Source Code
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These source-code files are part of a reconstructed copy of Luminary 98, a
development version of the Apollo 11 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Luminary 99 revision 1 previously
transcribed from a digitized copy of that program. The code was then updated
by undoing changes described in original Luminary memo 85, using asterisks
indicating changed lines in the listing as a guide. While no listing of this
version is known to exist, nor are the memory-bank checksums available,
the reconstruction is believed to be correct because it was an an intermediate
step in reconstructing Luminary 97 whose reconstruction was
verified by matching memory-bank checksums to those listed in drawing 2021152G.
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 98 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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033604,000002: ## Copyright: Public domain.
033605,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033606,000004: ## Purpose: A section of Luminary revision 98.
033607,000005: ## It is part of the reconstructed source code for the a
033608,000006: ## development version of the flight software for the Lunar
033609,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 11.
033610,000008: ## The code has been recreated from a copy of Luminary 99
033611,000009: ## revision 001, using asterisks indicating changed lines in
033612,000010: ## the listing and Luminary Memo #85, which lists changes between
033613,000011: ## Luminary 98 and 99.
033614,000012: ## Reference: pp. 793-797
033615,000013: ## Assembler: yaYUL
033616,000014: ## Contact: Ron Burkey <info@sandroid.org>.
033617,000015: ## Website: www.ibiblio.org/apollo/index.html
033618,000016: ## Mod history: 2019-07-28 MAS Created from Luminary 99.
033619,000017:
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Page 793
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033621,000019: 31,2216 BANK 31
033622,000020: 31,2000 SETLOC FTHROT
033623,000021: 31,2000 BANK
033624,000022: 31,2216 E7,1612 EBANK= PIF
033625,000023: 31,2216 COUNT* $$/THROT
033626,000024:
033627,000025: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033628,000026: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033629,000027:
033630,000028: 31,2216 31246 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033631,000029: 31,2217 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033632,000030: 31,2220 72417 MP /AF/CNST
033633,000031: 31,2221 00006 +3 EXTEND
033634,000032: 31,2222 23607 QXCH RTNHOLD
033635,000033: 31,2223 02400 AFDUMP TC MASSMULT
033636,000034: 31,2224 53470 DXCH FP # FP = PRESENT THRUST
033637,000035: 31,2225 00006 EXTEND
033638,000036: 31,2226 31464 DCA /AFC/
033639,000037: 31,2227 02400 TC MASSMULT
033640,000038: 31,2230 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033641,000039: 31,2231 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033642,000040:
033643,000041: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033644,000042:
033645,000043: 31,2232 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
033646,000044: 31,2233 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033647,000045: 31,2234 74733 MASK POSMAX
033648,000046: 31,2235 40000 COM
033649,000047: 31,2236 65002 AD 3SECS
033650,000048: 31,2237 00006 EXTEND
033651,000049: 31,2240 62244 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
033652,000050: 31,2241 00006 EXTEND
033653,000051: 31,2242 31611 DCA FWEIGHT
033654,000052: 31,2243 21470 DAS FP
033655,000053:
033656,000054: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033657,000055: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033658,000056: # PROVIDES THE UPPER.
033659,000057:
033660,000058: 31,2244 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033661,000059: 31,2245 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
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Page 794
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033663,000061: 31,2246 E5,1506 EBANK= LOWCRIT
033664,000062: 31,2246 00006 EXTEND
033665,000063: 31,2247 31507 DCA LOWCRIT
033666,000064: 31,2250 52131 DXCH L*WCR*T
033667,000065: 31,2251 35016 CA EBANK7
033668,000066: 31,2252 54003 TS EBANK
033669,000067: 31,2253 E7,1612 EBANK= PIF
033670,000068: 31,2253 44755 CS ZERO # INITIALIZE PIFPSET
033671,000069: 31,2254 55606 TS PIFPSET
033672,000070: 31,2255 40131 CS H*GHCR*T
033673,000071: 31,2256 61620 AD FCOLD
033674,000072: 31,2257 00006 EXTEND
033675,000073: 31,2260 62272 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033676,000074: 31,2261 40130 CS L*WCR*T
033677,000075: 31,2262 61465 AD FCODD
033678,000076: 31,2263 00006 EXTEND
033679,000077: 31,2264 62267 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033680,000078: 31,2265 31467 CA FP # SEE NOTE 1
033681,000079: 31,2266 12277 TCF FLATOUT1
033682,000080:
033683,000081: 31,2267 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033684,000082: 31,2270 61467 AD FP
033685,000083: 31,2271 12301 TCF FLATOUT2
033686,000084:
033687,000085: 31,2272 40131 LOWFCOLD CS H*GHCR*T
033688,000086: 31,2273 61465 AD FCODD
033689,000087: 31,2274 00006 EXTEND
033690,000088: 31,2275 62302 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033691,000089:
033692,000090: 31,2276 32003 CA FMAXPOS # NO: THROTTLE-UP
033693,000091: 31,2277 53466 FLATOUT1 DXCH FCODD
033694,000092: 31,2300 34737 CA FEXTRA
033695,000093: 31,2301 55606 FLATOUT2 TS PIFPSET
033696,000094:
033697,000095: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033698,000096: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033699,000097:
033700,000098: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
033701,000099: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
033702,000100: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033703,000101: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033704,000102: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033705,000103: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
033706,000104:
033707,000105: 31,2302 03740 DOPIF TC FASTCHNG
033708,000106: 31,2303 00006 EXTEND
033709,000107: 31,2304 31466 DCA FCODD
033710,000108: 31,2305 55620 TS FCOLD
033711,000109: 31,2306 53613 DXCH PIF
033712,000110: 31,2307 00006 EXTEND
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Page 795
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033714,000112: 31,2310 41470 DCS FP
033715,000113: 31,2311 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033716,000114:
033717,000115: 31,2312 31612 DOIT CA PIF
033718,000116: 31,2313 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033719,000117: 31,2314 55614 TS PSEUDO55
033720,000118: 31,2315 54055 TS THRUST
033721,000119: 31,2316 34750 CAF BIT4
033722,000120: 31,2317 00006 EXTEND
033723,000121: 31,2320 05014 WOR CHAN14
033724,000122: 31,2321 30025 CA TIME1
033725,000123: 31,2322 55617 TS TTHROT
033726,000124:
033727,000125: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033728,000126: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033729,000127: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033730,000128:
033731,000129: # PIF(PPROCESS + TL) PIF /PIF/
033732,000130: # FWEIGHT = ------------------ + -------------
033733,000131: # PGUID 2 PGUID FRATE
033734,000132:
033735,000133: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033736,000134: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033737,000135: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033738,000136:
033739,000137: 31,2323 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
033740,000138: 31,2324 54130 TS BUF
033741,000139:
033742,000140: 31,2325 41011 CS MODREG # ARE WE IN FACT IN P66?
033743,000141: 31,2326 62501 AD DEC66
033744,000142: 31,2327 00006 EXTEND
033745,000143: 31,2330 12335 BZF FWCOMP # YES
033746,000144:
033747,000145: 31,2331 31235 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033748,000146: 31,2332 54130 TS BUF
033749,000147: 31,2333 35003 CAF 4SECS
033750,000148: 31,2334 12336 TCF FWCOMP +1
033751,000149:
033752,000150: 31,2335 35000 FWCOMP CAF 2SECS
033753,000151: 31,2336 54002 +1 TS Q
033754,000152: 31,2337 00006 EXTEND
033755,000153: 31,2340 74746 MP BIT6
033756,000154: 31,2341 22131 LXCH BUF +1
033757,000155: 31,2342 40130 CS BUF # TIME OF LAST PIPA READING.
033758,000156: 31,2343 60025 AD TIME1
033759,000157: 31,2344 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033760,000158: 31,2345 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033761,000159: 31,2346 22007 ZL
033762,000160: 31,2347 00006 EXTEND
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Page 796
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033764,000162: 31,2350 10002 DV Q
033765,000163: 31,2351 00006 EXTEND
033766,000164: 31,2352 71612 MP PIF
033767,000165: 31,2353 60000 DOUBLE
033768,000166: 31,2354 53611 DXCH FWEIGHT
033769,000167: 31,2355 11612 CCS PIF
033770,000168: 31,2356 64753 AD ONE
033771,000169: 31,2357 12361 TCF +2
033772,000170: 31,2360 64753 AD ONE
033773,000171: 31,2361 00006 EXTEND
033774,000172: 31,2362 71612 MP PIF
033775,000173: 31,2363 00006 EXTEND
033776,000174: 31,2364 10131 DV BUF +1
033777,000175: 31,2365 22007 ZL
033778,000176: 31,2366 21611 DAS FWEIGHT
033779,000177:
033780,000178: 31,2367 01607 THDUMP TC RTNHOLD
033781,000179:
033782,000180: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033783,000181:
033784,000182: 31,2370 34737 FLATOUT CAF BIT13 # 4096 PULSES
033785,000183: 31,2371 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033786,000184: 31,2372 44755 CS ZERO
033787,000185: 31,2373 55620 TS FCOLD
033788,000186: 31,2374 55612 TS PIF
033789,000187: 31,2375 00006 EXTEND
033790,000188: 31,2376 23607 QXCH RTNHOLD
033791,000189: 31,2377 12312 TCF DOIT
033792,000190:
033793,000191: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
033794,000192:
033795,000193: 31,2400 00006 MASSMULT EXTEND
033796,000194: 31,2401 22130 QXCH BUF
033797,000195: 31,2402 52155 DXCH MPAC
033798,000196: 31,2403 07103 TC DMP
033799,000197: 31,2404 01244 ADRES MASS
033800,000198: 31,2405 07103 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
033801,000199: 31,2406 02005 ADRES SCALEFAC
033802,000200: 31,2407 07257 TC TPAGREE
033803,000201: 31,2410 30154 CA MPAC
033804,000202: 31,2411 00006 EXTEND
033805,000203: 31,2412 12415 BZF +3
033806,000204: 31,2413 34733 CAF POSMAX
033807,000205: 31,2414 00130 TC BUF
033808,000206: 31,2415 52156 DXCH MPAC +1
033809,000207: 31,2416 00130 TC BUF
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Page 797
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033811,000209: # CONSTANTS:-
033812,000210:
033813,000211: 31,2417 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
033814,000212:
033815,000213: 31,2417 04143 /AF/CNST DEC .13107
033816,000214:
033817,000215: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc