Source Code
|
This is a reconstruction of the AGC program Luminary 99 Rev 0. It was the third release
of the Lunar Module flight software targeted for use in Apollo 11, after Luminary 96 and 97.
A bug (which had been around since at least Apollo 10, Luminary 69) was
discovered in Rev 0 shortly before the Apollo 11 flight, resulting in a last minute
revision into Rev 1,
which is what actually flew rather than
the Rev 0 presented here. A hardcopy of Rev 0 is known to
exist — it belonged to AGC developer Allan Klumpp for many years — but
unfortunately the Virtual AGC Project has not had access to that hardcopy. Thus
the code you see here had been reconstructed (we believe accurately) rather than
transcribed. The first step of the reconstruction of the Rev 0 source code was
the transcription of the Rev 1 source code from a hardcopy in the MIT Museum collection.
The process of reverting the active portion of the source code (i.e., other than
program comments) from Rev 1 to Rev 0 was very minor, consisting
only of moving the position of the STARTSB1 label in
FRESH START AND RESTART. Allan had previously given
us the checksums of the memory banks of Rev 0, and we have verified the program presented here has checksums
identical to all banks of Allan's listing of Rev 0. The notations on Allan's Rev 0 program listing read,
in part:GAP: ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-051 A single program comment is known to differ between Rev 0 and Rev 1, but these are harder to reconstruct and verify than changes to the active portion of the code. Thus it is possible that there are additional differences between the program comments in Rev 0 and Rev 1 that are unknown to us, and therefore are not reflected in the code presented here. |
035072,000002: ## Copyright: Public domain.
035073,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
035074,000004: ## Purpose: Part of the reconstructed source code for LMY99 Rev 0,
035075,000005: ## otherwise known as Luminary Rev 99, the third release
035076,000006: ## of the Apollo Guidance Computer (AGC) software for Apollo 11.
035077,000007: ## It differs from LMY99 Rev 1 (the flown version) only in the
035078,000008: ## placement of a single label. The corrections shown here have
035079,000009: ## been verified to have the same bank checksums as AGC developer
035080,000010: ## Allan Klumpp's copy of Luminary Rev 99, and so are believed
035081,000011: ## to be accurate. This file is intended to be a faithful
035082,000012: ## recreation, except that the code format has been changed to
035083,000013: ## conform to the requirements of the yaYUL assembler rather than
035084,000014: ## the original YUL assembler.
035085,000015: ##
035086,000016: ## Assembler: yaYUL
035087,000017: ## Contact: HARTMUTH GUTSCHE <hgutsche@xplornet.com>.
035088,000018: ## Website: www.ibiblio.org/apollo.
035089,000019: ## Pages: 793-797
035090,000020: ## Mod history: 2009-05-20 HG Transcribed from page images.
035091,000021: ## 2010-12-31 JL Fixed page number comments.
035092,000022: ## 2016-12-16 RSB Proofed text comments with octopus/ProoferComments
035093,000023: ## and corrected the errors found.
035094,000024: ## 2017-03-16 RSB Comment-text fixes identified in 5-way
035095,000025: ## side-by-side diff of Luminary 69/99/116/131/210.
035096,000026: ## 2017-08-01 MAS Created from LMY99 Rev 1.
035097,000027:
035098,000028: ## This source code has been transcribed or otherwise adapted from
035099,000029: ## digitized images of a hardcopy from the MIT Museum. The digitization
035100,000030: ## was performed by Paul Fjeld, and arranged for by Deborah Douglas of
035101,000031: ## the Museum. Many thanks to both. The images (with suitable reduction
035102,000032: ## in storage size and consequent reduction in image quality as well) are
035103,000033: ## available online at www.ibiblio.org/apollo. If for some reason you
035104,000034: ## find that the images are illegible, contact me at info@sandroid.org
035105,000035: ## about getting access to the (much) higher-quality images which Paul
035106,000036: ## actually created.
035107,000037: ##
035108,000038: ## The code has been modified to match LMY99 Revision 0, otherwise
035109,000039: ## known as Luminary Revision 99, the Apollo 11 software release preceeding
035110,000040: ## the listing from which it was transcribed. It has been verified to
035111,000041: ## contain the same bank checksums as AGC developer Allan Klumpp's listing
035112,000042: ## of Luminary Revision 99 (for which we do not have scans).
035113,000043: ##
035114,000044: ## Notations on Allan Klumpp's listing read, in part:
035115,000045: ##
035116,000046: ## ASSEMBLE REVISION 099 OF AGC PROGRAM LUMINARY BY NASA 2021112-51
035117,000047:
|
|
Page 793 |
035119,000049: 31,2216 BANK 31
035120,000050: 31,2000 SETLOC FTHROT
035121,000051: 31,2000 BANK
035122,000052: 31,2216 E7,1612 EBANK= PIF
035123,000053: 31,2216 COUNT* $$/THROT
035124,000054:
035125,000055: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
035126,000056: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
035127,000057:
035128,000058: 31,2216 31246 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
035129,000059: 31,2217 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
035130,000060: 31,2220 72417 MP /AF/CNST
035131,000061: 31,2221 00006 +3 EXTEND
035132,000062: 31,2222 23607 QXCH RTNHOLD
035133,000063: 31,2223 02400 AFDUMP TC MASSMULT
035134,000064: 31,2224 53470 DXCH FP # FP = PRESENT THRUST
035135,000065: 31,2225 00006 EXTEND
035136,000066: 31,2226 31464 DCA /AFC/
035137,000067: 31,2227 02400 TC MASSMULT
035138,000068: 31,2230 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
035139,000069: 31,2231 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
035140,000070:
035141,000071: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
035142,000072:
035143,000073: 31,2232 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
035144,000074: 31,2233 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
035145,000075: 31,2234 74733 MASK POSMAX
035146,000076: 31,2235 40000 COM
035147,000077: 31,2236 65002 AD 3SECS
035148,000078: 31,2237 00006 EXTEND
035149,000079: 31,2240 62244 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
035150,000080: 31,2241 00006 EXTEND
035151,000081: 31,2242 31611 DCA FWEIGHT
035152,000082: 31,2243 21470 DAS FP
035153,000083:
035154,000084: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
035155,000085: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
035156,000086: # PROVIDES THE UPPER.
035157,000087:
035158,000088: 31,2244 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
035159,000089: 31,2245 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
|
|
Page 794 |
035161,000091: 31,2246 E5,1506 EBANK= LOWCRIT
035162,000092: 31,2246 00006 EXTEND
035163,000093: 31,2247 31507 DCA LOWCRIT
035164,000094: 31,2250 52131 DXCH L*WCR*T
035165,000095: 31,2251 35016 CA EBANK7
035166,000096: 31,2252 54003 TS EBANK
035167,000097: 31,2253 E7,1612 EBANK= PIF
035168,000098: 31,2253 44755 CS ZERO # INITIALIZE PIFPSET
035169,000099: 31,2254 55606 TS PIFPSET
035170,000100: 31,2255 40131 CS H*GHCR*T
035171,000101: 31,2256 61620 AD FCOLD
035172,000102: 31,2257 00006 EXTEND
035173,000103: 31,2260 62272 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
035174,000104: 31,2261 40130 CS L*WCR*T
035175,000105: 31,2262 61465 AD FCODD
035176,000106: 31,2263 00006 EXTEND
035177,000107: 31,2264 62267 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
035178,000108: 31,2265 31467 CA FP # SEE NOTE 1
035179,000109: 31,2266 12277 TCF FLATOUT1
035180,000110:
035181,000111: 31,2267 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
035182,000112: 31,2270 61467 AD FP
035183,000113: 31,2271 12301 TCF FLATOUT2
035184,000114:
035185,000115: 31,2272 40131 LOWFCOLD CS H*GHCR*T
035186,000116: 31,2273 61465 AD FCODD
035187,000117: 31,2274 00006 EXTEND
035188,000118: 31,2275 62302 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
035189,000119:
035190,000120: 31,2276 32003 CA FMAXPOS # NO: THROTTLE-UP
035191,000121: 31,2277 53466 FLATOUT1 DXCH FCODD
035192,000122: 31,2300 34737 CA FEXTRA
035193,000123: 31,2301 55606 FLATOUT2 TS PIFPSET
035194,000124:
035195,000125: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
035196,000126: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
035197,000127:
035198,000128: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
035199,000129: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
035200,000130: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
035201,000131: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
035202,000132: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
035203,000133: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
035204,000134:
035205,000135: 31,2302 03740 DOPIF TC FASTCHNG
035206,000136: 31,2303 00006 EXTEND
035207,000137: 31,2304 31466 DCA FCODD
035208,000138: 31,2305 55620 TS FCOLD
035209,000139: 31,2306 53613 DXCH PIF
035210,000140: 31,2307 00006 EXTEND
|
|
Page 795 |
035212,000142: 31,2310 41470 DCS FP
035213,000143: 31,2311 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
035214,000144:
035215,000145: 31,2312 31612 DOIT CA PIF
035216,000146: 31,2313 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
035217,000147: 31,2314 55614 TS PSEUDO55
035218,000148: 31,2315 54055 TS THRUST
035219,000149: 31,2316 34750 CAF BIT4
035220,000150: 31,2317 00006 EXTEND
035221,000151: 31,2320 05014 WOR CHAN14
035222,000152: 31,2321 30025 CA TIME1
035223,000153: 31,2322 55617 TS TTHROT
035224,000154:
035225,000155: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
035226,000156: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
035227,000157: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
035228,000158:
035229,000159: # PIF(PPROCESS + TL) PIF /PIF/
035230,000160: # FWEIGHT = ------------------ + -------------
035231,000161: # PGUID 2 PGUID FRATE
035232,000162:
035233,000163: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
035234,000164: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
035235,000165: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
035236,000166:
035237,000167: 31,2323 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
035238,000168: 31,2324 54130 TS BUF
035239,000169:
035240,000170: 31,2325 41011 CS MODREG # ARE WE IN FACT IN P66?
035241,000171: 31,2326 62501 AD DEC66
035242,000172: 31,2327 00006 EXTEND
035243,000173: 31,2330 12335 BZF FWCOMP # YES
035244,000174:
035245,000175: 31,2331 31235 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
035246,000176: 31,2332 54130 TS BUF
035247,000177: 31,2333 35003 CAF 4SECS
035248,000178: 31,2334 12336 TCF FWCOMP +1
035249,000179:
035250,000180: 31,2335 35000 FWCOMP CAF 2SECS
035251,000181: 31,2336 54002 +1 TS Q
035252,000182: 31,2337 00006 EXTEND
035253,000183: 31,2340 74746 MP BIT6
035254,000184: 31,2341 22131 LXCH BUF +1
035255,000185: 31,2342 40130 CS BUF # TIME OF LAST PIPA READING.
035256,000186: 31,2343 60025 AD TIME1
035257,000187: 31,2344 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
035258,000188: 31,2345 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
035259,000189: 31,2346 22007 ZL
035260,000190: 31,2347 00006 EXTEND
|
|
Page 796 |
035262,000192: 31,2350 10002 DV Q
035263,000193: 31,2351 00006 EXTEND
035264,000194: 31,2352 71612 MP PIF
035265,000195: 31,2353 60000 DOUBLE
035266,000196: 31,2354 53611 DXCH FWEIGHT
035267,000197: 31,2355 11612 CCS PIF
035268,000198: 31,2356 64753 AD ONE
035269,000199: 31,2357 12361 TCF +2
035270,000200: 31,2360 64753 AD ONE
035271,000201: 31,2361 00006 EXTEND
035272,000202: 31,2362 71612 MP PIF
035273,000203: 31,2363 00006 EXTEND
035274,000204: 31,2364 10131 DV BUF +1
035275,000205: 31,2365 22007 ZL
035276,000206: 31,2366 21611 DAS FWEIGHT
035277,000207:
035278,000208: 31,2367 01607 THDUMP TC RTNHOLD
035279,000209:
035280,000210: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
035281,000211:
035282,000212: 31,2370 34737 FLATOUT CAF BIT13 # 4096 PULSES
035283,000213: 31,2371 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
035284,000214: 31,2372 44755 CS ZERO
035285,000215: 31,2373 55620 TS FCOLD
035286,000216: 31,2374 55612 TS PIF
035287,000217: 31,2375 00006 EXTEND
035288,000218: 31,2376 23607 QXCH RTNHOLD
035289,000219: 31,2377 12312 TCF DOIT
035290,000220:
035291,000221: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
035292,000222:
035293,000223: 31,2400 00006 MASSMULT EXTEND
035294,000224: 31,2401 22130 QXCH BUF
035295,000225: 31,2402 52155 DXCH MPAC
035296,000226: 31,2403 07103 TC DMP
035297,000227: 31,2404 01244 ADRES MASS
035298,000228: 31,2405 07103 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
035299,000229: 31,2406 02005 ADRES SCALEFAC
035300,000230: 31,2407 07257 TC TPAGREE
035301,000231: 31,2410 30154 CA MPAC
035302,000232: 31,2411 00006 EXTEND
035303,000233: 31,2412 12415 BZF +3
035304,000234: 31,2413 34733 CAF POSMAX
035305,000235: 31,2414 00130 TC BUF
035306,000236: 31,2415 52156 DXCH MPAC +1
035307,000237: 31,2416 00130 TC BUF
|
|
Page 797 |
035309,000239: # CONSTANTS:-
035310,000240:
035311,000241: 31,2417 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
035312,000242:
035313,000243: 31,2417 04143 /AF/CNST DEC .13107
035314,000244:
035315,000245: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc