Source Code
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This is a reconstructed version of Luminary 130, the initial AGC program released
in November 1969 for the Apollo 13 LM. Three more releases
followed before the flown revision was finally manufactured in February 1970.
This reconstruction was created from a previous transcription of the original listing of
Luminary 131, combined with Luminary memo #129 which describes the small difference
between the Luminary 130 and 131. The reconstructed source code was verified by
matching memory-bank checksums to those listed for Luminary 130 in drawing 2021152G.
In this source code, program comments from the original (Luminary 131) code are
prefixed with '#', while those added later by the Virtual AGC project are prefixed
with '##'.
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033704,000002: ## Copyright: Public domain.
033705,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033706,000004: ## Purpose: A section of the reconstructed source code for Luminary 130.
033707,000005: ## This was the original program released for the Apollo 13 LM,
033708,000006: ## although several more revisions would follow. It has been
033709,000007: ## reconstructed from a listing of Luminary 131, from which it
033710,000008: ## differs on only two lines in P70-P71. The difference is
033711,000009: ## described in detail in Luminary memo #129, which was used
033712,000010: ## to perform the reconstruction. This file is intended to be a
033713,000011: ## faithful reconstruction, except that the code format has been
033714,000012: ## changed to conform to the requirements of the yaYUL assembler
033715,000013: ## rather than the original YUL assembler.
033716,000014: ## Reference: pp. 788-792
033717,000015: ## Contact: Ron Burkey <info@sandroid.org>.
033718,000016: ## Website: www.ibiblio.org/apollo/index.html
033719,000017: ## Mod history: 05/24/03 RSB. Began transcribing.
033720,000018: ## 05/14/05 RSB Corrected website reference above.
033721,000019: ## 2017-01-06 RSB Page numbers now agree with those on the
033722,000020: ## original hardcopy, as opposed to the PDF page
033723,000021: ## numbers in 1701.pdf.
033724,000022: ## 2017-02-25 RSB Proofed comment text using octopus/ProoferComments.
033725,000023: ## 2017-03-16 RSB Comment-text fixes identified in 5-way
033726,000024: ## side-by-side diff of Luminary 69/99/116/131/210.
033727,000025: ## 2018-09-04 MAS Copied from Luminary 131 for Luminary 130.
033728,000026:
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Page 788
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033730,000028: 31,2144 BANK 31
033731,000029: 31,2000 SETLOC FTHROT
033732,000030: 31,2000 BANK
033733,000031: 31,2144 E7,1612 EBANK= PIF
033734,000032: 31,2144 COUNT* $$/THROT
033735,000033:
033736,000034: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033737,000035: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033738,000036:
033739,000037: 31,2144 31245 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033740,000038: 31,2145 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033741,000039: 31,2146 72356 MP /AF/CNST
033742,000040: 31,2147 00006 +3 EXTEND
033743,000041: 31,2150 23607 QXCH RTNHOLD
033744,000042: 31,2151 02337 AFDUMP TC MASSMULT
033745,000043: 31,2152 53470 DXCH FP # FP = PRESENT THRUST
033746,000044: 31,2153 00006 EXTEND
033747,000045: 31,2154 31464 DCA /AFC/
033748,000046: 31,2155 02337 TC MASSMULT
033749,000047: 31,2156 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033750,000048: 31,2157 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033751,000049:
033752,000050: # COMPUTE DESIRED THRUST FOR DISPLAY AS A PERCENTAGE OF 10,500 POUNDS
033753,000051:
033754,000052: 31,2160 32360 CAF 4FMAXNOM # MOVE 4FMAXNOM TO ERASABLE FOR DV BELOW
033755,000053: 31,2161 54002 TS Q
033756,000054: 31,2162 31615 CA FC
033757,000055: 31,2163 72357 MASK OCT17777 # FOR SAFETY
033758,000056: 31,2164 00006 EXTEND
033759,000057: 31,2165 10002 DV Q
033760,000058: 31,2166 00006 EXTEND
033761,000059: 31,2167 75003 MP 4SECS
033762,000060: 31,2170 55750 TS THRDISP # FOR DISPLAY IN N92
033763,000061:
033764,000062: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033765,000063:
033766,000064: 31,2171 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
033767,000065: 31,2172 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033768,000066: 31,2173 74733 MASK POSMAX
033769,000067: 31,2174 40000 COM
033770,000068: 31,2175 65002 AD 3SECS
033771,000069: 31,2176 00006 EXTEND
033772,000070: 31,2177 62203 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
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Page 789
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033774,000072: 31,2200 00006 EXTEND
033775,000073: 31,2201 31611 DCA FWEIGHT
033776,000074: 31,2202 21470 DAS FP
033777,000075:
033778,000076: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033779,000077: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033780,000078: # PROVIDES THE UPPER.
033781,000079:
033782,000080: 31,2203 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033783,000081: 31,2204 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
033784,000082: 31,2205 E5,1506 EBANK= LOWCRIT
033785,000083: 31,2205 00006 EXTEND
033786,000084: 31,2206 31507 DCA LOWCRIT
033787,000085: 31,2207 52131 DXCH L*WCR*T
033788,000086: 31,2210 35016 CA EBANK7
033789,000087: 31,2211 54003 TS EBANK
033790,000088: 31,2212 E7,1612 EBANK= PIF
033791,000089: 31,2212 44755 CS ZERO # INITIALIZE PIFPSET
033792,000090: 31,2213 55606 TS PIFPSET
033793,000091: 31,2214 40131 CS H*GHCR*T
033794,000092: 31,2215 61620 AD FCOLD
033795,000093: 31,2216 00006 EXTEND
033796,000094: 31,2217 62231 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033797,000095: 31,2220 40130 CS L*WCR*T
033798,000096: 31,2221 61465 AD FCODD
033799,000097: 31,2222 00006 EXTEND
033800,000098: 31,2223 62226 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033801,000099: 31,2224 31467 CA FP # SEE NOTE 1
033802,000100: 31,2225 12236 TCF FLATOUT1
033803,000101:
033804,000102: 31,2226 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033805,000103: 31,2227 61467 AD FP
033806,000104: 31,2230 12240 TCF FLATOUT2
033807,000105:
033808,000106: 31,2231 40131 LOWFCOLD CS H*GHCR*T
033809,000107: 31,2232 61465 AD FCODD
033810,000108: 31,2233 00006 EXTEND
033811,000109: 31,2234 62241 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033812,000110:
033813,000111: 31,2235 32003 CA FMAXPOS # NO: THROTTLE-UP
033814,000112: 31,2236 53466 FLATOUT1 DXCH FCODD
033815,000113: 31,2237 34737 CA FEXTRA
033816,000114: 31,2240 55606 FLATOUT2 TS PIFPSET
033817,000115:
033818,000116: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033819,000117: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033820,000118:
033821,000119: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
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Page 790
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033823,000121: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
033824,000122: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033825,000123: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033826,000124: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033827,000125: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
033828,000126:
033829,000127: 31,2241 03677 DOPIF TC FASTCHNG
033830,000128: 31,2242 00006 EXTEND
033831,000129: 31,2243 31466 DCA FCODD
033832,000130: 31,2244 55620 TS FCOLD
033833,000131: 31,2245 53613 DXCH PIF
033834,000132: 31,2246 00006 EXTEND
033835,000133: 31,2247 41470 DCS FP
033836,000134: 31,2250 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033837,000135:
033838,000136: 31,2251 31612 DOIT CA PIF
033839,000137: 31,2252 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033840,000138: 31,2253 55614 TS PSEUDO55
033841,000139: 31,2254 54055 TS THRUST
033842,000140: 31,2255 34750 CAF BIT4
033843,000141: 31,2256 00006 EXTEND
033844,000142: 31,2257 05014 WOR CHAN14
033845,000143: 31,2260 30025 CA TIME1
033846,000144: 31,2261 55617 TS TTHROT
033847,000145:
033848,000146: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033849,000147: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033850,000148: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033851,000149: # PIF(PPROCESS + TL) PIF /PIF/
033852,000150: # FWEIGHT = ------------------ + -------------
033853,000151: # PGUID 2 PGUID FRATE
033854,000152: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033855,000153: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033856,000154: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033857,000155:
033858,000156: 31,2262 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
033859,000157: 31,2263 54130 TS BUF
033860,000158:
033861,000159: 31,2264 41010 CS MODREG # ARE WE IN FACT IN P66?
033862,000160: 31,2265 62452 AD DEC66
033863,000161: 31,2266 00006 EXTEND
033864,000162: 31,2267 12274 BZF FWCOMP # YES
033865,000163:
033866,000164: 31,2270 31234 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033867,000165: 31,2271 54130 TS BUF
033868,000166: 31,2272 35003 CAF 4SECS
033869,000167: 31,2273 12275 TCF FWCOMP +1
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Page 791
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033871,000169:
033872,000170: 31,2274 35000 FWCOMP CAF 2SECS
033873,000171: 31,2275 54002 +1 TS Q
033874,000172: 31,2276 00006 EXTEND
033875,000173: 31,2277 74746 MP BIT6
033876,000174: 31,2300 22131 LXCH BUF +1
033877,000175: 31,2301 40130 CS BUF # TIME OF LAST PIPA READING.
033878,000176: 31,2302 60025 AD TIME1
033879,000177: 31,2303 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033880,000178: 31,2304 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033881,000179: 31,2305 22007 ZL
033882,000180: 31,2306 00006 EXTEND
033883,000181: 31,2307 10002 DV Q
033884,000182: 31,2310 00006 EXTEND
033885,000183: 31,2311 71612 MP PIF
033886,000184: 31,2312 60000 DOUBLE
033887,000185: 31,2313 53611 DXCH FWEIGHT
033888,000186: 31,2314 11612 CCS PIF
033889,000187: 31,2315 64753 AD ONE
033890,000188: 31,2316 12320 TCF +2
033891,000189: 31,2317 64753 AD ONE
033892,000190: 31,2320 00006 EXTEND
033893,000191: 31,2321 71612 MP PIF
033894,000192: 31,2322 00006 EXTEND
033895,000193: 31,2323 10131 DV BUF +1
033896,000194: 31,2324 22007 ZL
033897,000195: 31,2325 21611 DAS FWEIGHT
033898,000196:
033899,000197: 31,2326 01607 THDUMP TC RTNHOLD
033900,000198:
033901,000199: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033902,000200:
033903,000201: 31,2327 34737 FLATOUT CAF BIT13 # 4096 PULSES
033904,000202: 31,2330 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033905,000203: 31,2331 44755 CS ZERO
033906,000204: 31,2332 55620 TS FCOLD
033907,000205: 31,2333 55612 TS PIF
033908,000206: 31,2334 00006 EXTEND
033909,000207: 31,2335 23607 QXCH RTNHOLD
033910,000208: 31,2336 12251 TCF DOIT
033911,000209:
033912,000210: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
033913,000211:
033914,000212: 31,2337 00006 MASSMULT EXTEND
033915,000213: 31,2340 22130 QXCH BUF
033916,000214: 31,2341 52155 DXCH MPAC
033917,000215: 31,2342 07106 TC DMP
033918,000216: 31,2343 01243 ADRES MASS
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Page 792
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033920,000218: 31,2344 07106 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
033921,000219: 31,2345 02005 ADRES SCALEFAC
033922,000220: 31,2346 07262 TC TPAGREE
033923,000221: 31,2347 30154 CA MPAC
033924,000222: 31,2350 00006 EXTEND
033925,000223: 31,2351 12354 BZF +3
033926,000224: 31,2352 34733 CAF POSMAX
033927,000225: 31,2353 00130 TC BUF
033928,000226: 31,2354 52156 DXCH MPAC +1
033929,000227: 31,2355 00130 TC BUF
033930,000228:
033931,000229: # CONSTANTS:-
033932,000230:
033933,000231: 31,2356 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
033934,000232:
033935,000233: 31,2356 04143 /AF/CNST DEC .13107
033936,000234:
033937,000235: 31,2357 17777 OCT17777 OCT 17777
033938,000236: 31,2360 35074 4FMAXNOM DEC 14908 B-14 # EQUIVALENT TO 10,500 LBS.
033939,000237:
033940,000238: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc