GAP: ASSEMBLE REVISION 001 OF AGC PROGRAM LMY99 BY NASA 2021112-061 16:27 JULY 14,1969Note that the date is the date of the printout, not the date of the program revision.
Source Code
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These source-code files were from the printout at the MIT Museum, with many thanks
to Deborah Douglas, the Museum's Curator of Science and Technology, for releasing
it to us. The printout was digitally photographed by Paul Fjeld. A team of
volunteers transcribed the source code manually from these images or, where
appropriate, modified already-transcribed but similar source Luminary 131 (Apollo 13)
source code to agree with the images from the printout. Note that the page images
presented online are of reduced quality, and that higher-quality images
are available. Report any conversion errors or legibility
problems in page images to info@sandroid.org.
Notations on the program listing read, in part:GAP: ASSEMBLE REVISION 001 OF AGC PROGRAM LMY99 BY NASA 2021112-061 16:27 JULY 14,1969Note that the date is the date of the printout, not the date of the program revision. |
034440,000002: ## Copyright: Public domain.
034441,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
034442,000004: ## Purpose: Part of the source code for Luminary 1A build 099.
034443,000005: ## It is part of the source code for the Lunar Module's (LM)
034444,000006: ## Apollo Guidance Computer (AGC), for Apollo 11.
034445,000007: ## Assembler: yaYUL
034446,000008: ## Contact: HARTMUTH GUTSCHE <hgutsche@xplornet.com>.
034447,000009: ## Website: www.ibiblio.org/apollo.
034448,000010: ## Pages: 793-797
034449,000011: ## Mod history: 2009-05-20 HG Transcribed from page images.
034450,000012: ## 2010-12-31 JL Fixed page number comments.
034451,000013: ## 2016-12-16 RSB Proofed text comments with octopus/ProoferComments
034452,000014: ## and corrected the errors found.
034453,000015: ## 2017-03-16 RSB Comment-text fixes identified in 5-way
034454,000016: ## side-by-side diff of Luminary 69/99/116/131/210.
034455,000017:
034456,000018: ## This source code has been transcribed or otherwise adapted from
034457,000019: ## digitized images of a hardcopy from the MIT Museum. The digitization
034458,000020: ## was performed by Paul Fjeld, and arranged for by Deborah Douglas of
034459,000021: ## the Museum. Many thanks to both. The images (with suitable reduction
034460,000022: ## in storage size and consequent reduction in image quality as well) are
034461,000023: ## available online at www.ibiblio.org/apollo. If for some reason you
034462,000024: ## find that the images are illegible, contact me at info@sandroid.org
034463,000025: ## about getting access to the (much) higher-quality images which Paul
034464,000026: ## actually created.
034465,000027: ##
034466,000028: ## Notations on the hardcopy document read, in part:
034467,000029: ##
034468,000030: ## Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
034469,000031: ## 16:27 JULY 14, 1969
034470,000032:
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Page 793 |
034472,000034: 31,2216 BANK 31
034473,000035: 31,2000 SETLOC FTHROT
034474,000036: 31,2000 BANK
034475,000037: 31,2216 E7,1612 EBANK= PIF
034476,000038: 31,2216 COUNT* $$/THROT
034477,000039:
034478,000040: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
034479,000041: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
034480,000042:
034481,000043: 31,2216 31246 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
034482,000044: 31,2217 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
034483,000045: 31,2220 72417 MP /AF/CNST
034484,000046: 31,2221 00006 +3 EXTEND
034485,000047: 31,2222 23607 QXCH RTNHOLD
034486,000048: 31,2223 02400 AFDUMP TC MASSMULT
034487,000049: 31,2224 53470 DXCH FP # FP = PRESENT THRUST
034488,000050: 31,2225 00006 EXTEND
034489,000051: 31,2226 31464 DCA /AFC/
034490,000052: 31,2227 02400 TC MASSMULT
034491,000053: 31,2230 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
034492,000054: 31,2231 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
034493,000055:
034494,000056: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
034495,000057:
034496,000058: 31,2232 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
034497,000059: 31,2233 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
034498,000060: 31,2234 74733 MASK POSMAX
034499,000061: 31,2235 40000 COM
034500,000062: 31,2236 65002 AD 3SECS
034501,000063: 31,2237 00006 EXTEND
034502,000064: 31,2240 62244 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
034503,000065: 31,2241 00006 EXTEND
034504,000066: 31,2242 31611 DCA FWEIGHT
034505,000067: 31,2243 21470 DAS FP
034506,000068:
034507,000069: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
034508,000070: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
034509,000071: # PROVIDES THE UPPER.
034510,000072:
034511,000073: 31,2244 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
034512,000074: 31,2245 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
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Page 794 |
034514,000076: 31,2246 E5,1506 EBANK= LOWCRIT
034515,000077: 31,2246 00006 EXTEND
034516,000078: 31,2247 31507 DCA LOWCRIT
034517,000079: 31,2250 52131 DXCH L*WCR*T
034518,000080: 31,2251 35016 CA EBANK7
034519,000081: 31,2252 54003 TS EBANK
034520,000082: 31,2253 E7,1612 EBANK= PIF
034521,000083: 31,2253 44755 CS ZERO # INITIALIZE PIFPSET
034522,000084: 31,2254 55606 TS PIFPSET
034523,000085: 31,2255 40131 CS H*GHCR*T
034524,000086: 31,2256 61620 AD FCOLD
034525,000087: 31,2257 00006 EXTEND
034526,000088: 31,2260 62272 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
034527,000089: 31,2261 40130 CS L*WCR*T
034528,000090: 31,2262 61465 AD FCODD
034529,000091: 31,2263 00006 EXTEND
034530,000092: 31,2264 62267 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
034531,000093: 31,2265 31467 CA FP # SEE NOTE 1
034532,000094: 31,2266 12277 TCF FLATOUT1
034533,000095:
034534,000096: 31,2267 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
034535,000097: 31,2270 61467 AD FP
034536,000098: 31,2271 12301 TCF FLATOUT2
034537,000099:
034538,000100: 31,2272 40131 LOWFCOLD CS H*GHCR*T
034539,000101: 31,2273 61465 AD FCODD
034540,000102: 31,2274 00006 EXTEND
034541,000103: 31,2275 62302 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
034542,000104:
034543,000105: 31,2276 32003 CA FMAXPOS # NO: THROTTLE-UP
034544,000106: 31,2277 53466 FLATOUT1 DXCH FCODD
034545,000107: 31,2300 34737 CA FEXTRA
034546,000108: 31,2301 55606 FLATOUT2 TS PIFPSET
034547,000109:
034548,000110: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
034549,000111: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
034550,000112:
034551,000113: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
034552,000114: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
034553,000115: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
034554,000116: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
034555,000117: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
034556,000118: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
034557,000119:
034558,000120: 31,2302 03740 DOPIF TC FASTCHNG
034559,000121: 31,2303 00006 EXTEND
034560,000122: 31,2304 31466 DCA FCODD
034561,000123: 31,2305 55620 TS FCOLD
034562,000124: 31,2306 53613 DXCH PIF
034563,000125: 31,2307 00006 EXTEND
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Page 795 |
034565,000127: 31,2310 41470 DCS FP
034566,000128: 31,2311 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
034567,000129:
034568,000130: 31,2312 31612 DOIT CA PIF
034569,000131: 31,2313 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
034570,000132: 31,2314 55614 TS PSEUDO55
034571,000133: 31,2315 54055 TS THRUST
034572,000134: 31,2316 34750 CAF BIT4
034573,000135: 31,2317 00006 EXTEND
034574,000136: 31,2320 05014 WOR CHAN14
034575,000137: 31,2321 30025 CA TIME1
034576,000138: 31,2322 55617 TS TTHROT
034577,000139:
034578,000140: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
034579,000141: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
034580,000142: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
034581,000143:
034582,000144: # PIF(PPROCESS + TL) PIF /PIF/
034583,000145: # FWEIGHT = ------------------ + -------------
034584,000146: # PGUID 2 PGUID FRATE
034585,000147:
034586,000148: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
034587,000149: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
034588,000150: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
034589,000151:
034590,000152: 31,2323 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
034591,000153: 31,2324 54130 TS BUF
034592,000154:
034593,000155: 31,2325 41011 CS MODREG # ARE WE IN FACT IN P66?
034594,000156: 31,2326 62501 AD DEC66
034595,000157: 31,2327 00006 EXTEND
034596,000158: 31,2330 12335 BZF FWCOMP # YES
034597,000159:
034598,000160: 31,2331 31235 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
034599,000161: 31,2332 54130 TS BUF
034600,000162: 31,2333 35003 CAF 4SECS
034601,000163: 31,2334 12336 TCF FWCOMP +1
034602,000164:
034603,000165: 31,2335 35000 FWCOMP CAF 2SECS
034604,000166: 31,2336 54002 +1 TS Q
034605,000167: 31,2337 00006 EXTEND
034606,000168: 31,2340 74746 MP BIT6
034607,000169: 31,2341 22131 LXCH BUF +1
034608,000170: 31,2342 40130 CS BUF # TIME OF LAST PIPA READING.
034609,000171: 31,2343 60025 AD TIME1
034610,000172: 31,2344 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
034611,000173: 31,2345 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
034612,000174: 31,2346 22007 ZL
034613,000175: 31,2347 00006 EXTEND
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Page 796 |
034615,000177: 31,2350 10002 DV Q
034616,000178: 31,2351 00006 EXTEND
034617,000179: 31,2352 71612 MP PIF
034618,000180: 31,2353 60000 DOUBLE
034619,000181: 31,2354 53611 DXCH FWEIGHT
034620,000182: 31,2355 11612 CCS PIF
034621,000183: 31,2356 64753 AD ONE
034622,000184: 31,2357 12361 TCF +2
034623,000185: 31,2360 64753 AD ONE
034624,000186: 31,2361 00006 EXTEND
034625,000187: 31,2362 71612 MP PIF
034626,000188: 31,2363 00006 EXTEND
034627,000189: 31,2364 10131 DV BUF +1
034628,000190: 31,2365 22007 ZL
034629,000191: 31,2366 21611 DAS FWEIGHT
034630,000192:
034631,000193: 31,2367 01607 THDUMP TC RTNHOLD
034632,000194:
034633,000195: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
034634,000196:
034635,000197: 31,2370 34737 FLATOUT CAF BIT13 # 4096 PULSES
034636,000198: 31,2371 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
034637,000199: 31,2372 44755 CS ZERO
034638,000200: 31,2373 55620 TS FCOLD
034639,000201: 31,2374 55612 TS PIF
034640,000202: 31,2375 00006 EXTEND
034641,000203: 31,2376 23607 QXCH RTNHOLD
034642,000204: 31,2377 12312 TCF DOIT
034643,000205:
034644,000206: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
034645,000207:
034646,000208: 31,2400 00006 MASSMULT EXTEND
034647,000209: 31,2401 22130 QXCH BUF
034648,000210: 31,2402 52155 DXCH MPAC
034649,000211: 31,2403 07103 TC DMP
034650,000212: 31,2404 01244 ADRES MASS
034651,000213: 31,2405 07103 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
034652,000214: 31,2406 02005 ADRES SCALEFAC
034653,000215: 31,2407 07257 TC TPAGREE
034654,000216: 31,2410 30154 CA MPAC
034655,000217: 31,2411 00006 EXTEND
034656,000218: 31,2412 12415 BZF +3
034657,000219: 31,2413 34733 CAF POSMAX
034658,000220: 31,2414 00130 TC BUF
034659,000221: 31,2415 52156 DXCH MPAC +1
034660,000222: 31,2416 00130 TC BUF
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Page 797 |
034662,000224: # CONSTANTS:-
034663,000225:
034664,000226: 31,2417 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
034665,000227:
034666,000228: 31,2417 04143 /AF/CNST DEC .13107
034667,000229:
034668,000230: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc