GAP: ASSEMBLE REVISION 131 OF AGC PROGRAM LUMINARY BY NASA 2021112-091 17:53 DEC. 19, 1969Note that the date is the date the printout was made, not the date on which the program revision was released, although these happen to be very close together.
Source Code
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This source code is very close to the Apollo Guidance Computer software for the
Apollo 13 Lunar module. This revision of the Luminary 131 program is from December
of 1969, whereas there was a later revision in January of 1970, and still another
revision in February, which is the code that flew on the mission.
As far as this transcription is concerned, it was originally from a copy made in 1991 of
a printout from the collection of AGC developer Don Eyles for collector David Craig.
It was subsequently scanned by Gary Neff, reprocessed for online
presentation at the now-discontinued History of Recent Science and Technology (HRST) website
of MIT's Dibner Institute (the full-quality scans being discarded in the process),
and finally transcribed by Ron Burkey for the Virtual AGC Project. Although a
high-quality replacement scan for a completely illegible page was later provided by Gary
Neff, the reduced legibility of the reprocessed HRST posting nevertheless caused many
errors to be introduced into the transcription. Accordingly, a second scan of the same physical
printout was made in 2017 for the Virtual AGC Project's collection at the Internet Archive,
and used to correct the transcription errors. All of the scanned materials mentioned,
as well as other Luminary 131 related material, are available online.
Don Eyles apprently made additional hand-written notes in printout between 1991 and 2017,
so the two scans are not identical in that respect. The page-headings in the printout read, in part:GAP: ASSEMBLE REVISION 131 OF AGC PROGRAM LUMINARY BY NASA 2021112-091 17:53 DEC. 19, 1969Note that the date is the date the printout was made, not the date on which the program revision was released, although these happen to be very close together. |
020778,000002: ## Copyright: Public domain.
020779,000003: ## Filename: S-BAND_ANTENNA_FOR_LM.agc
020780,000004: ## Purpose: A section of Luminary 1C, revision 131.
020781,000005: ## It is part of the source code for the Lunar Module's (LM)
020782,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
020783,000007: ## This file is intended to be a faithful transcription, except
020784,000008: ## that the code format has been changed to conform to the
020785,000009: ## requirements of the yaYUL assembler rather than the
020786,000010: ## original YUL assembler.
020787,000011: ## Reference: pp. 490-493
020788,000012: ## Contact: Ron Burkey <info@sandroid.org>.
020789,000013: ## Website: www.ibiblio.org/apollo/index.html
020790,000014: ## Mod history: 05/14/03 RSB. Began transcribing.
020791,000015: ## 05/14/05 RSB Corrected website references above.
020792,000016: ## 2017-01-06 RSB Page numbers now agree with those on the
020793,000017: ## original harcopy, as opposed to the PDF page
020794,000018: ## numbers in 1701.pdf.
020795,000019: ## 2017-02-24 RSB Proofed comment text using octopus/ProoferComments.
020796,000020:
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Page 490 |
020798,000022: # SUBROUTINE NAME: R05 - S-BAND ANTENNA FOR LM
020799,000023:
020800,000024: # MOD0 BY T. JAMES
020801,000025: # MOD1 BY P. SHAKIR
020802,000026:
020803,000027: # FUNCTIONAL DESCRIPTION
020804,000028:
020805,000029: # THE S-BAND ANTENNA ROUTINE, R05, COMPUTES AND DISPLAYS THE PITCH AND
020806,000030: # YAW ANTENNA GIMBAL ANGLES REQUIRED TO POINT THE LM STEERABLE ANTENNA
020807,000031: # TOWARD THE CENTER OF THE EARTH. THIS ROUTINE IS SELECTED BY THE ASTRO-
020808,000032: # NAUT VIA DSKY ENTRY DURING COASTING FLIGHT OR WHEN THE LM IS ON THE MOON
020809,000033: # SURFACE. THE EARTH OR MOON REFERENCE COORDINATE SYSTEM IS USED DEPENDING
020810,000034: # ON WHETHER THE LM IS ABOUT TO ENTER OR HAS ALREADY ENTERED THE MOON
020811,000035: # SPHERE OF INFLUENCE, RESPECTIVELY. CAN BE CALLED ANY TIME EXCEPT WHEN
020812,000036: # ANOTHER EXTENDED VERB IS IN USE. DISPLAY IS MEANINGLESS WITH IMU OFF.
020813,000037:
020814,000038: # TO CALL SUBROUTINE, ASTRONAUT KEYS IN V 64 E
020815,000039:
020816,000040: # SUBROUTINES CALLED -
020817,000041: # INTPRET
020818,000042: # LOADTIME
020819,000043: # LEMCONIC
020820,000044: # LUNPOS
020821,000045: # CDUTRIG
020822,000046: # *SMNB*
020823,000047: # BANKCALL
020824,000048: # B5OFF
020825,000049: # ENDOFJOB
020826,000050: # BLANKET
020827,000051:
020828,000052: # RETURNS WITH
020829,000053: # PITCH ANGLE IN PITCHANG REV. B0
020830,000054: # YAW ANGLE IN YAWANG REV. B0
020831,000055:
020832,000056: # ERASABLES USED
020833,000057: # PITCHANG
020834,000058: # YAWANG
020835,000059: # RLM
020836,000060: # VAC AREA
020837,000061:
020838,000062: 41,3750 BANK 41
020839,000063: 42,2000 SETLOC SBAND
020840,000064: 42,2000 BANK
020841,000065:
020842,000066: 42,3606 E7,1471 EBANK= WHOCARES
020843,000067: 42,3606 COUNT* $$/R05
020844,000068: 42,3606 06042 SBANDANT TC INTPRET
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Page 491 |
020846,000070: 42,3607 47001 SETPD RTB
020847,000071: 42,3610 00001 0D
020848,000072: 42,3611 21574 LOADTIME # PICK UP CURRENT TIME
020849,000073: 42,3612 34041 STCALL TDEC1 # ADVANCE INTEGRATION TO TIME IN TDEC1
020850,000074: 42,3613 27077 LEMCONIC # USING CONIC INTEGRATION
020851,000075: 42,3614 46135 SLOAD BHIZ
020852,000076: 42,3615 00050 X2 # X2 =0 EARTH SPHERE, X2 =2 MOON SPHERE
020853,000077: 42,3616 65634 CONV4
020854,000078: 42,3617 77775 VLOAD
020855,000079: 42,3620 00001 RATT
020856,000080: 42,3621 16205 STODL RLM
020857,000081: 42,3622 00015 TAT
020858,000082: 42,3623 77624 CONV3 CALL
020859,000083: 42,3624 33647 LUNPOS # UNIT POSITION VECTOR FROM EARTH TO MOON
020860,000084: 42,3625 74375 VLOAD VXSC
020861,000085: 42,3626 02723 VMOON
020862,000086: 42,3627 24001 REMDIST # MEAN DISTANCE FROM EARTH TO MOON
020863,000087: 42,3630 53372 VSL1 VAD
020864,000088: 42,3631 02205 RLM
020865,000089: 42,3632 77650 GOTO
020866,000090: 42,3633 65636 CONV5
020867,000091: 42,3634 77775 CONV4 VLOAD
020868,000092: 42,3635 00001 RATT # UE = -UNIT(RATT) EARTH SPHERE
020869,000093: 42,3636 53401 CONV5 SETPD UNIT # UE = -UNIT((REM)(UEM) + RL) MOON SPHERE
020870,000094: 42,3637 00001 0D # SET PL POINTER TO 0
020871,000095: 42,3640 45076 VCOMP CALL
020872,000096: 42,3641 47541 CDUTRIG # COMPUTE SINES AND COSINES OF CDU ANGLES
020873,000097: 42,3642 76521 MXV VSL1 # TRANSFORM REF. COORDINATE SYSTEM TO
020874,000098: 42,3643 01734 REFSMMAT # STABLE MEMBER B-1 X B-1 X B+1 = B-1
020875,000099: 42,3644 71206 PUSH DLOAD # 8D
020876,000100: 42,3645 06524 HI6ZEROS
020877,000101: 42,3646 02201 STORE PITCHANG
020878,000102: 42,3647 26203 STOVL YAWANG # ZERO OUT ANGLES
020879,000103: 42,3650 77624 CALL
020880,000104: 42,3651 47673 *SMNB*
020881,000105: 42,3652 16205 STODL RLM # PRE-MULTIPLY RLM BY (NBSA) MATRIX(B0)
020882,000106: 42,3653 02207 RLM +2
020883,000107: 42,3654 45206 PUSH DSU
020884,000108: 42,3655 02205 RLM
020885,000109: 42,3656 77605 DMP
020886,000110: 42,3657 25767 1OVSQRT2
020887,000111: 42,3660 16207 STODL RLM +2
020888,000112: 42,3661 41215 DAD DMP
020889,000113: 42,3662 02205 RLM
020890,000114: 42,3663 25767 1OVSQRT2
020891,000115: 42,3664 26205 STOVL RLM # R B-1
020892,000116: 42,3665 02205 RLM
020893,000117: 42,3666 63256 UNIT PDVL
020894,000118: 42,3667 02205 RLM
020895,000119: 42,3670 72431 VPROJ VSL2 # PROJECTION OF R ONTO LM XZ PLANE
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Page 492 |
020897,000121: 42,3671 06520 HIUNITY
020898,000122: 42,3672 40045 BVSU BOV # CLEAR OVERFLOW INDICATOR IF ON
020899,000123: 42,3673 02205 RLM
020900,000124: 42,3674 65675 COVCNV
020901,000125: 42,3675 40056 COVCNV UNIT BOV # EXIT ON OVERFLOW
020902,000126: 42,3676 65743 SBANDEX
020903,000127: 42,3677 47206 PUSH VXV # URP VECTOR B-1
020904,000128: 42,3700 06516 HIUNITZ
020905,000129: 42,3701 57572 VSL1 VCOMP # UZ X URP = -(URP X UZ)
020906,000130: 42,3702 02205 STORE RLM # X VEC B-1
020907,000131: 42,3703 63241 DOT PDVL # SGN(X.UY) UNSCALED
020908,000132: 42,3704 06520 HIUNITY
020909,000133: 42,3705 02205 RLM
020910,000134: 42,3706 75246 ABVAL SIGN
020911,000135: 42,3707 77736 ASIN # ASIN((SGN(X.UY))ABV(X)) REV B0
020912,000136: 42,3710 26201 STOVL PITCHANG
020913,000137: 42,3711 00007 URP
020914,000138: 42,3712 51041 DOT BPL
020915,000139: 42,3713 06516 HIUNITZ
020916,000140: 42,3714 65721 NOADJUST # YES, -90 TO +90
020917,000141: 42,3715 45345 DLOAD DSU
020918,000142: 42,3716 06522 HIDPHALF
020919,000143: 42,3717 02201 PITCHANG
020920,000144: 42,3720 02201 STORE PITCHANG
020921,000145: 42,3721 47375 NOADJUST VLOAD VXV
020922,000146: 42,3722 00001 UR # Z = (UR X URP)
020923,000147: 42,3723 00007 URP
020924,000148: 42,3724 77772 VSL1
020925,000149: 42,3725 16205 STODL RLM # Z VEC B-1
020926,000150: 42,3726 02201 PITCHANG
020927,000151: 42,3727 74356 SIN VXSC
020928,000152: 42,3730 06516 HIUNITZ
020929,000153: 42,3731 71525 PDDL COS
020930,000154: 42,3732 02201 PITCHANG
020931,000155: 42,3733 52361 VXSC VSU
020932,000156: 42,3734 06522 HIUNITX # (UX COS ALPHA) - (UZ SIN ALPHA)
020933,000157: 42,3735 63241 DOT PDVL # YAW.Z
020934,000158: 42,3736 02205 RLM
020935,000159: 42,3737 02205 RLM
020936,000160: 42,3740 75246 ABVAL SIGN
020937,000161: 42,3741 77736 ASIN
020938,000162: 42,3742 02203 STORE YAWANG
020939,000163: 42,3743 77776 SBANDEX EXIT
020940,000164: 42,3744 31043 CA EXTVBACT
020941,000165: 42,3745 74747 MASK BIT5 # IS BIT5 STILL ON
020942,000166: 42,3746 00006 EXTEND
020943,000167: 42,3747 15472 BZF ENDEXT # NO
020944,000168: 42,3750 35017 CAF PRIO5
020945,000169: 42,3751 05146 TC PRIOCHNG
020946,000170: 42,3752 33765 CAF V06N51 # DISPLAY ANGLES
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Page 493 |
020948,000172: 42,3753 04616 TC BANKCALL
020949,000173: 42,3754 20353 CADR GOMARKFR
020950,000174: 42,3755 05563 TC B5OFF # TERMINATE
020951,000175: 42,3756 05563 TC B5OFF # PROCEED
020952,000176: 42,3757 05155 TC ENDOFJOB # RECYCLE
020953,000177: 42,3760 34751 CAF BIT3 # IMMEDIATE RETURN
020954,000178: 42,3761 05464 TC BLANKET # BLANK R3
020955,000179: 42,3762 34740 CAF PRIO4
020956,000180: 42,3763 05146 TC PRIOCHNG
020957,000181: 42,3764 03606 TC SBANDANT # YES, CONTINUE DISPLAYING ANGLES.
020958,000182: 42,3765 01463 V06N51 VN 0651
020959,000183: 42,3766 26501 07463 1OVSQRT2 2DEC .7071067815 # 1/SQRT(2)
020960,000184:
020961,000185: 42,3770 UR EQUALS 0D
020962,000186: 42,3770 URP EQUALS 6D
020963,000187: 42,3770 30,2000 SBANK= LOWSUPER
020964,000188:
End of include-file S-BAND_ANTENNA_FOR_LM.agc. Parent file is MAIN.agc