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. |
014024,000002: ## Copyright: Public domain.
014025,000003: ## Filename: R63.agc
014026,000004: ## Purpose: A section of Luminary 1C, revision 131.
014027,000005: ## It is part of the source code for the Lunar Module's (LM)
014028,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
014029,000007: ## This file is intended to be a faithful transcription, except
014030,000008: ## that the code format has been changed to conform to the
014031,000009: ## requirements of the yaYUL assembler rather than the
014032,000010: ## original YUL assembler.
014033,000011: ## Reference: pp. 340-343
014034,000012: ## Contact: Ron Burkey <info@sandroid.org>.
014035,000013: ## Website: www.ibiblio.org/apollo/index.html
014036,000014: ## Mod history: 05/06/03 RSB. Began transcribing.
014037,000015: ## 05/14/05 RSB Corrected website reference above.
014038,000016: ## 2017-01-06 RSB Page numbers now agree with those on the
014039,000017: ## original hardcopy, as opposed to the PDF page
014040,000018: ## numbers in 1701.pdf.
014041,000019: ## 2017-01-26 RSB Back-ported a comment-text fix from Luminary 69.
014042,000020: ## 2017-02-23 RSB Proofed comment text using octopus/ProoferComments.
014043,000021: ## 2017-02-28 RSB Fixed lingering typos.
014044,000022: ## 2017-03-07 RSB Comment-text fixes noted in proofing Luminary 116.
014045,000023:
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Page 340 |
014047,000025: # SUBROUTINE NAME: V89CALL
014048,000026: # MOD NO: 0 DATE: 9 JAN 1968
014049,000027: # MOD BY: DIGITAL DEVEL GROUP LOG SECTION: R63
014050,000028:
014051,000029: # FUNCTIONAL DESCRIPTION:
014052,000030:
014053,000031: # CALLED BY VERB 89 ENTER DURING P00. PRIO 10 USED. CALCULATES AND
014054,000032: # DISPLAYS FINAL FDAI BALL ANGLES TO POINT LM +X OR +Z AXIS AT CSM.
014055,000033:
014056,000034: # 1. KEY IN V 89 E ONLY IF IN PROG 00. IF NOT IN P00, OPERATOR ERROR AND
014057,000035: # EXIT R63, OTHERWISE CONTINUE.
014058,000036:
014059,000037: # 2. IF IN P00, DO IMU STATUS CHECK ROUTINE (R02BOTH). IF IMU ON AND ITS
014060,000038: # ORIENTATION KNOWN TO LGC, CONTINUE.
014061,000039:
014062,000040: # 3. FLASH DISPLAY V 04 N 06. R2 INDICATES WHICH SPACECRAFT AXIS IS TO
014063,000041: # BE POINTED AT CSM. INITIAL CHOICE IS PREFERRED (+Z) AXIS (R2=1).
014064,000042: # ASTRONAUT CAN CHANGE TO (+X) AXIS (R2 NOT =1) BY V 22 E 2 E. CONTINUE
014065,000043: # AFTER KEYING IN PROCEED.
014066,000044:
014067,000045: # 4. BOTH VEHICLE STATE VECTORS UPDATED BY CONIC EQS.
014068,000046:
014069,000047: # 5. HALF MAGNITUDE UNIT LOS VECTOR (IN STABLE MEMBER COORDINATES) AND
014070,000048: # HALF MAGNITUDE UNIT SPACECRAFT AXIS VECTOR (IN BODY COORDINATES)
014071,000049: # PREPARED FOR VECPOINT.
014072,000050:
014073,000051: # 6. GIMBAL ANGLES FROM VECPOINT TRANSFORMED INTO FDAI BALL ANGLES BY
014074,000052: # BALLANGS. FLASH DISPLAY V 06 N 18 AND AWAIT RESPONSE.
014075,000053:
014076,000054: # 7. RECYCLE - RETURN TO STEP 4.
014077,000055: # TERMINATE - EXIT R63.
014078,000056: # PROCEED - RESET 3AXISFLG AND CALL R60LEM FOR ATTITUDE MANEUVER.
014079,000057:
014080,000058: # CALLING SEQUENCE: V 89 E.
014081,000059:
014082,000060: # SUBROUTINES CALLED: CHKPOOH, R02BOTH, GOXDSPF, CSMCONIC, LEMCONIC,
014083,000061: # VECPOINT, BALLANGS, R60LEM.
014084,000062:
014085,000063: # NORMAL EXIT MODES: TC ENDEXT
014086,000064:
014087,000065: # ALARMS: 1. OPERATOR ERROR IF NOT IN P00.
014088,000066: # 2. PROGRAM ALARM IF IMU IS OFF.
014089,000067: # 3. PROGRAM ALARM IF IMU ORIENTATION IS UNKNOWN.
014090,000068:
014091,000069: # OUTPUT: NONE
014092,000070:
014093,000071: # ERASABLE INITIALIZATION REQUIRED: NONE
014094,000072:
014095,000073: # DEBRIS: OPTION1, +1, TDEC1, POINTVSM, SCAXIS, CPHI, CTHETA, CPSI,
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Page 341 |
014097,000075: # 3AXISFLG.
014098,000076:
014099,000077: 06,3723 E4,1606 EBANK= RONE
014100,000078: 32,2217 BANK 32
014101,000079: 26,2000 SETLOC BAWLANGS
014102,000080: 26,2000 BANK
014103,000081:
014104,000082: 26,2022 COUNT* $$/R63
014105,000083: 26,2022 04616 V89CALL TC BANKCALL # IMU STATUS CHECK. RETURNS IF ORIENTATION
014106,000084: 26,2023 11233 CADR R02BOTH # KNOWN. ALARMS IF NOT.
014107,000085: 26,2024 36250 CAF THREE # ALLOW ASTRONAUT TO SELECT DESIRED
014108,000086: 26,2025 55050 TS OPTIONX # TRACKING ATTITUDE AXIS.
014109,000087: 26,2026 34753 CAF ONE
014110,000088: 26,2027 55051 TS OPTIONX +1
014111,000089: 26,2030 32117 CAF VB04N12 # V 04 N 12
014112,000090: 26,2031 04616 TC BANKCALL
014113,000091: 26,2032 20477 CADR GOFLASH
014114,000092: 26,2033 05472 TC ENDEXT # TERMINATE
014115,000093: 26,2034 02036 TC +2 # PROCEED
014116,000094: 26,2035 02030 TC -5 # DATA IN. OPTION1+1 = 1 FOR Z AXIS
014117,000095: 26,2036 06042 V89RECL TC INTPRET # = 2 FOR X AXIS
014118,000096: 26,2037 43234 RTB DAD
014119,000097: 26,2040 21574 LOADTIME # READ PRESENT TIME
014120,000098: 26,2041 14122 DP1MIN
014121,000099: 26,2042 02205 STORE TSTART82 # SAVE TIME FOR LEMCONIC CALL
014122,000100: 26,2043 34041 STCALL TDEC1 # STORE TIME FOR CSMCONIC CALL
014123,000101: 26,2044 27065 CSMCONIC # CSM STATE VECTOR UPDATE
014124,000102: 26,2045 77775 VLOAD # CSMCONIC LEFT R VECTOR IN RATT
014125,000103: 26,2046 00001 RATT
014126,000104: 26,2047 16207 STODL RONE # SAVE FOR LINE OF SIGHT (LOS) COMPUTATION
014127,000105: 26,2050 02205 TSTART82
014128,000106: 26,2051 34041 STCALL TDEC1 # STORE TIME FOR LEMCONIC CALL
014129,000107: 26,2052 27077 LEMCONIC # LEM STATE VECTOR UPDATE
014130,000108: 26,2053 52375 VLOAD VSU # CSM POSITION - LEM POSITION = LOS
014131,000109: 26,2054 02207 RONE # LOS VECTOR LEFT IN MPAC
014132,000110: 26,2055 00001 RATT
014133,000111: 26,2056 47121 MXV RTB # (REFSMMAT X LOS). TRANSFORMS LOS FROM
014134,000112: 26,2057 01734 REFSMMAT # REFERENCE COORD TO STAB MEMB COORD.
014135,000113: 26,2060 21727 NORMUNIT
014136,000114: 26,2061 03773 STORE POINTVSM # STORE LOS FOR VECPOINT CALL
014137,000115: 26,2062 77776 EXIT
014138,000116: 26,2063 41051 CS OPTIONX +1 # 1 FOR Z AXIS. 2 FOR X AXIS.
014139,000117: 26,2064 64753 AD ONE
014140,000118: 26,2065 00006 EXTEND
014141,000119: 26,2066 12113 BZF ALINEZ
014142,000120: 26,2067 06042 ALINEX TC INTPRET # X AXIS ALIGNMENT
014143,000121: 26,2070 77775 VLOAD
014144,000122: 26,2071 06522 UNITX # READ (.5, 0, 0)
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Page 342 |
014146,000124: 26,2072 37765 V89CALL1 STCALL SCAXIS # STORE SELECTED ALIGNMENT AXIS
014147,000125: 26,2073 56040 VECPOINT # PUTS DESIRED GIM ANG (OG,IG,MG) IN TMPAC
014148,000126: 26,2074 00322 STORE CPHI # STORE GIMBAL ANGLES FOR BALLANGS CALL.
014149,000127: 26,2075 77776 EXIT
014150,000128: 26,2076 04616 TC BANKCALL
014151,000129: 26,2077 54272 CADR BALLANGS # PUTS DESIRED BALL ANGLES IN FDAIX,Y,Z
014152,000130: 26,2100 32120 CAF VB06N18 # V 06 N 18
014153,000131: 26,2101 04616 TC BANKCALL # NOUN 18 REFERS TO FDAIX,Y,Z
014154,000132: 26,2102 20477 CADR GOFLASH
014155,000133: 26,2103 05472 TC ENDEXT # TERMINATE
014156,000134: 26,2104 02106 TC +2 # PROCEED
014157,000135: 26,2105 02036 TC V89RECL # RECYCLE
014158,000136: 26,2106 05516 TC DOWNFLAG # RESET 3 AXIS FLAG
014159,000137: 26,2107 00124 ADRES 3AXISFLG # RESET BIT6 FLAG WORD 5
014160,000138: 26,2110 04616 TC BANKCALL # PERFORMS LEM MANEUVER TO ALIGN SELECTED
014161,000139: 26,2111 54123 CADR R60LEM # SPACECRAFT AXIS TO CSM.
014162,000140: 26,2112 15472 TCF ENDEXT # TERMINATE R63
014163,000141:
014164,000142: 26,2113 06042 ALINEZ TC INTPRET # Z AXIS ALIGNMENT
014165,000143: 26,2114 52175 VLOAD GOTO
014166,000144: 26,2115 06516 UNITZ # READ (0, 0, .5)
014167,000145: 26,2116 54072 V89CALL1
014168,000146:
014169,000147: 26,2117 01014 VB04N12 VN 412
014170,000148: 26,2120 01422 VB06N18 VN 0618
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Page 343 |
014172,000150: 26,2121 00000 13560 DP1MIN 2DEC 6000 B-28
014173,000151:
End of include-file R63.agc. Parent file is MAIN.agc