Source Code
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These source-code files are part of a reconstructed copy of Luminary 178, the
final release of the Apollo 14 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Zerlina 56, Luminary 210, and
Luminary 131, previously transcribed from digitized copies of those programs.
The code was created by combining the three, using Zerlina 56 as a base, since
it was based off of Luminary 183. The differences between the three were
carefully merged using the Luminary memos as a guide, with all changes made
after Luminary 178 being backed out. 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 178 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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047725,000002: ## Copyright: Public domain.
047726,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
047727,000004: ## Purpose: A section of Luminary revision 178.
047728,000005: ## It is part of the reconstructed source code for the final
047729,000006: ## release of the flight software for the Lunar Module's
047730,000007: ## (LM) Apollo Guidance Computer (AGC) for Apollo 14. The
047731,000008: ## code has been recreated from copies of Zerlina 56, Luminary
047732,000009: ## 210, and Luminary 131, as well as many Luminary memos.
047733,000010: ## It has been adapted such that the resulting bugger words
047734,000011: ## exactly match those specified for Luminary 178 in NASA
047735,000012: ## drawing 2021152N, which gives relatively high confidence
047736,000013: ## that the reconstruction is correct.
047737,000014: ## Reference: pp. 1124-1130
047738,000015: ## Assembler: yaYUL
047739,000016: ## Contact: Ron Burkey <info@sandroid.org>.
047740,000017: ## Website: www.ibiblio.org/apollo/index.html
047741,000018: ## Mod history: 2019-08-14 MAS Created from Zerlina 56.
047742,000019:
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Page 1124
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047744,000021: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047745,000022:
047746,000023: # CALLING SEQUENCE
047747,000024:
047748,000025: # L-1 CALL
047749,000026: # L LAT-LONG
047750,000027: # SUBROUTINES USED
047751,000028:
047752,000029: # R-TO-RP,ARCTAN,SETGAMMA,SETRE
047753,000030: # ERASABLE INIT. REQ.
047754,000031:
047755,000032: # AXO,-AYO,AZO,TEPHEM (SET AT LAUNCH TIME)
047756,000033: # ALPHAV = POSITION VECTOR METERS B-29
047757,000034: # MPAC-- TIME (CSECS B-28)
047758,000035: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047759,000036: # LUNAFLAG=0 FOR EARTH,1 FOR MOON
047760,000037: # OUTPUT
047761,000038:
047762,000039: # LATITUDE IN LAT (REVS. B-0)
047763,000040: # LONGITUDE IN LONG (REVS. B-0)
047764,000041: # ALTITUDE IN ALT METERS B-29
047765,000042: 30,3757 BANK 30
047766,000043: 13,2000 SETLOC LATLONG
047767,000044: 13,2000 BANK
047768,000045:
047769,000046: 13,2347 COUNT* $$/LT-LG
047770,000047: 13,2347 E4,1431 EBANK= ALPHAV
047771,000048: 13,2347 40220 LAT-LONG STQ SETPD
047772,000049: 13,2350 03674 INCORPEX
047773,000050: 13,2351 00001 0D
047774,000051: 13,2352 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
047775,000052: 13,2353 02032 ALPHAV
047776,000053: 13,2354 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
047777,000054: 13,2355 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
047778,000055: 13,2356 24007 ZEROVEC # SET MPAC=0 FOR EARTH,NON-ZERO FOR MOON
047779,000056: 13,2357 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
047780,000057: 13,2360 01743 LUNAFLAG # 0=EARTH,1=MOON
047781,000058: 13,2361 26362 CALLRTRP
047782,000059: 13,2362 77624 CALLRTRP CALL
047783,000060: 13,2363 51642 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
047784,000061: 13,2364 77656 UNIT # UNIT RP B-1
047785,000062: 13,2365 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
047786,000063: 13,2366 26546 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH,=1 FOR MOON
047787,000064: 13,2367 77624 CALL # SCALED B-1
047788,000065: 13,2370 26556 SETRE # CALC RE METERS B-29
047789,000066: 13,2371 63545 DLOAD DSQ
047790,000067: 13,2372 02032 ALPHAV
047791,000068: 13,2373 63525 PDDL DSQ
047792,000069: 13,2374 02034 ALPHAV +2
047793,000070: 13,2375 75415 DAD SQRT
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Page 1125
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047795,000072: 13,2376 76405 DMP SL1R
047796,000073: 13,2377 00011 GAMRP
047797,000074: 13,2400 14021 STODL COSTH # COS(LAT) B-1
047798,000075: 13,2401 02036 ALPHAV +4
047799,000076: 13,2402 34023 STCALL SINTH # SIN(LAT) B-1
047800,000077: 13,2403 26506 ARCTAN
047801,000078: 13,2404 15120 STODL LAT # LAT B0
047802,000079: 13,2405 02032 ALPHAV
047803,000080: 13,2406 14021 STODL COSTH # COS(LONG) B-1
047804,000081: 13,2407 02034 ALPHAV +2
047805,000082: 13,2410 34023 STCALL SINTH # SIN(LONG) B-1
047806,000083: 13,2411 26506 ARCTAN
047807,000084: 13,2412 15122 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047808,000085: 13,2413 02070 ALPHAM
047809,000086: 13,2414 77625 DSU # ALT= R-RE METERS B-29
047810,000087: 13,2415 03673 ERADM
047811,000088: 13,2416 35124 STCALL ALT # EXIT WITH ALT METERS B-29
047812,000089: 13,2417 03674 INCORPEX
047813,000090:
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Page 1126
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047815,000092: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047816,000093: # CALLING SEQUENCE
047817,000094:
047818,000095: # L-1 CALL
047819,000096: # L LALOTORV
047820,000097: # SUBROUTINES USED
047821,000098:
047822,000099: # SETGAMMA,SETRE,RP-TO-R
047823,000100: # ERASABLE INIT. REQ.
047824,000101:
047825,000102: # AXO,AYO,AZO,TEPHEM SET AT LAUNCH TIME
047826,000103: # LAT-- LATITUDE (REVS B0)
047827,000104: # LONG-- LONGITUDE (REVS B0)
047828,000105: # ALT--ALTITUDE (METERS) B-29
047829,000106: # MPAC-- TIME (CSECS B-28)
047830,000107: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047831,000108: # LUNAFLAG=0 FOR EARTH,1 FOR MOON
047832,000109: # OUTPUT
047833,000110:
047834,000111: # R-VECTOR IN ALPHAV (METERS B-29)
047835,000112: 13,2420 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
047836,000113: 13,2421 03674 INCORPEX
047837,000114: 13,2422 00001 0D
047838,000115: 13,2423 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
047839,000116: 13,2424 26546 SETGAMMA # GAMMA=B2/A2 FOR EARTH,1 FOR MOON B-1
047840,000117: 13,2425 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
047841,000118: 13,2426 01120 LAT # UNIT RP= SIN(LONG)COS(LAT) 2-3D
047842,000119: 13,2427 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
047843,000120: 13,2430 00011 GAMRP
047844,000121: 13,2431 01120 LAT # 0-1D= GAMMA*SIN(LAT) B-2
047845,000122: 13,2432 65346 COS PDDL # PD4 2-3D=COS(LAT) B-1 TEMPORARILY
047846,000123: 13,2433 01122 LONG
047847,000124: 13,2434 57356 SIN DMPR # PD 2
047848,000125: 13,2435 71525 PDDL COS # PD 4 2-3D=SIN(LONG)COS(LAT) B-2
047849,000126: 13,2436 01120 LAT
047850,000127: 13,2437 71525 PDDL COS # PD 6 4-5D=COS(LAT) B-1 TEMPORARILY
047851,000128: 13,2440 01122 LONG
047852,000129: 13,2441 55475 DMPR VDEF # PD 4 MPAC= COS(LONG)COS(LAT) B-2
047853,000130: 13,2442 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
047854,000131: 13,2443 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
047855,000132: 13,2444 26556 SETRE # RE METERS B-29
047856,000133: 13,2445 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH,NON-ZERO FOR MOON
047857,000134: 13,2446 24007 ZEROVEC
047858,000135: 13,2447 01743 LUNAFLAG
047859,000136: 13,2450 26452 CALLRPRT
047860,000137: 13,2451 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
047861,000138: 13,2452 77624 CALLRPRT CALL
047862,000139: 13,2453 55720 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
047863,000140: 13,2454 16032 STODL ALPHAV
047864,000141: 13,2455 03673 ERADM
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Page 1127
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047866,000143: 13,2456 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
047867,000144: 13,2457 01124 ALT
047868,000145: 13,2460 02032 ALPHAV
047869,000146: 13,2461 77772 VSL1 # R METERS B-29
047870,000147: 13,2462 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
047871,000148: 13,2463 03674 INCORPEX
047872,000149: # SUBROUTINE TO COMPUTE EARTH RADIUS
047873,000150:
047874,000151: # INPUT
047875,000152:
047876,000153: # 1/2 SIN LAT IN ALPHAV +4
047877,000154:
047878,000155: # OUTPUT
047879,000156:
047880,000157: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047881,000158:
047882,000159: 13,2464 63545 GETERAD DLOAD DSQ
047883,000160: 13,2465 02036 ALPHAV +4 # SIN**2(L)
047884,000161: 13,2466 44352 SL1 BDSU
047885,000162: 13,2467 24005 DP1/2 # COS**2(L)
047886,000163: 13,2470 44275 DMPR BDSU
047887,000164: 13,2471 26505 EE
047888,000165: 13,2472 24005 DP1/2
047889,000166: 13,2473 75465 BDDV SQRT
047890,000167: 13,2474 26501 B2XSC
047891,000168: 13,2475 77622 SR4R
047892,000169: 13,2476 03673 STORE ERADM
047893,000170: 13,2477 77616 RVQ
047894,000171:
047895,000172: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166,B=6356784 METERS
047896,000173: # B2XSC= B**2 SCALED B-51
047897,000174: # B2/A2= B**2/A**2 SCALED B-1
047898,000175: # EE=(1-B**2/A**2) SCALED B-0
047899,000176: 13,2500 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
047900,000177:
047901,000178: 13,2502 12,2004 DP1/2 = XUNIT
047902,000179: 13,2502 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
047903,000180:
047904,000181: 13,2504 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
047905,000182:
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Page 1128
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047907,000184: # ARCTAN SUBROUTINE
047908,000185:
047909,000186:
047910,000187: # CALLING SEQUENCE
047911,000188:
047912,000189: # SIN THETA IN SINTH B-1
047913,000190: # COS THETA IN COSTH B-1
047914,000191: # CALL ARCTAN
047915,000192:
047916,000193: # OUTPUT
047917,000194: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047918,000195:
047919,000196:
047920,000197: 13,2506 77600 ARCTAN BOV
047921,000198: 13,2507 26510 CLROVFLW
047922,000199: 13,2510 63545 CLROVFLW DLOAD DSQ
047923,000200: 13,2511 00023 SINTH
047924,000201: 13,2512 63525 PDDL DSQ
047925,000202: 13,2513 00021 COSTH
047926,000203: 13,2514 77615 DAD
047927,000204: 13,2515 75454 BZE SQRT
047928,000205: 13,2516 26534 ARCTANXX # ATAN=0/0 SET THETA=0
047929,000206: 13,2517 40065 BDDV BOV
047930,000207: 13,2520 00023 SINTH
047931,000208: 13,2521 26541 ATAN=90
047932,000209: 13,2522 67542 SR1 ASIN
047933,000210: 13,2523 00025 STORE THETA
047934,000211: 13,2524 50125 PDDL BMN
047935,000212: 13,2525 00021 COSTH
047936,000213: 13,2526 26530 NEGCOS
047937,000214: 13,2527 43545 DLOAD RVQ
047938,000215: 13,2530 57545 NEGCOS DLOAD DCOMP
047939,000216: 13,2531 43244 BPL DAD
047940,000217: 13,2532 26536 NEGOUT
047941,000218: 13,2533 24005 DP1/2
047942,000219: 13,2534 00025 ARCTANXX STORE THETA
047943,000220: 13,2535 77616 RVQ
047944,000221:
047945,000222: 13,2536 52025 NEGOUT DSU GOTO
047946,000223: 13,2537 24005 DP1/2
047947,000224: 13,2540 26534 ARCTANXX
047948,000225: 13,2541 75345 ATAN=90 DLOAD SIGN
047949,000226: 13,2542 11011 LODP1/4
047950,000227: 13,2543 00023 SINTH
047951,000228: 13,2544 00025 STORE THETA
047952,000229: 13,2545 77616 RVQ
047953,000230:
047954,000231: 13,2546 12,2006 2DZERO = DPZERO
047955,000232:
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Page 1129
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047957,000234: # ..... SETGAMMA SUBROUTINE .....
047958,000235: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047959,000236:
047960,000237: # GAMMA = B**2/A**2 FOR EARTH (B-1)
047961,000238: # GAMMA = 1 FOR MOON (B-1)
047962,000239:
047963,000240: # CALLING SEQUENCE
047964,000241: # L CALL
047965,000242: # L+1 SETGAMMA
047966,000243:
047967,000244: # INPUT
047968,000245: # LUNAFLAG=0 FOR EARTH,=1 FOR MOON
047969,000246:
047970,000247: # OUTPUT
047971,000248: # GAMMA IN GAMRP (B-1)
047972,000249:
047973,000250: 13,2546 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
047974,000251: 13,2547 26503 B2/A2 # EARTH GAMMA
047975,000252: 13,2550 01743 LUNAFLAG
047976,000253: 13,2551 26554 SETGMEX
047977,000254: 13,2552 77735 SLOAD
047978,000255: 13,2553 24005 1B1 # MOON GAMMA
047979,000256: 13,2554 00011 SETGMEX STORE GAMRP
047980,000257: 13,2555 77616 RVQ
047981,000258: 13,2556 GAMRP = 8D
047982,000259:
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Page 1130
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047984,000261: # .....SETRE SUBROUTINE .....
047985,000262: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047986,000263:
047987,000264: # RE= RM FOR MOON
047988,000265: # RE= RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047989,000266:
047990,000267: # CALLING SEQUENCE
047991,000268: # L CALL
047992,000269: # L+1 SETRE
047993,000270:
047994,000271: # SUBROUTINES USED
047995,000272: # GETERAD
047996,000273:
047997,000274: # INPUT
047998,000275: # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED RE
047999,000276: # ALPHAV +4= 1/2 SINL IF GETERAD IS CALLED
048000,000277: # LUNAFLAG=0 FOR EARTH,=1 FOR MOON
048001,000278:
048002,000279: # OUTPUT
048003,000280: # ERADM= 504RM FOR MOON (METERS B-29)
048004,000281: # ERADM= ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
048005,000282:
048006,000283: 13,2556 71220 SETRE STQ DLOAD
048007,000284: 13,2557 00051 SETREX
048008,000285: 13,2560 10003 504RM
048009,000286: 13,2561 71214 BON DLOAD # BRANCH FOR MOON
048010,000287: 13,2562 01703 LUNAFLAG
048011,000288: 13,2563 26573 TSTRLSRM
048012,000289: 13,2564 10001 ERAD
048013,000290: 13,2565 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE,1 FOR COMPUTED
048014,000291: 13,2566 00742 ERADFLAG
048015,000292: 13,2567 26571 SETRXX
048016,000293: 13,2570 26464 GETERAD
048017,000294: 13,2571 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
048018,000295: 13,2572 00051 SETREX
048019,000296: 13,2573 77214 TSTRLSRM BON VLOAD # ERADFLAG=0,SET R0=RLS
048020,000297: 13,2574 00702 ERADFLAG # =1 R0=RM
048021,000298: 13,2575 26571 SETRXX
048022,000299: 13,2576 02021 RLS
048023,000300: 13,2577 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
048024,000301: 13,2600 77650 GOTO
048025,000302: 13,2601 26571 SETRXX
048026,000303: 13,2602 0000051 SETREX = S2
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc