Source Code
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This is a reconstructed version of Luminary 130, the initial AGC program released
in November 1969 for the Apollo 13 LM. Three more releases
followed before the flown revision was finally manufactured in February 1970.
This reconstruction was created from a previous transcription of the original listing of
Luminary 131, combined with Luminary memo #129 which describes the small difference
between the Luminary 130 and 131. The reconstructed source code was verified by
matching memory-bank checksums to those listed for Luminary 130 in drawing 2021152G.
In this source code, program comments from the original (Luminary 131) code are
prefixed with '#', while those added later by the Virtual AGC project are prefixed
with '##'.
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047445,000002: ## Copyright: Public domain.
047446,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
047447,000004: ## Purpose: A section of the reconstructed source code for Luminary 130.
047448,000005: ## This was the original program released for the Apollo 13 LM,
047449,000006: ## although several more revisions would follow. It has been
047450,000007: ## reconstructed from a listing of Luminary 131, from which it
047451,000008: ## differs on only two lines in P70-P71. The difference is
047452,000009: ## described in detail in Luminary memo #129, which was used
047453,000010: ## to perform the reconstruction. This file is intended to be a
047454,000011: ## faithful reconstruction, except that the code format has been
047455,000012: ## changed to conform to the requirements of the yaYUL assembler
047456,000013: ## rather than the original YUL assembler.
047457,000014: ## Reference: pp. 1127-1133
047458,000015: ## Contact: Ron Burkey <info@sandroid.org>.
047459,000016: ## Website: www.ibiblio.org/apollo/index.html
047460,000017: ## Mod history: 05/31/03 RSB. Began transcribing.
047461,000018: ## 05/14/05 RSB Corrected website reference above.
047462,000019: ## 2011-01-05 JL Fixed indentation of RVQ instruction.
047463,000020: ## 2017-01-06 RSB Page numbers now agree with those on the
047464,000021: ## original harcopy, as opposed to the PDF page
047465,000022: ## numbers in 1701.pdf.
047466,000023: ## 2017-02-05 RSB Back-ported comment corrections
047467,000024: ## identified while proofing Artemis 072.
047468,000025: ## 2017-02-27 RSB Proofed comment text using octopus/ProoferComments.
047469,000026: ## 2017-03-13 RSB Comment-text fixes noted in proofing Luminary 116.
047470,000027: ## 2017-03-15 RSB Comment-text fixes identified in 5-way
047471,000028: ## side-by-side diff of Luminary 69/99/116/131/210.
047472,000029: ## 2018-09-04 MAS Copied from Luminary 131 for Luminary 130.
047473,000030:
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Page 1127
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047475,000032: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047476,000033:
047477,000034: # CALLING SEQUENCE
047478,000035: # L-1 CALL
047479,000036: # L LAT-LONG
047480,000037:
047481,000038: # SUBROUTINES USED
047482,000039: # R-TO-RP, ARCTAN, SETGAMMA, SETRE
047483,000040:
047484,000041: # ERASABLE INIT. REQ.
047485,000042: # AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
047486,000043: # ALPHAV = POSITION VECTOR METERS B-29
047487,000044: # MPAC -- TIME (CSECS B-28)
047488,000045: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047489,000046: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047490,000047:
047491,000048: # OUTPUT
047492,000049: # LATITUDE IN LAT (REVS. B-0)
047493,000050: # LONGITUDE IN LONG (REVS. B-0)
047494,000051: # ALTITUDE IN ALT METERS B-29
047495,000052:
047496,000053: 30,3766 BANK 30
047497,000054: 13,2000 SETLOC LATLONG
047498,000055: 13,2000 BANK
047499,000056:
047500,000057: 13,2347 COUNT* $$/LT-LG
047501,000058: 13,2347 E4,1431 EBANK= ALPHAV
047502,000059: 13,2347 40220 LAT-LONG STQ SETPD
047503,000060: 13,2350 03674 INCORPEX
047504,000061: 13,2351 00001 0D
047505,000062: 13,2352 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
047506,000063: 13,2353 02032 ALPHAV
047507,000064: 13,2354 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
047508,000065: 13,2355 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
047509,000066: 13,2356 24007 ZEROVEC # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047510,000067: 13,2357 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
047511,000068: 13,2360 01743 LUNAFLAG # 0=EARTH, 1=MOON
047512,000069: 13,2361 26362 CALLRTRP
047513,000070: 13,2362 77624 CALLRTRP CALL
047514,000071: 13,2363 51700 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
047515,000072: 13,2364 77656 UNIT # UNIT RP B-1
047516,000073: 13,2365 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
047517,000074: 13,2366 26546 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
047518,000075: 13,2367 77624 CALL # SCALED B-1
047519,000076: 13,2370 26556 SETRE # CALC RE METERS B-29
047520,000077: 13,2371 63545 DLOAD DSQ
047521,000078: 13,2372 02032 ALPHAV
047522,000079: 13,2373 63525 PDDL DSQ
047523,000080: 13,2374 02034 ALPHAV +2
047524,000081: 13,2375 75415 DAD SQRT
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Page 1128
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047526,000083: 13,2376 76405 DMP SL1R
047527,000084: 13,2377 00011 GAMRP
047528,000085: 13,2400 14021 STODL COSTH # COS(LAT) B-1
047529,000086: 13,2401 02036 ALPHAV +4
047530,000087: 13,2402 34023 STCALL SINTH # SIN(LAT) B-1
047531,000088: 13,2403 26506 ARCTAN
047532,000089: 13,2404 15120 STODL LAT # LAT B0
047533,000090: 13,2405 02032 ALPHAV
047534,000091: 13,2406 14021 STODL COSTH # COS(LONG) B-1
047535,000092: 13,2407 02034 ALPHAV +2
047536,000093: 13,2410 34023 STCALL SINTH # SIN(LONG) B-1
047537,000094: 13,2411 26506 ARCTAN
047538,000095: 13,2412 15122 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047539,000096: 13,2413 02070 ALPHAM
047540,000097: 13,2414 77625 DSU # ALT= R-RE METERS B-29
047541,000098: 13,2415 03673 ERADM
047542,000099: 13,2416 35124 STCALL ALT # EXIT WITH ALT METERS B-29
047543,000100: 13,2417 03674 INCORPEX
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Page 1129
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047545,000102: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047546,000103:
047547,000104: # CALLING SEQUENCE
047548,000105: # L-1 CALL
047549,000106: # L LALOTORV
047550,000107:
047551,000108: # SUBROUTINES USED
047552,000109: # SETGAMMA, SETRE, RP-TO-R
047553,000110:
047554,000111: # ERASABLE INIT. REQ.
047555,000112: # AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
047556,000113: # LAT -- LATITUDE (REVS B0)
047557,000114: # LONG -- LONGITUDE (REVS B0)
047558,000115: # ALT -- ALTITUDE (METERS) B-29
047559,000116: # MPAC -- TIME (CSECS B-28)
047560,000117: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047561,000118: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047562,000119:
047563,000120: # OUTPUT
047564,000121: # R-VECTOR IN ALPHAV (METERS B-29)
047565,000122:
047566,000123: 13,2420 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
047567,000124: 13,2421 03674 INCORPEX
047568,000125: 13,2422 00001 0D
047569,000126: 13,2423 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
047570,000127: 13,2424 26546 SETGAMMA # GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
047571,000128: 13,2425 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
047572,000129: 13,2426 01120 LAT # UNIT RP = SIN(LONG)COS(LAT) 2-3D
047573,000130: 13,2427 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
047574,000131: 13,2430 00011 GAMRP
047575,000132: 13,2431 01120 LAT # 0-1D= GAMMA*SIN(LAT) B-2
047576,000133: 13,2432 65346 COS PDDL # PD4 2-3D= COS(LAT) B-1 TEMPORARILY
047577,000134: 13,2433 01122 LONG
047578,000135: 13,2434 57356 SIN DMPR # PD 2
047579,000136: 13,2435 71525 PDDL COS # PD 4 2-3D = SIN(LONG)COS(LAT) B-2
047580,000137: 13,2436 01120 LAT
047581,000138: 13,2437 71525 PDDL COS # PD 6 4-5D = COS(LAT) B-1 TEMPORARILY
047582,000139: 13,2440 01122 LONG
047583,000140: 13,2441 55475 DMPR VDEF # PD4 MPAC= COS(LONG)COS(LAT) B-2
047584,000141: 13,2442 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
047585,000142: 13,2443 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
047586,000143: 13,2444 26556 SETRE # RE METERS B-29
047587,000144: 13,2445 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047588,000145: 13,2446 24007 ZEROVEC
047589,000146: 13,2447 01743 LUNAFLAG
047590,000147: 13,2450 26452 CALLRPRT
047591,000148: 13,2451 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
047592,000149: 13,2452 77624 CALLRPRT CALL
047593,000150: 13,2453 55716 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
047594,000151: 13,2454 16032 STODL ALPHAV
047595,000152: 13,2455 03673 ERADM
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Page 1130
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047597,000154: 13,2456 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
047598,000155: 13,2457 01124 ALT
047599,000156: 13,2460 02032 ALPHAV
047600,000157: 13,2461 77772 VSL1 # R METERS B-29
047601,000158: 13,2462 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
047602,000159: 13,2463 03674 INCORPEX
047603,000160:
047604,000161: # SUBROUTINE TO COMPUTE EARTH RADIUS
047605,000162:
047606,000163: # INPUT
047607,000164: # 1/2 SIN LAT IN ALPHAV +4
047608,000165:
047609,000166: # OUTPUT
047610,000167: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047611,000168:
047612,000169: 13,2464 63545 GETERAD DLOAD DSQ
047613,000170: 13,2465 02036 ALPHAV +4 # SIN**2(L)
047614,000171: 13,2466 44352 SL1 BDSU
047615,000172: 13,2467 24005 DP1/2 # COS**2(L)
047616,000173: 13,2470 44275 DMPR BDSU
047617,000174: 13,2471 26505 EE
047618,000175: 13,2472 24005 DP1/2
047619,000176: 13,2473 75465 BDDV SQRT
047620,000177: 13,2474 26501 B2XSC
047621,000178: 13,2475 77622 SR4R
047622,000179: 13,2476 03673 STORE ERADM
047623,000180: 13,2477 77616 RVQ
047624,000181:
047625,000182: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
047626,000183: # B2XSC = B**2 SCALED B-51
047627,000184: # B2/A2 = B**2/A**2 SCALED B-1
047628,000185: # EE = (1-B**2/A**2) SCALED B-0
047629,000186:
047630,000187: 13,2500 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
047631,000188: 13,2502 12,2004 DP1/2 = XUNIT
047632,000189: 13,2502 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
047633,000190: 13,2504 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
047634,000191:
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Page 1131
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047636,000193: # ARCTAN SUBROUTINE
047637,000194:
047638,000195: # CALLING SEQUENCE
047639,000196: # SIN THETA IN SINTH B-1
047640,000197: # COS THETA IN COSTH B-1
047641,000198: # CALL ARCTAN
047642,000199:
047643,000200: # OUTPUT
047644,000201: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047645,000202:
047646,000203: 13,2506 77600 ARCTAN BOV
047647,000204: 13,2507 26510 CLROVFLW
047648,000205: 13,2510 63545 CLROVFLW DLOAD DSQ
047649,000206: 13,2511 00023 SINTH
047650,000207: 13,2512 63525 PDDL DSQ
047651,000208: 13,2513 00021 COSTH
047652,000209: 13,2514 77615 DAD
047653,000210: 13,2515 75454 BZE SQRT
047654,000211: 13,2516 26534 ARCTANXX # ATAN=0/0 SET THETA=0
047655,000212: 13,2517 40065 BDDV BOV
047656,000213: 13,2520 00023 SINTH
047657,000214: 13,2521 26541 ATAN=90
047658,000215: 13,2522 67542 SR1 ASIN
047659,000216: 13,2523 00025 STORE THETA
047660,000217: 13,2524 50125 PDDL BMN
047661,000218: 13,2525 00021 COSTH
047662,000219: 13,2526 26530 NEGCOS
047663,000220: 13,2527 43545 DLOAD RVQ
047664,000221: 13,2530 57545 NEGCOS DLOAD DCOMP
047665,000222: 13,2531 43244 BPL DAD
047666,000223: 13,2532 26536 NEGOUT
047667,000224: 13,2533 24005 DP1/2
047668,000225: 13,2534 00025 ARCTANXX STORE THETA
047669,000226: 13,2535 77616 RVQ
047670,000227:
047671,000228: 13,2536 52025 NEGOUT DSU GOTO
047672,000229: 13,2537 24005 DP1/2
047673,000230: 13,2540 26534 ARCTANXX
047674,000231: 13,2541 75345 ATAN=90 DLOAD SIGN
047675,000232: 13,2542 11003 LODP1/4
047676,000233: 13,2543 00023 SINTH
047677,000234: 13,2544 00025 STORE THETA
047678,000235: 13,2545 77616 RVQ
047679,000236:
047680,000237: 13,2546 12,2006 2DZERO = DPZERO
047681,000238:
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Page 1132
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047683,000240: # ..... SETGAMMA SUBROUTINE .....
047684,000241: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047685,000242:
047686,000243: # GAMMA = B**2/A**2 FOR EARTH (B-1)
047687,000244: # GAMMA = 1 FOR MOON (B-1)
047688,000245:
047689,000246: # CALLING SEQUENCE
047690,000247: # L CALL
047691,000248: # L+1 SETGAMMA
047692,000249:
047693,000250: # INPUT
047694,000251: # LUNAFLAG=0 FOR EARTH, =1 FOR MOON
047695,000252:
047696,000253: # OUTPUT
047697,000254: # GAMMA IN GAMRP (B-1)
047698,000255:
047699,000256: 13,2546 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
047700,000257: 13,2547 26503 B2/A2 # EARTH GAMMA
047701,000258: 13,2550 01743 LUNAFLAG
047702,000259: 13,2551 26554 SETGMEX
047703,000260: 13,2552 77735 SLOAD
047704,000261: 13,2553 24005 1B1 # MOON GAMMA
047705,000262: 13,2554 00011 SETGMEX STORE GAMRP
047706,000263: 13,2555 77616 RVQ
047707,000264: 13,2556 GAMRP = 8D
047708,000265:
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Page 1133
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047710,000267: # ..... SETRE SUBROUTINE .....
047711,000268: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047712,000269:
047713,000270: # RE = RM FOR MOON
047714,000271: # RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047715,000272:
047716,000273: # CALLING SEQUENCE
047717,000274: # L CALL
047718,000275: # L+1 SETRE
047719,000276:
047720,000277: # SUBROUTINES USED
047721,000278: # GETERAD
047722,000279:
047723,000280: # INPUT
047724,000281: # ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
047725,000282: # ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
047726,000283: # LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
047727,000284:
047728,000285: # OUTPUT
047729,000286: # ERADM = 504RM FOR MOON (METERS B-29)
047730,000287: # ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
047731,000288:
047732,000289: 13,2556 71220 SETRE STQ DLOAD
047733,000290: 13,2557 00051 SETREX
047734,000291: 13,2560 10003 504RM
047735,000292: 13,2561 71214 BON DLOAD # BRANCH FOR MOON
047736,000293: 13,2562 01703 LUNAFLAG
047737,000294: 13,2563 26573 TSTRLSRM
047738,000295: 13,2564 10001 ERAD
047739,000296: 13,2565 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
047740,000297: 13,2566 00742 ERADFLAG
047741,000298: 13,2567 26571 SETRXX
047742,000299: 13,2570 26464 GETERAD
047743,000300: 13,2571 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
047744,000301: 13,2572 00051 SETREX
047745,000302: 13,2573 77214 TSTRLSRM BON VLOAD # ERADFLAG=0, SET R0=RLS
047746,000303: 13,2574 00702 ERADFLAG # =1 R0=RM
047747,000304: 13,2575 26571 SETRXX
047748,000305: 13,2576 02023 RLS
047749,000306: 13,2577 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
047750,000307: 13,2600 77650 GOTO
047751,000308: 13,2601 26571 SETRXX
047752,000309: 13,2602 0000051 SETREX = S2
047753,000310:
047754,000311:
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc