Source Code
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These source-code files are part of a reconstructed copy of Comanche 051, the
original release of the Apollo 11 Command Module (CM) Apollo Guidance Computer
(AGC) software.
The reconstruction began with source code of Comanche 055 previously transcribed
from a digitized copy of that program. The code was then updated by undoing
changes related to the R-2 lunar potential model, using hints from program
comments and change-indicating asterisks in the Comanche 055 listing as a guide.
The reconstruction was verified by matching memory-bank checksums to those listed
in drawing 2021153D. Note that page numbers in the reconstructed code match those
on the Comanche 055 printout, although the added code would likely have changed page
numbers for a real Comanche 051 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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036489,000002: ## Copyright: Public domain.
036490,000003: ## Filename: ENTRY_LEXICON.agc
036491,000004: ## Purpose: A section of Comanche revision 051.
036492,000005: ## It is part of the reconstructed source code for the
036493,000006: ## original release of the flight software for the Command
036494,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
036495,000008: ## The code has been recreated from a copy of Comanche 055. It
036496,000009: ## has been adapted such that the resulting bugger words
036497,000010: ## exactly match those specified for Comanche 51 in NASA drawing
036498,000011: ## 2021153D, which gives relatively high confidence that the
036499,000012: ## reconstruction is correct.
036500,000013: ## Reference: pp. 837-843
036501,000014: ## Assembler: yaYUL
036502,000015: ## Contact: Ron Burkey <info@sandroid.org>.
036503,000016: ## Website: www.ibiblio.org/apollo/index.html
036504,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
036505,000018:
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Page 837
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036507,000020: # VARIABLE DESCRIPTION MAXIMUM VALUE * COMPUTER NAME
036508,000021: # -------- ----------- ------- ----- -------- ----
036509,000022: # -
036510,000023: # URT0 INITIAL TARGET VECTOR 2 (UNIT VECTOR) = RTINIT
036511,000024: # -
036512,000025: # UZ UNIT VECTOR NORTH 1 = UNITW
036513,000026: # -
036514,000027: # V VELOCITY VECTOR 2 VSAT = VEL
036515,000028: # -
036516,000029: # R POSITION VECTOR 2 EXP 29 METERS = RN
036517,000030: # -
036518,000031: # VI INERTIAL VELOCITY 128 M/CENTISEC = VN
036519,000032: # -
036520,000033: # RTE VECTOR EAST AT INITIAL TARGET 2 = RTEAST
036521,000034: # -
036522,000035: # UTR NORMAL TO RTE AND UZ 2 = RTNORM
036523,000036: # -
036524,000037: # URT TARGET VECTOR 2 = RT
036525,000038: # -
036526,000039: # UNI UNIT NORMAL TO TRAJECTORY PLANE 2
036527,000040: # -
036528,000041: # DELV INTEGRATED ACCEL. FROM PIPAS 5.85 16384 CM/S
036529,000042: # -
036530,000043: # G GRAVITY VECTOR 128 M/CENTISEC = GDT/2
036531,000044:
036532,000045: # A0 INITIAL DRAG FOR UPCONTRL 805 FPSS FPSS=FT/SEC/SEC
036533,000046:
036534,000047: # AHOOKDV TERM IN GAMMAL CALC. = AHOOK DVL 16
036535,000048:
036536,000049: # A1 DRAG VALUE IN FACTOR CALCULATION 805 FPSS
036537,000050:
036538,000051: # ALP CONST FOR UPCONTRL 1
036539,000052:
036540,000053: # ASKEP KEPLER RANGE 21600 NM NM = NAUTICAL MILE
036541,000054:
036542,000055: # ASP1 FINAL PHASE RANGE 21600 NM
036543,000056:
036544,000057: # ASPUP UP-RANGE 21600 NM
036545,000058:
036546,000059: # ASP3 GAMMA CORRECTION 21600 NM
036547,000060:
036548,000061: # ASPDWN RANGE DOWN TO PULL-UP 21600 NM
036549,000062:
036550,000063: # ASP PREDICTED RANGE 21600 NM NOT STORED
036551,000064:
036552,000065: # COSG COSINE(GAMMAL) 2 = COSG/2
036553,000066:
036554,000067: # C/D0 RECIPROCAL DRAG, -4/D0 B-8 64/FPSS
036555,000068:
036556,000069: # D TOTAL ACCELERATION 805 FPSS
036557,000070:
036558,000071: # D0 CONTROLLED CONSTANT D 805 FPSS
036559,000072:
036560,000073: # DHOOK TERM IN GAMMAL COMPUTATION 805 FPSS
036561,000074:
036562,000075: # DIFF THETNM-ASP (RANGE DIFFERENCE) 21600 NM
036563,000076:
036564,000077: # DIFFOLD PREVIOUS VALUE OF DIFF 21600 NM
036565,000078:
036566,000079: # DLEWD CHANGE IN LEWD 1
036567,000080:
036568,000081: # DR REFERENCE DRAG FOR DOWNCONTROL 805 FPSS NOT STORED
036569,000082:
036570,000083: # DREFR REFERENCE DRAG 805 FPSS NOT STORED
036571,000084:
036572,000085: # DVL VS1-VL 2 VSAT
036573,000086:
036574,000087: # E ECCENTRICITY 4 NOT STORED
036575,000088:
036576,000089: # F1 DRANGE/D DRAG (FINAL PHASE) 2700/805 = FX +5
036577,000090:
036578,000091: # F2 DRANGE/D RDOT (FINAL PHASE) 2700/2VS NM/FPS = FX +4
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Page 838
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036580,000093:
036581,000094: # F3 DRANGE/D (L/D) 2700 NM = FX
036582,000095:
036583,000096: # FACT1 CONST FOR UPCONTRL 805 FPSS
036584,000097:
036585,000098: # FACT2 CONST FOR UPCONTRL 1/805 FPSS
036586,000099:
036587,000100: # FACTOR USED IN UPCONTRL 1 * MAXIMUM VALUE DENOTES UNSCALED
036588,000101: #
036589,000102: # GAMMAL FLIGHT PATH ANGLE AT VL 1 RADIAN VARIABLE VALUE WHEN SCALED
036590,000103:
036591,000104: # GAMMAL1 SIMPLE FORM OF GAMMAL 1 RADIAN VARIABLE HAS MAXIMUM VALUE OF ONE.
036592,000105:
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Page 839
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036594,000107: # VARIABLE DESCRIPTION MAXIMUM VALUE COMPUTER NAME
036595,000108: # -------- ----------- ------- ----- -------- ----
036596,000109:
036597,000110: # HEADSUP INDICATOR FOR INITIAL ROLL 1
036598,000111:
036599,000112: # KA DRAG TO LIFT UP IF DOWN 805 FPSS = KAT
036600,000113:
036601,000114: # KLAT LATERAL SWITCH GAIN 1 (NOM = .0125)
036602,000115:
036603,000116: # K2ROLL INDICATOR FOR ROLL SWITCH
036604,000117:
036605,000118: # LAD MAX L/D (MIN ACTUAL VEHICLE L/D) 1
036606,000119:
036607,000120: # LADPAD NOMINAL VEHICLE L/D, SP PAD LOAD 1 (NOM = 0.3)
036608,000121:
036609,000122: # LATANG LATERAL RANGE 4 RADIANS
036610,000123:
036611,000124: # LEQ EXCESS C.F. OVER GRAV=(VSQ-1)GS 128.8 FPSS
036612,000125:
036613,000126: # LEWD UPCONTROL REFERENCE L/D 1
036614,000127:
036615,000128: # LOD FINAL PHASE L/D 1 (NOM = 0.18)
036616,000129:
036617,000130: # LODPAD FINAL PHASE L/D, SP PAD LOAD 1
036618,000131:
036619,000132: # L/D DESIRED LIFT TO DRAG RATIO 1
036620,000133: # (VERTICAL PLANE)
036621,000134: #
036622,000135: # L/D1 TEMP STORAGE FOR L/D IN LATERAL 1
036623,000136:
036624,000137: # L/DCMINR LAD COS(15DEG) 1 (NOM = 0.2895)
036625,000138:
036626,000139: # PREDANGL PREDICTED RANGE (FINAL PHASE) 2700 NM = PREDANG
036627,000140:
036628,000141: # Q2 FINAL PHASE RANGE -23500 Q3 21600 NM
036629,000142: # Q2 = FCN(LAD)
036630,000143:
036631,000144: # Q7 MINIMUM DRAG FOR UPCONTROL 805FPSS
036632,000145:
036633,000146: # RDOT ALTITUDE RATE 2 VSAT
036634,000147:
036635,000148: # RDOTREF REFERENCE RDOT FOR UPCONTROL 2 VSAT
036636,000149:
036637,000150: # RDTR REFERENCE RDOT FOR DOWNCONT 2 VSAT NOT SAVED
036638,000151:
036639,000152: # ROLLC ROLL COMMAND 1 REVOLUTION
036640,000153:
036641,000154: # RTOGO RANGE TO GO (FINAL PHASE) 2700 NM = FX +2
036642,000155:
036643,000156: # SL SINE OF LATITUDE 1 NOT SAVED
036644,000157:
036645,000158: # T TIME B 28 CENTISEC = TIME2,TIME1
036646,000159:
036647,000160: # THETA DESIRED RANGE (RADIANS) 2 PI RADIANS = THETAH
036648,000161:
036649,000162: # THETNM DESIRED RANGE (NM) 21600 NM NON EXISTENT
036650,000163:
036651,000164: # V VELOCITY MAGNITUDE 2 VSAT
036652,000165: #
036653,000166: # V1 INITIAL VELOCITY FOR UPCONTROL 2 VSAT
036654,000167:
036655,000168: # VL EXIT VELOCITY FOR UPCONTROL 2 VSAT
036656,000169:
036657,000170: # VREF REFERENCE VELOCITY FOR UPCONTROL 2 VSAT
036658,000171:
036659,000172: # VS1 VSAT OR V1, WHICHEVER IS SMALLER 2 VSAT
036660,000173: # 2 2
036661,000174: # VBARS VL /VSAT 4
036662,000175: # 2 2
036663,000176: # VSQ NORMALISED VEL. SQUARED = V /VSAT 4 = VSQUARE
036664,000177:
036665,000178: # WT EARTH RATE TIMES TIME 1 REVOLUTION NOT SAVED
036666,000179: # = WIE (DTEAROT)
036667,000180: # X INTERMEDIATE VARIABLE IN G-LIMITER 2 VSAT NOT SAVED
036668,000181:
036669,000182: # Y LATERAL MISS LIMIT 4 RADIANS NOT SAVED
036670,000183:
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Page 840
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036672,000185: # EXTRA COMPUTER ERASABLE LOCATIONS NOT SHOWN ON FLOW CHARTS
036673,000186: # -----------------------------------------------------------
036674,000187:
036675,000188: # VARIABLE DESCRIPTION MAXIMUM VALUE
036676,000189: # -------- ----------- ------- -----
036677,000190:
036678,000191: # GOTOADDR ADDRESS SELECTED BY SEQUENCER
036679,000192:
036680,000193: # XPIPBUF BUFFER TO STORE X PIPA COUNTS
036681,000194:
036682,000195: # YPIPBUF BUFFER TO STORE Y PIPA COUNTS
036683,000196:
036684,000197: # ZPIPBUF BUFFER TO STORE Z PIPA COUNTS
036685,000198:
036686,000199: # PIPCTR COUNTS PASSES THRU PIPA READ ROUTINE
036687,000200:
036688,000201: # JJ INDEX IN FINAL PHASE TABLE LOOK-UP
036689,000202:
036690,000203: # MM INDEX IN FINAL PHASE TABLE LOOK-UP
036691,000204:
036692,000205: # GRAD INTERPOLATION FACTOR IN FINAL PHASE
036693,000206:
036694,000207: # FX DRANGE/D L/D = F3 2700 NM
036695,000208:
036696,000209: # FX +1 AREF 805 FPSS
036697,000210:
036698,000211: # FX +2 RTOGO 2700 NM
036699,000212:
036700,000213: # FX +3 RDOTREF VSAT/4
036701,000214:
036702,000215: # FX +4 DRANGE/D RDOT = F2 21600/2VS NM/FPS
036703,000216:
036704,000217: # FX +5 DRANGE/D DRAG = F1 2700/805 NM/FPSS
036705,000218:
036706,000219: # TEM1B TEMPORARY LOCATION
036707,000220:
036708,000221: # TIME/RTO TIME OF INITIAL TARGET RTINIT B 28 CENTISEC
036709,000222:
036710,000223: # DTEAROT EST TIME BETWEEN RTINIT AND RT B 28 CENTISEC
036711,000224: # -
036712,000225: # UNITV UNIT V VECTOR 2
036713,000226: # -
036714,000227: # UNITR UNIT R VECTOR 2
036715,000228: # -
036716,000229: # -VREL NEGATIVE VELOCITY REL TO ATMOSP 2 VSAT
036717,000230:
036718,000231: # COMPUTER SWITCHES INITIAL STATE CM/FLAGS = STATE +6
036719,000232: # -------- -------- ------------- -------------------
036720,000233:
036721,000234: # ENTRYDSP DO ENTRY DISPLAY, IF SET NON-BRANCH (1) 92D, BIT 13
036722,000235: # GONEPAST INDICATES OVERSHOOT OF TARGET NON-BRANCH (0) 95D, BIT 10
036723,000236: # RELVELSW RELATIVE VELOCITY SWITCH NON-BRANCH (0) 96D, BIT 9
036724,000237: # EGSW FINAL PHASE SWITCH NON-BRANCH (0) 97D, BIT 8
036725,000238: # FIRSTPAS INITIAL PASS THRU HUNTEST NON-BRANCH (0) 98D, BIT 7
036726,000239: # HIND INDICATES ITERATION IN HUNTEST NON-BRANCH (0) 99D, BIT 6
036727,000240: # INRLSW INDICATES INIT ROLL ATTITUDE SET NON-BRANCH (0) 100D, BIT 5
036728,000241: # LATSW INHIBIT DOWNLIFT SWITCH IF NOT SET BRANCH (1) 101D, BIT 4
036729,000242: # .05GSW INDICATES DRAG EXCEEDS .05 GS BRANCH (0) 102D, BIT 3
036730,000243:
036731,000244: # GONEBY INDICATES GONE PAST TARGET (SET) SELF-INITIALZNG 112D, BIT 8
036732,000245:
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Page 841
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036734,000247: # CONSTANTS AND GAINS VALUE
036735,000248: # ------------------- -----
036736,000249:
036737,000250: # C1 FACTOR IN ALP COMPUTATION 1.25
036738,000251: # C16 CONSTD GAIN ON DRAG .01
036739,000252: # C17 CONSTD GAIN ON RDOT .001
036740,000253: # C18 BIAS VEL. FOR FINAL PHASE START 500 FPS
036741,000254: # C20 MAX DRAG FOR DOWN-LIFT 175 FPSS
036742,000255: # CHOOK FACTOR IN AHOOK COMPUTATION .25
036743,000256: # CH1 FACTOR IN GAMMAL COMPUTATION 1.0
036744,000257: # COS15 COS( 15 DEG ) .965
036745,000258: # DLEWD0 INITIAL VARIATION IN LEWD -.05
036746,000259: # D2 DRAG TO CHANGE LEWD 175 FPSS
036747,000260: # DT COMPUTATION CYCLE TIME INTERVAL 2 SEC.
036748,000261: # GMAX MAXIMUM ACCELERATION 257.6 FPSS (8 G-S)
036749,000262: # KA1 FACTOR IN KA CALC 1.3 GS
036750,000263: # KA2 FACTOR IN KA CALC .2 GS
036751,000264: # KA3 FACTOR IN D0 CALC 90 FPSS
036752,000265: # KA4 FACTOR IN D0 CALC 40 FPSS
036753,000266: # KB1 OPTIMIZED UPCONTROL GAIN 3.4
036754,000267: # KB2 OPTIMIZED UPCONTROL GAIN .0034
036755,000268: # KDMIN INCREMENT ON Q7 TO DETECT END OF KEPLER PHASE .5 FPSS
036756,000269: # KTETA TIME OF FLIGHT CONSTANT 1000
036757,000270: # KLAT1 FACTOR IN KLAT CALC 1/24
036758,000271: # K44 GAIN USED IN INITIAL ROLL SECTION 19749550 FPS
036759,000272: # LATBIAS LATERAL SWITCH BIAS TERM .41252961 NM
036760,000273: # LEWD1 NOMINAL UPCONTROL L/D .15
036761,000274: # POINT1 FACTOR TO REDUCE UPCONTROL GAIN .1
036762,000275: # Q2 FINAL PHASE RANGE - 23500 Q3 -1002 NM
036763,000276: # Q3 FINAL PHASE DRANGE/D V .07 NM/FPS
036764,000277: # Q5 FINAL PHASE DRANGE/D GAMMA 7050 NM/RAD
036765,000278: # Q6 FINAL PHASE INITIAL FLIGHT PATH ANGLE .0349 RAD
036766,000279: # Q7F MIN DRAG FOR UPCONTROL 6 FPSS
036767,000280: # Q7MIN MIN VALUE FOR Q7 IN FACTOR CALCULATION 40 FPSS
036768,000281: # Q19 FACTOR IN GAMMAL1 CALCULATION .5
036769,000282: # Q21 FACTOR IN Q2 CALCULATION. 1000 NM
036770,000283: # Q22 FACTOR IN Q2 CALCULATION. -1302 NM
036771,000284: # VFINAL1 VELOCITY TO START FINAL PHASE ON INITIAL ENTRY 27000 FPS
036772,000285: # VFINAL FACTOR IN INITIAL UP-DOWN CALC 26600 FPS
036773,000286: # VLMIN MINIMUM VL 18000 FPS
036774,000287: # VMIN VELOCITY TO SWITCH TO RELATIVE VEL VSAT/2
036775,000288: # VRCONTRL RDOT TO START INTO HUNTEST 700 FPS
036776,000289: # VRCONT=COMPUTER NAME
036777,000290: # 25NM TOLERANCE TO STOP RANGE ITERATION 25 NM
036778,000291: # VQUIT VELOCITY TO STOP STEERING 1000 FPS
036779,000292:
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Page 842
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036781,000294: # CONVERSION FACTORS AND SCALING CONSTANTS
036782,000295: # ---------- ------- --- ------- ---------
036783,000296:
036784,000297: # ATK ANGLE IN RAD TO NM 3437.7468 NM/RAD
036785,000298: # GS NOMINAL G VALUE FOR SCALING 32.2 FPSS
036786,000299: # HS ATMOSPHERE SCALE HEIGHT 28500 FT
036787,000300: # J GRAVITY HARMONIC COEFFICIENT .00162346
036788,000301: # KWE EQUATORIAL EARTH RATE 1546.70168 FPS
036789,000302: # MUE EARTH GRAVITATIONAL CONSTANT 3.986032233 E14 CUBIC M/ SEC SEC
036790,000303: # RE EARTH RADIUS 21202900 FT
036791,000304: # REQ EARTH EQUATORIAL RADIUS 20925738.2 FT
036792,000305: # VSAT SATELLITE VELOCITY AT RE 25766.1973 FPS
036793,000306: # WIE EARTH RATE .0000729211505 RAD/SEC
036794,000307:
036795,000308: # (END GSOP AS-278, VOL 1, FIG. 5.6-3 CONSTANTS, GAINS, ETC.)
036796,000309:
036797,000310: # DISPLAY QUANTITIES
036798,000311: # ------------------
036799,000312:
036800,000313: # (SEE SECTION 4 OF THE GSOP FOR SIGN CONVENTIONS.)
036801,000314:
036802,000315: # VARIABLE DESCRIPTION MAXIMUM VALUE
036803,000316: # -------- ----------- ------- -----
036804,000317:
036805,000318: # QMAX PREDICTED MAXIMUM ENTRY ACCEL 163.84 GS N 60
036806,000319: # VPRED PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 60
036807,000320: # 400K FT ABOVE FISCHER RADIUS.
036808,000321: # GAMMAEI PREDICTED GAMMA AT ALTITUDE 1 REVOLUTION N 60
036809,000322: # 400K FT ABOVE FISCHER RADIUS.
036810,000323: # D DRAG ACCELERATION 805 FPSS N 64
036811,000324: # VMAGI INERTIAL VELOCITY MAGNITUDE 128 M/CENTISEC N 64, N 68
036812,000325: # THETAH DESIRED RANGE ANGLE NM 1 REVOLUTION N 64, N 67
036813,000326: # LAT PRESENT LATITUDE 1 REVOLUTION N 67
036814,000327: # LONG PRESENT LONGITUDE 1 REVOLUTION N 67
036815,000328: # RTOGO RANGE ANGLE TO SPLASH FROM 1 REVOLUTION N 63
036816,000329: # EMSALT FT ABOVE FISCHER RADIUS. (IN NM)
036817,000330: # VIO PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 63
036818,000331: # EMSALT FT ABOVE FISCHER RADIUS.
036819,000332: # TTE TIME OF FREE FALL TO ALT B 28 CENTISEC N 63
036820,000333: # EMSALT FT ABOVE FISCHER RADIUS.
036821,000334: # ROLLC ROLL COMMAND 1 REVOLUTION N 66, N 68, N 69
036822,000335: # LATANG CROSS-RANGE ERROR (XRNGERR) 4 RADIANS N 66
036823,000336: # DNRNGERR DOWN RANGE ERROR 1 REVOLUTION N 66
036824,000337: # (PREDANG - THETAH IN NM)
036825,000338: # HDOT ALTITUDE RATE 128 M/CENTISEC N 68
036826,000339: # Q7 MINIMUM DRAG FOR UPCONTROL 805 FPSS N 69
036827,000340: # VL EXIT VELOCITY FOR UP-CONTROL 2 VSAT N 69
036828,000341:
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Page 843
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036830,000343: # BODY ATTITUDE QUANTITIES (CM/POSE)
036831,000344: # -----------------------------------
036832,000345:
036833,000346: # VARIABLE DESCRIPTION MAXIMUM VALUE
036834,000347: # -------- ----------- ------- -----
036835,000348: # -
036836,000349: # -VREL NEGATIVE VELOCITY REL TO ATMOS. 2 VSAT
036837,000350: # -
036838,000351: # OLDUYA USED FOR UYA BELOW 1000 FPS 2
036839,000352: # -
036840,000353: # UXA/2 UNIT VECTOR TRIAD 2
036841,000354: # -
036842,000355: # UYA/2 BASED ON 2
036843,000356: # -
036844,000357: # UZA/2 THE TRAJECTORY. 2
036845,000358: # -
036846,000359: # UBX/2 UNIT VECTOR 2
036847,000360: # -
036848,000361: # UBY/2 BODY TRIAD 2
036849,000362: # -
036850,000363: # UBZ/2 FOR CM. 2
036851,000364:
End of include-file ENTRY_LEXICON.agc. Parent file is MAIN.agc