Source Code
![]() |
This source code is very close to the Apollo Guidance Computer software for the
Apollo 13 Lunar module. This revision of the Luminary 131 program is from December
of 1969, whereas there was a later revision in January of 1970, and still another
revision in February, which is the code that flew on the mission.
As far as this transcription is concerned, it was originally from a copy made in 1991 of
a printout from the collection of AGC developer Don Eyles for collector David Craig.
It was subsequently scanned by Gary Neff, reprocessed for online
presentation at the now-discontinued History of Recent Science and Technology (HRST) website
of MIT's Dibner Institute (the full-quality scans being discarded in the process),
and finally transcribed by Ron Burkey for the Virtual AGC Project. Although a
high-quality replacement scan for a completely illegible page was later provided by Gary
Neff, the reduced legibility of the reprocessed HRST posting nevertheless caused many
errors to be introduced into the transcription. Accordingly, a second scan of the same physical
printout was made in 2017 for the Virtual AGC Project's collection at the Internet Archive,
and used to correct the transcription errors. All of the scanned materials mentioned,
as well as other Luminary 131 related material, are available online.
Don Eyles apprently made additional hand-written notes in printout between 1991 and 2017,
so the two scans are not identical in that respect. The page-headings in the printout read, in part:GAP: ASSEMBLE REVISION 131 OF AGC PROGRAM LUMINARY BY NASA 2021112-091 17:53 DEC. 19, 1969Note that the date is the date the printout was made, not the date on which the program revision was released, although these happen to be very close together. |
020175,000002: ## Copyright: Public domain.
020176,000003: ## Filename: R60_62.agc
020177,000004: ## Purpose: A section of Luminary 1C, revision 131.
020178,000005: ## It is part of the source code for the Lunar Module's (LM)
020179,000006: ## Apollo Guidance Computer (AGC) for Apollo 13.
020180,000007: ## This file is intended to be a faithful transcription, except
020181,000008: ## that the code format has been changed to conform to the
020182,000009: ## requirements of the yaYUL assembler rather than the
020183,000010: ## original YUL assembler.
020184,000011: ## Reference: pp. 476-489
020185,000012: ## Contact: Ron Burkey <info@sandroid.org>.
020186,000013: ## Website: www.ibiblio.org/apollo/index.html
020187,000014: ## Mod history: 05/14/03 RSB. Began transcribing.
020188,000015: ## 05/14/05 RSB Corrected website reference above.
020189,000016: ## 2017-01-06 RSB Page numbers now agree with those on the
020190,000017: ## original harcopy, as opposed to the PDF page
020191,000018: ## numbers in 1701.pdf.
020192,000019: ## 2017-01-27 RSB Back-ported a comment-text fix identified in Luminary 69.
020193,000020: ## 2017-02-23 RSB Proofed comment text using octopus/ProoferComments.
020194,000021: ## 2017-02-28 RSB Fixed lingering typos.
020195,000022: ## 2017-03-09 RSB Comment text fixes noted in proofing Luminary 116.
020196,000023:
![]() |
Page 476 |
020198,000025: # MOD NO: 0 DATE: 1 MAY 1968
020199,000026: # MOD BY: DIGITAL DEVEL GROUP LOG SECTION R60,R62
020200,000027:
020201,000028: # FUNCTIONAL DESCRIPTION:
020202,000029:
020203,000030: # CALLED AS A GENERAL SUBROUTINE TO MANEUVER THE LM TO A SPECIFIED
020204,000031: # ATTITUDE.
020205,000032:
020206,000033: # 1. IF THE 3-AXIS FLAG IS NOT SET THE FINAL CDU ANGLES ARE
020207,000034: # CALCULATED (VECPOINT).
020208,000035:
020209,000036: # 2. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
020210,000037:
020211,000038: # 3. REQUEST FLASHING DISPLAY V50 N18 PLEASE PERFORM AUTO MANEUVER.
020212,000039:
020213,000040: # 4. IF PRIORITY DISPLAY FLAG IS SET DO A PHASECHANGE. THEN AWAIT
020214,000041: # ASTRONAUT RESPONSE.
020215,000042:
020216,000043: # 5. DISPLAY RESPONSE RETURNS:
020217,000044:
020218,000045: # A. ENTER - RESET 3-AXIS FLAG AND RETURN TO CLIENT.
020219,000046:
020220,000047: # B. TERMINATE - IF IN P00 GO TO STEP 5A. OTHERWISE CHECK IF R61 IS
020221,000048: # THE CALLING PROGRAM. IF IN R61 AN EXIT IS MADE TO GOTOV56. IF
020222,000049: # NOT IN R61 AN EXIT IS DONE VIA GOTOP00H.
020223,000050:
020224,000051: # C. PROCEED - CONTINUE WITH PROGRAM AT STEP 6.
020225,000052:
020226,000053: # 6. IF THE 3-AXIS FLAG IS NOT SET, THE FINAL CDU ANGLES ARE CALCULATED
020227,000054: # (VECPOINT).
020228,000055:
020229,000056: # 7. THE FDAI BALL ANGLES (NOUN 18) ARE CALCULATED (BALLANGS).
020230,000057:
020231,000058: # 8. IF THE G+N SWITCH IS NOT SET GO BACK TO STEP 3.
020232,000059: #
020233,000060: # 9. IF THE AUTO SWITCH IS NOT SET GO BACK TO STEP 3.
020234,000061:
020235,000062: # 10. NONFLASHING DISPLAY V06N18 (FDAI ANGLES).
020236,000063:
020237,000064: # 11. DO A PHASECHANGE.
020238,000065:
020239,000066: # 12. DO A MANEUVER CALCULATION AND ICDU DRIVE ROUTINE TO ACHIEVE FINAL
020240,000067: # GIMBAL ANGLES (GOMANUR).
020241,000068:
020242,000069: # 13. AT END OF MANEUVER GO TO STEP 3.
020243,000070:
020244,000071: # IF SATISFACTORY MANEUVER STEP 5A EXITS R60.
020245,000072: # FOR FURTHER ADJUSTMENT OF THE VEHICLE ATTITUDE ABOUT THE
020246,000073: # DESIRED VECTOR, THE ROUTINE MAY BE PERFORMED AGAIN STARTING AT
![]() |
Page 477 |
020248,000075: # STEP 5C.
020249,000076:
020250,000077: # CALLING SEQUENCE: TC BANKCALL
020251,000078: # CADR R60LEM
020252,000079:
020253,000080: # ERASABLE INITIALIZATION REQUIRED: SCAXIS, POINTVSM (FOR VECPOINT)
020254,000081: # 3AXISFLG.
020255,000082:
020256,000083: # SUBROUTINES CALLED: VECPOINT, BALLANGS, GOPERF2R, LINUS, GODSPER,
020257,000084: # GOMANUR, DOWNFLAG, PHASCHNG, UPFLAG
020258,000085:
020259,000086: # NORMAL EXIT MODES: CAE TEMPR60 (CALLERS RETURN ADDRESS)
020260,000087: # TC BANKJUMP
020261,000088:
020262,000089: # ALARMS: NONE
020263,000090:
020264,000091: # OUTPUT: NONE
020265,000092:
020266,000093: # DEBRIS: CPHI, CTHETA, CPSI, 3AXISFLG, TBASE2
020267,000094:
020268,000095: 34,2000 BANK 34
020269,000096: 26,2000 SETLOC MANUVER
020270,000097: 26,2000 BANK
020271,000098:
020272,000099: 26,2123 1163 EBANK= TEMPR60
020273,000100:
020274,000101: 26,2123 COUNT* $$/R06
020275,000102: 26,2123 04645 R60LEM TC MAKECADR
020276,000103: 26,2124 55163 TS TEMPR60
020277,000104:
020278,000105: 26,2125 34746 REDOMANN CAF 3AXISBIT
020279,000106: 26,2126 70101 MASK FLAGWRD5 # IS 3-AXIS FLAG SET
020280,000107: 26,2127 10000 CCS A
020281,000108: 26,2130 12136 TCF TOBALL # YES
020282,000109: 26,2131 06042 TC INTPRET
020283,000110: 26,2132 77624 CALL
020284,000111: 26,2133 56040 VECPOINT # TO COMPUTE FINAL ANGLES
020285,000112: 26,2134 00322 STORE CPHI # STORE FINAL ANGLES - CPHI, CTHETA, CPSI
020286,000113: 26,2135 77776 EXIT
020287,000114:
020288,000115: 26,2136 05504 TOBALL TC UPFLAG # INSURE THAT TOTAL ATTITUDE ERRORS ARE
020289,000116: 26,2137 00013 ADRES NEEDLFLG # DISPLAYED ON FDAI ERROR NEEDLES
020290,000117: 26,2140 05516 TC DOWNFLAG
020291,000118: 26,2141 00000 ADRES NEED2FLG
020292,000119: 26,2142 04616 TC BANKCALL
020293,000120: 26,2143 54272 CADR BALLANGS # TO CONVERT ANGLES TO FDAI
020294,000121: 26,2144 32260 TOBALLA CAF V06N18
020295,000122: 26,2145 04616 TC BANKCALL
![]() |
Page 478 |
020297,000124: 26,2146 20711 CADR GOPERF2R # DISPLAY PLEASE PERFORM AUTO MANEUVER
020298,000125: 26,2147 02246 TC R61TEST
020299,000126: 26,2150 02154 TC REDOMANC # PROCEED
020300,000127: 26,2151 02201 TC ENDMANU1 # ENTER I.E. FINISHED WITH R60
020301,000128: 26,2152 02205 TC CHKLINUS # TO CHECK FOR PRIORITY DISPLAYS
020302,000129: 26,2153 05155 TC ENDOFJOB
020303,000130:
020304,000131: 26,2154 34746 REDOMANC CAF 3AXISBIT
020305,000132: 26,2155 70101 MASK FLAGWRD5 # IS 3-AXIS FLAG SET
020306,000133: 26,2156 10000 CCS A
020307,000134: 26,2157 12165 TCF TOBALLC # YES
020308,000135: 26,2160 06042 TC INTPRET
020309,000136: 26,2161 77624 CALL
020310,000137: 26,2162 56040 VECPOINT # TO COMPUTE FINAL ANGLES
020311,000138: 26,2163 00322 STORE CPHI # STORE ANGLES
020312,000139: 26,2164 77776 EXIT
020313,000140:
020314,000141: 26,2165 04616 TOBALLC TC BANKCALL
020315,000142: 26,2166 54272 CADR BALLANGS # TO CONVERT ANGLES TO FDAI
020316,000143: 26,2167 02261 TC G+N,AUTO # CHECK AUTO MODE
020317,000144: 26,2170 10000 CCS A
020318,000145: 26,2171 12144 TCF TOBALLA # NOT AUTO, GO REREQUEST AUTO MANEUVER.
020319,000146:
020320,000147: 26,2172 32260 AUTOMANV CAF V06N18 # STATIC DISPLAY DURING AUTO MANEUVER
020321,000148: 26,2173 04616 TC BANKCALL # -
020322,000149: 26,2174 20452 CADR GODSPR # -
020323,000150: 26,2175 02205 TC CHKLINUS # TO CHECK FOR PRIORITY DISPLAYS
020324,000151:
020325,000152: 26,2176 04616 STARTMNV TC BANKCALL # PERFORM MANEUVER VIA KALCMANU
020326,000153: 26,2177 17741 CADR GOMANUR
020327,000154:
020328,000155: 26,2200 12144 ENDMANUV TCF TOBALLA # FINISHED MANEUVER.
020329,000156: 26,2201 05516 ENDMANU1 TC DOWNFLAG # RESET 3-AXIS FLAG
020330,000157: 26,2202 00124 ADRES 3AXISFLG
020331,000158: 26,2203 31163 CAE TEMPR60 # -
020332,000159: 26,2204 04640 TC BANKJUMP # -
020333,000160:
020334,000161: 26,2205 40100 CHKLINUS CS FLAGWRD4
020335,000162: 26,2206 74740 MASK PDSPFBIT # IS PRIORITY DISPLAY FLAG SET?
020336,000163: 26,2207 10000 CCS A # -
020337,000164: 26,2210 00002 TC Q # NO - EXIT
020338,000165: 26,2211 30002 CA Q
020339,000166: 26,2212 54156 TS MPAC +2 # SAVE RETURN
020340,000167: 26,2213 46250 CS THREE # OBTAIN LOCATION FOR RESTART
020341,000168: 26,2214 60133 AD BUF2 # HOLDS Q OF LAST DISPLAY
020342,000169: 26,2215 55054 TS TBASE2
020343,000170:
020344,000171: 26,2216 05353 TC PHASCHNG
020345,000172: 26,2217 00132 OCT 00132
![]() |
Page 479 |
020347,000174: 26,2220 34745 CAF BIT7
020348,000175: 26,2221 05464 TC LINUS # GO SET BITS FOR PRIORITY DISPLAY -
020349,000176: 26,2222 00156 TC MPAC +2
020350,000177:
020351,000178: 26,2223 37717 RELINUS CAF PRIO26 # RESTORE ORIGINAL PRIORITY
020352,000179: 26,2224 05146 TC PRIOCHNG
020353,000180:
020354,000181: 26,2225 34747 CAF TRACKBIT # DON'T CONTINUE R60 UNLESS TRACKFLAG ON.
020355,000182: 26,2226 70075 MASK FLAGWRD1
020356,000183: 26,2227 10000 CCS A
020357,000184: 26,2230 12243 TCF RER60
020358,000185:
020359,000186: 26,2231 34745 CAF RNDVZBIT # IS IT P20?
020360,000187: 26,2232 70074 MASK FLAGWRD0
020361,000188: 26,2233 10000 CCS A
020362,000189: 26,2234 02240 TC +4 # YES
020363,000190: 26,2235 05353 TC PHASCHNG # NO, MUST BE P25, SET 2.11 SPOT
020364,000191: 26,2236 40112 OCT 40112
020365,000192:
020366,000193: 26,2237 05155 TC ENDOFJOB
020367,000194:
020368,000195: 26,2240 05353 TC PHASCHNG # SET 2.7 SPOT FOR P20
020369,000196: 26,2241 40072 OCT 40072
020370,000197:
020371,000198: 26,2242 05155 TC ENDOFJOB
020372,000199:
020373,000200: 26,2243 05504 RER60 TC UPFLAG # SET PRIO DISPLAY FLAG AFTER RESTART
020374,000201: 26,2244 00077 ADRES PDSPFLAG
020375,000202:
020376,000203: 26,2245 01054 TC TBASE2
020377,000204:
020378,000205: 26,2246 31010 R61TEST CA MODREG # IF WE ARE IN P00 IT MUST BE V49 OR V89
020379,000206: 26,2247 00006 EXTEND
020380,000207: 26,2250 12201 BZF ENDMANU1 # THUS WE GO TO ENDEXT VIA USER
020381,000208:
020382,000209: 26,2251 30100 CA FLAGWRD4 # ARE WE IN R61 (P20 OR P25)
020383,000210: 26,2252 74740 MASK PDSPFBIT
020384,000211: 26,2253 00006 EXTEND
020385,000212: 26,2254 16001 BZF GOTOPOOH # NO
020386,000213: 26,2255 06025 TC GOTOV56 # YES
020387,000214:
020388,000215: 26,2256 20100 BIT14+7 OCT 20100 # -
020389,000216: 26,2257 00203 OCT203 OCT 203
020390,000217: 26,2260 01422 V06N18 VN 0618
020391,000218:
020392,000219: # SUBROUTINE TO CHECK FOR G+N CONTROL, AUTO STABILIZATION
020393,000220:
020394,000221: # RETURNS WITH C(A) = + IF NOT SET FOR G+N, AUTO
020395,000222: # RETURNS WITH C(A) = +0 IF SWITCHES ARE SET
020396,000223:
020397,000224: 26,2261 00006 G+N,AUTO EXTEND
![]() |
Page 480 |
020399,000226: 26,2262 00030 READ CHAN30
020400,000227: 26,2263 74742 MASK BIT10
020401,000228: 26,2264 10000 CCS A
020402,000229: 26,2265 00002 TC Q # NOT IN G+N C(A) = +
020403,000230: 26,2266 00006 ISITAUTO EXTEND # CHECK FOR AUTO MODE
020404,000231: 26,2267 00031 READ CHAN31
020405,000232: 26,2270 74736 MASK BIT14
020406,000233: 26,2271 00002 TC Q # (+) = NOT IN AUTO, (+0) = AOK
020407,000234:
![]() |
Page 481 |
020409,000236: # PROGRAM DESCRIPTION BALLANGS
020410,000237: # MOD NO. LOG SECTION R60,R62
020411,000238: # WRITTEN BY RAMA M. AIYAWAR
020412,000239:
020413,000240: # FUNCTIONAL DESCRIPTION
020414,000241:
020415,000242: # COMPUTES LM FDAI BALL DISPLAY ANGLES
020416,000243:
020417,000244: # CALLING SEQUENCE
020418,000245:
020419,000246: # TC BALLANGS
020420,000247:
020421,000248: # NORMAL EXIT MODE
020422,000249:
020423,000250: # TC BALLEXIT (SAVED Q)
020424,000251:
020425,000252: # ALARM OR EXIT MODE NIL
020426,000253:
020427,000254: # SUBROUTINES CALLED
020428,000255:
020429,000256: # CD*TR*G
020430,000257: # ARCTAN
020431,000258:
020432,000259: # INPUT
020433,000260:
020434,000261: # CPHI,CTHETA,CPSI ARE THE ANGLES CORRESPONDING TO AOG, AIG, AMG. THEY ARE
020435,000262: # SP,2S COMPLIMENT SCALED TO HALF REVOLUTION.
020436,000263:
020437,000264: # OUTPUT
020438,000265:
020439,000266: # FDAIX, FDAIY, FDAIZ ARE THE REQUIRED BALL ANGLES SCALED TO HALF REVOLUTION
020440,000267: # SP,2S COMPLIMENT.
020441,000268:
020442,000269: # THESE ANGLES WILL BE DISPLAYED AS DEGREES AND HUNDREDTHS, IN THE ORDER ROLL, PITCH, YAW, USING NOUNS 18 & 19.
020443,000270:
020444,000271: # ERASABLE INITIALIZATION REQUIRED
020445,000272:
020446,000273: # CPHI, CTHETA, CPSI EACH A SP REGISTER
020447,000274:
020448,000275: # DEBRIS
020449,000276:
020450,000277: # A,L,Q,MPAC,SINCDU,COSCDU,PUSHLIST,BALLEXIT
020451,000278:
020452,000279: # NOMENCLATURE: CPHI, CTHETA, & CPSI REPRESENT THE OUTER, INNER, & MIDDLE GIMBAL ANGLES, RESPECTIVELY; OR
020453,000280: # EQUIVALENTLY, CDUX, CDUY, & CDUZ.
020454,000281:
020455,000282: # NOTE: ARCTAN CHECKS FOR OVERFLOW AND SHOULD BE ABLE TO HANDLE ANY SINGULARITIES.
020456,000283:
020457,000284: 26,2000 SETLOC BAWLANGS
020458,000285: 26,2000 BANK
020459,000286:
020460,000287: 26,2272 COUNT* $$/BALL
020461,000288: 26,2272 04645 BALLANGS TC MAKECADR
020462,000289: 26,2273 55337 TS BALLEXIT
020463,000290: 26,2274 30321 CA CPHI
![]() |
Page 482 |
020465,000292: 26,2275 54771 TS CDUSPOT +4
020466,000293: 26,2276 30322 CA CTHETA
020467,000294: 26,2277 54765 TS CDUSPOT
020468,000295: 26,2300 30323 CA CPSI
020469,000296: 26,2301 54767 TS CDUSPOT +2
020470,000297:
020471,000298: 26,2302 06042 TC INTPRET
020472,000299: 26,2303 45001 SETPD CALL
020473,000300: 26,2304 00001 0D
020474,000301: 26,2305 47545 CD*TR*G
020475,000302:
020476,000303: 26,2306 41345 DLOAD DMP
020477,000304: 26,2307 00742 SINCDUX # SIN (OGA)
020478,000305: 26,2310 00746 COSCDUZ # COS (MGA)
020479,000306:
020480,000307: 26,2311 57552 SL1 DCOMP # SCALE
020481,000308: 26,2312 65336 ARCSIN PDDL # YAW = ARCSIN(-SXCZ) INTO 0 PD
020482,000309: 26,2313 00740 SINCDUZ
020483,000310: 26,2314 14023 STODL SINTH # (SINTH = 18D IN PD)
020484,000311: 26,2315 00746 COSCDUZ
020485,000312: 26,2316 72405 DMP SL1 # RESCALE
020486,000313: 26,2317 00750 COSCDUX
020487,000314: 26,2320 34021 STCALL COSTH # (COSTH = 16D IN PD)
020488,000315: 26,2321 26506 ARCTAN
020489,000316: 26,2322 41325 PDDL DMP # ROLL = ARCTAN(SZ/CZCX) INTO 2 PD
020490,000317: 26,2323 00740 SINCDUZ
020491,000318: 26,2324 00742 SINCDUX
020492,000319: 26,2325 41512 SL2 PUSH # SXSZ INTO 4 PD
020493,000320: 26,2326 65205 DMP PDDL # SXSZCY INTO 4 PD
020494,000321: 26,2327 00744 COSCDUY
020495,000322: 26,2330 65205 DMP PDDL # SXSZSY INTO 6 PD
020496,000323: 26,2331 00736 SINCDUY
020497,000324: 26,2332 00750 COSCDUX
020498,000325: 26,2333 72405 DMP SL1 # CXCY
020499,000326: 26,2334 00744 COSCDUY
020500,000327: 26,2335 45425 DSU STADR # PULL UP FROM 6 PD
020501,000328: 26,2336 63756 STODL COSTH # COSTH = CXCY - SXSZSY
020502,000329: 26,2337 00736 SINCDUY
020503,000330: 26,2340 72405 DMP SL1
020504,000331: 26,2341 00750 COSCDUX # CXSY
020505,000332: 26,2342 45415 DAD STADR # PULL UP FROM 4 PD
020506,000333: 26,2343 43754 STCALL SINTH # SINTH = CXSY + SXSZCY
020507,000334: 26,2344 26506 ARCTAN # RETURNS WITH D(MPAC) = PITCH
020508,000335: 26,2345 55525 PDDL VDEF # PITCH INTO 2 PD, ROLL INTO MPAC FROM 2PD
020509,000336: 26,2346 77634 RTB # VDEF MAKES V(MPAC) = ROLL, PITCH, YAW
020510,000337: 26,2347 21621 V1STO2S
020511,000338: 26,2350 02345 STORE FDAIX # MODE IS TP
020512,000339: 26,2351 77776 EXIT
020513,000340:
020514,000341: 26,2352 31337 ENDBALL CA BALLEXIT
020515,000342:
![]() |
Page 483 |
020517,000344: 26,2353 04640 TC BANKJUMP
020518,000345:
![]() |
Page 484 |
020520,000347: # PROGRAM DESCRIPTION - VECPOINT
020521,000348:
020522,000349: # THIS INTERPRETIVE SUBROUTINE MAY BE USED TO POINT A SPACECRAFT AXIS IN A DESIRED DIRECTION. THE AXIS
020523,000350: # TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN SUCCESSIVE LOCATIONS OF ERASABLE MEMORY
020524,000351: # BEGINNING WITH THE LOCATION CALLED SCAXIS. THE COMPONENTS OF THIS VECTOR ARE GIVEN IN SPACECRAFT COORDINATES.
020525,000352: # THE DIRECTION IN WHICH THIS AXIS IS TO BE POINTED MUST APPEAR AS A HALF UNIT DOUBLE PRECISION VECTOR IN
020526,000353: # SUCCESSIVE LOCATIONS OF ERASABLE MEMORY BEGINNING WITH THE ADDRESS CALLED POINTVSM. THE COMPONENTS OF THIS
020527,000354: # VECTOR ARE GIVEN IN STABLE MEMBER COORDINATES. WITH THIS INFORMATION VECPOINT COMPUTES A SET OF THREE GIMBAL
020528,000355: # ANGLES (2S COMPLEMENT) CORESPONDING TO THE CROSS-PRODUCT ROTATION BETWEEN SCAXIS AND POINTVSM AND STORES THEM
020529,000356: # IN T(MPAC) BEFORE RETURNING TO THE CALLER.
020530,000357:
020531,000358: # THIS ROTATION, HOWEVER, MAY BRING THE S/C INTO GIMBAL LOCK. WHEN POINTING A VECTOR IN THE Y-Z PLANE,
020532,000359: # THE TRANSPONDER AXIS, OR THE AOT FOR THE LEM, THE PROGRAM WILL CORRECT THIS PROBLEM BY ROTATING THE CROSS-
020533,000360: # PRODUCT ATTITUDE ABOUT POINTVSM BY A FIXED AMOUNT SUFFICIENT TO ROTATE THE DESIRED S/C ATTITUDE OUT OF GIMBAL
020534,000361: # LOCK. IF THE AXIS TO BE POINTED IS MORE THAN 40.6 DEGREES BUT LESS THAN 60.5 DEG FROM THE +X (OR -X) AXIS,
020535,000362: # THE ADDITIONAL ROTATION TO AVOID GIMAL LOCK IS 35 DEGREES. IF THE AXIS IS MORE THAN 60.5 DEGEES FROM +X (OR -X)
020536,000363: # THE ADDITIONAL ROTATION IS 35 DEGREES. THE GIMBAL ANGLES CORRESPONDING TO THIS ATTITUDE ARE THEN COMPUTED AND
020537,000364: # STORED AS 2S COMPLIMENT ANGLES IN T(MPAC) BEFORE RETURNING TO THE CALLER.
020538,000365:
020539,000366: # WHEN POINTING THE X-AXIS, OR THE THRUST VECTOR, OR ANY VECTOR WITHIN 40.6 DEG OF THE X-AXIS, VECPOINT
020540,000367: # CANNOT CORRECT FOR A CROSS-PRODUCT ROTATION INTO GIMBAL LOCK. IN THIS CASE A PLATFORM REALIGNMENT WOULD BE
020541,000368: # REQUIRED TO POINT THE VECTOR IN THE DESIRED DIRECTION. AT PRESENT NO INDICATION IS GIVEN FOR THIS SITUATION
020542,000369: # EXCEPT THAT THE FINAL MIDDLE GIMBAL ANGLE IN MPAC +2 IS GREATER THAN 59 DEGREES.
020543,000370:
020544,000371: # CALLING SEQUENCE -
020545,000372:
020546,000373: # 1) LOAD SCAXIS, POINTVSM
020547,000374: # 2) CALL
020548,000375: # VECPOINT
020549,000376:
020550,000377: # RETURNS WITH
020551,000378:
020552,000379: # 1) DESIRED OUTER GIMBAL ANGLE IN MPAC
020553,000380: # 2) DESIRED INNER GIMBAL ANGLE IN MPAC +1
020554,000381: # 3) DESIRED MIDDLE GIMBAL ANGLE IN MPAC +2
020555,000382:
020556,000383: # ERASABLES USED -
020557,000384:
020558,000385: # 1) SCAXIS 6
020559,000386: # 2) POINTVSM 6
020560,000387: # 3) MIS 18
020561,000388: # 4) DEL 18
020562,000389: # 5) COF 6
020563,000390: # 6) VECQTEMP 1
020564,000391: # 7) ALL OF VAC AREA 43
020565,000392:
020566,000393: # TOTAL 99
020567,000394:
020568,000395: 27,2000 SETLOC VECPT
020569,000396: 27,2000 BANK
![]() |
Page 485 |
020571,000398: 27,2032 COUNT* $$/VECPT
020572,000399:
020573,000400: 27,2032 E6,1675 EBANK= BCDU
020574,000401:
020575,000402: 27,2032 40020 VECPNT1 STQ BOV # THIS ENTRY USES DESIRED CDUS
020576,000403: 27,2033 03324 VECQTEMP # NOT PRESENT - ENTER WITH CDUD'S IN MPAC
020577,000404: 27,2034 56035 VECPNT2
020578,000405: 27,2035 52164 VECPNT2 AXC,2 GOTO
020579,000406: 27,2036 03245 MIS
020580,000407: 27,2037 56046 STORANG
020581,000408: 27,2040 40020 VECPOINT STQ BOV # SAVE RETURN ADDRESS
020582,000409: 27,2041 03324 VECQTEMP
020583,000410: 27,2042 56043 VECLEAR # AND CLEAR OVFIND
020584,000411: 27,2043 47164 VECLEAR AXC,2 RTB
020585,000412: 27,2044 03245 MIS # READ THE PRESENT CDU ANGLES AND
020586,000413: 27,2045 44403 READCDUK # STORE THEM IN PD25, 26, 27
020587,000414: 27,2046 34032 STORANG STCALL 25D
020588,000415: 27,2047 44410 CDUTODCM # S/C AXES TO STABLE MEMBER AXES (MIS)
020589,000416: 27,2050 61375 VLOAD VXM
020590,000417: 27,2051 03773 POINTVSM # RESOLVE THE POINTING DIRECTION VF INTO
020591,000418: 27,2052 03246 MIS # INITIAL S/C AXES (VF = POINTVSM)
020592,000419: 27,2053 77656 UNIT
020593,000420: 27,2054 00035 STORE 28D
020594,000421: # PD 28 29 30 31 32 33
020595,000422: 27,2055 53435 VXV UNIT # TAKE THE CROSS PRODUCT VF X VI
020596,000423: 27,2056 03765 SCAXIS # WHERE VI = SCAXIS
020597,000424: 27,2057 57400 BOV VCOMP
020598,000425: 27,2060 56170 PICKAXIS
020599,000426: 27,2061 17270 STODL COF # CHECK MAGNITUDE
020600,000427: 27,2062 00045 36D # OF CROSS PRODUCT
020601,000428: 27,2063 50025 DSU BMN # VECTOR, IF LESS
020602,000429: 27,2064 14415 DPB-14 # THAN B-14 ASSUME
020603,000430: 27,2065 56170 PICKAXIS # UNIT OPERATION
020604,000431: 27,2066 50375 VLOAD DOT # INVALID.
020605,000432: 27,2067 03765 SCAXIS
020606,000433: 27,2070 00035 28D
020607,000434: 27,2071 65552 SL1 ARCCOS
020608,000435: 27,2072 77624 COMPMATX CALL # NOW COMPUTE THE TRANSFORMATION FROM
020609,000436: 27,2073 44527 DELCOMP # FINAL S/C AXES TO INITIAL S/C AXES MFI
020610,000437: 27,2074 75160 AXC,1 AXC,2
020611,000438: 27,2075 03245 MIS # COMPUTE THE TRANSFORMATION FROM FINAL
020612,000439: 27,2076 02230 KEL # S/C AXES TO STABLE MEMBER AXES
020613,000440: 27,2077 77624 CALL # MFS = MIS MFI
020614,000441: 27,2100 44312 MXM3 # (IN PD LIST)
020615,000442:
020616,000443: 27,2101 51545 DLOAD ABS
020617,000444: 27,2102 00007 6 # MFS6 = SIN(CPSI) $2
020618,000445: 27,2103 50025 DSU BMN
020619,000446: 27,2104 14402 SINGIMLC # = SIN(59 DEGS) $2
020620,000447: 27,2105 56160 FINDGIMB # /CPSI/ LESS THAN 59 DEGS
![]() |
Page 486 |
020622,000449: # I.E. DESIRED ATTITUDE NOT IN GIMBAL LOCK
020623,000450:
020624,000451: 27,2106 51545 DLOAD ABS # CHECK TO SEE IF WE ARE POINTING
020625,000452: 27,2107 03765 SCAXIS # THE THRUST AXIS
020626,000453: 27,2110 51025 DSU BPL
020627,000454: 27,2111 14404 SINVEC1 # SIN 49.4 DEGS $2
020628,000455: 27,2112 56160 FINDGIMB # IF SO, WE ARE TRYING TO POINT IT INTO
020629,000456: 27,2113 77775 VLOAD # GIMBAL LOCK, ABORT COULD GO HERE
020630,000457: 27,2114 77626 STADR
020631,000458: 27,2115 50515 STOVL MIS +12D
020632,000459: 27,2116 77626 STADR # STORE MFS (IN PD LIST) IN MIS
020633,000460: 27,2117 50523 STOVL MIS +6
020634,000461: 27,2120 77626 STADR
020635,000462: 27,2121 50531 STOVL MIS
020636,000463: 27,2122 03254 MIS +6 # INNER GIMBAL AXIS IN FINAL S/C AXES
020637,000464: 27,2123 57444 BPL VCOMP # LOCATE THE IG AXIS DIRECTION CLOSEST TO
020638,000465: 27,2124 56125 IGSAMEX # FINAL X S/C AXIS
020639,000466:
020640,000467: 27,2125 50035 IGSAMEX VXV BMN # FIND THE SHORTEST WAY OF ROTATING THE
020641,000468: 27,2126 03765 SCAXIS # S/C OUT OF GIMBAL LOCK BY A ROTATION
020642,000469: 27,2127 56134 U=SCAXIS # ABOUT +- SCAXIS, I.E. IF (IG (SGN MFS3)
020643,000470: # X SCAXIS . XF) LESS THAN 0, U = SCAXIS
020644,000471: # OTHERWISE U = -SCAXIS
020645,000472:
020646,000473: 27,2130 57575 VLOAD VCOMP
020647,000474: 27,2131 03765 SCAXIS
020648,000475: 27,2132 37270 STCALL COF # ROTATE ABOUT -SCAXIS
020649,000476: 27,2133 56137 CHEKAXIS
020650,000477: 27,2134 77775 U=SCAXIS VLOAD
020651,000478: 27,2135 03765 SCAXIS
020652,000479: 27,2136 03270 STORE COF # ROTATE ABOUT + SCAXIS
020653,000480: 27,2137 51545 CHEKAXIS DLOAD ABS
020654,000481: 27,2140 03765 SCAXIS # SEE IF WE ARE POINTING THE AOT
020655,000482: 27,2141 51025 DSU BPL
020656,000483: 27,2142 14406 SINVEC2 # SIN 29.5 DEGS $2
020657,000484: 27,2143 56147 PICKANG1 # IF SO, ROTATE 50 DEGS ABOUT +- SCAXIS
020658,000485: 27,2144 52145 DLOAD GOTO # IF NOT, MUST BE POINTING THE TRANSPONDER
020659,000486: 27,2145 14412 VECANG2 # OR SOME VECTOR IN THE Y, OR Z PLANE
020660,000487: 27,2146 56151 COMPMFSN # IN THIS CASE ROTATE 35 DEGS TO GET OUT
020661,000488: # OF GIMBAL LOCK (VECANG2 $360)
020662,000489: 27,2147 77745 PICKANG1 DLOAD
020663,000490: 27,2150 14410 VECANG1 # = 50 DEGS $ 360
020664,000491: 27,2151 77624 COMPMFSN CALL
020665,000492: 27,2152 44527 DELCOMP # COMPUTE THE ROTATION ABOUT SCAXIS TO
020666,000493: 27,2153 75160 AXC,1 AXC,2 # BRING MFS OUT OF GIMBAL LOCK
020667,000494: 27,2154 03245 MIS
020668,000495: 27,2155 02230 KEL
020669,000496: 27,2156 77624 CALL # COMPUTE THE NEW TRANSFORMATION FROM
020670,000497: 27,2157 44312 MXM3 # DESIRED S/C AXES TO STABLE MEMBER AXES
020671,000498: # WHICH WILL ALIGN VI WITH VF AND AVOID
![]() |
Page 487 |
020673,000500: # GIMBAL LOCK
020674,000501: 27,2160 45160 FINDGIMB AXC,1 CALL
020675,000502: 27,2161 00000 0 # EXTRACT THE COMMANDED CDU ANGLES FROM
020676,000503: 27,2162 44654 DCMTOCDU # THIS MATRIX
020677,000504: 27,2163 40234 RTB SETPD
020678,000505: 27,2164 21621 V1STO2S # CONVERT TO 2:S COMPLEMENT
020679,000506: 27,2165 00001 0
020680,000507: 27,2166 77650 GOTO
020681,000508: 27,2167 03324 VECQTEMP # RETURN TO CALLER
020682,000509:
020683,000510: 27,2170 50375 PICKAXIS VLOAD DOT # IF VF X VI = 0, FIND VF . VI
020684,000511: 27,2171 00035 28D
020685,000512: 27,2172 03765 SCAXIS
020686,000513: 27,2173 72240 BMN TLOAD
020687,000514: 27,2174 54354 ROT180
020688,000515: 27,2175 00032 25D
020689,000516: 27,2176 77650 GOTO # IF VF = VI, CDU DESIRED = PRESENT CDU
020690,000517: 27,2177 03324 VECQTEMP # PRESENT CDU ANGLES
020691,000518:
020692,000519: 35,2000 BANK 35
020693,000520: 26,2000 SETLOC MANUVER1
020694,000521: 26,2000 BANK
020695,000522: 26,2354 47375 ROT180 VLOAD VXV # IF VF, VI ANTIPARALLEL, 108 DEG ROTATION
020696,000523: 26,2355 03254 MIS +6 # IS REQUIRED. Y STABLE MEMBER AXIS IN
020697,000524: 26,2356 06522 HIDPHALF # INITIAL S/C AXES.
020698,000525: 26,2357 47256 UNIT VXV # FIND Y(SM) X X(I)
020699,000526: 26,2360 03765 SCAXIS # FIND UNIT(VI X UNIT(Y(SM) X X(I)))
020700,000527: 26,2361 40056 UNIT BOV # I.E. PICK A VECTOR IN THE PLANE OF X(I),
020701,000528: 26,2362 54376 PICKX # Y(SM) PERPENDICULAR TO VI
020702,000529: 26,2363 17270 STODL COF
020703,000530: 26,2364 00045 36D # CHECK MAGNITUDE
020704,000531: 26,2365 50025 DSU BMN # OF THIS VECTOR.
020705,000532: 26,2366 14415 DPB-14 # IF LESS THAN B-14,
020706,000533: 26,2367 54376 PICKX # PICK X-AXIS.
020707,000534: 26,2370 77775 VLOAD
020708,000535: 26,2371 03270 COF
020709,000536: 26,2372 17270 XROT STODL COF
020710,000537: 26,2373 06522 HIDPHALF
020711,000538: 26,2374 77650 GOTO
020712,000539: 26,2375 56072 COMPMATX
020713,000540: 26,2376 52175 PICKX VLOAD GOTO # PICK THE XAXIS IN THIS CASE
020714,000541: 26,2377 06522 HIDPHALF
020715,000542: 26,2400 54372 XROT
020716,000543: 26,2401 15555 35172 SINGIMLC 2DEC .4285836003 # = SIN(59) $2
020717,000544: 26,2403 14113 36326 SINVEC1 2DEC .3796356537 # = SIN(49.4) $2
020718,000545: 26,2405 07701 35703 SINVEC2 2DEC .2462117800 # = SIN(29.5) $2
020719,000546: 26,2407 04343 21616 VECANG1 2DEC .1388888889 # = 50 DEGREES $360
![]() |
Page 488 |
020721,000548: 26,2411 03070 34344 VECANG2 2DEC .09722222222 # = 35 DEGREES $360
020722,000549:
020723,000550: 26,2413 00000 1BITDP OCT 0 # KEEP THIS BEFORE DPB(-14) *********
020724,000551: 26,2414 00001 DPB-14 OCT 00001
020725,000552: 26,2415 00000 OCT 00000
020726,000553:
![]() |
Page 489 |
020728,000555: # ROUTINE FOR INITIATING AUTOMATIC MANEUVER VIA KEYBOARD (V49)
020729,000556:
020730,000557: 34,2000 BANK 34
020731,000558: 23,2000 SETLOC R62
020732,000559: 23,2000 BANK
020733,000560: 23,2103 E6,1675 EBANK= BCDU
020734,000561:
020735,000562: 23,2103 COUNT* $$/R62
020736,000563:
020737,000564: 23,2103 23,2103 R62DISP EQUALS R62FLASH
020738,000565:
020739,000566: 23,2103 35010 R62FLASH CAF V06N22 # FLASH V06N22 AND
020740,000567: 23,2104 04616 TC BANKCALL # ICDU ANGLES
020741,000568: 23,2105 20477 CADR GOFLASH
020742,000569: 23,2106 15472 TCF ENDEXT # TERMINATE
020743,000570: 23,2107 12111 TCF GOMOVE # PROCEED
020744,000571: 23,2110 12103 TCF R62FLASH # ENTER
020745,000572:
020746,000573: # ASTRONAUT MAY LOAD NEW ICDUS AT THIS
020747,000574: # POINT
020748,000575: 23,2111 05504 GOMOVE TC UPFLAG # SET FOR 3-AXIS MANEUVER
020749,000576: 23,2112 00124 ADRES 3AXISFLG
020750,000577:
020751,000578: 23,2113 04616 TC BANKCALL
020752,000579: 23,2114 54123 CADR R60LEM
020753,000580: 23,2115 15472 TCF ENDEXT # END R62
020754,000581:
End of include-file R60,R62.agc. Parent file is MAIN.agc