Source Code
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These source-code files are part of a reconstructed copy of Luminary 96, the
original release of the Apollo 11 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with reconstructed source code for Luminary 97. Changes
between revisions 96 and 97 were backed out, as described by anomal report LNY-59.
transcribed from a digitized copy of that program. The reconstruction was
verified by matching memory-bank checksums to those listed in drawing 2021152D.
Note that page numbers in the reconstructed code match those on the Luminary 099
revision 001 printout, although the added code would likely have changed page
numbers for a real Luminary 96 listing.
Comments from the original source code are prefixed with a single '#' symbol,
whereas comments added later are prefixed by "##" or "###". Report any errors
noted by creating an
issue report at the Virtual AGC
project's GitHub repository.
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033699,000002: ## Copyright: Public domain.
033700,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033701,000004: ## Purpose: A section of Luminary revision 96.
033702,000005: ## It is part of the reconstructed source code for the
033703,000006: ## original release of the flight software for the Lunar
033704,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 11.
033705,000008: ## The code has been recreated from a previously reconstructed
033706,000009: ## copy of Luminary 97 by undoing changes described in anomaly
033707,000010: ## report LNY-59. The code has been adapted such that the
033708,000011: ## resulting bugger words exactly match those specified for
033709,000012: ## Luminary 96 in NASA drawing 2021152D, which gives relatively
033710,000013: ## high confidence that the reconstruction is correct.
033711,000014: ## Reference: pp. 793-797
033712,000015: ## Assembler: yaYUL
033713,000016: ## Contact: Ron Burkey <info@sandroid.org>.
033714,000017: ## Website: www.ibiblio.org/apollo/index.html
033715,000018: ## Mod history: 2019-08-04 MAS Created from Luminary 97.
033716,000019:
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Page 793
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033718,000021: 31,2216 BANK 31
033719,000022: 31,2000 SETLOC FTHROT
033720,000023: 31,2000 BANK
033721,000024: 31,2216 E7,1612 EBANK= PIF
033722,000025: 31,2216 COUNT* $$/THROT
033723,000026:
033724,000027: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033725,000028: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033726,000029:
033727,000030: 31,2216 31246 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033728,000031: 31,2217 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033729,000032: 31,2220 72417 MP /AF/CNST
033730,000033: 31,2221 00006 +3 EXTEND
033731,000034: 31,2222 23607 QXCH RTNHOLD
033732,000035: 31,2223 02400 AFDUMP TC MASSMULT
033733,000036: 31,2224 53470 DXCH FP # FP = PRESENT THRUST
033734,000037: 31,2225 00006 EXTEND
033735,000038: 31,2226 31464 DCA /AFC/
033736,000039: 31,2227 02400 TC MASSMULT
033737,000040: 31,2230 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033738,000041: 31,2231 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033739,000042:
033740,000043: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033741,000044:
033742,000045: 31,2232 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
033743,000046: 31,2233 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033744,000047: 31,2234 74733 MASK POSMAX
033745,000048: 31,2235 40000 COM
033746,000049: 31,2236 65002 AD 3SECS
033747,000050: 31,2237 00006 EXTEND
033748,000051: 31,2240 62244 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
033749,000052: 31,2241 00006 EXTEND
033750,000053: 31,2242 31611 DCA FWEIGHT
033751,000054: 31,2243 21470 DAS FP
033752,000055:
033753,000056: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033754,000057: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033755,000058: # PROVIDES THE UPPER.
033756,000059:
033757,000060: 31,2244 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033758,000061: 31,2245 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
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Page 794
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033760,000063: 31,2246 E5,1506 EBANK= LOWCRIT
033761,000064: 31,2246 00006 EXTEND
033762,000065: 31,2247 31507 DCA LOWCRIT
033763,000066: 31,2250 52131 DXCH L*WCR*T
033764,000067: 31,2251 35016 CA EBANK7
033765,000068: 31,2252 54003 TS EBANK
033766,000069: 31,2253 E7,1612 EBANK= PIF
033767,000070: 31,2253 44755 CS ZERO # INITIALIZE PIFPSET
033768,000071: 31,2254 55606 TS PIFPSET
033769,000072: 31,2255 40131 CS H*GHCR*T
033770,000073: 31,2256 61620 AD FCOLD
033771,000074: 31,2257 00006 EXTEND
033772,000075: 31,2260 62272 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033773,000076: 31,2261 40130 CS L*WCR*T
033774,000077: 31,2262 61465 AD FCODD
033775,000078: 31,2263 00006 EXTEND
033776,000079: 31,2264 62267 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033777,000080: 31,2265 31467 CA FP # SEE NOTE 1
033778,000081: 31,2266 12277 TCF FLATOUT1
033779,000082:
033780,000083: 31,2267 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033781,000084: 31,2270 61467 AD FP
033782,000085: 31,2271 12301 TCF FLATOUT2
033783,000086:
033784,000087: 31,2272 40131 LOWFCOLD CS H*GHCR*T
033785,000088: 31,2273 61465 AD FCODD
033786,000089: 31,2274 00006 EXTEND
033787,000090: 31,2275 62302 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033788,000091:
033789,000092: 31,2276 32003 CA FMAXPOS # NO: THROTTLE-UP
033790,000093: 31,2277 53466 FLATOUT1 DXCH FCODD
033791,000094: 31,2300 34737 CA FEXTRA
033792,000095: 31,2301 55606 FLATOUT2 TS PIFPSET
033793,000096:
033794,000097: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033795,000098: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033796,000099:
033797,000100: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
033798,000101: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
033799,000102: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033800,000103: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033801,000104: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033802,000105: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
033803,000106:
033804,000107: 31,2302 03740 DOPIF TC FASTCHNG
033805,000108: 31,2303 00006 EXTEND
033806,000109: 31,2304 31466 DCA FCODD
033807,000110: 31,2305 55620 TS FCOLD
033808,000111: 31,2306 53613 DXCH PIF
033809,000112: 31,2307 00006 EXTEND
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Page 795
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033811,000114: 31,2310 41470 DCS FP
033812,000115: 31,2311 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033813,000116:
033814,000117: 31,2312 31612 DOIT CA PIF
033815,000118: 31,2313 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033816,000119: 31,2314 55614 TS PSEUDO55
033817,000120: 31,2315 54055 TS THRUST
033818,000121: 31,2316 34750 CAF BIT4
033819,000122: 31,2317 00006 EXTEND
033820,000123: 31,2320 05014 WOR CHAN14
033821,000124: 31,2321 30025 CA TIME1
033822,000125: 31,2322 55617 TS TTHROT
033823,000126:
033824,000127: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033825,000128: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033826,000129: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033827,000130:
033828,000131: # PIF(PPROCESS + TL) PIF /PIF/
033829,000132: # FWEIGHT = ------------------ + -------------
033830,000133: # PGUID 2 PGUID FRATE
033831,000134:
033832,000135: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033833,000136: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033834,000137: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033835,000138:
033836,000139: 31,2323 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
033837,000140: 31,2324 54130 TS BUF
033838,000141:
033839,000142: 31,2325 41011 CS MODREG # ARE WE IN FACT IN P66?
033840,000143: 31,2326 62501 AD DEC66
033841,000144: 31,2327 00006 EXTEND
033842,000145: 31,2330 12335 BZF FWCOMP # YES
033843,000146:
033844,000147: 31,2331 31235 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033845,000148: 31,2332 54130 TS BUF
033846,000149: 31,2333 35003 CAF 4SECS
033847,000150: 31,2334 12336 TCF FWCOMP +1
033848,000151:
033849,000152: 31,2335 35000 FWCOMP CAF 2SECS
033850,000153: 31,2336 54002 +1 TS Q
033851,000154: 31,2337 00006 EXTEND
033852,000155: 31,2340 74746 MP BIT6
033853,000156: 31,2341 22131 LXCH BUF +1
033854,000157: 31,2342 40130 CS BUF # TIME OF LAST PIPA READING.
033855,000158: 31,2343 60025 AD TIME1
033856,000159: 31,2344 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033857,000160: 31,2345 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033858,000161: 31,2346 22007 ZL
033859,000162: 31,2347 00006 EXTEND
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Page 796
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033861,000164: 31,2350 10002 DV Q
033862,000165: 31,2351 00006 EXTEND
033863,000166: 31,2352 71612 MP PIF
033864,000167: 31,2353 60000 DOUBLE
033865,000168: 31,2354 53611 DXCH FWEIGHT
033866,000169: 31,2355 11612 CCS PIF
033867,000170: 31,2356 64753 AD ONE
033868,000171: 31,2357 12361 TCF +2
033869,000172: 31,2360 64753 AD ONE
033870,000173: 31,2361 00006 EXTEND
033871,000174: 31,2362 71612 MP PIF
033872,000175: 31,2363 00006 EXTEND
033873,000176: 31,2364 10131 DV BUF +1
033874,000177: 31,2365 22007 ZL
033875,000178: 31,2366 21611 DAS FWEIGHT
033876,000179:
033877,000180: 31,2367 01607 THDUMP TC RTNHOLD
033878,000181:
033879,000182: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033880,000183:
033881,000184: 31,2370 34737 FLATOUT CAF BIT13 # 4096 PULSES
033882,000185: 31,2371 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033883,000186: 31,2372 44755 CS ZERO
033884,000187: 31,2373 55620 TS FCOLD
033885,000188: 31,2374 55612 TS PIF
033886,000189: 31,2375 00006 EXTEND
033887,000190: 31,2376 23607 QXCH RTNHOLD
033888,000191: 31,2377 12312 TCF DOIT
033889,000192:
033890,000193: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
033891,000194:
033892,000195: 31,2400 00006 MASSMULT EXTEND
033893,000196: 31,2401 22130 QXCH BUF
033894,000197: 31,2402 52155 DXCH MPAC
033895,000198: 31,2403 07103 TC DMP
033896,000199: 31,2404 01244 ADRES MASS
033897,000200: 31,2405 07103 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
033898,000201: 31,2406 02005 ADRES SCALEFAC
033899,000202: 31,2407 07257 TC TPAGREE
033900,000203: 31,2410 30154 CA MPAC
033901,000204: 31,2411 00006 EXTEND
033902,000205: 31,2412 12415 BZF +3
033903,000206: 31,2413 34733 CAF POSMAX
033904,000207: 31,2414 00130 TC BUF
033905,000208: 31,2415 52156 DXCH MPAC +1
033906,000209: 31,2416 00130 TC BUF
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Page 797
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033908,000211: # CONSTANTS:-
033909,000212:
033910,000213: 31,2417 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
033911,000214:
033912,000215: 31,2417 04143 /AF/CNST DEC .13107
033913,000216:
033914,000217: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc