Source Code
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These source-code files were derived from scans of the
Colossus 237 (Apollo 8 Command Module) program listing from the private collection of original
AGC developer Fred Martin. Scanning was by Ron Burkey. Pre-existing Colossus 249
(Apollo 9 CM) source files were used as a template, and changes between Colossus 249
and Colossus 237 were manually transcribed by a team of volunteers. Note
that the page images
presented online are of reduced quality, and that additional 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 237 OF AGC PROGRAM COLOSSUS BY NASA 2021111-031 1:17 AUG. 24, 1968Note that the date is the date of the printout, not the date of the program revision. |
051042,000002: ## Copyright: Public domain.
051043,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
051044,000004: ## Purpose: Part of the source code for Colossus build 237.
051045,000005: ## This is for the Command Module's (CM) Apollo Guidance
051046,000006: ## Computer (AGC), for Apollo 8.
051047,000007: ## Assembler: yaYUL
051048,000008: ## Contact: Jim Lawton <jim DOT lawton AT gmail DOT com>
051049,000009: ## Website: www.ibiblio.org/apollo/index.html
051050,000010: ## Page Scans: www.ibiblio.org/apollo/ScansForConversion/Colossus237/
051051,000011: ## Mod history: 2011-04-13 JL Adapted from corresponding Colossus 249 file.
051052,000012: ## 2017-01-01 RSB Proofed comment text using octopus/ProoferComments,
051053,000013: ## and fixed errors found.
051054,000014: ## 2017-02-05 RSB Back-ported comment corrections
051055,000015: ## identified while proofing Artemis 072.
051056,000016: ## 2017-03-15 RSB Comment-text fixes identified in 5-way
051057,000017: ## side-by-side diff of Luminary 69/99/116/131/210.
051058,000018:
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Page 1203 |
051060,000020: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
051061,000021:
051062,000022: # CALLING SEQUENCE
051063,000023:
051064,000024: # L-1 CALL
051065,000025: # L LAT-LONG
051066,000026: # SUBROUTINES USED
051067,000027:
051068,000028: # R-TO-RP,ARCTAN,SETGAMMA,SETRE
051069,000029: # ERASABLE INIT. REQ.
051070,000030:
051071,000031: # AXO,-AYO,AZO,TEPHEM (SET AT LAUNCH TIME)
051072,000032: # ALPHAV = POSITION VECTOR METERS B-29
051073,000033: # MPAC-- TIME (CSECS B-28)
051074,000034: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
051075,000035: # LUNAFLAG=0 FOR EARTH,1 FOR MOON
051076,000036: # OUTPUT
051077,000037:
051078,000038: # LATITUDE IN LAT (REVS. B-0)
051079,000039: # LONGITUDE IN LONG (REVS. B-0)
051080,000040: # ALTITUDE IN ALT METERS B-29
051081,000041: 30,3776 BANK 30
051082,000042: 13,2000 SETLOC LATLONG
051083,000043: 13,2000 BANK
051084,000044:
051085,000045: 13,2322 COUNT 13/LT-LG
051086,000046:
051087,000047: 13,2322 E4,1551 EBANK= ALPHAV
051088,000048: 13,2322 40220 LAT-LONG STQ SETPD
051089,000049: 13,2323 02242 INCORPEX
051090,000050: 13,2324 00001 0D
051091,000051: 13,2325 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
051092,000052: 13,2326 02152 ALPHAV
051093,000053: 13,2327 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
051094,000054: 13,2330 16310 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
051095,000055: 13,2331 11453 ZEROVEC # SET MPAC=0 FOR EARTH,NON-ZERO FOR MOON
051096,000056: 13,2332 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
051097,000057: 13,2333 01743 LUNAFLAG # 0=EARTH,1=MOON
051098,000058: 13,2334 26335 CALLRTRP
051099,000059: 13,2335 77624 CALLRTRP CALL
051100,000060: 13,2336 55366 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
051101,000061: 13,2337 77656 UNIT # UNIT RP B-1
051102,000062: 13,2340 36152 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
051103,000063: 13,2341 26523 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH,=1 FOR MOON
051104,000064: 13,2342 77624 CALL # SCALED B-1
051105,000065: 13,2343 26533 SETRE # CALC RE METERS B-29
051106,000066: 13,2344 63545 DLOAD DSQ
051107,000067: 13,2345 02152 ALPHAV
051108,000068: 13,2346 63525 PDDL DSQ
051109,000069: 13,2347 02154 ALPHAV +2
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Page 1204 |
051111,000071: 13,2350 75415 DAD SQRT
051112,000072: 13,2351 76405 DMP SL1R
051113,000073: 13,2352 00011 GAMRP
051114,000074: 13,2353 14021 STODL COSTH # COS(LAT) B-1
051115,000075: 13,2354 02156 ALPHAV +4
051116,000076: 13,2355 34023 STCALL SINTH # SIN(LAT) B-1
051117,000077: 13,2356 26463 ARCTAN
051118,000078: 13,2357 15104 STODL LAT # LAT B0
051119,000079: 13,2360 02152 ALPHAV
051120,000080: 13,2361 14021 STODL COSTH # COS(LONG) B-1
051121,000081: 13,2362 02154 ALPHAV +2
051122,000082: 13,2363 34023 STCALL SINTH # SIN(LONG) B-1
051123,000083: 13,2364 26463 ARCTAN
051124,000084: 13,2365 15106 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
051125,000085: 13,2366 02310 ALPHAM
051126,000086: 13,2367 77625 DSU # ALT= R-RE METERS B-29
051127,000087: 13,2370 02241 ERADM
051128,000088: 13,2371 35110 STCALL ALT # EXIT WITH ALT METERS B-29
051129,000089: 13,2372 02242 INCORPEX
051130,000090:
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Page 1205 |
051132,000092: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
051133,000093: # CALLING SEQUENCE
051134,000094:
051135,000095: # L-1 CALL
051136,000096: # L LALOTORV
051137,000097: # SUBROUTINES USED
051138,000098:
051139,000099: # SETGAMMA,SETRE,RP-TO-R
051140,000100: # ERASABLE INIT. REQ.
051141,000101:
051142,000102: # AXO,AYO,AZO,TEPHEM SET AT LAUNCH TIME
051143,000103: # LAT-- LATITUDE (REVS B0)
051144,000104: # LONG-- LONGITUDE (REVS B0)
051145,000105: # ALT--ALTITUDE (METERS) B-29
051146,000106: # MPAC-- TIME (CSECS B-28)
051147,000107: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
051148,000108: # LUNAFLAG=0 FOR EARTH,1 FOR MOON
051149,000109: # OUTPUT
051150,000110:
051151,000111: # R-VECTOR IN ALPHAV (METERS B-29)
051152,000112: 13,2373 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
051153,000113: 13,2374 02242 INCORPEX
051154,000114: 13,2375 00001 0D
051155,000115: 13,2376 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
051156,000116: 13,2377 26523 SETGAMMA # GAMMA=B2/A2 FOR EARTH,1 FOR MOON B-1
051157,000117: 13,2400 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
051158,000118: 13,2401 01104 LAT # UNIT RP= SIN(LONG)COS(LAT) 2-3D
051159,000119: 13,2402 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
051160,000120: 13,2403 00011 GAMRP
051161,000121: 13,2404 01104 LAT # 0-1D= GAMMA*SIN(LAT) B-2
051162,000122: 13,2405 65346 COS PDDL # PD 4 2-3D=COS(LAT) B-1 TEMPORARILY
051163,000123: 13,2406 01106 LONG
051164,000124: 13,2407 57356 SIN DMPR # PD 2
051165,000125: 13,2410 71525 PDDL COS # PD 4 2-3D=SIN(LONG)COS(LAT) B-2
051166,000126: 13,2411 01104 LAT
051167,000127: 13,2412 71525 PDDL COS # PD 6 4-5D=COS(LAT) B-1 TEMPORARILY
051168,000128: 13,2413 01106 LONG
051169,000129: 13,2414 55475 DMPR VDEF # PD4 MPAC= COS(LONG)COS(LAT) B-2
051170,000130: 13,2415 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
051171,000131: 13,2416 36152 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
051172,000132: 13,2417 26533 SETRE # RE METERS B-29
051173,000133: 13,2420 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH,NON-ZERO FOR MOON
051174,000134: 13,2421 11453 ZEROVEC
051175,000135: 13,2422 01743 LUNAFLAG
051176,000136: 13,2423 26425 CALLRPRT
051177,000137: 13,2424 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
051178,000138: 13,2425 77624 CALLRPRT CALL
051179,000139: 13,2426 55341 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
051180,000140: 13,2427 16152 STODL ALPHAV
051181,000141: 13,2430 02241 ERADM
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Page 1206 |
051183,000143: 13,2431 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
051184,000144: 13,2432 01110 ALT
051185,000145: 13,2433 02152 ALPHAV
051186,000146: 13,2434 77772 VSL1 # R METERS B-29
051187,000147: 13,2435 36152 STCALL ALPHAV # EXIT WITH R IN METERS B-29
051188,000148: 13,2436 02242 INCORPEX
051189,000149: # SUBROUTINE TO COMPUTE EARTH RADIUS
051190,000150:
051191,000151: # INPUT
051192,000152:
051193,000153: # 1/2 SIN LAT IN ALPHAV +4
051194,000154:
051195,000155: # OUTPUT
051196,000156:
051197,000157: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
051198,000158:
051199,000159: 13,2437 63545 GETERAD DLOAD DSQ
051200,000160: 13,2440 02156 ALPHAV +4 # SIN**2(L)
051201,000161: 13,2441 44352 SL1 BDSU
051202,000162: 13,2442 11451 DP1/2 # COS**2(L)
051203,000163: 13,2443 44275 DMPR BDSU
051204,000164: 13,2444 26460 EE
051205,000165: 13,2445 11451 DP1/2
051206,000166: 13,2446 75465 BDDV SQRT
051207,000167: 13,2447 26454 B2XSC
051208,000168: 13,2450 77622 SR4R
051209,000169: 13,2451 02241 STORE ERADM
051210,000170: 13,2452 77616 RVQ
051211,000171:
051212,000172: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166,B=6356784 METERS
051213,000173: # B2XSC= B**2 SCALED B-51
051214,000174: # B2/A2= B**2/A**2 SCALED B-1
051215,000175: # EE=(1-B**2/A**2) SCALED B-0
051216,000176:
051217,000177: 13,2453 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
051218,000178: 13,2455 04,3450 DP1/2 = XUNIT
051219,000179: 13,2455 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
051220,000180: 13,2457 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
051221,000181: 13,2461 00302 17755 ERAD 2DEC 6373338 B-29 # PAD RADIUS
051222,000182:
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Page 1207 |
051224,000184: # ARCTAN SUBROUTINE
051225,000185:
051226,000186:
051227,000187: # CALLING SEQUENCE
051228,000188:
051229,000189: # SIN THETA IN SINTH B-1
051230,000190: # COS THETA IN COSTH B-1
051231,000191: # CALL ARCTAN
051232,000192:
051233,000193: # OUTPUT
051234,000194: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
051235,000195:
051236,000196:
051237,000197: 13,2463 77600 ARCTAN BOV
051238,000198: 13,2464 26465 CLROVFLW
051239,000199: 13,2465 63545 CLROVFLW DLOAD DSQ
051240,000200: 13,2466 00023 SINTH
051241,000201: 13,2467 63525 PDDL DSQ
051242,000202: 13,2470 00021 COSTH
051243,000203: 13,2471 77615 DAD
051244,000204: 13,2472 75454 BZE SQRT
051245,000205: 13,2473 26511 ARCTANXX # ATAN=0/0 SET THETA=0
051246,000206: 13,2474 40065 BDDV BOV
051247,000207: 13,2475 00023 SINTH
051248,000208: 13,2476 26516 ATAN=90
051249,000209: 13,2477 67542 SR1 ASIN
051250,000210: 13,2500 00025 STORE THETA
051251,000211: 13,2501 50125 PDDL BMN
051252,000212: 13,2502 00021 COSTH
051253,000213: 13,2503 26505 NEGCOS
051254,000214: 13,2504 43545 DLOAD RVQ
051255,000215: 13,2505 57545 NEGCOS DLOAD DCOMP
051256,000216: 13,2506 43244 BPL DAD
051257,000217: 13,2507 26513 NEGOUT
051258,000218: 13,2510 11451 DP1/2
051259,000219: 13,2511 00025 ARCTANXX STORE THETA
051260,000220: 13,2512 77616 RVQ
051261,000221:
051262,000222: 13,2513 52025 NEGOUT DSU GOTO
051263,000223: 13,2514 11451 DP1/2
051264,000224: 13,2515 26511 ARCTANXX
051265,000225: 13,2516 75345 ATAN=90 DLOAD SIGN
051266,000226: 13,2517 11477 LODP1/4
051267,000227: 13,2520 00023 SINTH
051268,000228: 13,2521 00025 STORE THETA
051269,000229: 13,2522 77616 RVQ
051270,000230:
051271,000231: 13,2523 04,3452 2DZERO = DPZERO
051272,000232:
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Page 1208 |
051274,000234: # ..... SETGAMMA SUBROUTINE .....
051275,000235: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
051276,000236:
051277,000237: # GAMMA = B**2/A**2 FOR EARTH (B-1)
051278,000238: # GAMMA = 1 FOR MOON (B-1)
051279,000239:
051280,000240: # CALLING SEQUENCE
051281,000241: # L CALL
051282,000242: # L+1 SETGAMMA
051283,000243:
051284,000244: # INPUT
051285,000245: # LUNAFLAG=0 FOR EARTH,=1 FOR MOON
051286,000246:
051287,000247: # OUTPUT
051288,000248: # GAMMA IN GAMRP (B-1)
051289,000249:
051290,000250: 13,2523 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
051291,000251: 13,2524 26456 B2/A2 # EARTH GAMMA
051292,000252: 13,2525 01743 LUNAFLAG
051293,000253: 13,2526 26531 SETGMEX
051294,000254: 13,2527 77735 SLOAD
051295,000255: 13,2530 11451 1B1 # MOON GAMMA
051296,000256: 13,2531 00011 SETGMEX STORE GAMRP
051297,000257: 13,2532 77616 RVQ
051298,000258: 13,2533 GAMRP = 8D
051299,000259:
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Page 1209 |
051301,000261: # .....SETRE SUBROUTINE .....
051302,000262: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
051303,000263:
051304,000264: # RE= RM FOR MOON
051305,000265: # RE= RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
051306,000266:
051307,000267: # CALLING SEQUENCE
051308,000268: # L CALL
051309,000269: # L+1 SETRE
051310,000270:
051311,000271: # SUBROUTINES USED
051312,000272: # GETERAD
051313,000273:
051314,000274: # INPUT
051315,000275: # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED RE
051316,000276: # ALPHAV +4= 1/2 SINL IF GETERAD IS CALLED
051317,000277: # LUNAFLAG=0 FOR EARTH,=1 FOR MOON
051318,000278:
051319,000279: # OUTPUT
051320,000280: # ERADM= 504RM FOR MOON (METERS B-29)
051321,000281: # ERADM= ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
051322,000282:
051323,000283: 13,2533 71220 SETRE STQ DLOAD
051324,000284: 13,2534 00051 SETREX
051325,000285: 13,2535 26560 504RM
051326,000286: 13,2536 71214 BON DLOAD # BRANCH FOR MOON
051327,000287: 13,2537 01703 LUNAFLAG
051328,000288: 13,2540 26550 TSTRLSRM
051329,000289: 13,2541 26462 ERAD
051330,000290: 13,2542 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE,1 FOR COMPUTED
051331,000291: 13,2543 00742 ERADFLAG
051332,000292: 13,2544 26546 SETRXX
051333,000293: 13,2545 26437 GETERAD
051334,000294: 13,2546 36241 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
051335,000295: 13,2547 00051 SETREX
051336,000296: 13,2550 77214 TSTRLSRM BON VLOAD # ERADFLAG=0,SET R0=RLS
051337,000297: 13,2551 00702 ERADFLAG # =1 R0=RM
051338,000298: 13,2552 26546 SETRXX
051339,000299: 13,2553 02026 RLS
051340,000300: 13,2554 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
051341,000301: 13,2555 77650 GOTO
051342,000302: 13,2556 26546 SETRXX
051343,000303: 13,2557 0000051 SETREX = S2
051344,000304: 13,2557 00065 01265 504RM 2DEC 1738090 B-29 # METERS B-29 (MOON RADIUS)
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc