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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047173,000002: ## Copyright: Public domain.
047174,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
047175,000004: ## Purpose: A section of Luminary revision 98.
047176,000005: ## It is part of the reconstructed source code for the a
047177,000006: ## development version of the flight software for the Lunar
047178,000007: ## Module's (LM) Apollo Guidance Computer (AGC) for Apollo 11.
047179,000008: ## The code has been recreated from a copy of Luminary 99
047180,000009: ## revision 001, using asterisks indicating changed lines in
047181,000010: ## the listing and Luminary Memo #85, which lists changes between
047182,000011: ## Luminary 98 and 99.
047183,000012: ## Reference: pp. 1133-1139
047184,000013: ## Assembler: yaYUL
047185,000014: ## Contact: Ron Burkey <info@sandroid.org>.
047186,000015: ## Website: www.ibiblio.org/apollo/index.html
047187,000016: ## Mod history: 2019-07-28 MAS Created from Luminary 99.
047188,000017:
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Page 1133
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047190,000019: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047191,000020:
047192,000021: # CALLING SEQUENCE
047193,000022: # L-1 CALL
047194,000023: # L LAT-LONG
047195,000024:
047196,000025: # SUBROUTINES USED
047197,000026: # R-TO-RP, ARCTAN, SETGAMMA, SETRE
047198,000027:
047199,000028: # ERASABLE INIT. REQ.
047200,000029: # AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
047201,000030: # ALPHAV = POSITION VECTOR METERS B-29
047202,000031: # MPAC -- TIME (CSECS B-28)
047203,000032: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047204,000033: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047205,000034:
047206,000035: # OUTPUT
047207,000036: # LATITUDE IN LAT (REVS. B-0)
047208,000037: # LONGITUDE IN LONG (REVS. B-0)
047209,000038: # ALTITUDE IN ALT METERS B-29
047210,000039:
047211,000040: 30,3775 BANK 30
047212,000041: 13,2000 SETLOC LATLONG
047213,000042: 13,2000 BANK
047214,000043:
047215,000044: 13,2351 COUNT* $$/LT-LG
047216,000045: 13,2351 E4,1431 EBANK= ALPHAV
047217,000046: 13,2351 40220 LAT-LONG STQ SETPD
047218,000047: 13,2352 03674 INCORPEX
047219,000048: 13,2353 00001 0D
047220,000049: 13,2354 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
047221,000050: 13,2355 02032 ALPHAV
047222,000051: 13,2356 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
047223,000052: 13,2357 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
047224,000053: 13,2360 24007 ZEROVEC # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047225,000054: 13,2361 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
047226,000055: 13,2362 01743 LUNAFLAG # 0=EARTH, 1=MOON
047227,000056: 13,2363 26364 CALLRTRP
047228,000057: 13,2364 77624 CALLRTRP CALL
047229,000058: 13,2365 51670 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
047230,000059: 13,2366 77656 UNIT # UNIT RP B-1
047231,000060: 13,2367 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
047232,000061: 13,2370 26550 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
047233,000062: 13,2371 77624 CALL # SCALED B-1
047234,000063: 13,2372 26560 SETRE # CALC RE METERS B-29
047235,000064: 13,2373 63545 DLOAD DSQ
047236,000065: 13,2374 02032 ALPHAV
047237,000066: 13,2375 63525 PDDL DSQ
047238,000067: 13,2376 02034 ALPHAV +2
047239,000068: 13,2377 75415 DAD SQRT
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Page 1134
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047241,000070: 13,2400 76405 DMP SL1R
047242,000071: 13,2401 00011 GAMRP
047243,000072: 13,2402 14021 STODL COSTH # COS(LAT) B-1
047244,000073: 13,2403 02036 ALPHAV +4
047245,000074: 13,2404 34023 STCALL SINTH # SIN(LAT) B-1
047246,000075: 13,2405 26510 ARCTAN
047247,000076: 13,2406 15121 STODL LAT # LAT B0
047248,000077: 13,2407 02032 ALPHAV
047249,000078: 13,2410 14021 STODL COSTH # COS(LONG) B-1
047250,000079: 13,2411 02034 ALPHAV +2
047251,000080: 13,2412 34023 STCALL SINTH # SIN(LONG) B-1
047252,000081: 13,2413 26510 ARCTAN
047253,000082: 13,2414 15123 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047254,000083: 13,2415 02070 ALPHAM
047255,000084: 13,2416 77625 DSU # ALT= R-RE METERS B-29
047256,000085: 13,2417 03673 ERADM
047257,000086: 13,2420 35125 STCALL ALT # EXIT WITH ALT METERS B-29
047258,000087: 13,2421 03674 INCORPEX
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Page 1135
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047260,000089: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047261,000090:
047262,000091: # CALLING SEQUENCE
047263,000092: # L-1 CALL
047264,000093: # L LALOTORV
047265,000094:
047266,000095: # SUBROUTINES USED
047267,000096: # SETGAMMA, SETRE, RP-TO-R
047268,000097:
047269,000098: # ERASABLE INIT. REQ.
047270,000099: # AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
047271,000100: # LAT -- LATITUDE (REVS B0)
047272,000101: # LONG -- LONGITUDE (REVS B0)
047273,000102: # ALT -- ALTITUDE (METERS) B-29
047274,000103: # MPAC -- TIME (CSECS B-28)
047275,000104: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047276,000105: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047277,000106:
047278,000107: # OUTPUT
047279,000108: # R-VECTOR IN ALPHAV (METERS B-29)
047280,000109:
047281,000110: 13,2422 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
047282,000111: 13,2423 03674 INCORPEX
047283,000112: 13,2424 00001 0D
047284,000113: 13,2425 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
047285,000114: 13,2426 26550 SETGAMMA # GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
047286,000115: 13,2427 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
047287,000116: 13,2430 01121 LAT # UNIT RP = SIN(LONG)COS(LAT) 2-3D
047288,000117: 13,2431 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
047289,000118: 13,2432 00011 GAMRP
047290,000119: 13,2433 01121 LAT # 0-1D = GAMMA*SIN(LAT) B-2
047291,000120: 13,2434 65346 COS PDDL # PD4 2-3D = COS(LAT) B-1 TEMPORARILY
047292,000121: 13,2435 01123 LONG
047293,000122: 13,2436 57356 SIN DMPR # PD 2
047294,000123: 13,2437 71525 PDDL COS # PD 4 2-3D = SIN(LONG)COS(LAT) B-2
047295,000124: 13,2440 01121 LAT
047296,000125: 13,2441 71525 PDDL COS # PD 6 4-5D = COS(LAT) B-1 TEMPORARILY
047297,000126: 13,2442 01123 LONG
047298,000127: 13,2443 55475 DMPR VDEF # PD 4 MPAC = COS(LONG)COS(LAT) B-2
047299,000128: 13,2444 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
047300,000129: 13,2445 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
047301,000130: 13,2446 26560 SETRE # RE METERS B-29
047302,000131: 13,2447 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047303,000132: 13,2450 24007 ZEROVEC
047304,000133: 13,2451 01743 LUNAFLAG
047305,000134: 13,2452 26454 CALLRPRT
047306,000135: 13,2453 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
047307,000136: 13,2454 77624 CALLRPRT CALL
047308,000137: 13,2455 55716 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
047309,000138: 13,2456 16032 STODL ALPHAV
047310,000139: 13,2457 03673 ERADM
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Page 1136
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047312,000141: 13,2460 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
047313,000142: 13,2461 01125 ALT
047314,000143: 13,2462 02032 ALPHAV
047315,000144: 13,2463 77772 VSL1 # R METERS B-29
047316,000145: 13,2464 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
047317,000146: 13,2465 03674 INCORPEX
047318,000147:
047319,000148: # SUBROUTINE TO COMPUTE EARTH RADIUS
047320,000149:
047321,000150: # INPUT
047322,000151: # 1/2 SIN LAT IN ALPHAV +4
047323,000152:
047324,000153: # OUTPUT
047325,000154: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047326,000155:
047327,000156: 13,2466 63545 GETERAD DLOAD DSQ
047328,000157: 13,2467 02036 ALPHAV +4 # SIN**2(L)
047329,000158: 13,2470 44352 SL1 BDSU
047330,000159: 13,2471 24005 DP1/2 # COS**2(L)
047331,000160: 13,2472 44275 DMPR BDSU
047332,000161: 13,2473 26507 EE
047333,000162: 13,2474 24005 DP1/2
047334,000163: 13,2475 75465 BDDV SQRT
047335,000164: 13,2476 26503 B2XSC
047336,000165: 13,2477 77622 SR4R
047337,000166: 13,2500 03673 STORE ERADM
047338,000167: 13,2501 77616 RVQ
047339,000168:
047340,000169: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
047341,000170: # B2XSC = B**2 SCALED B-51
047342,000171: # B2/A2 = B**2/A**2 SCALED B-1
047343,000172: # EE = (1-B**2/A**2) SCALED B-0
047344,000173:
047345,000174: 13,2502 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
047346,000175: 13,2504 12,2004 DP1/2 = XUNIT
047347,000176: 13,2504 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
047348,000177: 13,2506 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
047349,000178:
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Page 1137
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047351,000180: # ARCTAN SUBROUTINE
047352,000181:
047353,000182: # CALLING SEQUENCE
047354,000183: # SIN THETA IN SINTH B-1
047355,000184: # COS THETA IN COSTH B-1
047356,000185: # CALL ARCTAN
047357,000186:
047358,000187: # OUTPUT
047359,000188: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047360,000189:
047361,000190: 13,2510 77600 ARCTAN BOV
047362,000191: 13,2511 26512 CLROVFLW
047363,000192: 13,2512 63545 CLROVFLW DLOAD DSQ
047364,000193: 13,2513 00023 SINTH
047365,000194: 13,2514 63525 PDDL DSQ
047366,000195: 13,2515 00021 COSTH
047367,000196: 13,2516 77615 DAD
047368,000197: 13,2517 75454 BZE SQRT
047369,000198: 13,2520 26536 ARCTANXX # ATAN=0/0 SET THETA=0
047370,000199: 13,2521 40065 BDDV BOV
047371,000200: 13,2522 00023 SINTH
047372,000201: 13,2523 26543 ATAN=90
047373,000202: 13,2524 67542 SR1 ASIN
047374,000203: 13,2525 00025 STORE THETA
047375,000204: 13,2526 50125 PDDL BMN
047376,000205: 13,2527 00021 COSTH
047377,000206: 13,2530 26532 NEGCOS
047378,000207: 13,2531 43545 DLOAD RVQ
047379,000208: 13,2532 57545 NEGCOS DLOAD DCOMP
047380,000209: 13,2533 43244 BPL DAD
047381,000210: 13,2534 26540 NEGOUT
047382,000211: 13,2535 24005 DP1/2
047383,000212: 13,2536 00025 ARCTANXX STORE THETA
047384,000213: 13,2537 77616 RVQ
047385,000214:
047386,000215: 13,2540 52025 NEGOUT DSU GOTO
047387,000216: 13,2541 24005 DP1/2
047388,000217: 13,2542 26536 ARCTANXX
047389,000218: 13,2543 75345 ATAN=90 DLOAD SIGN
047390,000219: 13,2544 11037 LODP1/4
047391,000220: 13,2545 00023 SINTH
047392,000221: 13,2546 00025 STORE THETA
047393,000222: 13,2547 77616 RVQ
047394,000223:
047395,000224: 13,2550 12,2006 2DZERO = DPZERO
047396,000225:
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Page 1138
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047398,000227: # ..... SETGAMMA SUBROUTINE .....
047399,000228: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047400,000229:
047401,000230: # GAMMA = B**2/A**2 FOR EARTH (B-1)
047402,000231: # GAMMA = 1 FOR MOON (B-1)
047403,000232:
047404,000233: # CALLING SEQUENCE
047405,000234: # L CALL
047406,000235: # L+1 SETGAMMA
047407,000236:
047408,000237: # INPUT
047409,000238: # LUNAFLAG=0 FOR EARTH, =1 FOR MOON
047410,000239:
047411,000240: # OUTPUT
047412,000241: # GAMMA IN GAMRP (B-1)
047413,000242:
047414,000243: 13,2550 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
047415,000244: 13,2551 26505 B2/A2 # EARTH GAMMA
047416,000245: 13,2552 01743 LUNAFLAG
047417,000246: 13,2553 26556 SETGMEX
047418,000247: 13,2554 77735 SLOAD
047419,000248: 13,2555 24005 1B1 # MOON GAMMA
047420,000249: 13,2556 00011 SETGMEX STORE GAMRP
047421,000250: 13,2557 77616 RVQ
047422,000251: 13,2560 GAMRP = 8D
047423,000252:
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Page 1139
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047425,000254: # ..... SETRE SUBROUTINE .....
047426,000255: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047427,000256:
047428,000257: # RE = RM FOR MOON
047429,000258: # RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047430,000259:
047431,000260: # CALLING SEQUENCE
047432,000261: # L CALL
047433,000262: # L+1 SETRE
047434,000263:
047435,000264: # SUBROUTINES USED
047436,000265: # GETERAD
047437,000266:
047438,000267: # INPUT
047439,000268: # ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
047440,000269: # ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
047441,000270: # LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
047442,000271:
047443,000272: # OUTPUT
047444,000273: # ERADM = 504RM FOR MOON (METERS B-29)
047445,000274: # ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
047446,000275:
047447,000276: 13,2560 71220 SETRE STQ DLOAD
047448,000277: 13,2561 00051 SETREX
047449,000278: 13,2562 10003 504RM
047450,000279: 13,2563 71214 BON DLOAD # BRANCH FOR MOON
047451,000280: 13,2564 01703 LUNAFLAG
047452,000281: 13,2565 26575 TSTRLSRM
047453,000282: 13,2566 10001 ERAD
047454,000283: 13,2567 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
047455,000284: 13,2570 00742 ERADFLAG
047456,000285: 13,2571 26573 SETRXX
047457,000286: 13,2572 26466 GETERAD
047458,000287: 13,2573 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
047459,000288: 13,2574 00051 SETREX
047460,000289: 13,2575 77214 TSTRLSRM BON VLOAD # ERADFLAG=0, SET R0=RLS
047461,000290: 13,2576 00702 ERADFLAG # =1 R0=RM
047462,000291: 13,2577 26573 SETRXX
047463,000292: 13,2600 02023 RLS
047464,000293: 13,2601 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
047465,000294: 13,2602 77650 GOTO
047466,000295: 13,2603 26573 SETRXX
047467,000296: 13,2604 0000051 SETREX = S2
047468,000297:
047469,000298:
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc