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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033725,000002: ## Copyright: Public domain.
033726,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033727,000004: ## Purpose: A section of the reconstructed source code for Luminary 130.
033728,000005: ## This was the original program released for the Apollo 13 LM,
033729,000006: ## although several more revisions would follow. It has been
033730,000007: ## reconstructed from a listing of Luminary 131, from which it
033731,000008: ## differs on only two lines in P70-P71. The difference is
033732,000009: ## described in detail in Luminary memo #129, which was used
033733,000010: ## to perform the reconstruction. This file is intended to be a
033734,000011: ## faithful reconstruction, except that the code format has been
033735,000012: ## changed to conform to the requirements of the yaYUL assembler
033736,000013: ## rather than the original YUL assembler.
033737,000014: ## Reference: pp. 788-792
033738,000015: ## Contact: Ron Burkey <info@sandroid.org>.
033739,000016: ## Website: www.ibiblio.org/apollo/index.html
033740,000017: ## Mod history: 05/24/03 RSB. Began transcribing.
033741,000018: ## 05/14/05 RSB Corrected website reference above.
033742,000019: ## 2017-01-06 RSB Page numbers now agree with those on the
033743,000020: ## original hardcopy, as opposed to the PDF page
033744,000021: ## numbers in 1701.pdf.
033745,000022: ## 2017-02-25 RSB Proofed comment text using octopus/ProoferComments.
033746,000023: ## 2017-03-16 RSB Comment-text fixes identified in 5-way
033747,000024: ## side-by-side diff of Luminary 69/99/116/131/210.
033748,000025: ## 2018-09-04 MAS Copied from Luminary 131 for Luminary 130.
033749,000026:
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Page 788
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033751,000028: 31,2144 BANK 31
033752,000029: 31,2000 SETLOC FTHROT
033753,000030: 31,2000 BANK
033754,000031: 31,2144 E7,1612 EBANK= PIF
033755,000032: 31,2144 COUNT* $$/THROT
033756,000033:
033757,000034: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033758,000035: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033759,000036:
033760,000037: 31,2144 31245 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033761,000038: 31,2145 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033762,000039: 31,2146 72356 MP /AF/CNST
033763,000040: 31,2147 00006 +3 EXTEND
033764,000041: 31,2150 23607 QXCH RTNHOLD
033765,000042: 31,2151 02337 AFDUMP TC MASSMULT
033766,000043: 31,2152 53470 DXCH FP # FP = PRESENT THRUST
033767,000044: 31,2153 00006 EXTEND
033768,000045: 31,2154 31464 DCA /AFC/
033769,000046: 31,2155 02337 TC MASSMULT
033770,000047: 31,2156 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033771,000048: 31,2157 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033772,000049:
033773,000050: # COMPUTE DESIRED THRUST FOR DISPLAY AS A PERCENTAGE OF 10,500 POUNDS
033774,000051:
033775,000052: 31,2160 32360 CAF 4FMAXNOM # MOVE 4FMAXNOM TO ERASABLE FOR DV BELOW
033776,000053: 31,2161 54002 TS Q
033777,000054: 31,2162 31615 CA FC
033778,000055: 31,2163 72357 MASK OCT17777 # FOR SAFETY
033779,000056: 31,2164 00006 EXTEND
033780,000057: 31,2165 10002 DV Q
033781,000058: 31,2166 00006 EXTEND
033782,000059: 31,2167 75003 MP 4SECS
033783,000060: 31,2170 55750 TS THRDISP # FOR DISPLAY IN N92
033784,000061:
033785,000062: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033786,000063:
033787,000064: 31,2171 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
033788,000065: 31,2172 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033789,000066: 31,2173 74733 MASK POSMAX
033790,000067: 31,2174 40000 COM
033791,000068: 31,2175 65002 AD 3SECS
033792,000069: 31,2176 00006 EXTEND
033793,000070: 31,2177 62203 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
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Page 789
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033795,000072: 31,2200 00006 EXTEND
033796,000073: 31,2201 31611 DCA FWEIGHT
033797,000074: 31,2202 21470 DAS FP
033798,000075:
033799,000076: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033800,000077: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033801,000078: # PROVIDES THE UPPER.
033802,000079:
033803,000080: 31,2203 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033804,000081: 31,2204 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
033805,000082: 31,2205 E5,1506 EBANK= LOWCRIT
033806,000083: 31,2205 00006 EXTEND
033807,000084: 31,2206 31507 DCA LOWCRIT
033808,000085: 31,2207 52131 DXCH L*WCR*T
033809,000086: 31,2210 35016 CA EBANK7
033810,000087: 31,2211 54003 TS EBANK
033811,000088: 31,2212 E7,1612 EBANK= PIF
033812,000089: 31,2212 44755 CS ZERO # INITIALIZE PIFPSET
033813,000090: 31,2213 55606 TS PIFPSET
033814,000091: 31,2214 40131 CS H*GHCR*T
033815,000092: 31,2215 61620 AD FCOLD
033816,000093: 31,2216 00006 EXTEND
033817,000094: 31,2217 62231 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033818,000095: 31,2220 40130 CS L*WCR*T
033819,000096: 31,2221 61465 AD FCODD
033820,000097: 31,2222 00006 EXTEND
033821,000098: 31,2223 62226 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033822,000099: 31,2224 31467 CA FP # SEE NOTE 1
033823,000100: 31,2225 12236 TCF FLATOUT1
033824,000101:
033825,000102: 31,2226 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033826,000103: 31,2227 61467 AD FP
033827,000104: 31,2230 12240 TCF FLATOUT2
033828,000105:
033829,000106: 31,2231 40131 LOWFCOLD CS H*GHCR*T
033830,000107: 31,2232 61465 AD FCODD
033831,000108: 31,2233 00006 EXTEND
033832,000109: 31,2234 62241 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033833,000110:
033834,000111: 31,2235 32003 CA FMAXPOS # NO: THROTTLE-UP
033835,000112: 31,2236 53466 FLATOUT1 DXCH FCODD
033836,000113: 31,2237 34737 CA FEXTRA
033837,000114: 31,2240 55606 FLATOUT2 TS PIFPSET
033838,000115:
033839,000116: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033840,000117: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033841,000118:
033842,000119: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
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Page 790
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033844,000121: # (BELOW 55%) THE QUANTITY -(FMAXODD-FP) IS COMPUTED AND PUT
033845,000122: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033846,000123: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033847,000124: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033848,000125: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
033849,000126:
033850,000127: 31,2241 03677 DOPIF TC FASTCHNG
033851,000128: 31,2242 00006 EXTEND
033852,000129: 31,2243 31466 DCA FCODD
033853,000130: 31,2244 55620 TS FCOLD
033854,000131: 31,2245 53613 DXCH PIF
033855,000132: 31,2246 00006 EXTEND
033856,000133: 31,2247 41470 DCS FP
033857,000134: 31,2250 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033858,000135:
033859,000136: 31,2251 31612 DOIT CA PIF
033860,000137: 31,2252 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033861,000138: 31,2253 55614 TS PSEUDO55
033862,000139: 31,2254 54055 TS THRUST
033863,000140: 31,2255 34750 CAF BIT4
033864,000141: 31,2256 00006 EXTEND
033865,000142: 31,2257 05014 WOR CHAN14
033866,000143: 31,2260 30025 CA TIME1
033867,000144: 31,2261 55617 TS TTHROT
033868,000145:
033869,000146: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033870,000147: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033871,000148: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033872,000149: # PIF(PPROCESS + TL) PIF /PIF/
033873,000150: # FWEIGHT = ------------------ + -------------
033874,000151: # PGUID 2 PGUID FRATE
033875,000152: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033876,000153: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033877,000154: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033878,000155:
033879,000156: 31,2262 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
033880,000157: 31,2263 54130 TS BUF
033881,000158:
033882,000159: 31,2264 41010 CS MODREG # ARE WE IN FACT IN P66?
033883,000160: 31,2265 62452 AD DEC66
033884,000161: 31,2266 00006 EXTEND
033885,000162: 31,2267 12274 BZF FWCOMP # YES
033886,000163:
033887,000164: 31,2270 31234 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033888,000165: 31,2271 54130 TS BUF
033889,000166: 31,2272 35003 CAF 4SECS
033890,000167: 31,2273 12275 TCF FWCOMP +1
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Page 791
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033892,000169:
033893,000170: 31,2274 35000 FWCOMP CAF 2SECS
033894,000171: 31,2275 54002 +1 TS Q
033895,000172: 31,2276 00006 EXTEND
033896,000173: 31,2277 74746 MP BIT6
033897,000174: 31,2300 22131 LXCH BUF +1
033898,000175: 31,2301 40130 CS BUF # TIME OF LAST PIPA READING.
033899,000176: 31,2302 60025 AD TIME1
033900,000177: 31,2303 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033901,000178: 31,2304 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033902,000179: 31,2305 22007 ZL
033903,000180: 31,2306 00006 EXTEND
033904,000181: 31,2307 10002 DV Q
033905,000182: 31,2310 00006 EXTEND
033906,000183: 31,2311 71612 MP PIF
033907,000184: 31,2312 60000 DOUBLE
033908,000185: 31,2313 53611 DXCH FWEIGHT
033909,000186: 31,2314 11612 CCS PIF
033910,000187: 31,2315 64753 AD ONE
033911,000188: 31,2316 12320 TCF +2
033912,000189: 31,2317 64753 AD ONE
033913,000190: 31,2320 00006 EXTEND
033914,000191: 31,2321 71612 MP PIF
033915,000192: 31,2322 00006 EXTEND
033916,000193: 31,2323 10131 DV BUF +1
033917,000194: 31,2324 22007 ZL
033918,000195: 31,2325 21611 DAS FWEIGHT
033919,000196:
033920,000197: 31,2326 01607 THDUMP TC RTNHOLD
033921,000198:
033922,000199: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033923,000200:
033924,000201: 31,2327 34737 FLATOUT CAF BIT13 # 4096 PULSES
033925,000202: 31,2330 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033926,000203: 31,2331 44755 CS ZERO
033927,000204: 31,2332 55620 TS FCOLD
033928,000205: 31,2333 55612 TS PIF
033929,000206: 31,2334 00006 EXTEND
033930,000207: 31,2335 23607 QXCH RTNHOLD
033931,000208: 31,2336 12251 TCF DOIT
033932,000209:
033933,000210: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
033934,000211:
033935,000212: 31,2337 00006 MASSMULT EXTEND
033936,000213: 31,2340 22130 QXCH BUF
033937,000214: 31,2341 52155 DXCH MPAC
033938,000215: 31,2342 07106 TC DMP
033939,000216: 31,2343 01243 ADRES MASS
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Page 792
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033941,000218: 31,2344 07106 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
033942,000219: 31,2345 02005 ADRES SCALEFAC
033943,000220: 31,2346 07262 TC TPAGREE
033944,000221: 31,2347 30154 CA MPAC
033945,000222: 31,2350 00006 EXTEND
033946,000223: 31,2351 12354 BZF +3
033947,000224: 31,2352 34733 CAF POSMAX
033948,000225: 31,2353 00130 TC BUF
033949,000226: 31,2354 52156 DXCH MPAC +1
033950,000227: 31,2355 00130 TC BUF
033951,000228:
033952,000229: # CONSTANTS:-
033953,000230:
033954,000231: 31,2356 4737 FEXTRA = BIT13 # FEXT +5.13309020 E+4
033955,000232:
033956,000233: 31,2356 04143 /AF/CNST DEC .13107
033957,000234:
033958,000235: 31,2357 17777 OCT17777 OCT 17777
033959,000236: 31,2360 35074 4FMAXNOM DEC 14908 B-14 # EQUIVALENT TO 10,500 LBS.
033960,000237:
033961,000238: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc