Source Code
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These source-code files are part of a reconstructed copy of Luminary 69/2,
the flown, final release of the Apollo 10 Lunar Module (LM) Apollo Guidance Computer (AGC) software.
The reconstruction is based on the source code of Luminary 69 — i.e., the
initial, unflown version, "revision 0" — of which
a contemporary listing was available. The code was then updated by incorporating the
differences between Luminary 69 and Luminary 69/2, known from other contemporary
documentation. The only such difference is the implementation in
Luminary 69/2 of the "R-2 Lunar Potential Model", the source code for which was taken
from program Luminary 99/1 (Apollo 11 LM), of which a contemporary listing was also available.
Finally, the now-reconstructed Luminary 69/2 was then validated by assembling it to
executable form and verifying that its memory banks had the correct checksums,
known from still other contemporary documentation.
Note that page numbers in the reconstructed code match those in the original Luminary 69
program listing, or in the ORBITAL INTEGRATION log section, in Luminary 99/1. Page numbers
would certainly differ somewhat in a contemporary Luminary 69/2 listing.
Moreover, annotations that were not present in the contemporary source code have been added
to the reconstructed code to justify each change in Luminary 69/2 relative to
Luminary 69. Here's a guide to the Apollo documentation referenced in those annotations:
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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053785,000002: ## Copyright: Public domain.
053786,000003: ## Filename: INFLIGHT_ALIGNMENT_ROUTINES.agc
053787,000004: ## Purpose: A section of LUM69 revision 2.
053788,000005: ## It is part of the reconstructed source code for the flown
053789,000006: ## version of the flight software for the Lunar Module's (LM)
053790,000007: ## Apollo Guidance Computer (AGC) for Apollo 10. The code has
053791,000008: ## been recreated from a copy of Luminary revsion 069, using
053792,000009: ## changes present in Luminary 099 which were described in
053793,000010: ## Luminary memos 75 and 78. The code has been adapted such
053794,000011: ## that the resulting bugger words exactly match those specified
053795,000012: ## for LUM69 revision 2 in NASA drawing 2021152B, which gives
053796,000013: ## relatively high confidence that the reconstruction is correct.
053797,000014: ## Reference: pp. 1244-1253
053798,000015: ## Assembler: yaYUL
053799,000016: ## Contact: Ron Burkey <info@sandroid.org>.
053800,000017: ## Website: www.ibiblio.org/apollo/index.html
053801,000018: ## Mod history: 2019-07-27 MAS Created from Luminary 69.
053802,000019:
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Page 1244
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053804,000021: 22,3731 BANK 22
053805,000022: 23,2000 SETLOC INFLIGHT
053806,000023: 23,2000 BANK
053807,000024:
053808,000025: 23,3151 E5,1642 EBANK= XSM
053809,000026:
053810,000027: # CALCGTA COMPUTES THE GYRO TORQUE ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
053811,000028:
053812,000029: # THE INPUT IS THE DESIRED STABLE MEMBER COORDINATES REFERRED TO PRESENT STABLE MEMBER COORDINATES. THE THREE
053813,000030: # HALF-UNIT VECTORS ARE STORED AT XDC, YDC, AND ZDC.
053814,000031:
053815,000032: # THE OUTPUTS ARE THE THREE GYRO TORQUING ANGLES TO BE APPLIED TO THE Y, Z, AND X GYROS AND ARE STORED DP AT IGC,
053816,000033: # MGC, AND OGC RESPECTIVELY.
053817,000034:
053818,000035: 23,3151 COUNT* $$/INFLT
053819,000036: 23,3151 71220 CALCGTA ITA DLOAD # PUSHDOWN 00-03,16D-27D,34D-37D
053820,000037: 23,3152 00051 S2 # XDC = (XD1 XD2 XD3)
053821,000038: 23,3153 02665 XDC # YDC = (YD1 YD2 YD3)
053822,000039: 23,3154 65325 PDDL PDDL # ZDC = (ZD1 ZD2 ZD3)
053823,000040: 23,3155 06424 HI6ZEROS
053824,000041: 23,3156 02671 XDC +4
053825,000042: 23,3157 55476 DCOMP VDEF
053826,000043: 23,3160 77656 UNIT
053827,000044: 23,3161 14027 STODL ZPRIME # ZP = UNIT(-XD3 0 XD1) = (ZP1 ZP2 ZP3)
053828,000045: 23,3162 00027 ZPRIME
053829,000046:
053830,000047: 23,3163 77742 SR1
053831,000048: 23,3164 14023 STODL SINTH # SIN(IGC) = ZP1
053832,000049: 23,3165 00033 ZPRIME +4
053833,000050: 23,3166 77742 SR1
053834,000051: 23,3167 34021 STCALL COSTH # COS(IGC) = ZP3
053835,000052: 23,3170 47222 ARCTRIG
053836,000053:
053837,000054: 23,3171 16742 STODL IGC # Y GYRO TORQUING ANGLE FRACTION OF REV.
053838,000055: 23,3172 02667 XDC +2
053839,000056: 23,3173 77742 SR1
053840,000057: 23,3174 14023 STODL SINTH # SIN(MGC) = XD2
053841,000058: 23,3175 00027 ZPRIME
053842,000059:
053843,000060: 23,3176 65205 DMP PDDL
053844,000061: 23,3177 02671 XDC +4 # PD00 = (ZP1)(XD3)
053845,000062: 23,3200 00033 ZPRIME +4
053846,000063:
053847,000064: 23,3201 45205 DMP DSU
053848,000065: 23,3202 02665 XDC # MPAC = (ZP3)(XD1)
053849,000066: 23,3203 77626 STADR
053850,000067: 23,3204 43756 STCALL COSTH # COS(MGC) = MPAC - PD00
053851,000068: 23,3205 47222 ARCTRIG
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Page 1245
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053853,000070: 23,3206 26744 STOVL MGC # Z GYRO TORQUING ANGLE FRACTION OF REV.
053854,000071: 23,3207 00027 ZPRIME
053855,000072: 23,3210 77641 DOT
053856,000073: 23,3211 02701 ZDC
053857,000074: 23,3212 24021 STOVL COSTH # COS(OGC) = ZP . ZDC
053858,000075: 23,3213 00027 ZPRIME
053859,000076: 23,3214 77641 DOT
053860,000077: 23,3215 02673 YDC
053861,000078: 23,3216 34023 STCALL SINTH # SIN(OGC) = ZP . YDC
053862,000079: 23,3217 47222 ARCTRIG
053863,000080:
053864,000081: 23,3220 36740 STCALL OGC # X GYRO TORQUING ANGLE FRACTION OF REV.
053865,000082: 23,3221 00051 S2
053866,000083:
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Page 1246
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053868,000085: # ARCTRIG COMPUTES AN ANGLE GIVEN THE SINE AND COSINE OF THIS ANGLE.
053869,000086:
053870,000087: # THE INPUTS ARE SIN/4 AND COS/4 STORED DP AT SINTH AND COSTH.
053871,000088:
053872,000089: # THE OUTPUT IS THE CALCULATED ANGLE BETWEEN +.5 AND -.5 REVOLUTIONS AND STORED AT THETA. THE OUTPUT IS ALSO
053873,000090: # AVAILABLE AT MPAC.
053874,000091:
053875,000092: 23,3222 51545 ARCTRIG DLOAD ABS # PUSHDOWN 16D-21D
053876,000093: 23,3223 00023 SINTH
053877,000094: 23,3224 50025 DSU BMN
053878,000095: 23,3225 07440 QTSN45 # ABS(SIN/4) - SIN(45)/4
053879,000096: 23,3226 47235 TRIG1 # IF (-45,45) OR (135,-135)
053880,000097:
053881,000098: 23,3227 72545 DLOAD SL1 # (45,135) OR (-135,-45)
053882,000099: 23,3230 00021 COSTH
053883,000100: 23,3231 75326 ACOS SIGN
053884,000101: 23,3232 00023 SINTH
053885,000102: 23,3233 00025 STORE THETA # X = ARCCOS(COS) WITH SIGN(SIN)
053886,000103: 23,3234 77616 RVQ
053887,000104:
053888,000105: 23,3235 72545 TRIG1 DLOAD SL1 # (-45,45) OR (135,-135)
053889,000106: 23,3236 00023 SINTH
053890,000107: 23,3237 77736 ASIN
053891,000108: 23,3240 14025 STODL THETA # X = ARCSIN(SIN) WITH SIGN(SIN)
053892,000109: 23,3241 00021 COSTH
053893,000110: 23,3242 77640 BMN
053894,000111: 23,3243 47246 TRIG2 # IF (135,-135)
053895,000112:
053896,000113: 23,3244 43545 DLOAD RVQ
053897,000114: 23,3245 00025 THETA # X = ARCSIN(SIN) (-45,45)
053898,000115:
053899,000116: 23,3246 75345 TRIG2 DLOAD SIGN # (135,-135)
053900,000117: 23,3247 06422 HIDPHALF
053901,000118: 23,3250 00023 SINTH
053902,000119: 23,3251 77625 DSU
053903,000120: 23,3252 00025 THETA
053904,000121: 23,3253 00025 STORE THETA # X = .5 WITH SIGN(SIN) - ARCSIN(SIN)
053905,000122: 23,3254 77616 RVQ # (+) - (+) OR (-) - (-)
053906,000123:
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Page 1247
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053908,000125: # SMNB, NBSM, AND AXISROT, WHICH USED TO APPEAR HERE, HAVE BEEN
053909,000126: # COMBINED IN A ROUTINE CALLED AX*SR*T, WHICH APPEARS AMONG THE POWERED
053910,000127: # FLIGHT SUBROUTINES.
053911,000128:
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Page 1248
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053913,000130: # CALCGA COMPUTES THE CDU DRIVING ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
053914,000131:
053915,000132: # THE INPUTS ARE 1) THE NAVIGATION BASE COORDINATES REFERRED TO ANY COORDINATE SYSTEM. THE THREE HALF-UNIT
053916,000133: # VECTORS ARE STORED AT XNB, YNB, AND ZNB. 2) THE DESIRED STABLE MEMBER COORDINATES REFERRED TO THE SAME
053917,000134: # COORDINATE SYSTEM ARE STORED AT XSM, YSM, AND ZSM.
053918,000135:
053919,000136: # THE OUTPUTS ARE THE THREE CDU DRIVING ANGLES AND ARE STORED SP AT THETAD, THETAD +1, AND THETAD +2.
053920,000137:
053921,000138: 23,3255 77601 CALCGA SETPD # PUSHDOWN 00-05, 16D-21D, 34D-37D
053922,000139: 23,3256 00001 0
053923,000140: 23,3257 47375 VLOAD VXV
053924,000141: 23,3260 02665 XNB # XNB = OGA (OUTER GIMBAL AXIS)
053925,000142: 23,3261 02651 YSM # YSM = IGA (INNER GIMBAL AXIS)
053926,000143: 23,3262 41456 UNIT PUSH # PD0 = UNIT(OGA X IGA) = MGA
053927,000144:
053928,000145: 23,3263 44041 DOT ITA
053929,000146: 23,3264 02701 ZNB
053930,000147: 23,3265 00051 S2
053931,000148: 23,3266 24021 STOVL COSTH # COS(OG) = MGA . ZNB
053932,000149: 23,3267 00001 0
053933,000150: 23,3270 77641 DOT
053934,000151: 23,3271 02673 YNB
053935,000152: 23,3272 34023 STCALL SINTH # SIN(OG) = MGA . YNB
053936,000153: 23,3273 47222 ARCTRIG
053937,000154: 23,3274 26740 STOVL OGC
053938,000155: 23,3275 00001 0
053939,000156:
053940,000157: 23,3276 50235 VXV DOT # PROVISION FOR MG ANGLE OF 90 DEGREES
053941,000158: 23,3277 02665 XNB
053942,000159: 23,3300 02651 YSM
053943,000160: 23,3301 77752 SL1
053944,000161: 23,3302 24021 STOVL COSTH # COS(MG) = IGA . (MGA X OGA)
053945,000162: 23,3303 02651 YSM
053946,000163: 23,3304 77641 DOT
053947,000164: 23,3305 02665 XNB
053948,000165: 23,3306 34023 STCALL SINTH # SIN(MG) = IGA . OGA
053949,000166: 23,3307 47222 ARCTRIG
053950,000167: 23,3310 02744 STORE MGC
053951,000168:
053952,000169: 23,3311 45246 ABS DSU
053953,000170: 23,3312 07442 .166...
053954,000171: 23,3313 77644 BPL
053955,000172: 23,3314 47335 GIMLOCK1 # IF ANGLE GREATER THAN 60 DEGREES
053956,000173:
053957,000174: 23,3315 50375 CALCGA1 VLOAD DOT
053958,000175: 23,3316 02657 ZSM
053959,000176: 23,3317 00001 0
053960,000177: 23,3320 24021 STOVL COSTH # COS(IG) = ZSM . MGA
053961,000178: 23,3321 02643 XSM
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Page 1249
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053963,000180: 23,3322 45441 DOT STADR
053964,000181: 23,3323 43754 STCALL SINTH # SIN(IG) = XSM . MGA
053965,000182: 23,3324 47222 ARCTRIG
053966,000183:
053967,000184: 23,3325 26742 STOVL IGC
053968,000185: 23,3326 02740 OGC
053969,000186: 23,3327 43034 RTB BONCLR
053970,000187: 23,3330 21524 V1STO2S
053971,000188: 23,3331 00200 CPHIFLAG
053972,000189: 23,3332 00051 S2
053973,000190: 23,3333 34322 STCALL THETAD
053974,000191: 23,3334 00051 S2
053975,000192:
053976,000193: 23,3335 77776 GIMLOCK1 EXIT
053977,000194: 23,3336 05567 TC ALARM
053978,000195: 23,3337 00401 OCT 00401
053979,000196: 23,3340 05504 TC UPFLAG # GIMBAL LOCK HAS OCCURED
053980,000197: 23,3341 00056 ADRES GLOKFAIL
053981,000198:
053982,000199: 23,3342 06036 TC INTPRET
053983,000200: 23,3343 77650 GOTO
053984,000201: 23,3344 47315 CALCGA1
053985,000202:
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Page 1250
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053987,000204: # AXISGEN COMPUTES THE COORDINATES OF ONE COORDINATE SYSTEM REFERRED TO ANOTHER COORDINATE SYSTEM.
053988,000205:
053989,000206: # THE INPUTS ARE 1) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM A STORED AT STARAD. 2) THE STAR2 VECTOR
053990,000207: # REFERRED TO COORDINATE SYSTEM A STORED AT STARAD +6. 3) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM B STORED
053991,000208: # AT LOCATION 6 OF THE VAC AREA. 4) THE STAR2 VECTOR REFERRED TO COORDINATE SYSTEM B STORED AT LOCATION 12D OF
053992,000209: # THE VAC AREA.
053993,000210:
053994,000211: # THE OUTPUT DEFINES COORDINATE SYSTEM A REFERRED TO COORDINATE SYSTEM B. THE THREE HALF-UNIT VECTORS ARE STORED
053995,000212: # AT LOCATIONS XDC, XDC +6, XDC +12D, AND STARAD, STARAD +6, STARAD +12D.
053996,000213:
053997,000214: 23,3345 66370 AXISGEN AXT,1 SSP # PUSHDOWN 00-30D,34D-37D
053998,000215: 23,3346 02714 STARAD +6
053999,000216: 23,3347 00051 S1
054000,000217: 23,3350 02700 STARAD -6
054001,000218:
054002,000219: 23,3351 77601 SETPD
054003,000220: 23,3352 00001 0
054004,000221: 23,3353 46773 AXISGEN1 VLOAD* VXV* # 06D UA = S1
054005,000222: 23,3354 02723 STARAD +12D,1 # STARAD +00D UB = S1
054006,000223: 23,3355 02731 STARAD +18D,1
054007,000224: 23,3356 77656 UNIT # 12D VA = UNIT(S1 X S2)
054008,000225: 23,3357 06731 STORE STARAD +18D,1 # STARAD +06D VB = UNIT(S1 X S2)
054009,000226: 23,3360 77773 VLOAD*
054010,000227: 23,3361 02723 STARAD +12D,1
054011,000228:
054012,000229: 23,3362 76433 VXV* VSL1
054013,000230: 23,3363 02731 STARAD +18D,1 # 18D WA = UA X VA
054014,000231: 23,3364 06737 STORE STARAD +24D,1 # STARAD +12D WB = UB X VB
054015,000232:
054016,000233: 23,3365 77700 TIX,1
054017,000234: 23,3366 47353 AXISGEN1
054018,000235:
054019,000236: 23,3367 66160 AXC,1 SXA,1
054020,000237: 23,3370 00006 6
054021,000238: 23,3371 00036 30D
054022,000239:
054023,000240: 23,3372 66370 AXT,1 SSP
054024,000241: 23,3373 00022 18D
054025,000242: 23,3374 00051 S1
054026,000243: 23,3375 00006 6
054027,000244:
054028,000245: 23,3376 66374 AXT,2 SSP
054029,000246: 23,3377 00006 6
054030,000247: 23,3400 00052 S2
054031,000248: 23,3401 00002 2
054032,000249:
054033,000250: 23,3402 76720 AXISGEN2 XCHX,1 VLOAD*
054034,000251: 23,3403 00036 30D # X1=-6 X2=+6 X1=-6 X2=+4 X1=-6 X2=+2
054035,000252: 23,3404 00001 0,1
054036,000253:
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Page 1251
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054038,000255: 23,3405 62757 VXSC* PDVL* # J=(UA)(UB1) J=(UA)(UB2) J=(UA)(UB3)
054039,000256: 23,3406 75062 STARAD +6,2
054040,000257: 23,3407 00007 6,1
054041,000258: 23,3410 77757 VXSC*
054042,000259: 23,3411 75054 STARAD +12D,2
054043,000260: 23,3412 30031 STOVL* 24D # K=(VA)(VB1) J=(VA)(VB2) J=(VA)(VB3)
054044,000261: 23,3413 00015 12D,1
054045,000262:
054046,000263: 23,3414 53357 VXSC* VAD
054047,000264: 23,3415 75046 STARAD +18D,2 # L=(WA)(WB1) J=(WA)(WB2) J=(WA)(WB3)
054048,000265: 23,3416 76455 VAD VSL1
054049,000266: 23,3417 00031 24D
054050,000267: 23,3420 53520 XCHX,1 UNIT
054051,000268: 23,3421 00036 30D
054052,000269: 23,3422 06707 STORE XDC +18D,1 # XDC = L+J+K YDC = L+J+K ZDC = L+J+K
054053,000270:
054054,000271: 23,3423 77700 TIX,1
054055,000272: 23,3424 47425 AXISGEN3
054056,000273:
054057,000274: 23,3425 77704 AXISGEN3 TIX,2
054058,000275: 23,3426 47402 AXISGEN2
054059,000276:
054060,000277: 23,3427 77775 VLOAD
054061,000278: 23,3430 02665 XDC
054062,000279: 23,3431 26707 STOVL STARAD
054063,000280: 23,3432 02673 YDC
054064,000281: 23,3433 26715 STOVL STARAD +6
054065,000282: 23,3434 02701 ZDC
054066,000283: 23,3435 02723 STORE STARAD +12D
054067,000284:
054068,000285: 23,3436 77616 RVQ
054069,000286:
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Page 1252
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054071,000288: 23,3437 05520 26075 QTSN45 2DEC .1768
054072,000289:
054073,000290: 23,3441 05252 25253 .166... 2DEC .1666666667
054074,000291:
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Page 1253
Empty page
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054077,000294:
End of include-file INFLIGHT_ALIGNMENT_ROUTINES.agc. Parent file is MAIN.agc