GAP: ASSEMBLE REVISION 001 OF AGC PROGRAM LMY99 BY NASA 2021112-061 20'35 OCT. 28,1968Note that the date is the date of the printout, not the date of the program revision.
Source Code
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These source-code files were from the printout at the MIT Museum, with many thanks
to Deborah Douglas, the Museum's Curator of Science and Technology, for releasing
it to us. The printout was digitally photographed by Paul Fjeld. A team of
volunteers transcribed the source code manually from these images or, where
appropriate, modified already-transcribed but similar source Luminary 131 (Apollo 13)
source code to agree with the images from the printout. Note that the page images
presented online are of reduced quality, and that higher-quality images
are available. Report any conversion errors or legibility
problems in page images to info@sandroid.org.
Notations on the program listing read, in part:GAP: ASSEMBLE REVISION 001 OF AGC PROGRAM LMY99 BY NASA 2021112-061 20'35 OCT. 28,1968Note that the date is the date of the printout, not the date of the program revision. |
048312,000002: ## Copyright: Public domain.
048313,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
048314,000004: ## Purpose: Part of the source code for Luminary 1A build 099.
048315,000005: ## It is part of the source code for the Lunar Module's (LM)
048316,000006: ## Apollo Guidance Computer (AGC), for Apollo 11.
048317,000007: ##
048318,000008: ## Assembler: yaYUL
048319,000009: ## Contact: Jim Lawton <jim DOT lawton AT gmail DOT com>
048320,000010: ## Website: www.ibiblio.org/apollo.
048321,000011: ## Pages: 1133-1139
048322,000012: ## Mod history: 2009-05-28 JL Updated from page images.
048323,000013: ## 2011-01-06 JL Fixed interpretive indentation.
048324,000014: ## 2016-12-17 RSB Proofed text comments with octopus/ProoferComments
048325,000015: ## and corrected the errors found.
048326,000016: ## 2017-03-15 RSB Comment-text fixes identified in 5-way
048327,000017: ## side-by-side diff of Luminary 69/99/116/131/210.
048328,000018:
048329,000019: ## This source code has been transcribed or otherwise adapted from digitized
048330,000020: ## images of a hardcopy from the MIT Museum. The digitization was performed
048331,000021: ## by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many
048332,000022: ## thanks to both. The images (with suitable reduction in storage size and
048333,000023: ## consequent reduction in image quality as well) are available online at
048334,000024: ## www.ibiblio.org/apollo. If for some reason you find that the images are
048335,000025: ## illegible, contact me at info@sandroid.org about getting access to the
048336,000026: ## (much) higher-quality images which Paul actually created.
048337,000027: ##
048338,000028: ## Notations on the hardcopy document read, in part:
048339,000029: ##
048340,000030: ## Assemble revision 001 of AGC program LMY99 by NASA 2021112-061
048341,000031: ## 16:27 JULY 14, 1969
048342,000032:
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Page 1133 |
048344,000034: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
048345,000035:
048346,000036: # CALLING SEQUENCE
048347,000037: # L-1 CALL
048348,000038: # L LAT-LONG
048349,000039:
048350,000040: # SUBROUTINES USED
048351,000041: # R-TO-RP, ARCTAN, SETGAMMA, SETRE
048352,000042:
048353,000043: # ERASABLE INIT. REQ.
048354,000044: # AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
048355,000045: # ALPHAV = POSITION VECTOR METERS B-29
048356,000046: # MPAC -- TIME (CSECS B-28)
048357,000047: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
048358,000048: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
048359,000049:
048360,000050: # OUTPUT
048361,000051: # LATITUDE IN LAT (REVS. B-0)
048362,000052: # LONGITUDE IN LONG (REVS. B-0)
048363,000053: # ALTITUDE IN ALT METERS B-29
048364,000054:
048365,000055: 30,3775 BANK 30
048366,000056: 13,2000 SETLOC LATLONG
048367,000057: 13,2000 BANK
048368,000058:
048369,000059: 13,2351 COUNT* $$/LT-LG
048370,000060: 13,2351 E4,1431 EBANK= ALPHAV
048371,000061: 13,2351 40220 LAT-LONG STQ SETPD
048372,000062: 13,2352 03674 INCORPEX
048373,000063: 13,2353 00001 0D
048374,000064: 13,2354 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
048375,000065: 13,2355 02032 ALPHAV
048376,000066: 13,2356 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
048377,000067: 13,2357 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
048378,000068: 13,2360 24007 ZEROVEC # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
048379,000069: 13,2361 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
048380,000070: 13,2362 01743 LUNAFLAG # 0=EARTH, 1=MOON
048381,000071: 13,2363 26364 CALLRTRP
048382,000072: 13,2364 77624 CALLRTRP CALL
048383,000073: 13,2365 51670 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
048384,000074: 13,2366 77656 UNIT # UNIT RP B-1
048385,000075: 13,2367 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
048386,000076: 13,2370 26550 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
048387,000077: 13,2371 77624 CALL # SCALED B-1
048388,000078: 13,2372 26560 SETRE # CALC RE METERS B-29
048389,000079: 13,2373 63545 DLOAD DSQ
048390,000080: 13,2374 02032 ALPHAV
048391,000081: 13,2375 63525 PDDL DSQ
048392,000082: 13,2376 02034 ALPHAV +2
048393,000083: 13,2377 75415 DAD SQRT
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Page 1134 |
048395,000085: 13,2400 76405 DMP SL1R
048396,000086: 13,2401 00011 GAMRP
048397,000087: 13,2402 14021 STODL COSTH # COS(LAT) B-1
048398,000088: 13,2403 02036 ALPHAV +4
048399,000089: 13,2404 34023 STCALL SINTH # SIN(LAT) B-1
048400,000090: 13,2405 26510 ARCTAN
048401,000091: 13,2406 15121 STODL LAT # LAT B0
048402,000092: 13,2407 02032 ALPHAV
048403,000093: 13,2410 14021 STODL COSTH # COS(LONG) B-1
048404,000094: 13,2411 02034 ALPHAV +2
048405,000095: 13,2412 34023 STCALL SINTH # SIN(LONG) B-1
048406,000096: 13,2413 26510 ARCTAN
048407,000097: 13,2414 15123 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
048408,000098: 13,2415 02070 ALPHAM
048409,000099: 13,2416 77625 DSU # ALT= R-RE METERS B-29
048410,000100: 13,2417 03673 ERADM
048411,000101: 13,2420 35125 STCALL ALT # EXIT WITH ALT METERS B-29
048412,000102: 13,2421 03674 INCORPEX
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Page 1135 |
048414,000104: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
048415,000105:
048416,000106: # CALLING SEQUENCE
048417,000107: # L-1 CALL
048418,000108: # L LALOTORV
048419,000109:
048420,000110: # SUBROUTINES USED
048421,000111: # SETGAMMA, SETRE, RP-TO-R
048422,000112:
048423,000113: # ERASABLE INIT. REQ.
048424,000114: # AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
048425,000115: # LAT -- LATITUDE (REVS B0)
048426,000116: # LONG -- LONGITUDE (REVS B0)
048427,000117: # ALT -- ALTITUDE (METERS) B-29
048428,000118: # MPAC -- TIME (CSECS B-28)
048429,000119: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
048430,000120: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
048431,000121:
048432,000122: # OUTPUT
048433,000123: # R-VECTOR IN ALPHAV (METERS B-29)
048434,000124:
048435,000125: 13,2422 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
048436,000126: 13,2423 03674 INCORPEX
048437,000127: 13,2424 00001 0D
048438,000128: 13,2425 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
048439,000129: 13,2426 26550 SETGAMMA # GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
048440,000130: 13,2427 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
048441,000131: 13,2430 01121 LAT # UNIT RP = SIN(LONG)COS(LAT) 2-3D
048442,000132: 13,2431 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
048443,000133: 13,2432 00011 GAMRP
048444,000134: 13,2433 01121 LAT # 0-1D = GAMMA*SIN(LAT) B-2
048445,000135: 13,2434 65346 COS PDDL # PD4 2-3D = COS(LAT) B-1 TEMPORARILY
048446,000136: 13,2435 01123 LONG
