Source Code
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These source-code files are part of a reconstructed copy of Luminary 163, the
first (unflown) release of the Apollo 14 Lunar Module (LM) Apollo Guidance
Computer (AGC) software.
The reconstruction began with reconstructed source code for Luminary 173. Changes
between revision 163 and 173 were backed out, as described by Luminary memos 157
and 158. The reconstruction was verified by matching memory-bank checksums
to those listed in drawing 2021152N. Note that page numbers in the reconstructed
code match those for the baseline log section mentioned in each file's changelog;
the page numbers for a real Luminary 163 listing would be different.
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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033788,000002: ## Copyright: Public domain.
033789,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033790,000004: ## Purpose: A section of Luminary revision 163.
033791,000005: ## It is part of the reconstructed source code for the first
033792,000006: ## (unflown) release of the flight software for the Lunar
033793,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 14.
033794,000008: ## The code has been recreated from a reconstructed copy of
033795,000009: ## Luminary 173, as well as Luminary memos 157 amd 158.
033796,000010: ## It has been adapted such that the resulting bugger words
033797,000011: ## exactly match those specified for Luminary 163 in NASA
033798,000012: ## drawing 2021152N, which gives relatively high confidence
033799,000013: ## that the reconstruction is correct.
033800,000014: ## Reference: pp. 779-783
033801,000015: ## Assembler: yaYUL
033802,000016: ## Contact: Ron Burkey <info@sandroid.org>.
033803,000017: ## Website: www.ibiblio.org/apollo/index.html
033804,000018: ## Mod history: 2019-08-21 MAS Created from Luminary 173.
033805,000019:
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Page 789
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033807,000021: 31,2144 BANK 31
033808,000022:
033809,000023: 31,2000 SETLOC FTHROT
033810,000024:
033811,000025: 31,2000 BANK
033812,000026:
033813,000027: 31,2144 E7,1612 EBANK= PIF
033814,000028:
033815,000029: 31,2144 COUNT* $$/THROT
033816,000030: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033817,000031: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033818,000032:
033819,000033: 31,2144 31245 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033820,000034: 31,2145 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033821,000035: 31,2146 72363 MP /AF/CNST
033822,000036: 31,2147 00006 +3 EXTEND
033823,000037: 31,2150 23607 QXCH RTNHOLD
033824,000038: 31,2151 02344 AFDUMP TC MASSMULT
033825,000039: 31,2152 53470 DXCH FP # FP = PRESENT THRUST
033826,000040: 31,2153 00006 EXTEND
033827,000041: 31,2154 31464 DCA /AFC/
033828,000042: 31,2155 02344 TC MASSMULT
033829,000043: 31,2156 00004 INHINT # PREVENT A DOWNRUPT
033830,000044: 31,2157 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033831,000045: 31,2160 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033832,000046:
033833,000047:
033834,000048: 31,2161 00006 EXTEND
033835,000049: 31,2162 31234 DCA PIPTIME
033836,000050: 31,2163 53753 DXCH GTCTIME # DOWNLINK TIME AGREEMENT
033837,000051: 31,2164 00003 RELINT
033838,000052:
033839,000053: # COMPUTE DESIRED THRUST FOR DISPLAY AS A PERCENTAGE OF 10,500 POUNDS
033840,000054:
033841,000055: 31,2165 32365 CAF 4FMAXNOM # MOVE 4FMAXNOM TO ERASABLE FOR DV BELOW
033842,000056: 31,2166 54002 TS Q
033843,000057: 31,2167 31615 CA FC
033844,000058: 31,2170 72364 MASK OCT17777 # FOR SAFETY
033845,000059: 31,2171 00006 EXTEND
033846,000060: 31,2172 10002 DV Q
033847,000061: 31,2173 00006 EXTEND
033848,000062: 31,2174 75003 MP 4SECS
033849,000063: 31,2175 55750 TS THRDISP # FOR DISPLAY IN N92
033850,000064:
033851,000065: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033852,000066:
033853,000067: 31,2176 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
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Page 790
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033855,000069: 31,2177 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033856,000070: 31,2200 74733 MASK POSMAX
033857,000071: 31,2201 40000 COM
033858,000072: 31,2202 65002 AD 3SECS
033859,000073: 31,2203 00006 EXTEND
033860,000074: 31,2204 62210 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
033861,000075: 31,2205 00006 EXTEND
033862,000076: 31,2206 31611 DCA FWEIGHT
033863,000077: 31,2207 21470 DAS FP
033864,000078:
033865,000079:
033866,000080: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033867,000081: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033868,000082: # PROVIDES THE UPPER.
033869,000083:
033870,000084: 31,2210 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033871,000085: 31,2211 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
033872,000086: 31,2212 E5,1472 EBANK= LOWCRIT
033873,000087: 31,2212 00006 EXTEND
033874,000088: 31,2213 31473 DCA LOWCRIT
033875,000089: 31,2214 52131 DXCH L*WCR*T
033876,000090: 31,2215 35016 CA EBANK7
033877,000091: 31,2216 54003 TS EBANK
033878,000092: 31,2217 E7,1612 EBANK= PIF
033879,000093: 31,2217 44755 CS ZERO # INITIALIZE PIFPSET
033880,000094: 31,2220 55606 TS PIFPSET
033881,000095: 31,2221 40131 CS H*GHCR*T
033882,000096: 31,2222 61620 AD FCOLD
033883,000097: 31,2223 00006 EXTEND
033884,000098: 31,2224 62236 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033885,000099: 31,2225 40130 CS L*WCR*T
033886,000100: 31,2226 61465 AD FCODD
033887,000101: 31,2227 00006 EXTEND
033888,000102: 31,2230 62233 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033889,000103: 31,2231 31467 CA FP # SEE NOTE 1
033890,000104: 31,2232 12243 TCF FLATOUT1
033891,000105:
033892,000106: 31,2233 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033893,000107: 31,2234 61467 AD FP
033894,000108: 31,2235 12245 TCF FLATOUT2
033895,000109:
033896,000110: 31,2236 40131 LOWFCOLD CS H*GHCR*T
033897,000111: 31,2237 61465 AD FCODD
033898,000112: 31,2240 00006 EXTEND
033899,000113: 31,2241 62246 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033900,000114:
033901,000115: 31,2242 32003 CA FMAXPOS # NO: THROTTLE-UP
033902,000116: 31,2243 53466 FLATOUT1 DXCH FCODD
033903,000117: 31,2244 34737 CA FEXTRA
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Page 791
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033905,000119: 31,2245 55606 FLATOUT2 TS PIFPSET
033906,000120:
033907,000121: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033908,000122: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033909,000123:
033910,000124: # NOTE 2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
033911,000125: # (BELOW 55%) THE QUANTITY -(FMAXODD - FP) IS COMPUTED AND PUT
033912,000126: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033913,000127: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033914,000128: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033915,000129: # THROTTLE COMMAND PIF = FC - FP -(FMAXODD - FP) = FC - FMAXODD.
033916,000130:
033917,000131: 31,2246 03747 DOPIF TC FASTCHNG
033918,000132: 31,2247 00006 EXTEND
033919,000133: 31,2250 31466 DCA FCODD
033920,000134: 31,2251 55620 TS FCOLD
033921,000135: 31,2252 53613 DXCH PIF
033922,000136: 31,2253 00006 EXTEND
033923,000137: 31,2254 41470 DCS FP
033924,000138: 31,2255 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033925,000139:
033926,000140:
033927,000141: 31,2256 31612 DOIT CA PIF
033928,000142: 31,2257 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033929,000143: 31,2260 55614 TS PSEUDO55
033930,000144: 31,2261 54055 TS THRUST
033931,000145: 31,2262 34750 CAF BIT4
033932,000146: 31,2263 00006 EXTEND
033933,000147: 31,2264 05014 WOR CHAN14
033934,000148: 31,2265 30025 CA TIME1
033935,000149: 31,2266 55617 TS TTHROT
033936,000150:
033937,000151: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033938,000152: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033939,000153: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033940,000154:
033941,000155: # PIF(PPROCESS + TL) PIF /PIF/
033942,000156: # FWEIGHT = ------------------ + -------------
033943,000157: # PGUID 2 PGUID FRATE
033944,000158:
033945,000159: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033946,000160: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033947,000161: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033948,000162:
033949,000163: 31,2267 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
033950,000164: 31,2270 54130 TS BUF
033951,000165:
033952,000166: 31,2271 41010 CS MODREG # ARE WE IN FACT IN P66?
033953,000167: 31,2272 62454 AD DEC66
033954,000168: 31,2273 00006 EXTEND
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Page 792
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033956,000170: 31,2274 12301 BZF FWCOMP # YES
033957,000171:
033958,000172: 31,2275 31234 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033959,000173: 31,2276 54130 TS BUF
033960,000174: 31,2277 35003 CAF 4SECS
033961,000175: 31,2300 12302 TCF FWCOMP +1
033962,000176:
033963,000177: 31,2301 35000 FWCOMP CAF 2SECS
033964,000178: 31,2302 54002 +1 TS Q
033965,000179: 31,2303 00006 EXTEND
033966,000180: 31,2304 74746 MP BIT6
033967,000181: 31,2305 22131 LXCH BUF +1
033968,000182: 31,2306 40130 CS BUF # TIME OF LAST PIPA READING.
033969,000183: 31,2307 60025 AD TIME1
033970,000184: 31,2310 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033971,000185: 31,2311 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033972,000186: 31,2312 22007 ZL
033973,000187: 31,2313 00006 EXTEND
033974,000188: 31,2314 10002 DV Q
033975,000189: 31,2315 00006 EXTEND
033976,000190: 31,2316 71612 MP PIF
033977,000191: 31,2317 60000 DOUBLE
033978,000192: 31,2320 53611 DXCH FWEIGHT
033979,000193: 31,2321 11612 CCS PIF
033980,000194: 31,2322 64753 AD ONE
033981,000195: 31,2323 12325 TCF +2
033982,000196: 31,2324 64753 AD ONE
033983,000197: 31,2325 00006 EXTEND
033984,000198: 31,2326 71612 MP PIF
033985,000199: 31,2327 00006 EXTEND
033986,000200: 31,2330 10131 DV BUF +1
033987,000201: 31,2331 22007 ZL
033988,000202: 31,2332 21611 DAS FWEIGHT
033989,000203:
033990,000204:
033991,000205: 31,2333 01607 THDUMP TC RTNHOLD
033992,000206:
033993,000207:
033994,000208: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033995,000209:
033996,000210: 31,2334 34737 FLATOUT CAF BIT13 # 4096 PULSES
033997,000211: 31,2335 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033998,000212: 31,2336 44755 CS ZERO
033999,000213: 31,2337 55620 TS FCOLD
034000,000214: 31,2340 55612 TS PIF
034001,000215: 31,2341 00006 EXTEND
034002,000216: 31,2342 23607 QXCH RTNHOLD
034003,000217: 31,2343 12256 TCF DOIT
034004,000218:
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Page 793
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034006,000220: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
034007,000221:
034008,000222: 31,2344 00006 MASSMULT EXTEND
034009,000223: 31,2345 22130 QXCH BUF
034010,000224: 31,2346 52155 DXCH MPAC
034011,000225: 31,2347 07106 TC DMP
034012,000226: 31,2350 01243 ADRES MASS
034013,000227: 31,2351 07106 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
034014,000228: 31,2352 02005 ADRES SCALEFAC
034015,000229: 31,2353 07262 TC TPAGREE
034016,000230: 31,2354 30154 CA MPAC
034017,000231: 31,2355 00006 EXTEND
034018,000232: 31,2356 12361 BZF +3
034019,000233: 31,2357 34733 CAF POSMAX
034020,000234: 31,2360 00130 TC BUF
034021,000235: 31,2361 52156 DXCH MPAC +1
034022,000236: 31,2362 00130 TC BUF
034023,000237:
034024,000238:
034025,000239: # CONSTANTS:-
034026,000240:
034027,000241: 31,2363 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
034028,000242:
034029,000243: 31,2363 04143 /AF/CNST DEC .13107
034030,000244:
034031,000245: 31,2364 17777 OCT17777 OCT 17777
034032,000246: 31,2365 35074 4FMAXNOM DEC 14908 B-14 # EQUIVALENT TO 10,500 LBS.
034033,000247: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc