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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057617,000002: ## Copyright: Public domain.
057618,000003: ## Filename: INFLIGHT_ALIGNMENT_ROUTINES.agc
057619,000004: ## Purpose: A section of Comanche revision 051.
057620,000005: ## It is part of the reconstructed source code for the
057621,000006: ## original release of the flight software for the Command
057622,000007: ## Module's (CM) Apollo Guidance Computer (AGC) for Apollo 11.
057623,000008: ## The code has been recreated from a copy of Comanche 055. It
057624,000009: ## has been adapted such that the resulting bugger words
057625,000010: ## exactly match those specified for Comanche 51 in NASA drawing
057626,000011: ## 2021153D, which gives relatively high confidence that the
057627,000012: ## reconstruction is correct.
057628,000013: ## Reference: pp. 1355-1364
057629,000014: ## Assembler: yaYUL
057630,000015: ## Contact: Ron Burkey <info@sandroid.org>.
057631,000016: ## Website: www.ibiblio.org/apollo/index.html
057632,000017: ## Mod history: 2019-07-30 MAS Created from Comanche 55.
057633,000018:
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Page 1355
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057635,000020: 22,3510 BANK 22
057636,000021: 23,2000 SETLOC INFLIGHT
057637,000022: 23,2000 BANK
057638,000023:
057639,000024: 23,3205 E5,1671 EBANK= XSM
057640,000025:
057641,000026: # CALCGTA COMPUTES THE GYRO TORQUE ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
057642,000027:
057643,000028: # THE INPUT IS THE DESIRED STABLE MEMBER COORDINATES REFERRED TO PRESENT STABLE MEMBER COORDINATES. THE THREE
057644,000029: # HALF-UNIT VECTORS ARE STORED AT XDC, YDC, AND ZDC.
057645,000030:
057646,000031: # THE OUTPUTS ARE THE THREE GYRO TORQUING ANGLES TO BE APPLIED TO THE Y, Z, AND X GYROS AND ARE STORED DP AT IGC,
057647,000032: # MGC, AND OGC RESPECTIVELY.
057648,000033:
057649,000034: 23,3205 COUNT 23/INFLT
057650,000035:
057651,000036: 23,3205 71220 CALCGTA ITA DLOAD # PUSHDOWN 00-03, 16D-27D, 34D-37D
057652,000037: 23,3206 00051 S2 # XDC = (XD1 XD2 XD3)
057653,000038: 23,3207 02714 XDC # YDC = (YD1 YD2 YD3)
057654,000039: 23,3210 65325 PDDL PDDL # ZDC = (ZD1 ZD2 ZD3)
057655,000040: 23,3211 15335 HI6ZEROS
057656,000041: 23,3212 02720 XDC +4
057657,000042: 23,3213 55476 DCOMP VDEF
057658,000043: 23,3214 77656 UNIT
057659,000044: 23,3215 14027 STODL ZPRIME # ZP = UNIT(-XD3 0 XD1) = (ZP1 ZP2 ZP3)
057660,000045: 23,3216 00027 ZPRIME
057661,000046:
057662,000047: 23,3217 77742 SR1
057663,000048: 23,3220 14023 STODL SINTH # SIN(IGC) = ZP1
057664,000049: 23,3221 00033 ZPRIME +4
057665,000050: 23,3222 77742 SR1
057666,000051: 23,3223 34021 STCALL COSTH # COS(IGC) = ZP3
057667,000052: 23,3224 47256 ARCTRIG
057668,000053:
057669,000054: 23,3225 16762 STODL IGC # Y GYRO TORQUING ANGLE FRACTION OF REV.
057670,000055: 23,3226 02716 XDC +2
057671,000056: 23,3227 77742 SR1
057672,000057: 23,3230 14023 STODL SINTH # SIN(MGC) = XD2
057673,000058: 23,3231 00027 ZPRIME
057674,000059:
057675,000060: 23,3232 65205 DMP PDDL
057676,000061: 23,3233 02720 XDC +4 # PD00 = (ZP1)(XD3)
057677,000062: 23,3234 00033 ZPRIME +4
057678,000063:
057679,000064: 23,3235 45205 DMP DSU
057680,000065: 23,3236 02714 XDC # MPAC = (ZP3)(XD1)
057681,000066: 23,3237 77626 STADR
057682,000067: 23,3240 43756 STCALL COSTH # COS(MGC) = MPAC - PD00
057683,000068: 23,3241 47256 ARCTRIG
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Page 1356
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057685,000070: 23,3242 26764 STOVL MGC # Z GYRO TORQUING ANGLE FRACTION OF REV.
057686,000071: 23,3243 00027 ZPRIME
057687,000072: 23,3244 77641 DOT
057688,000073: 23,3245 02730 ZDC
057689,000074: 23,3246 24021 STOVL COSTH # COS(OGC) = ZP . ZDC
057690,000075: 23,3247 00027 ZPRIME
057691,000076: 23,3250 77641 DOT
057692,000077: 23,3251 02722 YDC
057693,000078: 23,3252 34023 STCALL SINTH # SIN(OGC) = ZP . YDC
057694,000079: 23,3253 47256 ARCTRIG
057695,000080:
057696,000081: 23,3254 36760 STCALL OGC # X GYRO TORQUING ANGLE FRACTION OF REV.
057697,000082: 23,3255 00051 S2
057698,000083:
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Page 1357
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057700,000085: # ARCTRIG COMPUTES AN ANGLE GIVEN THE SINE AND COSINE OF THIS ANGLE.
057701,000086:
057702,000087: # THE INPUTS ARE SIN/4 AND COS/4 STORED DP AT SINTH AND COSTH.
057703,000088:
057704,000089: # THE OUTPUT IS THE CALCULATED ANGLE BETWEEN +.5 AND -.5 REVOLUTIONS AND STORED AT THETA. THE OUTPUT IS ALSO
057705,000090: # AVAILABLE AT MPAC.
057706,000091:
057707,000092: 23,3256 51545 ARCTRIG DLOAD ABS # PUSHDOWN 16D-21D
057708,000093: 23,3257 00023 SINTH
057709,000094: 23,3260 50025 DSU BMN
057710,000095: 23,3261 07474 QTSN45 # ABS(SIN/4) - SIN(45)/4
057711,000096: 23,3262 47271 TRIG1 # IF (-45,45) OR (135,-135)
057712,000097:
057713,000098: 23,3263 72545 DLOAD SL1 # (45,135) OR (-135,-45)
057714,000099: 23,3264 00021 COSTH
057715,000100: 23,3265 75326 ACOS SIGN
057716,000101: 23,3266 00023 SINTH
057717,000102: 23,3267 00025 STORE THETA # X = ARCCOS(COS) WITH SIGN(SIN)
057718,000103: 23,3270 77616 RVQ
057719,000104:
057720,000105: 23,3271 72545 TRIG1 DLOAD SL1 # (-45,45) OR (135,-135)
057721,000106: 23,3272 00023 SINTH
057722,000107: 23,3273 77736 ASIN
057723,000108: 23,3274 14025 STODL THETA # X = ARCSIN(SIN) WITH SIGN(SIN)
057724,000109: 23,3275 00021 COSTH
057725,000110: 23,3276 77640 BMN
057726,000111: 23,3277 47302 TRIG2 # IF (135,-135)
057727,000112:
057728,000113: 23,3300 43545 DLOAD RVQ
057729,000114: 23,3301 00025 THETA # X = ARCSIN(SIN) (-45,45)
057730,000115:
057731,000116: 23,3302 75345 TRIG2 DLOAD SIGN # (135,-135)
057732,000117: 23,3303 15333 HIDPHALF
057733,000118: 23,3304 00023 SINTH
057734,000119: 23,3305 77625 DSU
057735,000120: 23,3306 00025 THETA
057736,000121: 23,3307 00025 STORE THETA # X = .5 WITH SIGN(SIN) - ARCSIN(SIN)
057737,000122: 23,3310 77616 RVQ # (+) - (+) OR (-) - (-)
057738,000123:
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Page 1358
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057740,000125: # SMNB, NBSM, AND AXISROT, WHICH USED TO APPEAR HERE, HAVE BEEN
057741,000126: # COMBINED IN A ROUTINE CALLED AX*SR*T, WHICH APPEARS AMONG THE POWERED
057742,000127: # FLIGHT SUBROUTINES.
057743,000128:
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Page 1359
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057745,000130: # CALCGA COMPUTES THE CDU DRIVING ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
057746,000131:
057747,000132: # THE INPUTS ARE 1) THE NAVIGATION BASE COORDINATES REFERRED TO ANY COORDINATE SYSTEM. THE THREE HALF-UNIT
057748,000133: # VECTORS ARE STORED AT XNB, YNB, AND ZNB. 2) THE DESIRED STABLE MEMBER COORDINATES REFERRED TO THE SAME
057749,000134: # COORDINATE SYSTEM ARE STORED AT XSM, YSM, AND ZSM.
057750,000135:
057751,000136: # THE OUTPUTS ARE THE THREE CDU DRIVING ANGLES AND ARE STORED SP AT THETAD, THETAD +1, AND THETAD +2.
057752,000137:
057753,000138: 23,3311 77601 CALCGA SETPD # PUSHDOWN 00-05, 16D-21D, 34D-37D
057754,000139: 23,3312 00001 0
057755,000140: 23,3313 47375 VLOAD VXV
057756,000141: 23,3314 02714 XNB # XNB = OGA (OUTER GIMBAL AXIS)
057757,000142: 23,3315 02700 YSM # YSM = IGA (INNER GIMBAL AXIS)
057758,000143: 23,3316 41456 UNIT PUSH # PD0 = UNIT(OGA X IGA) = MGA
057759,000144:
057760,000145: 23,3317 44041 DOT ITA
057761,000146: 23,3320 02730 ZNB
057762,000147: 23,3321 00051 S2
057763,000148: 23,3322 24021 STOVL COSTH # COS(OG) = MGA . ZNB
057764,000149: 23,3323 00001 0
057765,000150: 23,3324 77641 DOT
057766,000151: 23,3325 02722 YNB
057767,000152: 23,3326 34023 STCALL SINTH # SIN(OG) = MGA . YNB
057768,000153: 23,3327 47256 ARCTRIG
057769,000154: 23,3330 26760 STOVL OGC
057770,000155: 23,3331 00001 0
057771,000156:
057772,000157: 23,3332 50235 VXV DOT # PROVISION FOR MG ANGLE OF 90 DEGREES
057773,000158: 23,3333 02714 XNB
057774,000159: 23,3334 02700 YSM
057775,000160: 23,3335 77752 SL1
057776,000161: 23,3336 24021 STOVL COSTH # COS(MG) = IGA . (MGA X OGA)
057777,000162: 23,3337 02700 YSM
057778,000163: 23,3340 77641 DOT
057779,000164: 23,3341 02714 XNB
057780,000165: 23,3342 34023 STCALL SINTH # SIN(MG) = IGA . OGA
057781,000166: 23,3343 47256 ARCTRIG
057782,000167: 23,3344 02764 STORE MGC
057783,000168:
057784,000169: 23,3345 45246 ABS DSU
057785,000170: 23,3346 07476 .166...
057786,000171: 23,3347 77644 BPL
057787,000172: 23,3350 47371 GIMLOCK1 # IF ANGLE GREATER THAN 60 DEGREES
057788,000173:
057789,000174: 23,3351 50375 CALCGA1 VLOAD DOT
057790,000175: 23,3352 02706 ZSM
057791,000176: 23,3353 00001 0
057792,000177: 23,3354 24021 STOVL COSTH # COS(IG) = ZSM . MGA
057793,000178: 23,3355 02672 XSM
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Page 1360
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057795,000180: 23,3356 45441 DOT STADR
057796,000181: 23,3357 43754 STCALL SINTH # SIN(IG) = XSM . MGA
057797,000182: 23,3360 47256 ARCTRIG
057798,000183:
057799,000184: 23,3361 26762 STOVL IGC
057800,000185: 23,3362 02760 OGC
057801,000186: 23,3363 43034 RTB BONCLR
057802,000187: 23,3364 45552 V1STO2S
057803,000188: 23,3365 00200 CPHIFLAG
057804,000189: 23,3366 00051 S2
057805,000190: 23,3367 35156 STCALL THETAD
057806,000191: 23,3370 00051 S2
057807,000192:
057808,000193: 23,3371 77776 GIMLOCK1 EXIT
057809,000194: 23,3372 05650 TC ALARM
057810,000195: 23,3373 00401 OCT 00401
057811,000196: 23,3374 05546 TC UPFLAG # GIMBAL LOCK HAS OCCURED
057812,000197: 23,3375 00056 ADRES GLOKFAIL
057813,000198:
057814,000199: 23,3376 06006 TC INTPRET
057815,000200: 23,3377 77650 GOTO
057816,000201: 23,3400 47351 CALCGA1
057817,000202:
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Page 1361
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057819,000204: # AXISGEN COMPUTES THE COORDINATES OF ONE COORDINATE SYSTEM REFERRED TO ANOTHER COORDINATE SYSTEM.
057820,000205:
057821,000206: # THE INPUTS ARE 1) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM A STORED AT STARAD. 2) THE STAR2 VECTOR
057822,000207: # REFERRED TO COORDINATE SYSTEM A STORED AT STARAD +6. 3) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM B STORED
057823,000208: # AT LOCATION 6 OF THE VAC AREA. 4) THE STAR2 VECTOR REFERRED TO COORDINATE SYSTEM B STORED AT LOCATION 12D OF
057824,000209: # THE VAC AREA.
057825,000210:
057826,000211: # THE OUTPUT DEFINES COORDINATE SYSTEM A REFERRED TO COORDINATE SYSTEM B. THE THREE HALF-UNIT VECTORS ARE STORED
057827,000212: # AT LOCATIONS XDC, XDC +6, XDC +12D, AND STARAD, STARAD +6, STARAD +12D.
057828,000213:
057829,000214: 23,3401 66370 AXISGEN AXT,1 SSP # PUSHDOWN 00-30D, 34D-37D
057830,000215: 23,3402 02743 STARAD +6
057831,000216: 23,3403 00051 S1
057832,000217: 23,3404 02727 STARAD -6
057833,000218:
057834,000219: 23,3405 77601 SETPD
057835,000220: 23,3406 00001 0
057836,000221: 23,3407 46773 AXISGEN1 VLOAD* VXV* # 06D UA = S1
057837,000222: 23,3410 02752 STARAD +12D,1 # STARAD +00D UB = S1
057838,000223: 23,3411 02760 STARAD +18D,1
057839,000224: 23,3412 77656 UNIT # 12D VA = UNIT(S1 X S2)
057840,000225: 23,3413 06760 STORE STARAD +18D,1 # STARAD +06D VB = UNIT(S1 X S2)
057841,000226: 23,3414 77773 VLOAD*
057842,000227: 23,3415 02752 STARAD +12D,1
057843,000228:
057844,000229: 23,3416 76433 VXV* VSL1
057845,000230: 23,3417 02760 STARAD +18D,1 # 18D WA = UA X VA
057846,000231: 23,3420 06766 STORE STARAD +24D,1 # STARAD +12D WB = UB X VB
057847,000232:
057848,000233: 23,3421 77700 TIX,1
057849,000234: 23,3422 47407 AXISGEN1
057850,000235:
057851,000236: 23,3423 66160 AXC,1 SXA,1
057852,000237: 23,3424 00006 6
057853,000238: 23,3425 00036 30D
057854,000239:
057855,000240: 23,3426 66370 AXT,1 SSP
057856,000241: 23,3427 00022 18D
057857,000242: 23,3430 00051 S1
057858,000243: 23,3431 00006 6
057859,000244:
057860,000245: 23,3432 66374 AXT,2 SSP
057861,000246: 23,3433 00006 6
057862,000247: 23,3434 00052 S2
057863,000248: 23,3435 00002 2
057864,000249:
057865,000250: 23,3436 76720 AXISGEN2 XCHX,1 VLOAD*
057866,000251: 23,3437 00036 30D # X1=-6 X2=+6 X1=-6 X2=+4 X1=-6 X2=+2
057867,000252: 23,3440 00001 0,1
057868,000253:
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Page 1362
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057870,000255: 23,3441 62757 VXSC* PDVL* # J=(UA)(UB1) J=(UA)(UB2) J=(UA)(UB3)
057871,000256: 23,3442 75033 STARAD +6,2
057872,000257: 23,3443 00007 6,1
057873,000258: 23,3444 77757 VXSC*
057874,000259: 23,3445 75025 STARAD +12D,2
057875,000260: 23,3446 30031 STOVL* 24D # K=(VA)(VB1) J=(VA)(VB2) J=(VA)(VB3)
057876,000261: 23,3447 00015 12D,1
057877,000262:
057878,000263: 23,3450 53357 VXSC* VAD
057879,000264: 23,3451 75017 STARAD +18D,2 # L=(WA)(WB1) J=(WA)(WB2) J=(WA)(WB3)
057880,000265: 23,3452 76455 VAD VSL1
057881,000266: 23,3453 00031 24D
057882,000267: 23,3454 53520 XCHX,1 UNIT
057883,000268: 23,3455 00036 30D
057884,000269: 23,3456 06736 STORE XDC +18D,1 # XDC = L+J+K YDC = L+J+K ZDC = L+J+K
057885,000270:
057886,000271: 23,3457 77700 TIX,1
057887,000272: 23,3460 47461 AXISGEN3
057888,000273:
057889,000274: 23,3461 77704 AXISGEN3 TIX,2
057890,000275: 23,3462 47436 AXISGEN2
057891,000276:
057892,000277: 23,3463 77775 VLOAD
057893,000278: 23,3464 02714 XDC
057894,000279: 23,3465 26736 STOVL STARAD
057895,000280: 23,3466 02722 YDC
057896,000281: 23,3467 26744 STOVL STARAD +6
057897,000282: 23,3470 02730 ZDC
057898,000283: 23,3471 02752 STORE STARAD +12D
057899,000284:
057900,000285: 23,3472 77616 RVQ
057901,000286:
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Page 1363
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057903,000288: 23,3473 05520 26075 QTSN45 2DEC .1768
057904,000289: 23,3475 05252 25253 .166... 2DEC .1666666667
057905,000290:
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Page 1364
This page is empty.
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057908,000293:
057909,000294:
057910,000295:
End of include-file INFLIGHT_ALIGNMENT_ROUTINES.agc. Parent file is MAIN.agc