048447,000137: 13,2436 57356 SIN DMPR # PD 2
048448,000138: 13,2437 71525 PDDL COS # PD 4 2-3D = SIN(LONG)COS(LAT) B-2
048449,000139: 13,2440 01121 LAT
048450,000140: 13,2441 71525 PDDL COS # PD 6 4-5D = COS(LAT) B-1 TEMPORARILY
048451,000141: 13,2442 01123 LONG
048452,000142: 13,2443 55475 DMPR VDEF # PD 4 MPAC = COS(LONG)COS(LAT) B-2
048453,000143: 13,2444 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
048454,000144: 13,2445 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
048455,000145: 13,2446 26560 SETRE # RE METERS B-29
048456,000146: 13,2447 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
048457,000147: 13,2450 24007 ZEROVEC
048458,000148: 13,2451 01743 LUNAFLAG
048459,000149: 13,2452 26454 CALLRPRT
048460,000150: 13,2453 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
048461,000151: 13,2454 77624 CALLRPRT CALL
048462,000152: 13,2455 55716 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
048463,000153: 13,2456 16032 STODL ALPHAV
048464,000154: 13,2457 03673 ERADM
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Page 1136 |
048466,000156: 13,2460 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
048467,000157: 13,2461 01125 ALT
048468,000158: 13,2462 02032 ALPHAV
048469,000159: 13,2463 77772 VSL1 # R METERS B-29
048470,000160: 13,2464 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
048471,000161: 13,2465 03674 INCORPEX
048472,000162:
048473,000163: # SUBROUTINE TO COMPUTE EARTH RADIUS
048474,000164:
048475,000165: # INPUT
048476,000166: # 1/2 SIN LAT IN ALPHAV +4
048477,000167:
048478,000168: # OUTPUT
048479,000169: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
048480,000170:
048481,000171: 13,2466 63545 GETERAD DLOAD DSQ
048482,000172: 13,2467 02036 ALPHAV +4 # SIN**2(L)
048483,000173: 13,2470 44352 SL1 BDSU
048484,000174: 13,2471 24005 DP1/2 # COS**2(L)
048485,000175: 13,2472 44275 DMPR BDSU
048486,000176: 13,2473 26507 EE
048487,000177: 13,2474 24005 DP1/2
048488,000178: 13,2475 75465 BDDV SQRT
048489,000179: 13,2476 26503 B2XSC
048490,000180: 13,2477 77622 SR4R
048491,000181: 13,2500 03673 STORE ERADM
048492,000182: 13,2501 77616 RVQ
048493,000183:
048494,000184: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
048495,000185: # B2XSC = B**2 SCALED B-51
048496,000186: # B2/A2 = B**2/A**2 SCALED B-1
048497,000187: # EE = (1-B**2/A**2) SCALED B-0
048498,000188:
048499,000189: 13,2502 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
048500,000190: 13,2504 12,2004 DP1/2 = XUNIT
048501,000191: 13,2504 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
048502,000192: 13,2506 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
048503,000193:
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Page 1137 |
048505,000195: # ARCTAN SUBROUTINE
048506,000196:
048507,000197: # CALLING SEQUENCE
048508,000198: # SIN THETA IN SINTH B-1
048509,000199: # COS THETA IN COSTH B-1
048510,000200: # CALL ARCTAN
048511,000201:
048512,000202: # OUTPUT
048513,000203: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
048514,000204:
048515,000205: 13,2510 77600 ARCTAN BOV
048516,000206: 13,2511 26512 CLROVFLW
048517,000207: 13,2512 63545 CLROVFLW DLOAD DSQ
048518,000208: 13,2513 00023 SINTH
048519,000209: 13,2514 63525 PDDL DSQ
048520,000210: 13,2515 00021 COSTH
048521,000211: 13,2516 77615 DAD
048522,000212: 13,2517 75454 BZE SQRT
048523,000213: 13,2520 26536 ARCTANXX # ATAN=0/0 SET THETA=0
048524,000214: 13,2521 40065 BDDV BOV
048525,000215: 13,2522 00023 SINTH
048526,000216: 13,2523 26543 ATAN=90
048527,000217: 13,2524 67542 SR1 ASIN
048528,000218: 13,2525 00025 STORE THETA
048529,000219: 13,2526 50125 PDDL BMN
048530,000220: 13,2527 00021 COSTH
048531,000221: 13,2530 26532 NEGCOS
048532,000222: 13,2531 43545 DLOAD RVQ
048533,000223: 13,2532 57545 NEGCOS DLOAD DCOMP
048534,000224: 13,2533 43244 BPL DAD
048535,000225: 13,2534 26540 NEGOUT
048536,000226: 13,2535 24005 DP1/2
048537,000227: 13,2536 00025 ARCTANXX STORE THETA
048538,000228: 13,2537 77616 RVQ
048539,000229:
048540,000230: 13,2540 52025 NEGOUT DSU GOTO
048541,000231: 13,2541 24005 DP1/2
048542,000232: 13,2542 26536 ARCTANXX
048543,000233: 13,2543 75345 ATAN=90 DLOAD SIGN
048544,000234: 13,2544 11037 LODP1/4
048545,000235: 13,2545 00023 SINTH
048546,000236: 13,2546 00025 STORE THETA
048547,000237: 13,2547 77616 RVQ
048548,000238:
048549,000239: 13,2550 12,2006 2DZERO = DPZERO
048550,000240:
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Page 1138 |
048552,000242: # ..... SETGAMMA SUBROUTINE .....
048553,000243: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
048554,000244:
048555,000245: # GAMMA = B**2/A**2 FOR EARTH (B-1)
048556,000246: # GAMMA = 1 FOR MOON (B-1)
048557,000247:
048558,000248: # CALLING SEQUENCE
048559,000249: # L CALL
048560,000250: # L+1 SETGAMMA
048561,000251:
048562,000252: # INPUT
048563,000253: # LUNAFLAG=0 FOR EARTH, =1 FOR MOON
048564,000254:
048565,000255: # OUTPUT
048566,000256: # GAMMA IN GAMRP (B-1)
048567,000257:
048568,000258: 13,2550 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
048569,000259: 13,2551 26505 B2/A2 # EARTH GAMMA
048570,000260: 13,2552 01743 LUNAFLAG
048571,000261: 13,2553 26556 SETGMEX
048572,000262: 13,2554 77735 SLOAD
048573,000263: 13,2555 24005 1B1 # MOON GAMMA
048574,000264: 13,2556 00011 SETGMEX STORE GAMRP
048575,000265: 13,2557 77616 RVQ
048576,000266: 13,2560 GAMRP = 8D
048577,000267:
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Page 1139 |
048579,000269: # ..... SETRE SUBROUTINE .....
048580,000270: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
048581,000271:
048582,000272: # RE = RM FOR MOON
048583,000273: # RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
048584,000274:
048585,000275: # CALLING SEQUENCE
048586,000276: # L CALL
048587,000277: # L+1 SETRE
048588,000278:
048589,000279: # SUBROUTINES USED
048590,000280: # GETERAD
048591,000281:
048592,000282: # INPUT
048593,000283: # ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
048594,000284: # ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
048595,000285: # LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
048596,000286:
048597,000287: # OUTPUT
048598,000288: # ERADM = 504RM FOR MOON (METERS B-29)
048599,000289: # ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
048600,000290:
048601,000291: 13,2560 71220 SETRE STQ DLOAD
048602,000292: 13,2561 00051 SETREX
048603,000293: 13,2562 10003 504RM
048604,000294: 13,2563 71214 BON DLOAD # BRANCH FOR MOON
048605,000295: 13,2564 01703 LUNAFLAG
048606,000296: 13,2565 26575 TSTRLSRM
048607,000297: 13,2566 10001 ERAD
048608,000298: 13,2567 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
048609,000299: 13,2570 00742 ERADFLAG
048610,000300: 13,2571 26573 SETRXX
048611,000301: 13,2572 26466 GETERAD
048612,000302: 13,2573 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
048613,000303: 13,2574 00051 SETREX
048614,000304: 13,2575 77214 TSTRLSRM BON VLOAD # ERADFLAG=0, SET R0=RLS
048615,000305: 13,2576 00702 ERADFLAG # =1 R0=RM
048616,000306: 13,2577 26573 SETRXX
048617,000307: 13,2600 02023 RLS
048618,000308: 13,2601 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
048619,000309: 13,2602 77650 GOTO
048620,000310: 13,2603 26573 SETRXX
048621,000311: 13,2604 0000051 SETREX = S2
048622,000312:
048623,000313:
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc