Source Code
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These source-code files are part of a reconstructed copy of Luminary 98, a
development version of the Apollo 11 Lunar Module (LM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Luminary 99 revision 1 previously
transcribed from a digitized copy of that program. The code was then updated
by undoing changes described in original Luminary memo 85, using asterisks
indicating changed lines in the listing as a guide. While no listing of this
version is known to exist, nor are the memory-bank checksums available,
the reconstruction is believed to be correct because it was an an intermediate
step in reconstructing Luminary 97 whose reconstruction was
verified by matching memory-bank checksums to those listed in drawing 2021152G.
Note that page numbers in the reconstructed code match those on the Luminary 099
revision 001 printout, although the added code would likely have changed page
numbers for a real Luminary 98 listing.
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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047156,000002: ## Copyright: Public domain.
047157,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
047158,000004: ## Purpose: A section of Luminary revision 98.
047159,000005: ## It is part of the reconstructed source code for the a
047160,000006: ## development version of the flight software for the Lunar
047161,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 11.
047162,000008: ## The code has been recreated from a copy of Luminary 99
047163,000009: ## revision 001, using asterisks indicating changed lines in
047164,000010: ## the listing and Luminary Memo #85, which lists changes between
047165,000011: ## Luminary 98 and 99.
047166,000012: ## Reference: pp. 1133-1139
047167,000013: ## Assembler: yaYUL
047168,000014: ## Contact: Ron Burkey <info@sandroid.org>.
047169,000015: ## Website: www.ibiblio.org/apollo/index.html
047170,000016: ## Mod history: 2019-07-28 MAS Created from Luminary 99.
047171,000017:
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Page 1133
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047173,000019: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047174,000020:
047175,000021: # CALLING SEQUENCE
047176,000022: # L-1 CALL
047177,000023: # L LAT-LONG
047178,000024:
047179,000025: # SUBROUTINES USED
047180,000026: # R-TO-RP, ARCTAN, SETGAMMA, SETRE
047181,000027:
047182,000028: # ERASABLE INIT. REQ.
047183,000029: # AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
047184,000030: # ALPHAV = POSITION VECTOR METERS B-29
047185,000031: # MPAC -- TIME (CSECS B-28)
047186,000032: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047187,000033: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047188,000034:
047189,000035: # OUTPUT
047190,000036: # LATITUDE IN LAT (REVS. B-0)
047191,000037: # LONGITUDE IN LONG (REVS. B-0)
047192,000038: # ALTITUDE IN ALT METERS B-29
047193,000039:
047194,000040: 30,3775 BANK 30
047195,000041: 13,2000 SETLOC LATLONG
047196,000042: 13,2000 BANK
047197,000043:
047198,000044: 13,2351 COUNT* $$/LT-LG
047199,000045: 13,2351 E4,1431 EBANK= ALPHAV
047200,000046: 13,2351 40220 LAT-LONG STQ SETPD
047201,000047: 13,2352 03674 INCORPEX
047202,000048: 13,2353 00001 0D
047203,000049: 13,2354 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
047204,000050: 13,2355 02032 ALPHAV
047205,000051: 13,2356 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
047206,000052: 13,2357 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
047207,000053: 13,2360 24007 ZEROVEC # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047208,000054: 13,2361 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
047209,000055: 13,2362 01743 LUNAFLAG # 0=EARTH, 1=MOON
047210,000056: 13,2363 26364 CALLRTRP
047211,000057: 13,2364 77624 CALLRTRP CALL
047212,000058: 13,2365 51670 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
047213,000059: 13,2366 77656 UNIT # UNIT RP B-1
047214,000060: 13,2367 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
047215,000061: 13,2370 26550 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
047216,000062: 13,2371 77624 CALL # SCALED B-1
047217,000063: 13,2372 26560 SETRE # CALC RE METERS B-29
047218,000064: 13,2373 63545 DLOAD DSQ
047219,000065: 13,2374 02032 ALPHAV
047220,000066: 13,2375 63525 PDDL DSQ
047221,000067: 13,2376 02034 ALPHAV +2
047222,000068: 13,2377 75415 DAD SQRT
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Page 1134
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047224,000070: 13,2400 76405 DMP SL1R
047225,000071: 13,2401 00011 GAMRP
047226,000072: 13,2402 14021 STODL COSTH # COS(LAT) B-1
047227,000073: 13,2403 02036 ALPHAV +4
047228,000074: 13,2404 34023 STCALL SINTH # SIN(LAT) B-1
047229,000075: 13,2405 26510 ARCTAN
047230,000076: 13,2406 15121 STODL LAT # LAT B0
047231,000077: 13,2407 02032 ALPHAV
047232,000078: 13,2410 14021 STODL COSTH # COS(LONG) B-1
047233,000079: 13,2411 02034 ALPHAV +2
047234,000080: 13,2412 34023 STCALL SINTH # SIN(LONG) B-1
047235,000081: 13,2413 26510 ARCTAN
047236,000082: 13,2414 15123 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047237,000083: 13,2415 02070 ALPHAM
047238,000084: 13,2416 77625 DSU # ALT= R-RE METERS B-29
047239,000085: 13,2417 03673 ERADM
047240,000086: 13,2420 35125 STCALL ALT # EXIT WITH ALT METERS B-29
047241,000087: 13,2421 03674 INCORPEX
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Page 1135
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047243,000089: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047244,000090:
047245,000091: # CALLING SEQUENCE
047246,000092: # L-1 CALL
047247,000093: # L LALOTORV
047248,000094:
047249,000095: # SUBROUTINES USED
047250,000096: # SETGAMMA, SETRE, RP-TO-R
047251,000097:
047252,000098: # ERASABLE INIT. REQ.
047253,000099: # AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
047254,000100: # LAT -- LATITUDE (REVS B0)
047255,000101: # LONG -- LONGITUDE (REVS B0)
047256,000102: # ALT -- ALTITUDE (METERS) B-29
047257,000103: # MPAC -- TIME (CSECS B-28)
047258,000104: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047259,000105: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047260,000106:
047261,000107: # OUTPUT
047262,000108: # R-VECTOR IN ALPHAV (METERS B-29)
047263,000109:
047264,000110: 13,2422 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
047265,000111: 13,2423 03674 INCORPEX
047266,000112: 13,2424 00001 0D
047267,000113: 13,2425 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
047268,000114: 13,2426 26550 SETGAMMA # GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
047269,000115: 13,2427 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
047270,000116: 13,2430 01121 LAT # UNIT RP = SIN(LONG)COS(LAT) 2-3D
047271,000117: 13,2431 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
047272,000118: 13,2432 00011 GAMRP
047273,000119: 13,2433 01121 LAT # 0-1D = GAMMA*SIN(LAT) B-2
047274,000120: 13,2434 65346 COS PDDL # PD4 2-3D = COS(LAT) B-1 TEMPORARILY
047275,000121: 13,2435 01123 LONG
047276,000122: 13,2436 57356 SIN DMPR # PD 2
047277,000123: 13,2437 71525 PDDL COS # PD 4 2-3D = SIN(LONG)COS(LAT) B-2
047278,000124: 13,2440 01121 LAT
047279,000125: 13,2441 71525 PDDL COS # PD 6 4-5D = COS(LAT) B-1 TEMPORARILY
047280,000126: 13,2442 01123 LONG
047281,000127: 13,2443 55475 DMPR VDEF # PD 4 MPAC = COS(LONG)COS(LAT) B-2
047282,000128: 13,2444 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
047283,000129: 13,2445 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
047284,000130: 13,2446 26560 SETRE # RE METERS B-29
047285,000131: 13,2447 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047286,000132: 13,2450 24007 ZEROVEC
047287,000133: 13,2451 01743 LUNAFLAG
047288,000134: 13,2452 26454 CALLRPRT
047289,000135: 13,2453 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
047290,000136: 13,2454 77624 CALLRPRT CALL
047291,000137: 13,2455 55716 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
047292,000138: 13,2456 16032 STODL ALPHAV
047293,000139: 13,2457 03673 ERADM
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Page 1136
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047295,000141: 13,2460 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
047296,000142: 13,2461 01125 ALT
047297,000143: 13,2462 02032 ALPHAV
047298,000144: 13,2463 77772 VSL1 # R METERS B-29
047299,000145: 13,2464 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
047300,000146: 13,2465 03674 INCORPEX
047301,000147:
047302,000148: # SUBROUTINE TO COMPUTE EARTH RADIUS
047303,000149:
047304,000150: # INPUT
047305,000151: # 1/2 SIN LAT IN ALPHAV +4
047306,000152:
047307,000153: # OUTPUT
047308,000154: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047309,000155:
047310,000156: 13,2466 63545 GETERAD DLOAD DSQ
047311,000157: 13,2467 02036 ALPHAV +4 # SIN**2(L)
047312,000158: 13,2470 44352 SL1 BDSU
047313,000159: 13,2471 24005 DP1/2 # COS**2(L)
047314,000160: 13,2472 44275 DMPR BDSU
047315,000161: 13,2473 26507 EE
047316,000162: 13,2474 24005 DP1/2
047317,000163: 13,2475 75465 BDDV SQRT
047318,000164: 13,2476 26503 B2XSC
047319,000165: 13,2477 77622 SR4R
047320,000166: 13,2500 03673 STORE ERADM
047321,000167: 13,2501 77616 RVQ
047322,000168:
047323,000169: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
047324,000170: # B2XSC = B**2 SCALED B-51
047325,000171: # B2/A2 = B**2/A**2 SCALED B-1
047326,000172: # EE = (1-B**2/A**2) SCALED B-0
047327,000173:
047328,000174: 13,2502 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
047329,000175: 13,2504 12,2004 DP1/2 = XUNIT
047330,000176: 13,2504 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
047331,000177: 13,2506 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
047332,000178:
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Page 1137
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047334,000180: # ARCTAN SUBROUTINE
047335,000181:
047336,000182: # CALLING SEQUENCE
047337,000183: # SIN THETA IN SINTH B-1
047338,000184: # COS THETA IN COSTH B-1
047339,000185: # CALL ARCTAN
047340,000186:
047341,000187: # OUTPUT
047342,000188: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047343,000189:
047344,000190: 13,2510 77600 ARCTAN BOV
047345,000191: 13,2511 26512 CLROVFLW
047346,000192: 13,2512 63545 CLROVFLW DLOAD DSQ
047347,000193: 13,2513 00023 SINTH
047348,000194: 13,2514 63525 PDDL DSQ
047349,000195: 13,2515 00021 COSTH
047350,000196: 13,2516 77615 DAD
047351,000197: 13,2517 75454 BZE SQRT
047352,000198: 13,2520 26536 ARCTANXX # ATAN=0/0 SET THETA=0
047353,000199: 13,2521 40065 BDDV BOV
047354,000200: 13,2522 00023 SINTH
047355,000201: 13,2523 26543 ATAN=90
047356,000202: 13,2524 67542 SR1 ASIN
047357,000203: 13,2525 00025 STORE THETA
047358,000204: 13,2526 50125 PDDL BMN
047359,000205: 13,2527 00021 COSTH
047360,000206: 13,2530 26532 NEGCOS
047361,000207: 13,2531 43545 DLOAD RVQ
047362,000208: 13,2532 57545 NEGCOS DLOAD DCOMP
047363,000209: 13,2533 43244 BPL DAD
047364,000210: 13,2534 26540 NEGOUT
047365,000211: 13,2535 24005 DP1/2
047366,000212: 13,2536 00025 ARCTANXX STORE THETA
047367,000213: 13,2537 77616 RVQ
047368,000214:
047369,000215: 13,2540 52025 NEGOUT DSU GOTO
047370,000216: 13,2541 24005 DP1/2
047371,000217: 13,2542 26536 ARCTANXX
047372,000218: 13,2543 75345 ATAN=90 DLOAD SIGN
047373,000219: 13,2544 11037 LODP1/4
047374,000220: 13,2545 00023 SINTH
047375,000221: 13,2546 00025 STORE THETA
047376,000222: 13,2547 77616 RVQ
047377,000223:
047378,000224: 13,2550 12,2006 2DZERO = DPZERO
047379,000225:
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Page 1138
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047381,000227: # ..... SETGAMMA SUBROUTINE .....
047382,000228: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047383,000229:
047384,000230: # GAMMA = B**2/A**2 FOR EARTH (B-1)
047385,000231: # GAMMA = 1 FOR MOON (B-1)
047386,000232:
047387,000233: # CALLING SEQUENCE
047388,000234: # L CALL
047389,000235: # L+1 SETGAMMA
047390,000236:
047391,000237: # INPUT
047392,000238: # LUNAFLAG=0 FOR EARTH, =1 FOR MOON
047393,000239:
047394,000240: # OUTPUT
047395,000241: # GAMMA IN GAMRP (B-1)
047396,000242:
047397,000243: 13,2550 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
047398,000244: 13,2551 26505 B2/A2 # EARTH GAMMA
047399,000245: 13,2552 01743 LUNAFLAG
047400,000246: 13,2553 26556 SETGMEX
047401,000247: 13,2554 77735 SLOAD
047402,000248: 13,2555 24005 1B1 # MOON GAMMA
047403,000249: 13,2556 00011 SETGMEX STORE GAMRP
047404,000250: 13,2557 77616 RVQ
047405,000251: 13,2560 GAMRP = 8D
047406,000252:
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Page 1139
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047408,000254: # ..... SETRE SUBROUTINE .....
047409,000255: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047410,000256:
047411,000257: # RE = RM FOR MOON
047412,000258: # RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047413,000259:
047414,000260: # CALLING SEQUENCE
047415,000261: # L CALL
047416,000262: # L+1 SETRE
047417,000263:
047418,000264: # SUBROUTINES USED
047419,000265: # GETERAD
047420,000266:
047421,000267: # INPUT
047422,000268: # ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
047423,000269: # ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
047424,000270: # LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
047425,000271:
047426,000272: # OUTPUT
047427,000273: # ERADM = 504RM FOR MOON (METERS B-29)
047428,000274: # ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
047429,000275:
047430,000276: 13,2560 71220 SETRE STQ DLOAD
047431,000277: 13,2561 00051 SETREX
047432,000278: 13,2562 10003 504RM
047433,000279: 13,2563 71214 BON DLOAD # BRANCH FOR MOON
047434,000280: 13,2564 01703 LUNAFLAG
047435,000281: 13,2565 26575 TSTRLSRM
047436,000282: 13,2566 10001 ERAD
047437,000283: 13,2567 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
047438,000284: 13,2570 00742 ERADFLAG
047439,000285: 13,2571 26573 SETRXX
047440,000286: 13,2572 26466 GETERAD
047441,000287: 13,2573 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
047442,000288: 13,2574 00051 SETREX
047443,000289: 13,2575 77214 TSTRLSRM BON VLOAD # ERADFLAG=0, SET R0=RLS
047444,000290: 13,2576 00702 ERADFLAG # =1 R0=RM
047445,000291: 13,2577 26573 SETRXX
047446,000292: 13,2600 02023 RLS
047447,000293: 13,2601 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
047448,000294: 13,2602 77650 GOTO
047449,000295: 13,2603 26573 SETRXX
047450,000296: 13,2604 0000051 SETREX = S2
047451,000297:
047452,000298:
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc