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. |
027871,000002: ## Copyright: Public domain.
027872,000003: ## Filename: GROUND_TRACKING_DETERMINATION_PROGRAM.agc
027873,000004: ## Purpose: A section of Luminary 1C, revision 131.
027874,000005: ## It is part of the source code for the Lunar Module's (LM)
027875,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
027876,000007: ## This file is intended to be a faithful transcription, except
027877,000008: ## that the code format has been changed to conform to the
027878,000009: ## requirements of the yaYUL assembler rather than the
027879,000010: ## original YUL assembler.
027880,000011: ## Reference: pp. 656-659
027881,000012: ## Contact: Ron Burkey <info@sandroid.org>.
027882,000013: ## Website: www.ibiblio.org/apollo/index.html
027883,000014: ## Mod history: 05/21/03 RSB. Began transcribing.
027884,000015: ## 05/14/05 RSB Corrected website reference above.
027885,000016: ## 2017-01-06 RSB Page numbers now agree with those on the
027886,000017: ## original harcopy, as opposed to the PDF page
027887,000018: ## numbers in 1701.pdf.
027888,000019: ## 2017-02-24 RSB Proofed comment text using octopus/ProoferComments.
027889,000020: ## 2017-03-01 RSB Fixed a couple comment-text errors found while
027890,000021: ## diff'ing vs Luminary 116.
027891,000022:
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Page 656 |
027893,000024: # GROUND TRACKING DETERMINATION PROGRAM P21
027894,000025:
027895,000026: # PROGRAM DESCRIPTION
027896,000027: # MOD NO - 1
027897,000028: # MOD BY - N. M. NEVILLE
027898,000029:
027899,000030: # FUNCTIONAL DECRIPTION -
027900,000031: # TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
027901,000032: # THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
027902,000033:
027903,000034: # CALLING SEQUENCE -
027904,000035: # ASTRONAUT REQUEST THROUGH DSKY V37E21E
027905,000036:
027906,000037: # SUBROUTINES CALLED -
027907,000038: # GOPERF4
027908,000039: # GOFLASH
027909,000040: # THISPREC
027910,000041: # OTHPREC
027911,000042: # LAT-LONG
027912,000043:
027913,000044: # NORMAL EXIT MODES -
027914,000045: # ASTRONAUT REQUEST TROUGH DSKY TO TERMINATE PROGRAM V34E
027915,000046:
027916,000047: # ALARM OR ABORT EXIT MODES -
027917,000048: # NONE
027918,000049:
027919,000050: # OUTPUT -
027920,000051: # OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
027921,000052: # COMPUTED
027922,000053: # OPTION CODE 00002
027923,000054: # THIS 00001
027924,000055: # OTHER 00002
027925,000056: # DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS, MINUTES, SECONDS
027926,000057: # DECIMAL DISPLAY OF LAT,LONG,ALT
027927,000058:
027928,000059: # ERASABLE INITIALIZATION REQUIRED
027929,000060: # AX0 2DEC 4.652459653 E-5 RADIANS %68-69 CONSTANTS"
027930,000061: # -AY0 2DEC 2.147535898 E-5 RADIANS
027931,000062: # AZ0 2DEC .7753206164 REVOLUTIONS
027932,000063: # FOR LUNAR ORBITS 504LM VECTOR IS NEEDED
027933,000064: # 504LM 2DEC -2.700340600 E-5 RADIANS
027934,000065: # 504LM _2 2DEC -7.514128400 E-4 RADIANS
027935,000066: # 504LM _4 2DEC _2.553198641 E-4 RADIANS
027936,000067:
027937,000068: # NONE
027938,000069: # DEBRIS
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Page 657 |
027940,000071: # CENTRALS - A,Q,L
027941,000072: # OTHER - THOSE USED BY THE ABOVE LISTED SUBROUTINES
027942,000073: # SEE LEMPREC, LAT-LONG
027943,000074:
027944,000075: 35,2455 30,2000 SBANK= LOWSUPER # FOR LOW 2CADR'S.
027945,000076:
027946,000077: 33,2200 BANK 33
027947,000078: 24,2000 SETLOC P20S
027948,000079: 24,2000 BANK
027949,000080:
027950,000081: 24,3506 E7,1762 EBANK= P21TIME
027951,000082: 24,3506 COUNT* $$/P21
027952,000083: 24,3506 34753 PROG21 CAF ONE
027953,000084: 24,3507 55144 TS OPTION2 # ASSUMED VEHICLE IS LM, R2 = 00001
027954,000085: 24,3510 34752 CAF BIT2 # OPTION 2
027955,000086: 24,3511 04616 TC BANKCALL
027956,000087: 24,3512 20634 CADR GOPERF4
027957,000088: 24,3513 06001 TC GOTOPOOH # TERMINATE
027958,000089: 24,3514 03516 TC +2 # PROCEED VALUE OF ASSUMED VEHICLE OK
027959,000090: 24,3515 03510 TC -5 # R2 LOADED THROUGH DSKY
027960,000091: 24,3516 34755 CAF ZERO # INITIAL TIME = PRESENT TIME
027961,000092: 24,3517 55044 TS DSPTEM1
027962,000093: 24,3520 55045 TS DSPTEM1 +1
027963,000094: 24,3521 33675 P21PROG1 CAF V6N34 # LOAD DESIRED TIME OF LAT-LONG.
027964,000095: 24,3522 04616 TC BANKCALL
027965,000096: 24,3523 20477 CADR GOFLASH
027966,000097: 24,3524 06001 TC GOTOPOOH # TERM
027967,000098: 24,3525 03527 TC +2 # PROCEED VALUES OK
027968,000099: 24,3526 03521 TC -5 # TIME LOADED THROUGH DSKY
027969,000100: 24,3527 06042 TC INTPRET
027970,000101: 24,3530 53145 DLOAD BZE
027971,000102: 24,3531 01045 DSPTEM1
027972,000103: 24,3532 51667 P21PRTM
027973,000104: 24,3533 34041 P21PROG2 STCALL TDEC1 # INTEG TO TIME SPECIFIED IN TDEC1
027974,000105: 24,3534 27410 INTSTALL
027975,000106: 24,3535 43014 BON CLEAR
027976,000107: 24,3536 00304 P21FLAG
027977,000108: 24,3537 51555 P21CONT # ON---RECYCLE USING BASE VECTOR
027978,000109: 24,3540 01674 VINTFLAG # OFF--1ST PASS CALL BASE VECTOR
027979,000110: 24,3541 70535 SLOAD SR1
027980,000111: 24,3542 01145 OPTION2
027981,000112: 24,3543 43030 BHIZ SET
027982,000113: 24,3544 51546 +2 # ZERO--THIS VEHICLE (LM)
027983,000114: 24,3545 01474 VINTFLAG # ONE--OTHER VEHICLE (CM)
027984,000115: 24,3546 43014 CLEAR CLEAR
027985,000116: 24,3547 01676 DIM0FLAG
027986,000117: 24,3550 01673 INTYPFLG # PRECISION
027987,000118: 24,3551 77624 CALL
027988,000119: 24,3552 27133 INTEGRV # CALCULATE
027989,000120: 24,3553 77650 GOTO # -AND
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Page 658 |
027991,000122: 24,3554 51576 P21VSAVE # -SAVE BASE VECTOR
027992,000123: 24,3555 77775 P21CONT VLOAD
027993,000124: 24,3556 03676 P21BASER # RECYCLE--INTEG FROM BASE VECTOR
027994,000125: 24,3557 25535 STOVL RCV # --POS
027995,000126: 24,3560 03704 P21BASEV
027996,000127: 24,3561 15543 STODL VCV # --VEL
027997,000128: 24,3562 03763 P21TIME
027998,000129: 24,3563 01517 STORE TET # --TIME
027999,000130: 24,3564 43014 CLEAR CLEAR
028000,000131: 24,3565 01676 DIM0FLAG
028001,000132: 24,3566 00263 MOONFLAG
028002,000133: 24,3567 53135 SLOAD BZE
028003,000134: 24,3570 01163 P21ORIG
028004,000135: 24,3571 51574 +3 # ZERO = EARTH
028005,000136: 24,3572 77614 SET # ---2 = MOON
028006,000137: 24,3573 00063 MOONFLAG
028007,000138: 24,3574 77624 +3 CALL
028008,000139: 24,3575 27106 INTEGRVS
028009,000140: 24,3576 77745 P21VSAVE DLOAD # SAVE CURRENT BASE VECTOR
028010,000141: 24,3577 00015 TAT
028011,000142: 24,3600 27763 STOVL P21TIME # --TIME
028012,000143: 24,3601 00017 RATT1
028013,000144: 24,3602 27676 STOVL P21BASER # --POS B-29 OR B-27
028014,000145: 24,3603 00025 VATT1
028015,000146: 24,3604 03704 STORE P21BASEV # --VEL B-07 OR B-05
028016,000147: 24,3605 53646 ABVAL SL*
028017,000148: 24,3606 57576 0,2
028018,000149: 24,3607 27712 STOVL P21VEL # VEL/ FOR N91 DISP
028019,000150: 24,3610 00001 RATT
028020,000151: 24,3611 50256 UNIT DOT
028021,000152: 24,3612 00007 VATT # U(R).V
028022,000153: 24,3613 67471 DDV ASIN # U(R).U(V)
028023,000154: 24,3614 03712 P21VEL
028024,000155: 24,3615 03714 STORE P21GAM # SIN-1 U(R).U(V) , -90 TO &90
028025,000156: 24,3616 67334 SXA,2 SLOAD
028026,000157: 24,3617 01162 P21ORIG # 0 = EARTH
028027,000158: 24,3620 01145 OPTION2
028028,000159: 24,3621 46142 SR1 BHIZ
028029,000160: 24,3622 51625 +3
028030,000161: 24,3623 77650 GOTO
028031,000162: 24,3624 51630 +4
028032,000163: 24,3625 77614 +3 BON
028033,000164: 24,3626 04307 SURFFLAG
028034,000165: 24,3627 51632 P21DSP
028035,000166: 24,3630 77614 +4 SET
028036,000167: 24,3631 00064 P21FLAG
028037,000168: 24,3632 67214 P21DSP CLEAR SLOAD # GENERATE DISPLAY DATA
028038,000169: 24,3633 01663 LUNAFLAG
028039,000170: 24,3634 00050 X2
028040,000171: 24,3635 43054 BZE SET
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Page 659 |
028042,000173: 24,3636 51640 +2 # 0 = EARTH
028043,000174: 24,3637 01463 LUNAFLAG
028044,000175: 24,3640 77775 VLOAD
028045,000176: 24,3641 00001 RATT
028046,000177: 24,3642 16032 STODL ALPHAV
028047,000178: 24,3643 00015 TAT
028048,000179: 24,3644 45014 CLEAR CALL
028049,000180: 24,3645 00662 ERADFLAG
028050,000181: 24,3646 26347 LAT-LONG
028051,000182: 24,3647 77605 DMP # MPAC = ALT, METERS B-29
028052,000183: 24,3650 11677 K.01
028053,000184: 24,3651 03716 STORE P21ALT # ALT/100 FOR N91 DISP
028054,000185: 24,3652 77776 EXIT
028055,000186: 24,3653 33674 CAF V06N43 # DISPLAY LAT, LONG, ALT
028056,000187: 24,3654 04616 TC BANKCALL # LAT, LONG = 1/2 REVS B0
028057,000188: 24,3655 20477 CADR GOFLASH # ALT = KM B14
028058,000189: 24,3656 06001 TC GOTOPOOH # TERM
028059,000190: 24,3657 06001 TC GOTOPOOH
028060,000191: 24,3660 06042 TC INTPRET # V32E RECYCLE
028061,000192: 24,3661 43345 DLOAD DAD
028062,000193: 24,3662 03763 P21TIME
028063,000194: 24,3663 11673 600SEC # 600 SECONDS OR 10 MIN
028064,000195: 24,3664 01045 STORE DSPTEM1
028065,000196: 24,3665 77634 RTB
028066,000197: 24,3666 51521 P21PROG1
028067,000198: 24,3667 52034 P21PRTM RTB GOTO
028068,000199: 24,3670 21574 LOADTIME
028069,000200: 24,3671 51533 P21PROG2
028070,000201: 24,3672 00003 25140 600SEC 2DEC 60000 B-28 # 10 MIN
028071,000202:
028072,000203: 24,3674 01453 V06N43 VN 00643
028073,000204: 24,3675 01442 V6N34 VN 00634
028074,000205: 24,3676 00243 32703 K.01 2DEC .01
028075,000206:
End of include-file GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc. Parent file is MAIN.agc