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. |
008304,000002: ## Copyright: Public domain.
008305,000003: ## Filename: AGS_INITIALIZATION.agc
008306,000004: ## Purpose: A section of Luminary 1C, revision 131.
008307,000005: ## It is part of the source code for the Lunar Module's (LM)
008308,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
008309,000007: ## This file is intended to be a faithful transcription, except
008310,000008: ## that the code format has been changed to conform to the
008311,000009: ## requirements of the yaYUL assembler rather than the
008312,000010: ## original YUL assembler.
008313,000011: ## Reference: pp. 208-212
008314,000012: ## Contact: Ron Burkey <info@sandroid.org>.
008315,000013: ## Website: www.ibiblio.org/apollo/index.html
008316,000014: ## Mod history: 05/05/03 RSB. Began transcribing.
008317,000015: ## 05/14/05 RSB Corrected website reference above.
008318,000016: ## 2017-01-06 RSB Page numbers now agree with those on the
008319,000017: ## original harcopy, as opposed to the PDF page
008320,000018: ## numbers in 1701.pdf.
008321,000019: ## 2017-02-22 RSB Proofed comment text using octopus/ProoferComments.
008322,000020:
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Page 208 |
008324,000022:
008325,000023: # PROGRAM NAME: AGS INITIALIZATION (R47)
008326,000024:
008327,000025: # WRITTEN BY: RHODE/KILROY/FOLLETT
008328,000026:
008329,000027: # MOD NO.: 0
008330,000028: # DATE: 23 MARCH 1967
008331,000029: # MOD BY: KILROY
008332,000030:
008333,000031: # MOD NO.: 1
008334,000032: # DATE: 28 OCTOBER 1967
008335,000033: # MOD BY: FOLLETT
008336,000034:
008337,000035: # FUNCT. DESC.: (1) TO PROVIDE THE AGS ABORT ELECTRONICS ASSEMBLY (AEA) WITH THE LEM AND CSM STATE VECTORS
008338,000036: # (POSITION,VELOCITY,TIME) IN LEM IMU COORDINATES BY MEANS OF THE LGC DIGITAL DOWNLINK.
008339,000037:
008340,000038: # (2) TO ZERO THE ICDU, LGC AND AEA GIMBAL ANGLE COUNTERS SIMULTANEOUSLY IN ORDER TO ESTABLISH A
008341,000039: # COMMON ZERO REFERENCE FOR THE MEASUREMENT OF GIMBAL (EULER) ANGLES WHICH DEFINE LEM ATTITUDE
008342,000040:
008343,000041: # (3) TO ESTABLISH THE GROUND ELAPSED TIME OF AEA CLOCK ZERO. (IF AN AEA CLOCK ZERO IS
008344,000042: # REQUESTED DURING THIS PROGRAM
008345,000043:
008346,000044: # LOG SECTION: AGS INITIALIZATION
008347,000045:
008348,000046: # CALLING SEQ: PROGRAM IS ENTERED WHEN ASTRONAUT KEYS V47E ON DSKY.
008349,000047: # R47 MAY BE CALLED AT ANY TIME EXCEPT WHEN ANOTHER EXTENDED VERB IS IN PROGRESS
008350,000048:
008351,000049: # SUBROUTINES
008352,000050: # CALLED:
008353,000051:
008354,000052: # NORMAL EXIT: ENDEXT
008355,000053:
008356,000054: # ALARM/ABORT: ALARM - BAD REFSMMAT - CODE:220
008357,000055: # OPERATOR ERROR IF V47 SELECTED DURING ANOTHER EXTENDED VERB.
008358,000056:
008359,000057: # ERASABLES
008360,000058: # USED: SAMPTIME (2) TIME OF :ENTER: KEYSTROKE
008361,000059: # AGSK (2) GROUND ELAPSED TIME OF THE AEA CLOCK :ZERO:
008362,000060: # AGSBUFF (140) CONTAINS AGS INITIALIZATION DATA (SEE :OUTPUT: BELOW)
008363,000061: # AGSWORD (1) PREVIOUS DOWNLIST SAVED HERE
008364,000062:
008365,000063: 05,2447 E4,1600 EBANK= AGSBUFF
008366,000064:
008367,000065: 40,2000 BANK 40
008368,000066: 32,2000 SETLOC R47
008369,000067: 32,2000 BANK
008370,000068:
008371,000069: 32,2005 COUNT* $$/R47
008372,000070:
008373,000071: 32,2005 34737 AGSINIT CAF REFSMBIT
008374,000072: 32,2006 70077 MASK FLAGWRD3 # CHECK REFSMFLG.
008375,000073: 32,2007 10000 CCS A
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008377,000075: 32,2010 02017 TC REDSPTEM # REFSMMAT IS OK
008378,000076: 32,2011 05567 TC ALARM # REFSMMAT IS BAD
008379,000077: 32,2012 00220 OCT 220
008380,000078: 32,2013 05472 TC ENDEXT
008381,000079:
008382,000080: 32,2014 00006 NEWAGS EXTEND
008383,000081: 32,2015 30014 DCA SAMPTIME # TIME OF THE :ENTER: KEYSTROKE
008384,000082: 32,2016 53421 DXCH AGSK # BECOMES NEW AEA CLOCK :ZERO:
008385,000083:
008386,000084: 32,2017 00006 REDSPTEM EXTEND
008387,000085: 32,2020 31421 DCA AGSK
008388,000086: 32,2021 53051 DXCH DSPTEMX
008389,000087: 32,2022 32172 AGSDISPK CAF V06N16
008390,000088: 32,2023 04616 TC BANKCALL # R1 = 00XXX. HRS., R2 = 000XX MIN.,
008391,000089: 32,2024 20334 CADR GOMARKF # R3 = 0XX.XX SEC.
008392,000090: 32,2025 05472 TC ENDEXT # TERMINATE RETURN
008393,000091: 32,2026 02036 TC AGSVCALC # PROCEED RETURN
008394,000092: 32,2027 44746 CS BIT6 # IS ENTER VIA A V32
008395,000093: 32,2030 60154 AD MPAC
008396,000094: 32,2031 00006 EXTEND
008397,000095: 32,2032 12014 BZF NEWAGS # YES, USE KEYSTROKE TIME FOR NEW AGSK
008398,000096:
008399,000097: 32,2033 00006 EXTEND # NO, NEW AGSK LOADED VIA V25
008400,000098: 32,2034 31051 DCA DSPTEMX # LOADED INTO DSPTEMX BY KEYING
008401,000099: 32,2035 02016 TC REDSPTEM -1 # V25E FOLLOWED BY HRS.,MINS.,SECS.
008402,000100: # DISPLAY THE NEW K
008403,000101:
008404,000102: 32,2036 06042 AGSVCALC TC INTPRET
008405,000103: 32,2037 77614 SET
008406,000104: 32,2040 01076 NODOFLAG # DONT ALLOW V37
008407,000105: 32,2041 77414 SET EXIT
008408,000106: 32,2042 02076 XDSPFLAG
008409,000107:
008410,000108: 32,2043 32172 CAF V06N16
008411,000109: 32,2044 04616 TC BANKCALL
008412,000110: 32,2045 20621 CADR EXDSPRET
008413,000111:
008414,000112: 32,2046 06042 TC INTPRET # EXTRAPOLATE LEM AND CSM STATE VECTORS
008415,000113: 32,2047 77634 RTB # TO THE PRESENT TIME
008416,000114: 32,2050 21574 LOADTIME # LOAD MPAC WITH TIME2,TIME1
008417,000115: 32,2051 34041 STCALL TDEC1 # CALCULATE LEM STATE VECTOR
008418,000116: 32,2052 27056 LEMPREC
008419,000117: 32,2053 77624 CALL # CALL ROUTINE TO CONVERT TO SM COORDS AND
008420,000118: 32,2054 64132 SCALEVEC # PROVIDE PROPER SCALING
008421,000119: 32,2055 16201 STODL AGSBUFF # (LEMPREC AND CSMPREC LEAVE TDEC1 IN TAT)
008422,000120: 32,2056 00015 TAT # TAT = TIME TO WHICH RATT1 AND VATT1 ARE
008423,000121: 32,2057 34041 STCALL TDEC1 # COMPUTED (CSEC SINCE CLOCK START B-28).
008424,000122: 32,2060 27042 CSMPREC # CALCULATE CSM STATE VECTOR FOR SAME TIME
008425,000123: 32,2061 77624 CALL
008426,000124: 32,2062 64132 SCALEVEC
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008428,000126: 32,2063 16207 STODL AGSBUFF +6
008429,000127: 32,2064 00015 TAT
008430,000128: 32,2065 56225 DSU DDV # CALCULATE AND STORE THE TIME
008431,000129: 32,2066 02021 AGSK
008432,000130: 32,2067 24175 TSCALE
008433,000131: 32,2070 02215 STORE AGSBUFF +12D
008434,000132: 32,2071 77776 EXIT
008435,000133:
008436,000134: 32,2072 34753 CAF LAGSLIST
008437,000135: 32,2073 54333 TS DNLSTCOD
008438,000136:
008439,000137: 32,2074 32176 CAF 20SEC # DELAY FOR 20 SEC WHILE THE AGS
008440,000138: 32,2075 04616 TC BANKCALL # DOWNLIST IS TRANSMITTED
008441,000139: 32,2076 01736 CADR DELAYJOB
008442,000140:
008443,000141: 32,2077 31321 CA AGSWORD
008444,000142: 32,2100 54333 TS DNLSTCOD # RETURN TO THE OLD DOWNLIST
008445,000143: 32,2101 34744 CAF IMUSEBIT
008446,000144: 32,2102 70074 MASK FLAGWRD0 # CHECK IMUSE FLAG.
008447,000145: 32,2103 10000 CCS A
008448,000146: 32,2104 02122 TC AGSEND # IMU IS BEING USED - DO NOT ZERO
008449,000147: 32,2105 11301 CKSTALL CCS IMUCADR # CHECK FOR IMU USAGE WHICH AVOIDS THE
008450,000148: 32,2106 12111 TCF +3 # IMUSE BIT: I.E., IMU COMPENSATION.
008451,000149: 32,2107 12115 TCF +6 # FREE. GO AHEAD WITH THE IMU ZERO.
008452,000150: 32,2110 12111 TCF +1
008453,000151: 32,2111 34363 +3 CAF TEN # WAIT .1 SEC AND TRY AGAIN.
008454,000152: 32,2112 04616 TC BANKCALL
008455,000153: 32,2113 01736 CADR DELAYJOB
008456,000154: 32,2114 12105 TCF CKSTALL
008457,000155:
008458,000156: 32,2115 04616 +6 TC BANKCALL # IMU IS NOT IN USE
008459,000157: 32,2116 16705 CADR IMUZERO # SET IMU ZERO DISCRETE FOR 320 MSECS
008460,000158: 32,2117 04616 TC BANKCALL # WAIT 3SEC FOR COUNTERS TO INCREMENT
008461,000159: 32,2120 17707 CADR IMUSTALL
008462,000160: 32,2121 02122 TC AGSEND
008463,000161: 32,2122 05516 AGSEND TC DOWNFLAG # ALLOW V37
008464,000162: 32,2123 00054 ADRES NODOFLAG
008465,000163:
008466,000164: 32,2124 32173 CAF V50N16
008467,000165: 32,2125 04616 TC BANKCALL
008468,000166: 32,2126 20342 CADR GOMARK3
008469,000167: 32,2127 15472 TCF ENDEXT
008470,000168: 32,2130 15472 TCF ENDEXT
008471,000169: 32,2131 05472 TC ENDEXT
008472,000170:
008473,000171: 32,2132 64375 SCALEVEC VLOAD MXV
008474,000172: 32,2133 00025 VATT1
008475,000173: 32,2134 01734 REFSMMAT
008476,000174: 32,2135 72561 VXSC VSL2
008477,000175: 32,2136 24202 VSCALE
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008479,000177: 32,2137 53255 VAD VAD # THIS SECTION ROUNDS THE VECTOR, AND
008480,000178: 32,2140 24204 AGSRND1 # CORRECTS FOR THE FACT THAT THE AGS
008481,000179: 32,2141 24212 AGSRND2 # IS A 2 S COMPLIMENT MACHINE WHILE THE
008482,000180: 32,2142 77634 RTB # LGC IS A 1 S COMPLIMENT MACHINE.
008483,000181: 32,2143 21773 VECSGNAG
008484,000182: 32,2144 24025 STOVL VATT1
008485,000183: 32,2145 00017 RATT1
008486,000184: 32,2146 74321 MXV VXSC
008487,000185: 32,2147 01734 REFSMMAT
008488,000186: 32,2150 24200 RSCALE
008489,000187: 32,2151 53212 VSL8 VAD # AGAIN THIS SECTION ROUNDS. TWO VECTORS
008490,000188: 32,2152 24204 AGSRND1 # ARE ADDED TO DEFEAT ALSIGNAG IN THE
008491,000189: 32,2153 47055 VAD RTB # CASE OF A HIGH-ORDER ZERO COUPLED WITH
008492,000190: 32,2154 24212 AGSRND2 # A LOW ORDER NEGATIVE PART.
008493,000191: 32,2155 21773 VECSGNAG
008494,000192: 32,2156 77750 LXA,1
008495,000193: 32,2157 00024 VATT1
008496,000194: 32,2160 72130 SXA,1 LXA,1
008497,000195: 32,2161 00155 MPAC +1
008498,000196: 32,2162 00026 VATT1 +2
008499,000197: 32,2163 72130 SXA,1 LXA,1
008500,000198: 32,2164 00160 MPAC +4
008501,000199: 32,2165 00030 VATT1 +4
008502,000200: 32,2166 43530 SXA,1 RVQ
008503,000201: 32,2167 00162 MPAC +6
008504,000202:
008505,000203: 32,2170 4753 LAGSLIST = ONE
008506,000204: 32,2170 00216 V01N14 VN 0114
008507,000205: 32,2171 14400 V50N00A VN 5000
008508,000206: 32,2172 6010 V00N25 EQUALS OCT31
008509,000207: 32,2172 01420 V06N16 VN 0616
008510,000208: 32,2173 4242 V00N34 EQUALS 34DEC
008511,000209: 32,2173 14420 V50N16 VN 5016
008512,000210: 32,2174 03100 00000 TSCALE 2DEC 100 B-10 # CSEC TO SEC SCALE FACTOR
008513,000211: 32,2176 03720 20SEC DEC 2000 B-14
008514,000212: 32,2177 15077 05041 RSCALE 2DEC 3.280839 B-3 # METERS TO FEET SCALE FACTOR
008515,000213: 32,2201 24402 25724 VSCALE 2DEC 3.280839 E2 B-9 # METERS/CS TO FEET/SEC SCALE FACTOR
008516,000214: 32,2203 00000 60000 AGSRND1 2OCT 0000060000
008517,000215: 32,2205 00000 60000 2OCT 0000060000
008518,000216: 32,2207 00000 60000 2OCT 0000060000
008519,000217: 32,2211 00000 37777 AGSRND2 2OCT 0000037777
008520,000218: 32,2213 00000 37777 2OCT 0000037777
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008522,000220: 32,2215 00000 37777 2OCT 0000037777
008523,000221:
008524,000222: 32,2217 30,2000 SBANK= LOWSUPER # FOR SUBSEQUENT LOW 2CADRS.
008525,000223:
End of include-file AGS_INITIALIZATION.agc. Parent file is MAIN.agc