Source Code
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These source-code files were obtained by digitally photographing
a Solarium 55 (Apollo 6) program listing from the American Computer Museum in
Bozeman, Montana. Photography was by Ron Burkey, with assistance from
museum curator George Keremedjiev and Montana
State University curator Kim Scott. The listing originally belonged to Eldon C. Hall,
who donated it to the museum. Volunteers then manually typed in the
source code or else modified similar pre-existing Colossus 249
(Apollo 9) source files to incorporate changes, although this transcription was
principally done by Jim Lawton and corrected by Ron Burkey.
Notations on the program listing read, in part:
YUL SYSTEM FOR AGC4: REVISION 0 OF PROGRAM SOLRUM55
BY NASA 1021108-021 DEC. 4, 1966
Note that the date is the date of the printout, not the date of the program revision.
Due to statements by Jay Sampson, the original contractor from AC Electronics
who created Solarium 54 (Apollo 4)
from the earlier Corona (AS-202 mission) program, it is believed that Solarium 54 and
Solarium 55 (Apollo 6) are actually identical programs. The change in numbering,
from 54 to 55, is believed to be for some administrative purpose. Thus, it is believed
that the source-code represented here is equally appropriate for both Apollo 4 and
Apollo 6 missions.
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008357,000002: ## Copyright: Public domain.
008358,000003: ## Filename: IMU_COMPENSATION_PACKAGE.agc
008359,000004: ## Purpose: Part of the source code for Solarium build 55. This
008360,000005: ## is for the Command Module's (CM) Apollo Guidance
008361,000006: ## Computer (AGC), for Apollo 6.
008362,000007: ## Assembler: yaYUL --block1
008363,000008: ## Contact: Jim Lawton <jim DOT lawton AT gmail DOT com>
008364,000009: ## Website: www.ibiblio.org/apollo/index.html
008365,000010: ## Page Scans: www.ibiblio.org/apollo/ScansForConversion/Solarium055/
008366,000011: ## Mod history: 2009-09-29 JL Created.
008367,000012: ## 2016-08-18 RSB Typos.
008368,000013: ## 2016-12-28 RSB Proofed comment text using octopus/ProoferComments,
008369,000014: ## and fixed errors found.
008370,000015:
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Page 214
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008372,000017:
008373,000018: # THE FOLLWOING ROUTINE IS DESIGNED TO COMPENSATE FOR PIPA BIAS AND SCALE FACTOR ERROR. ATTHE SAME TIME,
008374,000019: # IT ACCUMULATES GYRO TORQUE COMMANDS NECESSARY TO COMPENSATE FOR THE ASSOCIATED BIAS AND ACCELERATION-CAUSED GYRO
008375,000020: # DRIFTS. THIS ROUTINE EXPECTS TO FIND PIPA READINGS IN THE MAJOR PARTS OF DELV (DELVX, DELVY, DELVZ), WITH THE
008376,000021: # MINOR PARTS IRRELEVANT. OUTPUT FROM 1/PIPA IS DOUBLE PRECISION COMPENSATED DATA, THE MINOR PART OF WHICH USUALLY
008377,000022: # CONTAINS ALL THE COMPENSATION. 1/PIPA MUST BE CALLED AT LEAST EVERY 2.56 SECONDS, DUE TO SCALING CONSIDERATIONS.
008378,000023: # SPECIFICALLY, THE CORRECTION IS:
008379,000024:
008380,000025: # PIPA = PIPA (1 + SCALE FACTOR ERROR) - BIAS DELTAT
008381,000026: # C I
008382,000027:
008383,000028: # WHERE PIPA IS THE COMPENSATED DATA OBTAINED FROM THE SAMPLED PIPA .
008384,000029: # C I
008385,000030:
008386,000031:
008387,000032:
008388,000033: 14,7017 BANK 14
008389,000034: 14,7017 35502 1/PIPA CAF FOUR # LOOP TO PROCESS INPUT PIPA DATA.
008390,000035: 14,7020 50101 +1 TS BUF +2
008391,000036: 14,7021 20000 INDEX A
008392,000037: 14,7022 41001 CS DELVX # SAMPLED PIPA INTO MPAC
008393,000038: 14,7023 50115 TS MPAC
008394,000039: 14,7024 20101 INDEX BUF +2 # SUBTRACT BIAS TERM (LESS THAN 1 BIT).
008395,000040: 14,7025 40736 CS PIPABIAS
008396,000041: 14,7026 25777 EXTEND
008397,000042: 14,7027 40755 MP 1/PIPADT # SUPPLIED BY USER SCALED AT CS 2(-8),
008398,000043: 14,7030 50116 TS MPAC +1
008399,000044:
008400,000045: 14,7031 40115 CS MPAC # SHIFT THE PIPA READING LEFT THREE PLACES
008401,000046: 14,7032 50115 TS MPAC
008402,000047: 14,7033 25777 EXTEND # IN PREPARATION FOR SCALE FACTOR
008403,000048: 14,7034 44513 MP BIT4 # CORRECTION. IF IT OVERFLOWS, SHIFT THE
008404,000049: 14,7035 10000 CCS A # SCALE FACTOR ERROR RIGHT 11 PLACES
008405,000050: 14,7036 07216 TC PIPOVF # TAKING A LOSS IN PRECISION.
008406,000051:
008407,000052: 14,7037 07041 TC +2 # THE ABOVE HAPPENS AT DELTA VS OF OVER
008408,000053: 14,7040 07216 TC PIPOVF # 12 G-SECS., RESULTING IN A SCALE FACTOR
008409,000054: 14,7041 20101 INDEX BUF +2 # CORRECTION GOOD ONLY TO 60 PPM.
008410,000055: 14,7042 40737 CS PIPASCF
008411,000056: 14,7043 40000 COM
008412,000057: 14,7044 25777 EXTEND
008413,000058: 14,7045 40003 MP LP
008414,000059: 14,7046 60116 AD MPAC +1 # ADD TO BIAS CORRECTION.
008415,000060: 14,7047 20101 INDEX BUF +2
008416,000061: 14,7050 51002 TS DELVX +1 # AND MAYBE SKIP.
008417,000062: 14,7051 35501 CAF ZERO
008418,000063:
008419,000064: 14,7052 60115 AD MPAC
008420,000065: 14,7053 20101 INDEX BUF +2
008421,000066: 14,7054 51001 TS DELVX
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008423,000068:
008424,000069: 14,7055 10101 PIPJUMP CCS BUF +2 # LOOP TO PROCESS NEXT COMPONENT.
008425,000070: 14,7056 64335 AD NEG1
008426,000071: 14,7057 07020 TC 1/PIPA +1
008427,000072: 14,7060 00756 LGCOMP ADRES GCOMP
008428,000073:
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Page 216
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008430,000075:
008431,000076: # THE FOLLOWING ROUTINE COMPUTES THE GYRO TORQUES NECESSARY TO COMPENSATE FOR THE ACCELERATION-SENSITIVE
008432,000077: # DRIFTS DUE TO THE DATA JUST PROCESSED, AND SUMS THEM INTO THE GCOMP REGISTERS.
008433,000078:
008434,000079: 14,7061 50101 TS GCOMPSW # SET GYRO TORQUE INDICATOR TO ZERO.
008435,000080: 14,7062 50077 TS BUF # RELATIVE ADDRESS OF PRESENT COMPONENT.
008436,000081:
008437,000082: 14,7063 41001 CS DELVX # PROCESS X COMPONENT.
008438,000083: 14,7064 50115 TS MPAC
008439,000084: 14,7065 41002 CS DELVX +1
008440,000085: 14,7066 50116 TS MPAC +1
008441,000086: 14,7067 40747 CS ADIAX
008442,000087: 14,7070 07145 TC GCOMPSUB -1
008443,000088:
008444,000089: 14,7071 41003 CS DELVY
008445,000090: 14,7072 50115 TS MPAC
008446,000091: 14,7073 41004 CS DELVY +1
008447,000092: 14,7074 50116 TS MPAC +1
008448,000093: 14,7075 40752 CS ADSRAX
008449,000094: 14,7076 07146 TC GCOMPSUB
008450,000095:
008451,000096: 14,7077 40744 CS GBIASX # ADD IN BIAS DRIFTS.
008452,000097: 14,7100 07171 TC DRIFTSUB
008453,000098:
008454,000099: 14,7101 41003 CS DELVY # COMPUTE Y GYRO COMPENSATION.
008455,000100: 14,7102 50115 TS MPAC
008456,000101: 14,7103 41004 CS DELVY +1
008457,000102: 14,7104 50116 TS MPAC +1
008458,000103: 14,7105 40750 CS ADIAY
008459,000104: 14,7106 07145 TC GCOMPSUB -1
008460,000105:
008461,000106: 14,7107 41005 CS DELVZ
008462,000107: 14,7110 50115 TS MPAC
008463,000108: 14,7111 41006 CS DELVZ +1
008464,000109: 14,7112 50116 TS MPAC +1
008465,000110: 14,7113 40753 CS ADSRAY
008466,000111: 14,7114 07146 TC GCOMPSUB
008467,000112:
008468,000113: 14,7115 40745 CS GBIASY
008469,000114: 14,7116 07171 TC DRIFTSUB
008470,000115:
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008472,000117: 14,7117 41003 CS DELVY # CORRESPONDING PATTERN FOR Z GYRO.
008473,000118: 14,7120 50115 TS MPAC
008474,000119: 14,7121 41004 CS DELVY +1
008475,000120: 14,7122 50116 TS MPAC +1
008476,000121: 14,7123 40754 CS ADSRAZ
008477,000122: 14,7124 07145 TC GCOMPSUB -1
008478,000123:
008479,000124: 14,7125 41005 CS DELVZ
008480,000125: 14,7126 50115 TS MPAC
008481,000126: 14,7127 41006 CS DELVZ +1
008482,000127: 14,7130 50116 TS MPAC +1
008483,000128: 14,7131 40751 CS ADIAZ
008484,000129: 14,7132 07145 TC GCOMPSUB -1
008485,000130:
008486,000131: 14,7133 40746 CS GBIASZ
008487,000132: 14,7134 07171 TC DRIFTSUB
008488,000133:
008489,000134: 14,7135 10101 CCS GCOMPSW # NON-ZERO IF TIME TO PUT OUT COMPENSATION
008490,000135: 14,7136 07140 TC +2
008491,000136: 14,7137 05702 TC SWRETURN # TORQUES NOT BIG ENOUGH YET.
008492,000137:
008493,000138: 14,7140 20017 INHINT
008494,000139: 14,7141 32170 CAF PRIO35 # REQUEST COMPENSATION JOB
008495,000140: 14,7142 02052 TC NOVAC
008496,000141: 14,7143 31237 CADR 1/GYRO
008497,000142:
008498,000143: 14,7144 06020 TC MODEEXIT # RELINT AND RETURN TO SWRETURN.
008499,000144:
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008501,000146:
008502,000147: # SUBROUTINES USED TO ACCUMULATE GYRO COMPENSATION COMMANDS.
008503,000148:
008504,000149: 14,7145 40000 -1 COM # (ENTERS HERE TO RE-COMPLEMENT INPUT).
008505,000150: 14,7146 30116 GCOMPSUB XCH MPAC +1 # DOES DP BY SINGLE MULTIPLY WITH DP ADD
008506,000151: 14,7147 25777 EXTEND # TO STORAGE.
008507,000152: 14,7150 40116 MP MPAC +1
008508,000153: 14,7151 30116 XCH MPAC +1
008509,000154: 14,7152 25777 EXTEND
008510,000155: 14,7153 40115 MP MPAC
008511,000156: 14,7154 50034 TS OVCTR
008512,000157: 14,7155 30003 XCH LP
008513,000158: 14,7156 60116 AD MPAC +1 # (AND MAYBE INCREMENT OVCTR).
008514,000159:
008515,000160: 14,7157 20077 BIASCOMP INDEX BUF # BIAS COMPENSATION ENTERS HERE.
008516,000161: 14,7160 60757 AD GCOMP +1
008517,000162: 14,7161 20077 INDEX BUF
008518,000163: 14,7162 30757 XCH GCOMP +1
008519,000164: 14,7163 30034 XCH OVCTR
008520,000165: 14,7164 20077 INDEX BUF
008521,000166: 14,7165 60756 AD GCOMP
008522,000167: 14,7166 20077 INDEX BUF
008523,000168: 14,7167 50756 TS GCOMP
008524,000169:
008525,000170: 14,7170 00001 TC Q
008526,000171:
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008528,000173:
008529,000174: # SUBROUTINE WHICH ADDS IN GYRO BIAS DRIFT, TESTS TORQUE SIZE TO SEE IF COMMANDS SHOULD BE PUT OUT, AND
008530,000175: # ADVANCES GCOMP POINTER.
008531,000176:
008532,000177: 14,7171 30001 DRIFTSUB XCH Q
008533,000178: 14,7172 50100 TS BUF +1
008534,000179: 14,7173 30001 XCH Q
008535,000180: 14,7174 25777 EXTEND
008536,000181: 14,7175 40755 MP 1/PIPADT
008537,000182: 14,7176 25777 EXTEND # RESULT WAS IN GYRO PULSES X 2(+2).
008538,000183: 14,7177 45502 MP FOUR # RE-SCALE TO ADD INTO GCOMP REGISTER.
008539,000184: 14,7200 50034 TS OVCTR
008540,000185: 14,7201 30003 XCH LP # GO TO STANDARD INCREMENT ROUTINE.
008541,000186: 14,7202 07157 DRFTSUB2 TC BIASCOMP
008542,000187:
008543,000188: 14,7203 35503 CAF TWO # INCREMENT POINTER AND
008544,000189: 14,7204 60077 AD BUF
008545,000190: 14,7205 30077 XCH BUF # CHECK MAGNITUDE OF TORQUE COMMAND. IF
008546,000191: 14,7206 20000 INDEX A # SUFFICIENTLY LARGE, SET GCOMPSW PNZ TO
008547,000192: 14,7207 10756 CCS GCOMP # CALL FOR COMPENSATION JOB, 1/GYRO.
008548,000193: 14,7210 07212 TC +2 # GETS DABS OF COMMAND.
008549,000194: 14,7211 00100 TC BUF +1
008550,000195:
008551,000196: 14,7212 77260 MASK COMPCHK
008552,000197: 14,7213 10000 CCS A
008553,000198: 14,7214 50101 TS GCOMPSW
008554,000199: 14,7215 00100 TC BUF +1 # RETURN.
008555,000200:
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008557,000202:
008558,000203: # (1/PIPA COMES HERE IF PIPA COUNTER SHOWED A DELTA V OF OVER 12 G-SEC.)
008559,000204:
008560,000205: 14,7216 20101 PIPOVF INDEX BUF +2 # SHIFT THE SCALE FACTOR RIGHT 11 ON OVF.
008561,000206: 14,7217 40737 CS PIPASCF
008562,000207: 14,7220 40000 COM
008563,000208: 14,7221 25777 EXTEND
008564,000209: 14,7222 44513 MP BIT4
008565,000210: 14,7223 25777 EXTEND # FORM DP INCREMENT TO DELV IN THIS CASE.
008566,000211: 14,7224 40115 MP MPAC
008567,000212: 14,7225 50034 TS OVCTR
008568,000213:
008569,000214: 14,7226 30003 XCH LP
008570,000215: 14,7227 60116 AD MPAC +1 # MAYBE INCREMENTING OVCTR.
008571,000216: 14,7230 20101 INDEX BUF +2
008572,000217: 14,7231 31002 XCH DELVX +1 # NO SKIP SINCE OVCTR SET.
008573,000218: 14,7232 30034 XCH OVCTR
008574,000219: 14,7233 60115 AD MPAC
008575,000220: 14,7234 20101 INDEX BUF +2
008576,000221: 14,7235 31001 XCH DELVX
008577,000222: 14,7236 07055 TC PIPJUMP # JUMP ON LOOP COUNTER.
008578,000223:
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008580,000225:
008581,000226: # THE FOLLOWING JOB IS INITIATED BY 1/PIPA TO PUT OUT COMPENSATING GYRO TORQUE COMMANDS.
008582,000227:
008583,000228: 14,7237 34504 1/GYRO CAF BIT11 # IF MODE SWITCH IN PROGRESS, DONT PUT
008584,000229: 14,7240 70646 MASK FLAGWRD1 # OUT COMPENSATION THIS TIME.
008585,000230: 14,7241 10000 CCS A
008586,000231: 14,7242 02124 TC ENDOFJOB
008587,000232:
008588,000233: 14,7243 03416 TC FLAG1UP # SHOW IMU ACTIVITY
008589,000234: 14,7244 02000 OCT 02000 # FLAG TURNED OFF BY GYRO ROUTINES.
008590,000235:
008591,000236: 14,7245 37060 CAF LGCOMP # DISABLE THE T4RUPT CDU DRIVE THEMSELVES.
008592,000237: 14,7246 05654 TC BANKCALL
008593,000238: 14,7247 31347 CADR GYROSPNT # NO TWITCH (2+2-) ON ZERO INPUT.
008594,000239:
008595,000240: 14,7250 05654 TC BANKCALL
008596,000241: 14,7251 30331 CADR IMUSTALL
008597,000242: 14,7252 03066 TC CURTAINS
008598,000243:
008599,000244: 14,7253 35501 CAF ZERO # ZERO GCOMP REGSITERS SINCE COMMANDS HAVE
008600,000245: 14,7254 50756 TS GCOMP # BEEN PUT OUT.
008601,000246: 14,7255 50760 TS GCOMP +2
008602,000247: 14,7256 50762 TS GCOMP +4
008603,000248:
008604,000249: 14,7257 02124 TC ENDOFJOB
008605,000250:
008606,000251: 14,7260 77740 COMPCHK OCT -37 # COMMANDS MUST BE AT LEAST 32 PLS.
008607,000252:
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008609,000254:
008610,000255: # THE FOLLOWING ROUTINE SUPPLIES GYRO DRIFT COMPENSATION DURING THOSE PORTIONS OF A MISSION WHICH DO NOT
008611,000256: # USE PIPA DATA. THIS JOB IS CALLED EVERY 81.93 SECONDS (WHEN APPROPRIATE) BY THE IDLE TASK.
008612,000257:
008613,000258: 14,7261 40036 BIASONLY CS TIME1 # COMPUTE TIME DIFFERENCE (ALMOST ALWAYS
008614,000259: 14,7262 40000 COM # 81.93 SECS.).
008615,000260: 14,7263 30755 XCH OLDBT1
008616,000261: 14,7264 40000 COM
008617,000262: 14,7265 60755 AD OLDBT1
008618,000263: 14,7266 10000 BONLY2 CCS A # LASTBIAS ENTERS HERE.
008619,000264: 14,7267 64516 AD ONE
008620,000265: 14,7270 07275 TC BONLY3
008621,000266: 14,7271 07273 TC +2
008622,000267: 14,7272 02124 TC ENDOFJOB # MAY HAVE A COMPUTED DIFF = 0.
008623,000268:
008624,000269: 14,7273 40000 COM
008625,000270: 14,7274 64476 AD POSMAX
008626,000271:
008627,000272: 14,7275 25777 BONLY3 EXTEND # FORM DELTA-T AT 2(+8) CS.
008628,000273: 14,7276 44506 MP BIT9 # SHIFT RIGHT 6.
008629,000274: 14,7277 50115 TS MPAC
008630,000275: 14,7300 50106 TS TEM9
008631,000276: 14,7301 30003 XCH LP
008632,000277: 14,7302 50116 TS MPAC +1
008633,000278: 14,7303 50107 TS TEM10
008634,000279: 14,7304 35501 CAF ZERO
008635,000280: 14,7305 50101 TS GCOMPSW
008636,000281: 14,7306 50077 TS BUF
008637,000282:
008638,000283: 14,7307 40744 CS GBIASX # DO X, Y, AND THEN Z.
008639,000284: 14,7310 07331 TC FBIASSUB
008640,000285:
008641,000286: 14,7311 40106 CS TEM9 # RELOAD DT.
008642,000287: 14,7312 50115 TS MPAC
008643,000288: 14,7313 40107 CS TEM10
008644,000289: 14,7314 50116 TS MPAC +1
008645,000290: 14,7315 40745 CS GBIASY
008646,000291: 14,7316 07330 TC FBIASSUB -1
008647,000292:
008648,000293: 14,7317 40106 CS TEM9
008649,000294: 14,7320 50115 TS MPAC
008650,000295: 14,7321 40107 CS TEM10
008651,000296: 14,7322 50116 TS MPAC +1
008652,000297: 14,7323 40746 CS GBIASZ
008653,000298: 14,7324 07330 TC FBIASSUB -1
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008655,000300: 14,7325 10101 CCS GCOMPSW # PUT OUT COMPENSATION IF CALLED FOR.
008656,000301: 14,7326 07237 TC 1/GYRO
008657,000302: 14,7327 02124 TC ENDOFJOB
008658,000303:
008659,000304: 14,7330 40000 -1 COM
008660,000305: 14,7331 30001 FBIASSUB XCH Q
008661,000306: 14,7332 50100 TS BUF +1
008662,000307: 14,7333 35501 CAF ZERO
008663,000308: 14,7334 50117 TS MPAC +2
008664,000309: 14,7335 30001 XCH Q
008665,000310: 14,7336 05416 TC SHORTMP
008666,000311: 14,7337 30115 XCH MPAC
008667,000312: 14,7340 50034 TS OVCTR
008668,000313: 14,7341 30116 XCH MPAC +1
008669,000314: 14,7342 07202 TC DRFTSUB2 # RETURN TO CALLER VIA BUF +1.
008670,000315:
008671,000316: 14,7343 30755 LASTBIAS XCH OLDBT1 # COMES HERE FOR TRANSITION TO PIPA READ-
008672,000317: 14,7344 40000 COM # ING MODE. NEW VALUE OF 1/PIPADT ARRIVES
008673,000318: 14,7345 60115 AD MPAC # IN A WITH WITH TIME1 AT PIPA ZEROING IN
008674,000319: 14,7346 07266 TC BONLY2 # MPAC. EXITS VIA ENDOFJOB.
End of include-file IMU_COMPENSATION_PACKAGE.agc. Parent file is MAIN.agc