Source Code
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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:
In most cases, only the titles (rather than the full texts) of PCRs are known. In addition to the
explanatory annotations, there is also
a step-by-step 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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041190,000002: ## Copyright: Public domain.
041191,000003: ## Filename: S-BAND_ANTENNA_FOR_CM.agc
041192,000004: ## Purpose: A section of Comanche revision 044.
041193,000005: ## It is part of the reconstructed source code for the
041194,000006: ## original release of the flight software for the Command
041195,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 10.
041196,000008: ## The code has been recreated from a copy of Comanche 055. It
041197,000009: ## has been adapted such that the resulting bugger words
041198,000010: ## exactly match those specified for Comanche 44 in NASA drawing
041199,000011: ## 2021153D, which gives relatively high confidence that the
041200,000012: ## reconstruction is correct.
041201,000013: ## Assembler: yaYUL
041202,000014: ## Contact: Ron Burkey <info@sandroid.org>.
041203,000015: ## Website: www.ibiblio.org/apollo/index.html
041204,000016: ## Mod history: 2020-12-03 MAS Created from Comanche 51.
041205,000017:
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Page 934
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041207,000019: 23,3205 BANK 23
041208,000020: 42,2000 SETLOC SBAND
041209,000021: 42,2000 BANK
041210,000022:
041211,000023: 42,3652 COUNT* $$/R05
041212,000024: 42,3652 E4,1417 EBANK= EMSALT
041213,000025:
041214,000026: 42,3652 04662 SBANDANT TC BANKCALL # V 64 E GETS US HERE
041215,000027: 42,3653 17653 CADR R02BOTH # CHECK IF IMU IS ON AND ALIGNED
041216,000028: 42,3654 06006 TC INTPRET
041217,000029: 42,3655 45034 RTB CALL
041218,000030: 42,3656 45510 LOADTIME # PICKUP CURRENT TIME SCALED B-28
041219,000031: 42,3657 47477 CDUTRIG # COMPUTE SINES AND COSINES OF CDU ANGLES
041220,000032: 42,3660 34041 STCALL TDEC1 # ADVANCE INTEGRATION TO TIME IN TDEC1
041221,000033: 42,3661 27114 CSMCONIC # USING CONIC INTEGRATION
041222,000034: 42,3662 46135 SLOAD BHIZ # ORIGIN OF REFERENCE INERTIAL SYSTEM IS
041223,000035: 42,3663 00050 X2 # EARTH = 0, MOON = 2
041224,000036: 42,3664 65677 EISOI
041225,000037: 42,3665 77775 VLOAD
041226,000038: 42,3666 00001 RATT
041227,000039: 42,3667 00003 STORE RCM # MOVE RATT TO PREVENT WIPEOUT
041228,000040: 42,3670 45145 DLOAD CALL # MOON, PUSH ON
041229,000041: 42,3671 00015 TAT # GET ORIGINAL TIME
041230,000042: 42,3672 54115 LUNPOS # COMPUTE POSITION VECTOR OF MOON
041231,000043: 42,3673 57455 VAD VCOMP # R= -(REM+RCM) = NEG. OF S/C POS. VEC
041232,000044: 42,3674 00003 RCM
041233,000045: 42,3675 77650 GOTO
041234,000046: 42,3676 65701 EISOI +2
041235,000047: 42,3677 57575 EISOI VLOAD VCOMP # EARTH, R= -RCM
041236,000048: 42,3700 00001 RATT
041237,000049: 42,3701 64201 SETPD MXV # RCS TO STABLE MEMBER- B-1X B-29X B+1
041238,000050: 42,3702 00003 2D # 2D
041239,000051: 42,3703 01736 REFSMMAT # STABLE MEMBER. B-1X B-29X B+1= B-29
041240,000052: 42,3704 65372 VSL1 PDDL # 8D
041241,000053: 42,3705 15335 HI6ZEROS
041242,000054: 42,3706 24025 STOVL YAWANG # ZERO OUT YAWANG, SET UP FOR SMNB
041243,000055: 42,3707 00003 RCM # TRANSFORMATION. SM COORD. SCALED B-29
041244,000056: 42,3710 77624 CALL
041245,000057: 42,3711 47644 *SMNB*
041246,000058: 42,3712 00003 STORE R # SAVE NAV. BASE COORDINATES
041247,000059: 42,3713 63256 UNIT PDVL # 14D
041248,000060: 42,3714 00003 R
041249,000061: 42,3715 72431 VPROJ VSL2 # COMPUTE PROJECTION OF VECTOR INTO CM
041250,000062: 42,3716 15327 HIUNITZ # XY-PLANE, R-(R.UZ)UZ
041251,000063: 42,3717 40045 BVSU BOV # CLEAR OVERFLOW INDICATOR IF SET
041252,000064: 42,3720 00003 R
041253,000065: 42,3721 65722 COVCNV
041254,000066: 42,3722 40056 COVCNV UNIT BOV # TEST OVERFLOW FOR INDICATION OF NULL
041255,000067: 42,3723 65737 NOADJUST # VECTOR
041256,000068: 42,3724 50206 PUSH DOT # 20D
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Page 935
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041258,000070: 42,3725 15333 HIUNITX # COMPUTE YAW ANGLE = ACOS (URP.UX)
041259,000071: 42,3726 65552 SL1 ACOS # REVOLUTIONS SCALED B0
041260,000072: 42,3727 50315 PDVL DOT # 22D YAWANG
041261,000073: 42,3730 00017 URP
041262,000074: 42,3731 15331 HIUNITY # COMPUTE FOLLOWING- URP.UY
041263,000075: 42,3732 51152 SL1 BPL # POSITIVE
041264,000076: 42,3733 65737 NOADJUST # YES, 0-180 DEGREES
041265,000077: 42,3734 45345 DLOAD DSU # NO, 181-360 DEGREES 20D
041266,000078: 42,3735 15343 DPPOSMAX # COMPUTE 2 PI MINUS YAW ANGLE
041267,000079: 42,3736 77606 PUSH # 22D YAWANG
041268,000080: 42,3737 50375 NOADJUST VLOAD DOT # COMPUTE PITCH ANGLE
041269,000081: 42,3740 00011 UR # ACOS (UR.UZ) - PI/2
041270,000082: 42,3741 15327 HIUNITZ
041271,000083: 42,3742 65552 SL1 ACOS # REVOLUTIONS B0
041272,000084: 42,3743 77625 DSU
041273,000085: 42,3744 15325 HIDP1/4
041274,000086: 42,3745 16321 STODL RHOSB
041275,000087: 42,3746 00025 YAWANG
041276,000088: 42,3747 02323 STORE GAMMASB # PATCH FOR CHECKOUT
041277,000089: 42,3750 77776 EXIT
041278,000090: 42,3751 31044 CA EXTVBACT # IS BIT 5 STILL ON
041279,000091: 42,3752 75013 MASK BIT5
041280,000092: 42,3753 00006 EXTEND
041281,000093: 42,3754 15534 BZF ENDEXT # NO, WE HAVE BEEN ANSWERED
041282,000094: 42,3755 33771 CAF V06N51 # DISPLAY ANGLES
041283,000095: 42,3756 04662 TC BANKCALL
041284,000096: 42,3757 20600 CADR GOMARKFR
041285,000097: 42,3760 05625 TC B5OFF # TERMINATE
041286,000098: 42,3761 05625 TC B5OFF
041287,000099: 42,3762 05217 TC ENDOFJOB # RECYCLE
041288,000100: 42,3763 35015 CAF BIT3 # IMMEDIATE RETURN
041289,000101: 42,3764 05526 TC BLANKET # BLANK R3
041290,000102: 42,3765 35017 CAF BIT1 # DELAY MINIMUM TIME TO ALLOW DISPLAY IN
041291,000103: 42,3766 04662 TC BANKCALL
041292,000104: 42,3767 01732 CADR DELAYJOB
041293,000105: 42,3770 13654 TCF SBANDANT +2
041294,000106: 42,3771 01463 V06N51 VN 0651
041295,000107: 42,3772 RCM EQUALS 2D
041296,000108: 42,3772 UR EQUALS 8D
041297,000109: 42,3772 URP EQUALS 14D
041298,000110: 42,3772 YAWANG EQUALS 20D
041299,000111: 42,3772 PITCHANG EQUALS 22D
041300,000112: 42,3772 0000002 R EQUALS RCM
041301,000113: 42,3772 30,2000 SBANK= LOWSUPER
041302,000114:
End of include-file S-BAND_ANTENNA_FOR_CM.agc. Parent file is MAIN.agc