Notations on the program listing read, in part:
GAP: ASSEMBLE REVISION 116 OF AGC PROGRAM LUMINARY BY NASA 2021112-071 19:09 AUG. 11,1969Note that the date is the date of the printout, not the date of the program revision.
Source Code
|
|
These source-code files derive from a printout of Luminary 116 (the Apollo 12
Lunar Module guidance computer program), from the personal library of
original AGC developer Don Eyles, digitally photographed at archive.org,
financially sponsored by Ron Burkey, 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 116 OF AGC PROGRAM LUMINARY BY NASA 2021112-071 19:09 AUG. 11,1969Note that the date is the date of the printout, not the date of the program revision. |
033605,000002: ## Copyright: Public domain.
033606,000003: ## Filename: THROTTLE_CONTROL_ROUTINES.agc
033607,000004: ## Purpose: A section of Luminary revision 116.
033608,000005: ## It is part of the source code for the Lunar Module's (LM)
033609,000006: ## Apollo Guidance Computer (AGC) for Apollo 12.
033610,000007: ## This file is intended to be a faithful transcription, except
033611,000008: ## that the code format has been changed to conform to the
033612,000009: ## requirements of the yaYUL assembler rather than the
033613,000010: ## original YUL assembler.
033614,000011: ## Reference: pp. 786-790
033615,000012: ## Assembler: yaYUL
033616,000013: ## Contact: Ron Burkey <info@sandroid.org>.
033617,000014: ## Website: www.ibiblio.org/apollo/index.html
033618,000015: ## Mod history: 2017-01-22 MAS Created from Luminary 99.
033619,000016: ## 2017-03-01 HG Transcribed
033620,000017: ## 2017-03-14 RSB Proofed comment text via 3-way diff vs
033621,000018: ## Luminary 99 and 131. No problems were found,
033622,000019: ## but a ##-comment that wouldn't have been
033623,000020: ## displayed properly was fixed.
033624,000021: ## 2017-03-16 RSB Comment-text fixes identified in 5-way
033625,000022: ## side-by-side diff of Luminary 69/99/116/131/210.
033626,000023:
|
|
Page 786 |
033628,000025: 31,2144 BANK 31
033629,000026:
033630,000027: 31,2000 SETLOC FTHROT
033631,000028:
033632,000029: 31,2000 BANK
033633,000030:
033634,000031: 31,2144 E7,1612 EBANK= PIF
033635,000032:
033636,000033: 31,2144 COUNT* $$/THROT
033637,000034: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
033638,000035:
033639,000036: # HERE FC, DESIRED THRUST, AND FP, PRESENT THRUST, UNWEIGHTED, ARE COMPUTED.
033640,000037:
033641,000038:
033642,000039: 31,2144 31245 THROTTLE CA ABDELV # COMPUTE PRESENT ACCELERATION IN UNITS OF
033643,000040: 31,2145 00006 EXTEND # 2(-4) M/CS/CS, SAVING SERVICER TROUBLE
033644,000041: 31,2146 72345 MP /AF/CNST
033645,000042: 31,2147 00006 +3 EXTEND
033646,000043: 31,2150 23607 QXCH RTNHOLD
033647,000044: 31,2151 02326 AFDUMP TC MASSMULT
033648,000045: 31,2152 53470 DXCH FP # FP = PRESENT THRUST
033649,000046: 31,2153 00006 EXTEND
033650,000047: 31,2154 31464 DCA /AFC/
033651,000048: 31,2155 02326 TC MASSMULT
033652,000049: 31,2156 55615 TS FC # FC = THRUST DESIRED BY GUIDANCE
033653,000050: 31,2157 53466 DXCH FCODD # FCODD = WHAT IT IS GOING TO GET
033654,000051:
033655,000052:
033656,000053: # IF IT HAS BEEN LESS THAN 3 SECONDS SINCE THE LAST THROTTLING, AUGMENT FP USING THE FWEIGHT CALCULATED THEN.
033657,000054:
033658,000055:
033659,000056: 31,2160 41617 CS TTHROT # THIS CODING ASSUMES A FLATOUT WITHIN
033660,000057: 31,2161 60025 AD TIME1 # 80 SECONDS BEFORE FIRST THROTTLE CALL
033661,000058: 31,2162 74733 MASK POSMAX
033662,000059: 31,2163 40000 COM
033663,000060: 31,2164 65002 AD 3SECS
033664,000061: 31,2165 00006 EXTEND
033665,000062: 31,2166 62172 BZMF WHERETO # BRANCH IF (TIME1-TTHROT +1) > 3 SECONDS
033666,000063: 31,2167 00006 EXTEND
033667,000064: 31,2170 31611 DCA FWEIGHT
033668,000065: 31,2171 21470 DAS FP
033669,000066:
033670,000067:
033671,000068: # THIS LOGIC DETERMINES THE THROTTLING IN THE REGION 10% - 94%. THE MANUAL THROTTLE, NOMINALLY SET AT
033672,000069: # MINIMUM BY ASTRONAUT OR MISSION CONTROL PROGRAMS, PROVIDES THE LOWER BOUND. A STOP IN THE THROTTLE HARDWARE
033673,000070: # PROVIDES THE UPPER.
033674,000071:
033675,000072:
033676,000073: 31,2172 35014 WHERETO CA EBANK5 # INITIALIZE L*WCR*T AND H*GHCR*T FROM
033677,000074: 31,2173 54003 TS EBANK # PAD LOADED ERASABLES IN W-MATRIX
033678,000075:
|
|
Page 787 |
033680,000077: 31,2174 E5,1506 EBANK= LOWCRIT
033681,000078: 31,2174 00006 EXTEND
033682,000079: 31,2175 31507 DCA LOWCRIT
033683,000080: 31,2176 52131 DXCH L*WCR*T
033684,000081: 31,2177 35016 CA EBANK7
033685,000082: 31,2200 54003 TS EBANK
033686,000083: 31,2201 E7,1612 EBANK= PIF
033687,000084: 31,2201 44755 CS ZERO # INITIALIZE PIFPSET
033688,000085: 31,2202 55606 TS PIFPSET
033689,000086: 31,2203 40131 CS H*GHCR*T
033690,000087: 31,2204 61620 AD FCOLD
033691,000088: 31,2205 00006 EXTEND
033692,000089: 31,2206 62220 BZMF LOWFCOLD # BRANCH IF FCOLD < OR = HIGHCRIT
033693,000090: 31,2207 40130 CS L*WCR*T
033694,000091: 31,2210 61465 AD FCODD
033695,000092: 31,2211 00006 EXTEND
033696,000093: 31,2212 62215 BZMF FCOMPSET # BRANCH IF FC < OR = LOWCRIT
033697,000094: 31,2213 31467 CA FP # SEE NOTE 1
033698,000095: 31,2214 12225 TCF FLATOUT1
033699,000096:
033700,000097: 31,2215 42002 FCOMPSET CS FMAXODD # SEE NOTE 2
033701,000098: 31,2216 61467 AD FP
033702,000099: 31,2217 12227 TCF FLATOUT2
033703,000100:
033704,000101: 31,2220 40131 LOWFCOLD CS H*GHCR*T
033705,000102: 31,2221 61465 AD FCODD
033706,000103: 31,2222 00006 EXTEND
033707,000104: 31,2223 62230 BZMF DOPIF # BRANCH IF FC < OR = HIGHCRIT
033708,000105:
033709,000106: 31,2224 32003 CA FMAXPOS # NO: THROTTLE-UP
033710,000107: 31,2225 53466 FLATOUT1 DXCH FCODD
033711,000108: 31,2226 34737 CA FEXTRA
033712,000109: 31,2227 55606 FLATOUT2 TS PIFPSET
033713,000110:
033714,000111: # NOTE 1 FC IS SET EQUAL TO FP SO PIF WILL BE ZERO. THIS IS DESIRABLE
033715,000112: # AS THERE IS ACTUALLY NO THROTTLE CHANGE.
033716,000113:
033717,000114: # NOTE2 HERE, SINCE WE ARE ABOUT TO RETURN TO THE THROTTLEABLE REGION
033718,000115: # (BELOW 55%) THE QUANTITY -(FMAXODD - FP) IS COMPUTED AND PUT
033719,000116: # INTO PIFPSET TO COMPENSATE FOR THE DIFFERENCE BETWEEN THE
033720,000117: # NUMBER OF BITS CORRESPONDING TO FULL THROTTLE (FMAXODD) AND THE
033721,000118: # NUMBER CORRESPONDING TO ACTUAL THRUST (FP). THUS THE TOTAL
033722,000119: # THROTTLE COMMAND PIF = FC - FP - (FMAXODD - FP) = FC - FMAXODD.
033723,000120:
033724,000121: 31,2230 03717 DOPIF TC FASTCHNG
033725,000122: 31,2231 00006 EXTEND
033726,000123: 31,2232 31466 DCA FCODD
033727,000124: 31,2233 55620 TS FCOLD
033728,000125: 31,2234 53613 DXCH PIF
033729,000126: 31,2235 00006 EXTEND
033730,000127:
|
|
Page 788 |
033732,000129: 31,2236 41470 DCS FP
033733,000130: 31,2237 21613 DAS PIF # PIF = FC - FP, NEVER EQUALS +0
033734,000131:
033735,000132:
033736,000133: 31,2240 31612 DOIT CA PIF
033737,000134: 31,2241 61606 AD PIFPSET # ADD IN PIFPSET, WITHOUT CHANGING PIF
033738,000135: 31,2242 55614 TS PSEUDO55
|
|
Note: The above statement has a blue check mark right after the operand |
033740,000137: 31,2243 54055 TS THRUST
033741,000138: 31,2244 34750 CAF BIT4
033742,000139: 31,2245 00006 EXTEND
033743,000140: 31,2246 05014 WOR CHAN14
033744,000141: 31,2247 30025 CA TIME1
033745,000142: 31,2250 55617 TS TTHROT
|
|
Note: Three statements above are marked with a single light vertical pen mark to the right of the operands |
033747,000144:
033748,000145: # SINCE /AF/ IS NOT AN INSTANTANEOUS ACCELERATION, BUT RATHER AN "AVERAGE" OF THE ACCELERATION LEVELS DURING
033749,000146: # THE PRECEEDING PIPA INTERVAL, AND SINCE FP IS COMPUTED DIRECTLY FROM /AF/, FP IN ORDER TO CORRESPOND TO THE
033750,000147: # ACTUAL THRUST LEVEL AT THE END OF THE INTERVAL MUST BE WEIGHTED BY
033751,000148:
033752,000149: # PIF(PPROCESS + TL) PIF /PIF/
033753,000150: # FWEIGHT = ------------------ + -------------
033754,000151: # PGUID 2 PGUID FRATE
033755,000152:
033756,000153: # WHERE PPROCESS IS THE TIME BETWEEN PIPA READING AND THE START OF THROTTLING, PGUID IS THE GUIDANCE PERIOD, AND
033757,000154: # FRATE IS THE THROTTLING RATE (32 UNITS PER CENTISECOND). PGUID IS EITHER 1 OR 2 SECONDS. THE "TL" IN THE
033758,000155: # FIRST TERM REPRESENTS THE ENGINE'S RESPONSE LAG. HERE FWEIGHT IS COMPUTED FOR USE NEXT PASS.
033759,000156:
033760,000157: 31,2251 31762 CA THISTPIP +1 # INITIALIZE FWEIGHT COMP AS IF FOR P66
|
|
Note: the complete comment for the above statement has a box drawn arround it using a blue pen. |
033762,000159: 31,2252 54130 TS BUF
033763,000160:
033764,000161: 31,2253 41010 CS MODREG # ARE WE IN FACT IN P66?
033765,000162: 31,2254 62433 AD DEC66
033766,000163: 31,2255 00006 EXTEND
033767,000164: 31,2256 12263 BZF FWCOMP # YES
033768,000165:
033769,000166: 31,2257 31234 CA PIPTIME +1 # NO: INITIALIZE FOR TWO SECOND PERIOD
033770,000167: 31,2260 54130 TS BUF
033771,000168: 31,2261 35003 CAF 4SECS
033772,000169: 31,2262 12264 TCF FWCOMP +1
033773,000170:
033774,000171: 31,2263 35000 FWCOMP CAF 2SECS
033775,000172: 31,2264 54002 +1 TS Q
033776,000173: 31,2265 00006 EXTEND
033777,000174: 31,2266 74746 MP BIT6
033778,000175: 31,2267 22131 LXCH BUF +1
033779,000176: 31,2270 40130 CS BUF # TIME OF LAST PIPA READING.
033780,000177: 31,2271 60025 AD TIME1
033781,000178: 31,2272 62004 AD THROTLAG # COMPENSATE FOR ENGINE RESPONSE LAG
033782,000179: 31,2273 74357 MASK LOW8 # MAKE SURE SMALL AND POSITIVE
033783,000180: 31,2274 22007 ZL
033784,000181: 31,2275 00006 EXTEND
033785,000182:
|
|
Page 789 |
033787,000184: 31,2276 10002 DV Q
033788,000185: 31,2277 00006 EXTEND
033789,000186: 31,2300 71612 MP PIF
033790,000187: 31,2301 60000 DOUBLE
033791,000188: 31,2302 53611 DXCH FWEIGHT
033792,000189: 31,2303 11612 CCS PIF
033793,000190: 31,2304 64753 AD ONE
033794,000191: 31,2305 12307 TCF +2
033795,000192: 31,2306 64753 AD ONE
033796,000193: 31,2307 00006 EXTEND
033797,000194: 31,2310 71612 MP PIF
033798,000195: 31,2311 00006 EXTEND
033799,000196: 31,2312 10131 DV BUF +1
033800,000197: 31,2313 22007 ZL
033801,000198: 31,2314 21611 DAS FWEIGHT
033802,000199:
033803,000200:
033804,000201: 31,2315 01607 THDUMP TC RTNHOLD
033805,000202:
033806,000203:
033807,000204: # FLATOUT THROTTLES UP THE DESCENT ENGINE, AND IS CALLED AS A BASIC SUBROUTINE.
033808,000205:
033809,000206: 31,2316 34737 FLATOUT CAF BIT13 # 4096 PULSES
033810,000207: 31,2317 55606 WHATOUT TS PIFPSET # USE PIFPSET SO FWEIGHT WILL BE ZERO
033811,000208: 31,2320 44755 CS ZERO
033812,000209: 31,2321 55620 TS FCOLD
033813,000210: 31,2322 55612 TS PIF
033814,000211: 31,2323 00006 EXTEND
033815,000212: 31,2324 23607 QXCH RTNHOLD
033816,000213: 31,2325 12240 TCF DOIT
033817,000214:
033818,000215:
033819,000216: # MASSMULT SCALES ACCELERATION, ARRIVING IN A AND L IN UNITS OF 2(-4) M/CS/CS, TO FORCE IN PULSE UNITS.
033820,000217:
033821,000218: 31,2326 00006 MASSMULT EXTEND
033822,000219: 31,2327 22130 QXCH BUF
033823,000220: 31,2330 52155 DXCH MPAC
033824,000221: 31,2331 07106 TC DMP
033825,000222: 31,2332 01243 ADRES MASS
033826,000223: 31,2333 07106 TC DMP # LEAVES PROPERLY SCALED FORCE IM MPAC
033827,000224: 31,2334 02005 ADRES SCALEFAC
033828,000225: 31,2335 07262 TC TPAGREE
033829,000226: 31,2336 30154 CA MPAC
033830,000227: 31,2337 00006 EXTEND
033831,000228: 31,2340 12343 BZF +3
033832,000229: 31,2341 34733 CAF POSMAX
033833,000230: 31,2342 00130 TC BUF
033834,000231: 31,2343 52156 DXCH MPAC +1
033835,000232: 31,2344 00130 TC BUF
|
|
Note: There is a small drawing in blue pen in the comment section of the above statements starting in the
line of statement CA MPAC. The drawing resembles a linear step function.
|
033839,000236: ##
|
|
| | | ----| | / | | / | |----/ | | | | | |
033848,000245:
|
|
Page 790 |
033850,000247: # CONSTANTS:-
033851,000248:
033852,000249: 31,2345 4737 FEXTRA = BIT13 # FEXT +5.13309020E+4
033853,000250:
033854,000251: 31,2345 04143 /AF/CNST DEC .13107
033855,000252:
033856,000253: # * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
End of include-file THROTTLE_CONTROL_ROUTINES.agc. Parent file is MAIN.agc