCT TO USE. SEE ANGOVCOR.
038780,000283:
038781,000284: 37,3765 45730 53410 -KVSCALE 2DEC -.81491944 # -12800/(2 VS .3048)
038782,000285:
038783,000286: 37,3767 03146 TCDU DEC .1 # TCDU = .1 SEC.
038784,000287:
038785,000288: 37,3770 E6,1661 EBANK= AOG
038786,000289: 37,3770 03743 76066 REPOSADR 2CADR REDOPOSE
038787,000290:
End of include-file CM_BODY_ATTITUDE.agc. Parent file is MAIN.agc