Notations on the program listing read, in part:
GAP: ASSEMBLE REVISION 210 OF AGC PROGRAM LUMINARY BY NASA 2021112-161 17:11 MAR. 19,1971Note 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 derive from a printout of Luminary 210 (Apollo 15-17
Lunar Module guidance computer program), from the personal library of
original AGC developer Don Eyles, digitally photographed at archive.org,
financially sponsored by Jim Lawton, and transcribed to source code by a
team of volunteers. This colorized, syntax-highlighted form was created
by assembling that transcribed source code. Note that the full page images
are available on the
Virtual AGC project page at archive.org, while reduced-size images
are presented at the VirtualAGC project website. Report or fix any
transcription errors at
the Virtual AGC project code repository. Notations on the program listing read, in part: GAP: ASSEMBLE REVISION 210 OF AGC PROGRAM LUMINARY BY NASA 2021112-161 17:11 MAR. 19,1971Note that the date is the date of the printout, not the date of the program revision. |
034650,000002: ## Copyright: Public domain.
034651,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
034652,000004: ## Purpose: A section of Luminary revision 210.
034653,000005: ## It is part of the source code for the Lunar Module's (LM)
034654,000006: ## Apollo Guidance Computer (AGC) for Apollo 15-17.
034655,000007: ## This file is intended to be a faithful transcription, except
034656,000008: ## that the code format has been changed to conform to the
034657,000009: ## requirements of the yaYUL assembler rather than the
034658,000010: ## original YUL assembler.
034659,000011: ## Reference: pp. 789-793
034660,000012: ## Assembler: yaYUL
034661,000013: ## Contact: Ron Burkey <info@sandroid.org>.
034662,000014: ## Website: www.ibiblio.org/apollo/index.html
034663,000015: ## Mod history: 2016-11-17 JL Created from Luminary131 version.
034664,000016: ## 2016-12-01 RSB Completed transcription
034665,000017: ## 2016-12-10 HG fix operator DXCH -> XCH
034666,000018: ## DOUBLE -> DDOUBL
034667,000019: ## 2016-12-25 RSB Comment-text proofed using ProoferComments
034668,000020: ## and corrected errors found.
034669,000021:
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Page 789 |
034671,000023: 31,2144 BANK 31
034672,000024:
034673,000025: 31,2000 SETLOC FTHROT
034674,000026:
034675,000027: 31,2000 BANK
034676,000028:
034677,000029: 31,2144 E7,1612 EBANK= PIF
034678,000030:
034679,000031: 31,2144 COUNT* $$/THROT
034680,000032: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
034681,000033: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
034682,000034:
034683,000035: 31,2144 31245 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
034684,000036: 31,2145 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
034685,000037: 31,2146 72363 MP /AF/CNST
034686,000038: 31,2147 00006 +3 EXTEND
034687,000039: 31,2150 23607 QXCH RTNHOLD
034688,000040: 31,2151 02344 AFDUMP TC MASSMULT
034689,000041: 31,2152 53470 DXCH FP # FP = PRESENT THRUST
034690,000042: 31,2153 00006 EXTEND
034691,000043: 31,2154 31464 DCA /AFC/
034692,000044: 31,2155 02344 TC MASSMULT
034693,000045: 31,2156 00004 INHINT # PREVENT A DOWNRUPT
034694,000046: 31,2157 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
034695,000047: 31,2160 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
034696,000048:
034697,000049:
034698,000050: 31,2161 00006 EXTEND
034699,000051: 31,2162 31234 DCA PIPTIME
034700,000052: 31,2163 53753 DXCH GTCTIME # DOWNLINK TIME AGREEMENT
034701,000053: 31,2164 00003 RELINT
034702,000054:
034703,000055: # COMPUTE DESIRED THRUST FOR DISPLAY AS A PERCENTAGE OF 10,500 POUNDS
034704,000056:
034705,000057: 31,2165 32365 CAF 4FMAXNOM # MOVE 4FMAXNOM TO ERASABLE FOR DV BELOW
034706,000058: 31,2166 54002 TS Q
034707,000059: 31,2167 31615 CA FC
034708,000060: 31,2170 72364 MASK OCT17777 # FOR SAFETY
034709,000061: 31,2171 00006 EXTEND
034710,000062: 31,2172 10002 DV Q
034711,000063: 31,2173 00006 EXTEND
034712,000064: 31,2174 74774 MP 4SECS
034713,000065: 31,2175 55750 TS THRDISP # FOR DISPLAY IN N92
034714,000066:
034715,000067: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
034716,000068:
034717,000069: 31,2176 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
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Page 790 |
034719,000071: 31,2177 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
034720,000072: 31,2200 74724 MASK POSMAX
034721,000073: 31,2201 40000 COM
034722,000074: 31,2202 64773 AD 3SECS
034723,000075: 31,2203 00006 EXTEND
034724,000076: 31,2204 62210 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
034725,000077: 31,2205 00006 EXTEND
034726,000078: 31,2206 31611 DCA FWEIGHT
034727,000079: 31,2207 21470 DAS FP
034728,000080:
034729,000081:
034730,000082: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
034731,000083: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
034732,000084: # PROVIDES THE UPPER.
034733,000085:
034734,000086: 31,2210 35005 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
034735,000087: 31,2211 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
034736,000088: 31,2212 E5,1472 EBANK= LOWCRIT
034737,000089: 31,2212 00006 EXTEND
034738,000090: 31,2213 31473 DCA LOWCRIT
034739,000091: 31,2214 52131 DXCH L*WCR*T
034740,000092: 31,2215 35007 CA EBANK7
034741,000093: 31,2216 54003 TS EBANK
034742,000094: 31,2217 E7,1612 EBANK= PIF
034743,000095: 31,2217 44746 CS ZERO # INITIALIZE PIFPSET
034744,000096: 31,2220 55606 TS PIFPSET
034745,000097: 31,2221 40131 CS H*GHCR*T
034746,000098: 31,2222 61620 AD FCOLD
034747,000099: 31,2223 00006 EXTEND
034748,000100: 31,2224 62236 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
034749,000101: 31,2225 40130 CS L*WCR*T
034750,000102: 31,2226 61465 AD FCODD
034751,000103: 31,2227 00006 EXTEND
034752,000104: 31,2230 62233 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
034753,000105: 31,2231 31467 CA FP # SEE NOTE 1
034754,000106: 31,2232 12243 TCF FLATOUT1
034755,000107:
034756,000108: 31,2233 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
034757,000109: 31,2234 61467 AD FP
034758,000110: 31,2235 12245 TCF FLATOUT2
034759,000111:
034760,000112: 31,2236 40131 LOWFCOLD CS H*GHCR*T
034761,000113: 31,2237 61465 AD FCODD
034762,000114: 31,2240 00006 EXTEND
034763,000115: 31,2241 62246 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
034764,000116:
034765,000117: 31,2242 32003 CA FMAXPOS # NO: THROTTLE-UP
034766,000118: 31,2243 57465 FLATOUT1 XCH FCODD
034767,000119: 31,2244 34730 CA FEXTRA
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Page 791 |
034769,000121: 31,2245 55606 FLATOUT2 TS PIFPSET
034770,000122:
034771,000123: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
034772,000124: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
034773,000125:
034774,000126: # NOTE 2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
034775,000127: # (BELOW 55%) THE QUANTITY -(FMAXODD - FP) IS COMPUTED AND PUT
034776,000128: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
034777,000129: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
034778,000130: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
034779,000131: # THROTTLE COMMAND PIF = FC - FP -(FMAXODD - FP) = FC - FMAXODD.
034780,000132:
034781,000133: 31,2246 03751 DOPIF TC FASTCHNG
034782,000134: 31,2247 00006 EXTEND
034783,000135: 31,2250 31466 DCA FCODD
034784,000136: 31,2251 55620 TS FCOLD
034785,000137: 31,2252 53613 DXCH PIF
034786,000138: 31,2253 00006 EXTEND
034787,000139: 31,2254 41470 DCS FP
034788,000140: 31,2255 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
034789,000141:
034790,000142:
034791,000143: 31,2256 31612 DOIT CA PIF
034792,000144: 31,2257 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
034793,000145: 31,2260 55614 TS PSEUDO55
034794,000146: 31,2261 54055 TS THRUST
034795,000147: 31,2262 34741 CAF BIT4
034796,000148: 31,2263 00006 EXTEND
034797,000149: 31,2264 05014 WOR CHAN14
034798,000150: 31,2265 30025 CA TIME1
034799,000151: 31,2266 55617 TS TTHROT
034800,000152:
034801,000153: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
034802,000154: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
034803,000155: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
034804,000156:
034805,000157: # PIF(PPROCESS + TL) PIF /PIF/
034806,000158: # FWEIGHT = ------------------ + -------------
034807,000159: # PGUID 2 PGUID FRATE
034808,000160:
034809,000161: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
034810,000162: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
034811,000163: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
034812,000164:
034813,000165: 31,2267 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
034814,000166: 31,2270 54130 TS BUF
034815,000167:
034816,000168: 31,2271 41010 CS MODREG # ARE WE IN FACT IN P66?
034817,000169: 31,2272 62454 AD DEC66
034818,000170: 31,2273 00006 EXTEND
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Page 792 |
034820,000172: 31,2274 12301 BZF FWCOMP # YES
034821,000173:
034822,000174: 31,2275 31234 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
034823,000175: 31,2276 54130 TS BUF
034824,000176: 31,2277 34774 CAF 4SECS
034825,000177: 31,2300 12302 TCF FWCOMP +1
034826,000178:
034827,000179: 31,2301 34771 FWCOMP CAF 2SECS
034828,000180: 31,2302 54002 +1 TS Q
034829,000181: 31,2303 00006 EXTEND
034830,000182: 31,2304 74737 MP BIT6
034831,000183: 31,2305 22131 LXCH BUF +1
034832,000184: 31,2306 40130 CS BUF # TIME OF LAST PIPA READING.
034833,000185: 31,2307 60025 AD TIME1
034834,000186: 31,2310 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
034835,000187: 31,2311 74350 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
034836,000188: 31,2312 22007 ZL
034837,000189: 31,2313 00006 EXTEND
034838,000190: 31,2314 10002 DV Q
034839,000191: 31,2315 00006 EXTEND
034840,000192: 31,2316 71612 MP PIF
034841,000193: 31,2317 20001 DDOUBL
034842,000194: 31,2320 53611 DXCH FWEIGHT
034843,000195: 31,2321 11612 CCS PIF
034844,000196: 31,2322 64744 AD ONE
034845,000197: 31,2323 12325 TCF +2
034846,000198: 31,2324 64744 AD ONE
034847,000199: 31,2325 00006 EXTEND
034848,000200: 31,2326 71612 MP PIF
034849,000201: 31,2327 00006 EXTEND
034850,000202: 31,2330 10131 DV BUF +1
034851,000203: 31,2331 22007 ZL
034852,000204: 31,2332 21611 DAS FWEIGHT
034853,000205:
034854,000206:
034855,000207: 31,2333 01607 THDUMP TC RTNHOLD
034856,000208:
034857,000209:
034858,000210: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
034859,000211:
034860,000212: 31,2334 34730 FLATOUT CAF BIT13 # 4096 PULSES
034861,000213: 31,2335 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
034862,000214: 31,2336 44746 CS ZERO
034863,000215: 31,2337 55620 TS FCOLD
034864,000216: 31,2340 55612 TS PIF
034865,000217: 31,2341 00006 EXTEND
034866,000218: 31,2342 23607 QXCH RTNHOLD
034867,000219: 31,2343 12256 TCF DOIT
034868,000220:
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Page 793 |
034870,000222: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
034871,000223:
034872,000224: 31,2344 00006 MASSMULT EXTEND
034873,000225: 31,2345 22130 QXCH BUF
034874,000226: 31,2346 52155 DXCH MPAC
034875,000227: 31,2347 07124 TC DMP
034876,000228: 31,2350 01243 ADRES MASS
034877,000229: 31,2351 07124 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
034878,000230: 31,2352 02005 ADRES SCALEFAC
034879,000231: 31,2353 07300 TC TPAGREE
034880,000232: 31,2354 30154 CA MPAC
034881,000233: 31,2355 00006 EXTEND
034882,000234: 31,2356 12361 BZF +3
034883,000235: 31,2357 34724 CAF POSMAX
034884,000236: 31,2360 00130 TC BUF
034885,000237: 31,2361 52156 DXCH MPAC +1
034886,000238: 31,2362 00130 TC BUF
034887,000239:
034888,000240:
034889,000241: # CONSTANTS:-
034890,000242:
034891,000243: 31,2363 4730 FEXTRA = BIT13 # FEXT +5.13309020 E+4
034892,000244:
034893,000245: 31,2363 04143 /AF/CNST DEC .13107
034894,000246:
034895,000247: 31,2364 17777 OCT17777 OCT 17777
034896,000248: 31,2365 35074 4FMAXNOM DEC 14908 B-14 # EQUIVALENT TO 10,500 LBS.
034897,000249: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc