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. |
034519,000002: ## Copyright: Public domain.
034520,000003: ## Filename: ENTRY_LEXICON.agc
034521,000004: ## Purpose: Part of the source code for Colossus build 237.
034522,000005: ## This is for the Command Module's (CM) Apollo Guidance
034523,000006: ## Computer (AGC), for Apollo 8.
034524,000007: ## Assembler: yaYUL
034525,000008: ## Contact: Jim Lawton <jim DOT lawton AT gmail DOT com>
034526,000009: ## Website: www.ibiblio.org/apollo/index.html
034527,000010: ## Page Scans: www.ibiblio.org/apollo/ScansForConversion/Colossus237/
034528,000011: ## Mod history: 2011-03-02 JL Adapted from corresponding Colossus 249 file.
034529,000012: ## 2017-01-01 RSB Proofed comment text using octopus/ProoferComments,
034530,000013: ## and fixed errors found.
034531,000014: ## 2017-01-08 RSB Fixed comment errors detected in cross-diff vs
034532,000015: ## Colossus 249.
034533,000016: ## 2017-01-22 RSB Back-ported comment error fixes detected in diff'ing
034534,000017: ## Artemis 72 vs Comanche 55.
034535,000018:
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Page 788 |
034537,000020: # VARIABLE DESCRIPTION MAXIMUM VALUE * COMPUTER NAME
034538,000021: # -------- ----------- ------- ----- -------- ----
034539,000022:
034540,000023: # -
034541,000024: # URT0 INITIAL TARGET VECTOR 2 (UNIT VECTOR) = RTINIT
034542,000025: # -
034543,000026: # UZ UNIT VECTOR NORTH 1 = UNITW
034544,000027: # -
034545,000028: # V VELOCITY VECTOR 2 VSAT = VEL
034546,000029: # -
034547,000030: # R POSITION VECTOR 2 EXP 29 METERS = RN
034548,000031: # -
034549,000032: # VI INERTIAL VELOCITY 128 M/CENTISEC = VN
034550,000033: # -
034551,000034: # RTE VECTOR EAST AT INITIAL TARGET 2 = RTEAST
034552,000035: # -
034553,000036: # UTR NORMAL TO RTE AND UZ 2 = RTNORM
034554,000037: # -
034555,000038: # URT TARGET VECTOR 2 = RT
034556,000039: # -
034557,000040: # UNI UNIT NORMAL TO TRAJECTORY PLANE 2
034558,000041: # -
034559,000042: # DELV INTEGRATED ACCEL. FROM PIPAS 5.85 16384 CM/S
034560,000043: # -
034561,000044: # G GRAVITY VECTOR 128 M/CENTISEC = GDT/2
034562,000045:
034563,000046: # A0 INITIAL DRAG FOR UPCONTRL 805 FPSS FPSS=FT/SEC/SEC
034564,000047: # AHOOKDV TERM IN GAMMAL CALC. = AHOOK DVL 8
034565,000048: # A1 DRAG VALUE IN FACTOR CALCULATION 805 FPSS
034566,000049: # ALP CONST FOR UPCONTRL 1
034567,000050: # ASKEP KEPLER RANGE 21600 NM NM = NAUTICAL MILE
034568,000051: # ASP1 FINAL PHASE RANGE 21600 NM
034569,000052: # ASPUP UP-RANGE 21600 NM
034570,000053: # ASP3 GAMMA CORRECTION 21600 NM
034571,000054: # ASPDWN RANGE DOWN TO PULL-UP 21600 NM
034572,000055: # ASP PREDICTED RANGE 21600 NM NOT STORED
034573,000056: # COSG COSINE(GAMMAL) 2 = COSG/2
034574,000057: # C/D0 RECIPROCAL DRAG, -4/D0 B-8 64/FPSS
034575,000058: # D TOTAL ACCELERATION 805 FPSS
034576,000059: # D0 CONTROLLED CONSTANT D 805 FPSS
034577,000060: # DHOOK TERM IN GAMMAL COMPUTATION 805 FPSS
034578,000061: # DIFF THETNM-ASP (RANGE DIFFERENCE) 21600 NM
034579,000062: # DIFFOLD PREVIOUS VALUE OF DIFF 21600 NM
034580,000063: # DLEWD CHANGE IN LEWD 1
034581,000064: # DR REFERENCE DRAG FOR DOWNCONTROL 805 FPSS NOT STORED
034582,000065: # DREFR REFERENCE DRAG 805 FPSS NOT STORED
034583,000066: # DVL VS1-VL 2 VSAT
034584,000067: # E ECCENTRICITY 4 NOT STORED
034585,000068: # F1 DRANGE/D DRAG (FINAL PHASE) 2700/805 = FX +5
034586,000069: # F2 DRANGE/D RDOT (FINAL PHASE) 2700/2VS NM/FPS = FX +4
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Page 789 |
034588,000071: # F3 DRANGE/D (L/D) 2700 NM = FX
034589,000072: # FACT1 CONST FOR UPCONTRL 805 FPSS
034590,000073: # FACT2 CONST FOR UPCONTRL 1/805 FPSS
034591,000074: # FACTOR USED IN UPCONTRL 1 * MAXIMUM VALUE DENOTES UNSCALED
034592,000075: # GAMMAL FLIGHT PATH ANGLE AT VL 1 RADIAN VARIABLE VALUE WHEN SCALED
034593,000076: # GAMMAL1 SIMPLE FORM OF GAMMAL 1 RADIAN VARIABLE HAS MAXIMUM VALUE OF ONE.
034594,000077:
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Page 790 |
034596,000079: # VARIABLE DESCRIPTION MAXIMUM VALUE COMPUTER NAME
034597,000080: # -------- ----------- ------- ----- -------- ----
034598,000081:
034599,000082: # HEADSUP INDICATOR FOR INITIAL ROLL 1
034600,000083: # KA DRAG TO LIFT UP IF DOWN 805 FPSS = KAT
034601,000084: # KLAT LATERAL SWITCH GAIN 1 (NOM = .0125)
034602,000085: # K2ROLL INDICATOR FOR ROLL SWITCH
034603,000086: # LAD MAX L/D (MIN ACTUAL VEHICLE L/D) 1
034604,000087: # LADPAD NOMINAL VEHICLE L/D, SP PAD LOAD 1 (NOM = 0.3)
034605,000088: # LATANG LATERAL RANGE 4 RADIANS
034606,000089: # LEQ EXCESS C.F. OVER GRAV=(VSQ-1)GS 128.8 FPSS
034607,000090: # LEWD UPCONTROL REFERENCE L/D 1
034608,000091: # LOD FINAL PHASE L/D 1 (NOM = 0.18)
034609,000092: # LODPAD FINAL PHASE L/D, SP PAD LOAD 1
034610,000093: # L/D DESIRED LIFT TO DRAG RATIO 1
034611,000094: # (VERTICAL PLANE)
034612,000095: # L/D1 TEMP STORAGE FOR L/D IN LATERAL 1
034613,000096: # L/DCMINR LAD COS(15DEG) 1 (NOM = 0.2895)
034614,000097: # PREDANGL PREDICTED RANGE (FINAL PHASE) 2700 NM = PREDANG
034615,000098: # Q2 FINAL PHASE RANGE -23500 Q3 21600 NM
034616,000099: # Q2 = FCN(LAD)
034617,000100: # Q7 MINIMUM DRAG FOR UPCONTROL 805 FPSS
034618,000101: # RDOT ALTITUDE RATE 2 VSAT
034619,000102: # RDOTREF REFERENCE RDOT FOR UPCONTROL 2 VSAT
034620,000103: # RDTR REFERENCE RDOT FOR DOWNCONT 2 VSAT NOT SAVED
034621,000104: # ROLLC ROLL COMMAND 1 REVOLUTION
034622,000105: # RTOGO RANGE TO GO (FINAL PHASE) 2700 NM = FX +2
034623,000106: # SL SINE OF LATITUDE 1 NOT SAVED
034624,000107: # T TIME B 28 CENTISEC = TIME2,TIME1
034625,000108: # THETA DESIRED RANGE (RADIANS) 2 PI RADIANS = THETAH
034626,000109: # THETNM DESIRED RANGE (NM) 21600 NM NON EXISTENT
034627,000110: # V VELOCITY MAGNITUDE 2 VSAT
034628,000111: # V1 INITIAL VELOCITY FOR UPCONTROL 2 VSAT
034629,000112: # VL EXIT VELOCITY FOR UPCONTROL 2 VSAT
034630,000113: # VREF REFERENCE VELOCITY FOR UPCONTROL 2 VSAT
034631,000114: # VS1 VSAT OR V1, WHICHEVER IS SMALLER 2 VSAT
034632,000115: # 2 2
034633,000116: # VBARS VL /VSAT 4
034634,000117: # 2 2
034635,000118: # VSQ NORMALISED VEL. SQUARED = V /VSAT 4 = VSQUARE
034636,000119: # WT EARTH RATE TIMES TIME 1 REVOLUTION NOT SAVED
034637,000120: # = WIE (DTEAROT)
034638,000121: # X INTERMEDIATE VARIABLE IN G-LIMITER 2 VSAT NOT SAVED
034639,000122: # Y LATERAL MISS LIMIT 4 RADIANS NOT SAVED
034640,000123:
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Page 791 |
034642,000125: # EXTRA COMPUTER ERASABLE LOCATIONS NOT SHOWN ON FLOW CHARTS
034643,000126: # -----------------------------------------------------------
034644,000127:
034645,000128: # VARIABLE DESCRIPTION MAXIMUM VALUE
034646,000129: # -------- ----------- ------- -----
034647,000130:
034648,000131: # GOTOADDR ADDRESS SELECTED BY SEQUENCER
034649,000132: # XPIPBUF BUFFER TO STORE X PIPA COUNTS
034650,000133: # YPIPBUF BUFFER TO STORE Y PIPA COUNTS
034651,000134: # ZPIPBUF BUFFER TO STORE Z PIPA COUNTS
034652,000135: # PIPCTR COUNTS PASSES THRU PIPA READ ROUTINE
034653,000136: # JJ INDEX IN FINAL PHASE TABLE LOOK-UP
034654,000137: # MM INDEX IN FINAL PHASE TABLE LOOK-UP
034655,000138: # GRAD INTERPOLATION FACTOR IN FINAL PHASE
034656,000139: # FX DRANGE/D L/D = F3 2700 NM
034657,000140: # FX + 1 AREF 805 FPSS
034658,000141: # FX + 2 RTOGO 2700 NM
034659,000142: # FX + 3 RDOTREF VSAT/4
034660,000143: # FX + 4 DRANGE/D RDOT = F2 21600/2VS NM/FPS
034661,000144: # FX + 5 DRANGE/D DRAG = F1 2700/805 NM/FPSS
034662,000145: # TEM1B TEMPORARY LOCATION
034663,000146: # TIME/RTO TIME OF INITIAL TARGET RTINIT B 28 CENTISEC
034664,000147: # DTEAROT EST TIME BETWEEN RTINIT AND RT B 28 CENTISEC
034665,000148:
034666,000149: # -
034667,000150: # UNITV UNIT V VECTOR 2
034668,000151: # -
034669,000152: # UNITR UNIT R VECTOR 2
034670,000153: # -
034671,000154: # -VREL NEGATIVE VELOCITY REL TO ATMOSP 2 VSAT
034672,000155:
034673,000156: # COMPUTER SWITCHES INITIAL STATE CM/FLAGS = STATE +6
034674,000157: # -------- -------- ------------- -------------------
034675,000158:
034676,000159: # ENTRYDSP DO ENTRY DISPLAY, IF SET NON-BRANCH (1) 92D, BIT13
034677,000160: # GONEPAST INDICATES OVERSHOOT OF TARGET NON-BRANCH (0) 95D, BIT10
034678,000161: # RELVELSW RELATIVE VELOCITY SWITCH NON-BRANCH (0) 96D, BIT 9
034679,000162: # EGSW FINAL PHASE SWITCH NON-BRANCH (0) 97D, BIT 8
034680,000163: # FIRSTPAS INITIAL PASS THRU HUNTEST NON-BRANCH (0) 98D, BIT 7
034681,000164: # HIND INDICATES ITERATION IN HUNTEST NON-BRANCH (0) 99D, BIT 6
034682,000165: # INRLSW INDICATES INIT ROLL ATTITUDE SET NON-BRANCH (0) 100D, BIT 5
034683,000166: # LATSW INHIBIT DOWNLIFT SWITCH IF NOT SET BRANCH (1) 101D, BIT 4
034684,000167: # .05GSW INDICATES DRAG EXCEEDS .05 GS BRANCH (0) 102D, BIT 3
034685,000168:
034686,000169: # GONEBY INDICATES GONE PAST TARGET (SET) SELF-INITIALZNG 112D, BIT 8
034687,000170:
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Page 792 |
034689,000172: # CONSTANTS AND GAINS VALUE
034690,000173: # ------------------- -----
034691,000174:
034692,000175: # C1 FACTOR IN ALP COMPUTATION 1.25
034693,000176: # C16 CONSTD GAIN ON DRAG .01
034694,000177: # C17 CONSTD GAIN ON RDOT .001
034695,000178: # C18 BIAS VEL. FOR FINAL PHASE START 500 FPS
034696,000179: # C20 MAX DRAG FOR DOWN-LIFT 175 FPSS
034697,000180: # CHOOK FACTOR IN AHOOK COMPUTATION .25
034698,000181: # CH1 FACTOR IN GAMMAL COMPUTATION 1.0
034699,000182: # COS15 COS( 15 DEG) .965
034700,000183: # DLEWD0 INITIAL VARIATION IN LEWD -.05
034701,000184: # D2 DRAG TO CHANGE LEWD 175 FPSS
034702,000185: # DT COMPUTATION CYCLE TIME INTERVAL 2 SEC.
034703,000186: # GMAX MAXIMUM ACCELERATION 257.6 FPSS (8 G-S)
034704,000187: # KA1 FACTOR IN KA CALC 1.3 GS
034705,000188: # KA2 FACTOR IN KA CALC .2 GS
034706,000189: # KA3 FACTOR IN D0 CALC 90 FPSS
034707,000190: # KA4 FACTOR IN D0 CALC 40 FPSS
034708,000191: # KB1 OPTIMIZED UPCONTROL GAIN 3.4
034709,000192: # KB2 OPTIMIZED UPCONTROL GAIN .0034
034710,000193: # KDMIN INCREMENT ON Q7 TO DETECT END OF KEPLER PHASE .5 FPSS
034711,000194: # KTETA TIME OF FLIGHT CONSTANT 1000
034712,000195: # KLAT1 FACTOR IN KLAT CALC 1/24
034713,000196: # K44 GAIN USED IN INITIAL ROLL SECTION 19749550 FPS
034714,000197: # LATBIAS LATERAL SWITCH BIAS TERM .41252961 NM
034715,000198: # LEWD1 NOMINAL UPCONTROL L/D .15
034716,000199: # POINT1 FACTOR TO REDUCE UPCONTROL GAIN .1
034717,000200: # Q2 FINAL PHASE RANGE - 23500 Q3 -1002 NM
034718,000201: # Q3 FINAL PHASE DRANGE/D V .07 NM/FPS
034719,000202: # Q5 FINAL PHASE DRANGE/ D GAMMA 7050 NM/RAD
034720,000203: # Q6 FINAL PHASE INITIAL FLIGHT PATH ANGLE .0349 RAD
034721,000204: # Q7F MIN DRAG FOR UPCONTROL 6 FPSS
034722,000205: # Q7MIN MIN VALUE FOR Q7 IN FACTOR CALCULATION 40 FPSS
034723,000206: # Q19 FACTOR IN GAMMAL1 CALCULATION .5
034724,000207: # Q21 FACTOR IN Q2 CALCULATION. 1000 NM
034725,000208: # Q22 FACTOR IN Q2 CALCULATION. -1302 NM
034726,000209: # VFINAL1 VELOCITY TO START FINAL PHASE ON INITIAL ENTRY 27000 FPS
034727,000210: # VFINAL FACTOR IN INITIAL UP-DOWN CALC 26600 FPS
034728,000211: # VLMIN MINIMUM VL 18000 FPS
034729,000212: # VMIN VELOCITY TO SWITCH TO RELATIVE VEL VSAT/2
034730,000213: # VRCONTRL RDOT TO START INTO HUNTEST 700 FPS
034731,000214: # VRCONT = COMPUTER NAME
034732,000215: # 25NM TOLERANCE TO STOP RANGE ITERATION 25 NM
034733,000216: # VQUIT VELOCITY TO STOP STEERING 1000 FPS
034734,000217:
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Page 793 |
034736,000219: # CONVERSION FACTORS AND SCALING CONSTANTS
034737,000220: # ---------- ------- --- ------- ---------
034738,000221:
034739,000222: # ATK ANGLE IN RAD TO NM 3437.7468 NM/RAD
034740,000223: # GS NOMINAL G VALUE FOR SCALING 32.2 FPSS
034741,000224: # HS ATMOSPHERE SCALE HEIGHT 28500 FT
034742,000225: # J GRAVITY HARMONIC COEFFICIENT .00162346
034743,000226: # KWE EQUATORIAL EARTH RATE 1546.70168 FPS
034744,000227: # MUE EARTH GRAVITATIONAL CONSTANT 3.986032233 E 14 CUBIC M/ SEC SEC
034745,000228: # RE EARTH RADIUS 21202900 FT
034746,000229: # REQ EARTH EQUATORIAL RADIUS 20925738.2 FT
034747,000230: # VSAT SATELLITE VELOCITY AT RE 25766.1973 FPS
034748,000231: # WIE EARTH RATE .0000729211505 RAD/SEC
034749,000232:
034750,000233: # (END GSOP AS-278, VOL 1, FIG. 5.6-3 CONSTANTS,GAINS, ETC.)
034751,000234:
034752,000235:
034753,000236: # DISPLAY QUANTITIES
034754,000237: # ------------------
034755,000238:
034756,000239: # (SEE SECTION 4 OF THE GSOP FOR SIGN CONVENTIONS. )
034757,000240:
034758,000241: # VARIABLE DESCRIPTION MAXIMUM VALUE
034759,000242: # -------- ----------- ------- -----
034760,000243:
034761,000244: # QMAX PREDICTED MAXIMUM ENTRY ACCEL 163.84 GS N 60
034762,000245: # VPRED PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 60
034763,000246: # 400K FT ABOVE FISCHER RADIUS.
034764,000247: # GAMMAEI PREDICTED GAMMA AT ALTITUDE 1 REVOLUTION N 60
034765,000248: # 400K FT ABOVE FISCHER RADIUS.
034766,000249: # D DRAG ACCELERATION 805 FPSS N 64
034767,000250: # VMAGI INERTIAL VELOCITY MAGNITUDE 128 M/CENTISEC N 64, N 68
034768,000251: # THETAH DESIRED RANGE ANGLE NM 1 REVOLUTION N 64, N 67
034769,000252: # LAT PRESENT LATITUDE 1 REVOLUTION N 67
034770,000253: # LONG PRESENT LONGITUDE 1 REVOLUTION N 67
034771,000254: # RTOGO RANGE ANGLE TO SPLASH FROM 1 REVOLUTION N 63
034772,000255: # EMSALT FT ABOVE FISCHER RADIUS. (IN NM)
034773,000256: # VIO PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 63
034774,000257: # EMSALT FT ABOVE FISCHER RADIUS.
034775,000258: # TTE TIME OF FREE FALL TO ALT B 28 CENTISEC N 63
034776,000259: # EMSALT FT ABOVE FISCHER RADIUS.
034777,000260: # ROLLC ROLL COMMAND 1 REVOLUTION N 66, N 68, N 69
034778,000261: # LATANG CROSS-RANGE ERROR (XRNGERR) 4 RADIANS N 66
034779,000262: # DNRNGERR DOWN RANGE ERROR 1 REVOLUTION N 66
034780,000263: # (PREDANG - THETAH IN NM)
034781,000264: # HDOT ALTITUDE RATE 128 M/CENTISEC N 68
034782,000265: # Q7 MINIMUM DRAG FOR UPCONTROL 805 FPSS N 69
034783,000266: # VL EXIT VELOCITY FOR UP-CONTROL 2 VSAT N 69
034784,000267:
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Page 794 |
034786,000269: # BODY ATTITUDE QUANTITIES (CM/POSE)
034787,000270: # -----------------------------------
034788,000271:
034789,000272: # VARIABLE DESCRIPTION MAXIMUM VALUE
034790,000273: # -------- ----------- ------- -----
034791,000274:
034792,000275: # -
034793,000276: # -VREL NEGATIVE VELOCITY REL TO ATMOS. 2 VSAT
034794,000277: # -
034795,000278: # OLDUYA USED FOR UYA BELOW 1000 FPS 2
034796,000279: # -
034797,000280: # UXA/2 UNIT VECTOR TRIAD 2
034798,000281: # -
034799,000282: # UYA/2 BASED ON 2
034800,000283: # -
034801,000284: # UZA/2 THE TRAJECTORY. 2
034802,000285: # -
034803,000286: # UBX/2 UNIT VECTOR 2
034804,000287: # -
034805,000288: # UBY/2 BODY TRIAD 2
034806,000289: # -
034807,000290: # UBZ/2 FOR CM. 2
End of include-file ENTRY_LEXICON.agc. Parent file is MAIN.agc