623 lines
17 KiB
Plaintext
623 lines
17 KiB
Plaintext
# Copyright: Public domain.
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# Filename: TRIM_GIMBAL_CNTROL_SYSTEM.agc
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# Purpose: Part of the source code for Luminary 1A build 099.
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# It is part of the source code for the Lunar Module's (LM)
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# Apollo Guidance Computer (AGC), for Apollo 11.
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# Assembler: yaYUL
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# Contact: Ron Burkey <info@sandroid.org>.
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# Website: www.ibiblio.org/apollo.
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# Pages: 1472-1485
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# Mod history: 2009-05-27 RSB Adapted from the corresponding
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# Luminary131 file, using page
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# images from Luminary 1A.
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#
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# This source code has been transcribed or otherwise adapted from
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# digitized images of a hardcopy from the MIT Museum. The digitization
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# was performed by Paul Fjeld, and arranged for by Deborah Douglas of
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# the Museum. Many thanks to both. The images (with suitable reduction
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# in storage size and consequent reduction in image quality as well) are
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# available online at www.ibiblio.org/apollo. If for some reason you
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# find that the images are illegible, contact me at info@sandroid.org
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# about getting access to the (much) higher-quality images which Paul
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# actually created.
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#
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# Notations on the hardcopy document read, in part:
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#
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# Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
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# 16:27 JULY 14, 1969
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# Page 1472
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BANK 21
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EBANK= QDIFF
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SETLOC DAPS4
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BANK
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COUNT* $$/DAPGT
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# CONTROL REACHES THIS POINT UNDER EITHER OF THE FOLLOWING TWO CONDITIONS ONCE THE DESCENT ENGINE AND THE DIGITAL
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# AUTOPILOT ARE BOTH ON:
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# A) THE TRIM GIMBAL CONTROL LAW WAS ON DURING THE PREVIOUS Q,R-AXIS TIME5 INTERRUPT (OR THE DAPIDLER
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# INITIALIZATION WAS SET FOR TRIM GIMBAL CONTROL AND THIS IS THE FIRST PASS), OR
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# B) THE Q,R-AXES RCS AUTOPILOT DETERMINED THAT THE VEHICLE WAS ENTERING (OR HAD JUST ENTERED) A COAST
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# ZONE WITH A SMALL OFFSET ANGULAR ACCELERATION.
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# GTS IS THE ENTRY TO THE GIMBAL TRIM SYSTEM FOR CONTROLLING ATTITUDE ERRORS AND RATES AS WELL AS ACCELERATIONS.
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GTS CAF NEGONE # MAKE THE NEXT PASS THROUGH THE DAP BE
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TS COTROLER # THROUGH RCS CONTROL,
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CAF FOUR # AND ENSURE THAT IT IS NOT A SKIP.
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TS SKIPU
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TS SKIPV
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CAF TWO
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TS INGTS # SET INDICATOR OF GTS CONTROL POSITIVE.
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TS QGIMTIMR # SET TIMERS TO 200 MSEC TO AVOID BOTH
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TS RGIMTIMR # RUNAWAY AND INTERFERENCE BY NULLING.
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# THE DRIVE SETTING ALGORITHM
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#
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# DEL = SGN(OMEGA + ALPHA*ABS(ALPHA)/(2*K))
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# 2 1/2 2 3/2
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# NEGUSUM = ERROR*K + ALPHA*(DEL*OMEGA + ALPHA /(3*K)) + DEL*K (DEL*OMEGA + ALPHA /(2*K))
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#
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# DRIVE = -SGN(NEGUSUM)
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CA SR # SAVE THE SR. SHIFT IT LEFT TO CORRECT
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AD A # FOR THE RIGHT SHIFT DUE TO EDITING.
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TS SAVESR
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GTSGO+DN CAF TWO # SET INDEXER FOR R-AXIS CALCULATIONS.
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TCF GOQTRIMG +1
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GOQTRIMG CAF ZERO # SET INDEXER FOR Q-AXIS CALCULATIONS
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TS QRCNTR
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# Page 1473
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# RSB 2009 ---------------------------------------------------------------------
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# Everything between this line and the similar line below was simply filled-in
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# as-is from Luminary 131, and then verified to assemble to the proper binary
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# values. This area is blank on the Luminary 099 print-out, as if the
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# printer ribbon had run out.
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INDEX QRCNTR # AOS SCALED AT PI/2
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CA AOSQ
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EXTEND
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MP BIT2 # RESCALE AOS TO PI/4
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EXTEND
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BZF GTSQAXIS -3 # USE FULL SCALE FOR LARGER AOS ESTIMATES.
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INDEX A
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CS LIMITS # LIMITS +1 CONTAINS NEGMAX.
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XCH L # LIMITS -1 CONTAINS POSMAX.
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CCS QRCNTR # PICK UP RATE FOR THIS AXIS. RATE CELLS
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INDEX A # USE ADJACENT, NOT SEPARATED. AT PI/4
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CA EDOTQ
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GTSQAXIS DXCH WCENTRAL
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INDEX QRCNTR # COLLECT K FOR THIS AXIS
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CA KQ
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TS KCENTRAL
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EXTEND # CONTROL AUTHORITY ZERO. AVOID DRIVING
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BZF POSDRIVE +1 # ENGINE BELL TO THE STOPS.
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INDEX QRCNTR # QDIFF, RDIFF ARE STORED IN D.P.
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CAE QDIFF
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ALGORTHM EXTEND # Q(R)DIFF IS THETA (ERROR) SCALED AT PI.
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MP KCENTRAL # FORM K*ERROR AT PI(2)/2(8), IN D.P.
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LXCH K2THETA
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EXTEND
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MP BIT5 # RESCALE TO 4*PI(2)
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DXCH K2THETA
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EXTEND
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MP BIT5 # FIRST TERM OF NEGUSUM IN K2THETA.
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ADS K2THETA +1 # NO CARRY NEEDED D.P. AT 4*PI(2)
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CS ACENTRAL # FORM ALPHA(2)/(2*K) AT 16*PI, IN D.P.,
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EXTEND # LIMITING QUOTIENT TO AVOID OVERFLOW.
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MP BIT14 # -ALPHA/2 IN A, SCALED AT PI/4
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EXTEND
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MP ACENTRAL # -ALPHA(2)/2 IN A,L, SCALED AT PI(2)/16)
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AD KCENTRAL
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EXTEND
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BZMF HUGEQUOT # K-ALPHA(2)/2 SHOULD BE PNZ FO DIVISION
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EXTEND
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DCS A # ALPHA(2)/2 - K
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AD KCENTRAL
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# RSB 2009 ---------------------------------------------------------------------
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EXTEND
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DV KCENTRAL # HIGH ORDER OF QUOTIENT.
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XCH A2CNTRAL
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CA L # SHIFT UP THE REMAINDER.
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LXCH 7 # ZERO LOW-ORDER DIVIDEND.
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EXTEND
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# Page 1474
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DV KCENTRAL
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XCH A2CNTRAL +1 # QUOTIENT STORED AT 16*PI, D.P.
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TCF HAVEQUOT
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HUGEQUOT CA POSMAX
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TS L
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DXCH A2CNTRAL # LIMITED QUOTIENT STORED AT 16*PI, D.P.
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HAVEQUOT CA WCENTRAL
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EXTEND
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MP BIT9 # RESCALE OMEGA AT 16*PI IN D.P.
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DXCH K2CNTRAL # LOWER WORD OVERLAYS OMEGA IN WCENTRAL
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EXTEND
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DCA K2CNTRAL
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DXCH FUNCTION
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CA ACENTRAL # GET ALPHA*ABS(ALPHA)/(2*K)
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EXTEND
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BZMF +4
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EXTEND
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DCA A2CNTRAL
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TCF +3
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EXTEND
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DCS A2CNTRAL
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DAS FUNCTION # OMEGA + ALPHA*ABS(ALPHA)/(2*K) AT 16*PI
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CCS FUNCTION # DEL = +1 FOR FUNCT1 GREATER THAN ZERO.
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TCF POSFNCT1 # OTHERWISE DEL = -1
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TCF +2
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TCF NEGFNCT1
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CCS FUNCTION +1 # USE LOW ORDER WORD SINCE HIGH IS ZERO
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POSFNCT1 CAF BIT1
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TCF +2
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NEGFNCT1 CS BIT1
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TS DEL
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CCS DEL # REPLACE OMEGA BY DEL*OMEGA
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TCF FUNCT2 # POSITIVE DEL VALUE. PROCEED.
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TCF DEFUNCT
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TCF NEGFNCT2
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DEFUNCT TS K2CNTRAL
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TS K2CNTRAL +1
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TCF FUNCT2
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# Page 1475
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NEG1/3 DEC -.33333
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NEGFNCT2 EXTEND
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DCS K2CNTRAL
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DXCH K2CNTRAL
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FUNCT2 EXTEND
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DCA A2CNTRAL
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DAS K2CNTRAL # DEL*OMEGA + ALPHA(2)/(2*K) AT 16*PI, D.P.
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FUNCT3 CA A2CNTRAL
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EXTEND
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MP NEG1/3
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DXCH A2CNTRAL
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CA L
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EXTEND
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MP NEG1/3
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ADS A2CNTRAL +1
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TS L
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TCF +2 # A2CNTRAL NOW CONTAINS -ALPHA(2)/(6*K),
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ADS A2CNTRAL # SCALED AT 16*PI, IN D.P.
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EXTEND
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DCA K2CNTRAL # DEL*OMEGA + ALPHA(2)/(3*K) IN A2CNTRAL,
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DAS A2CNTRAL # SCALED AT 16*PI, D.P.
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CA A2CNTRAL
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EXTEND
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MP ACENTRAL
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DAS K2THETA
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CA A2CNTRAL +1
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EXTEND
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MP ACENTRAL # ACENTRAL MAY NOW BE OVERLAID.
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ADS K2THETA +1
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TS L
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TCF +2 # TWO TERMS OF NEGUSUM ACCUMULATED, SO FAR
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ADS K2THETA # SCALED AT 4*PI(2), IN D.P.
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GETROOT CA K2CNTRAL # K*(DEL*OMEGA + ALPHA(2)/(2*K)) IS THE
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EXTEND # TERM FOR WHICH A SQUARE ROOT IS NEEDED.
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MP KCENTRAL # K AT PI/2(8)
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DXCH FUNCTION
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CA K2CNTRAL +1
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EXTEND
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MP KCENTRAL
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ADS FUNCTION +1
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TS L
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TCF +2
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ADS FUNCTION # DESIRED TERM IN FUNCTION, AT PI(2)/16
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# Page 1476
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CCS DEL
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TCF RSTOFGTS
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TCF NEGUSUM
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TCF NEGATE
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TCF NEGUSUM
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NEGATE EXTEND
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DCS K2CNTRAL
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DXCH K2CNTRAL
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TCF RSTOFGTS
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BANK 16
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EBANK= NEGUQ
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SETLOC DAPS1
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BANK
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# THE WRCHN12 SUBROUTINE SETS BITS 9,10,11,12 OF CHANNEL 12 ON THE BASIS OF THE CONTENTS OF NEGUQ,NEGUR WHICH ARE
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# THE NEGATIVES OF THE DESIRED ACCELERATION CHANGES. ACDT+C12 SETS Q(R)ACCDOT TO REFLECT THE NEW DRIVES.
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#
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# WARNING: ACDT+C12 AND WRCHN12 MUST BE CALLED WITH INTERRUPT INHIBITED.
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BGIM OCTAL 07400
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CHNL12 EQUALS ITEMP6
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ACDT+C12 CS NEGUQ
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EXTEND # GIMBAL DRIVE REQUESTS.
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MP ACCDOTQ
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LXCH QACCDOT
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CS NEGUR
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EXTEND
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MP ACCDOTR
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LXCH RACCDOT
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CCS NEGUQ
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CAF BIT10
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TCF +2
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CAF BIT9
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TS CHNL12
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CCS NEGUR
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CAF BIT12
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TCF +2
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CAF BIT11
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ADS CHNL12 # (STORED RESULT NOT USED AT PRESENT)
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CS BGIM
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EXTEND
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RAND CHAN12
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AD CHNL12
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EXTEND
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WRITE CHAN12
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# Page 1477
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CS CALLGMBL # TURN OFF REQUEST FOR ACDT+C12 EXECUTION.
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MASK RCSFLAGS
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TS RCSFLAGS
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TC Q # RETURN TO CALLER.
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BANK 21
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EBANK= QDIFF
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SETLOC DAPS4
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BANK
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# Page 1478
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# SUBROUTINE TIMEGMBL: MOD 0, OCTOBER 1967, CRAIG WORK
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#
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# TIMEGMBL COMPUTES THE DRIVE TIME NEEDED FOR THE TRIM GIMBAL TO POSITION THE DESCENT ENGINE NOZZLE SO AS TO NULL
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# THE OFFSET ANGULAR ACCELERATION ABOUT THE Q (OR R) AXIS. INSTEAD OF USING AOSQ(R), TIMEGMBL USES .4*AOSQ(R),
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# SCALED AT PI/8. FOR EACH AXIS, THE DRIVE TIME IS COMPUTED AS ABS(ALPHA/ACCDOT). A ZERO
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# ALPHA OR ACCDOT OR A ZERO QUOTIENT TURNS OFF THE GIMBAL DRIVE IMMEDIATELY. OTHERWISE, THE GIMBAL IS TURNED ON
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# DRIVING IN THE CORRECT DIRECTION. THE Q(R)GIMTIMR IS SET TO TERMINATE THE DRIVE AND Q(R)ACCDOT
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# IS STORED TO REFLECT THE NEW ACCELERATION DERIVATIVE. NEGUQ(R) WILL CONTAIN +1,+0,-1 FOR A Q(R)ACCDOT VALUE
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# WHICH IS NEGATIVE, ZERO, OR POSITIVE.
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#
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# INPUTS: AOSQ,AOSR, SCALED AT P1/2, AND ACCDOTQ, ACCDOTR AT PI/2(7). PI/2(7).
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#
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# OUTPUTS: NEW GIMBAL DRIVE BITS IN CHANNEL 12, NEGUQ, NEGUR, QACCDOT, AND RACCDOT, THE LAST SCALED AT PI/2(7).
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# Q(R)GIMTIMR WILL BE SET TO TIME AND TERMINATE GIMBAL DRIVE(S).
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#
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# DEBRIS: A, L, Q, ITEMPS 2, 3, 6, AND RUPTREG2 AND ACDT+C12 DEBRIS.
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#
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# EXITS: VIA TC Q.
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#
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# ALARMS, ABORTS: NONE.
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#
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# SUBROUTINES: ACDT+C12, IBNKCALL
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#
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# WARNING: THIS SUBROUTINE WRITES INTO CHANNEL 12 AND USES THE ITEMPS. THEREFORE IT MAY ONLY BE CALLED WITH
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# INTERRUPT INHIBITED.
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#
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# ERASABLE STORAGE CONFIGURATION (NEEDED BY THE INDEXING METHODS):
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# NEGUQ ERASE +2 # NEGATIVE OF Q-AXIS GIMBAL DRIVE
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# (SPWORD) EQUALS NEGUQ +1 # ANY S.P. ERASABLE NUMBER, NOW THRSTCMD
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# NEGUR EQUALS NEGUQ +2 # NEGATIVE OF R-AXIS GIMBAL DRIVE
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# ACCDOTQ ERASE +2 # Q-JERK TERM SCALED AT PI/2(7) RAD/SEC(3)
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# (SPWORD) EQUALS ACCDOTQ +1 # ANY S.P. ERASABLE NUMBER NOW QACCDOT
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# ACCDOTR EQUALS ACCDOTQ +2 # R-JERK TERM SCALED AT PI/2(7) RAD/SEC(3)
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# # ACCDOTQ, ACCDOTR ARE MAGNITUDES.
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# AOSQ ERASE +4 # Q-AXIS ACC., D.P. AT PI/2 R/SEC(2)
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# AOSR EQUALS AOSQ +2 # R-AXIS ACCELERATION SCALED AT PI/2 R/S2
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QRNDXER EQUALS ITEMP6
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OCT23146 OCTAL 23146 # DECIMAL .6
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NZACCDOT EQUALS ITEMP3
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TIMEGMBL CAF ONE # INITIALZE ALLOWGTS.
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TS ALLOWGTS
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CAF TWO # SET UP LOOP FOR R AXIS.
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LXCH Q # SAVE RETURN ADDRESS.
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LXCH RUPTREG2
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# Page 1479
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TCF +2
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TIMQGMBL CAF ZERO # NOW DO THE Q-AXIS
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TS QRNDXER
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INDEX QRNDXER
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CA ACCDOTQ # ACCDOT IS PRESUMED TO BE AT PI/2(7).
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EXTEND
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BZMF TGOFFNOW # IS ACCDOT LESS THAN OR EQUAL TO 0?
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TS NZACCDOT # NO. STORE NON-ZERO, POSITIVE ACCDOT.
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ALPHATRY INDEX QRNDXER
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CS AOSQ
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EXTEND
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BZF TGOFFNOW # IS ALPHA ZERO?
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TS Q # SAVE A COPY OF -AOS.
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EXTEND # NO. RESCALE FOR TIMEGMBL USE.
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MP OCT23146 # OCTAL 23146 IS DECIMAL .6
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AD Q # -1.6*AOS AT PI/2 = -.4*AOS AT PI/8
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TS L # WAS THERE OVERFLOW?
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TCF SETNEGU # NO. COMPUTE DRIVE TIME.
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CS A # RECOVER -SGN(AOS) IN THE A REGISTER.
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INDEX QRNDXER # YES. START DRIVE WITHOUT WAITLIST.
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XCH NEGUQ
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TCF NOTALLOW # KNOCK DOWN THE ALLOWGTS FLAG.
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SETNEGU EXTEND
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BZMF POSALPH
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COM
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TS ITEMP2 # STORE -ABS(.4*AOS) SCALED AT PI/8.
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CS BIT1
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TCF POSALPH +2
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POSALPH TS ITEMP2 # STORE -ABS(.4*AOS) SCALED AT PI/8.
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CA BIT1
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+2 INDEX QRNDXER # SGN(AOS) INTO NEGU
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TS NEGUQ # STORE SGN(ALPHA) AS NEGU
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CA NZACCDOT
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EXTEND
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MP BIT12 # 2*ACCDOT, SCALED AT PI/8.
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AD ITEMP2 # -ABS(ALPHS) + 2*ACCDOT, AT PI/8.
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EXTEND
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BZMF NOTALLOW # IS DRIVE TIME MORE THAN TWO SECONDS?
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CS ITEMP2 # NO. COMPUTE DRIVE TIME.
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EXTEND # ABS(ALPHA) AT PI/8.
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MP OCT00240 # DECIMAL 10/1024
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EXTEND # QUOTIENT IS DRIVE TIME AT WAITLIST.
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DV NZACCDOT # ABS(ALPHA)/ACCDOT AT 2(14)/100
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# Page 1480
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EXTEND
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BZF TGOFFNOW # DRIVE TIME MUST BE GREATER THAN ZERO.
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TCF DRIVEON
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TGOFFNOW CAF ZERO # TURN OFF GIMBAL NOW.
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INDEX QRNDXER
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TS NEGUQ
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TCF DONEYET
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NOTALLOW CAF OCT31
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INDEX QRNDXER
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TS QGIMTIMR
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CAF ZERO # DRIVE TIME IS MORE THAN 2 SECONDS, SO
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TS ALLOWGTS # DO NOT PERMIT FURTHER GTS ATTITUDE-RATE
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# CONTROL UNTIL AOSTASK APPROVES.
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TCF DONEYET # NO WAITLIST CALL IS MADE.
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DRIVEON INDEX QRNDXER
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TS QGIMTIMR # CHOOSE Q OR R AXIS.
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DONEYET CCS QRNDXER
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TCF TIMQGMBL
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DXCH RUPTREG3 # PROTECT IBNKCALL ERASABLES. ACDT+C12
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DXCH ITEMP2 # LEAVES ITEMPS2,3 ALONE.
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TC IBNKCALL # TURN OFF CHANNEL BITS, SET Q(R)ACCDOTS.
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CADR ACDT+C12
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DXCH ITEMP2 # RESTORE ERASABLES FOR IBNKCALL.
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DXCH RUPTREG3
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TC RUPTREG2 # RETURN TO CALLER.
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OCT00240 OCTAL 00240 # DECIMAL 10/1024
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# Page 1481
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# THE FOLLOWING SECTION IS A CONTINUATION OF THE TRIM GIMBAL CONTROL FROM THE LAST GTS ENTRY. THE QUANTITY NEGUSUM
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# IS COMPUTED FOR EACH AXIS (Q,R), .707*DEL*FUNCTION(3/2) + K2THETA = NEGUSUM. NEW DRIVES ARE ENTERED TO CH 12.
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#
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# THE SUBROUTINE GTSQRT ACCEPTS A DOUBLE PRECISION VALUE IN FUNCTION, FUNCTION +1 AND RETURNS A SINGLE-PRECISION
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# SQUARE ROOT OF THE FOURTEEN MOST SIGNIFICANT BITS OF THE ARGUMENT. ALSO, THE CELL SHFTFLAG CONTAINS A BINARY
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# EXPONENT S, SUCH THAT THE SQUARE ROOT (RETURNED IN THE A REGISTER) MUST BE SHIFTED RIGHT (MULTIPLIED BY 2 TO THE
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# POWER (-S)) IN ORDER TO BE THE TRUE SQUARE ROOT OF THE FOURTEEN MOST SIGNIFICANT BITS OF FUNCTION, FUNCTION +1.
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# SQUARE ROOT ERROR IS NOT MORE THAN 2 IN THE 14TH SIGNIFICANT BIT. CELLS CLOBBERED ARE A, L, SHFTFLAG, ININDEX,
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# HALFARG, SCRATCH, SR, FUNCTION, FUNCTION +1. GTSQRT IS CALLED BY TC GTSQRT AND RETURNS VIA TC Q OR TC FUNCTION +1.
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# ZERO OR NEGATIVE ARGUMENTS YIELD ZERO FOR SQUARE ROOTS.
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|
|
|
GTSQRT CCS FUNCTION
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|
TCF GOODARG # FUNCTION IS POSITIVE. TAKE SQUARE ROOT.
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TCF +2 # HIGH ORDER WORD IS ZERO. TRY THE LOWER.
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TCF ZEROOT # NEGATIVE. USE ZERO FOR 1/2 POWER.
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|
|
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CA FUNCTION +1
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EXTEND
|
|
BZMF ZEROOT
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|
|
|
TCF ZEROHIGH # PROCEED.
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|
ZEROOT CA ZERO
|
|
TS SHFTFLAG
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|
TC Q
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|
|
|
ZEROHIGH XCH FUNCTION # 14 MOST SIGNIFICANT BITS ARE IN THE
|
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XCH FUNCTION +1 # LOWER WORD. EXCHANGE THEM.
|
|
CA SEVEN
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TCF GOODARG +1
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|
|
|
GOODARG CA ZERO
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|
TS SHFTFLAG
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CA TWELVE # INITIALIZE THE SCALING LOOP.
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|
TS ININDEX
|
|
TCF SCALLOOP
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|
|
|
SCALSTRT CA FUNCTION
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TCF SCALDONE
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|
|
|
MULBUSH CA NEG2 # IF ARG IS NOT LESS THAN 1/4, INDEX IS
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ADS ININDEX # ZERO, INDICATING NO SHIFT NEEDED.
|
|
EXTEND # BRANCH IF ARG IS NOT LESS THAN 1/4.
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|
BZMF SCALSTRT # OTHERWISE COMPARE ARG WITH A REFERENCE
|
|
# WHICH IS 4 TIMES LARGER THAN THE LAST.
|
|
SCALLOOP CS FUNCTION
|
|
INDEX ININDEX
|
|
AD BIT15 # REFERENCE MAGNITUDE LESS OR EQUAL TO 1/4
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|
EXTEND
|
|
BZMF MULBUSH # IF ARG IS NOT LESS THAN REFERENCE, GO
|
|
# AROUND THE MULBERRY BUSH ONCE MORE.
|
|
# Page 1482
|
|
INDEX ININDEX
|
|
CA BIT15 # THIS IS THE SCALE MAGNITUDE
|
|
XCH HALFARG # 2**(-ININDEX) IS THE SHIFT DIVISOR.
|
|
EXTEND # RESCALE ARGUMENT.
|
|
DCA FUNCTION
|
|
EXTEND
|
|
DV HALFARG
|
|
# ININDEX AND SHFTFLAG PRESERVE INFO FOR
|
|
# RESCALING AFTER ROOT PROCESS.
|
|
SCALDONE EXTEND
|
|
QXCH FUNCTION +1 # SAVE Q FOR RETURN
|
|
EXTEND
|
|
MP BIT14
|
|
TS HALFARG
|
|
MASK BIT13
|
|
CCS A
|
|
CA OCT11276
|
|
AD ROOTHALF # INITIAL GUESS IS ROOT 1/2 OR POSMAX
|
|
TC ROOTCYCL
|
|
TC ROOTCYCL
|
|
TC ROOTCYCL
|
|
TC FUNCTION +1
|
|
|
|
# ***************************************************************************
|
|
|
|
RSTOFGTS TC GTSQRT
|
|
PRODUCT XCH K2CNTRAL
|
|
EXTEND
|
|
MP K2CNTRAL
|
|
DXCH K2CNTRAL
|
|
EXTEND # THE PRODUCT OF
|
|
MP L # 1/2 2 1/2
|
|
ADS K2CNTRAL +1 # K *(DEL*OMEGA + ALPHA /(2*K))
|
|
TS L # AND
|
|
TCF +2 # 2
|
|
ADS K2CNTRAL # DEL*(DEL*OMEGA + ALPHA /(2*K)) NOW IN
|
|
# K2CNTRAL
|
|
|
|
DOSHIFT CA ININDEX
|
|
EXTEND # MULTIPLY IN THE FACTOR 2(-S), RETURNED
|
|
MP BIT14 # BY THE GTSQRT SUBROUTINE
|
|
ADS SHFTFLAG
|
|
EXTEND
|
|
BZF ADDITIN
|
|
INDEX SHFTFLAG
|
|
CA BIT15
|
|
# Page 1483
|
|
XCH K2CNTRAL
|
|
EXTEND
|
|
MP K2CNTRAL
|
|
DAS K2THETA
|
|
XCH K2CNTRAL
|
|
EXTEND
|
|
MP K2CNTRAL +1
|
|
ADS K2THETA +1
|
|
TS L
|
|
TCF +2
|
|
ADS K2THETA
|
|
|
|
TCF NEGUSUM
|
|
|
|
ADDITIN EXTEND
|
|
DCA K2CNTRAL
|
|
DAS K2THETA # NO ADD IN THE K2THETA TERM.
|
|
NEGUSUM CCS K2THETA # TEST SIGN OF HIGH ORDER PART.
|
|
TCF NEGDRIVE
|
|
TCF +2
|
|
TCF POSDRIVE
|
|
|
|
CCS K2THETA +1 # SIGN TEST FOR LOW ORDER PART.
|
|
NEGDRIVE CA BIT1
|
|
TCF +2 # STOP GIMBAL DRIVE FOR A ZERO NEGUSUM.
|
|
POSDRIVE CS BIT1
|
|
TS L # SAVE FOR DRIVE REVERSAL TEST.
|
|
INDEX QRCNTR
|
|
XCH NEGUQ
|
|
|
|
EXTEND
|
|
MP L # MULTIPLY OLD NEGU AND NEW NEGU.
|
|
CCS L
|
|
TCF LOUPE # NON-ZERO GIMBAL DRIVE BEING CONTINUED.
|
|
|
|
TCF ZEROLOUP # NO REVERSAL PROBLEM HERE.
|
|
|
|
TCF REVERSAL # NON-ZERO GIMBAL DRIVE BEING REVERSED.
|
|
TCF ZEROLOUP # NO REVERSAL PROBLEM HERE.
|
|
|
|
REVERSAL INDEX QRCNTR # A ZERO-DRIVE PAUSE IS NEEDED HERE. ZERO
|
|
TS QACCDOT # IS IN A REGISTER FROM CCS ON (-1).
|
|
INDEX QRCNTR
|
|
CS GMBLBITA
|
|
EXTEND
|
|
WAND CHAN12
|
|
|
|
ZEROLOUP CS RCSFLAGS # SET UP REQUEST FOR ACDT+C12 CALL.
|
|
MASK CALLGMBL
|
|
ADS RCSFLAGS
|
|
# Page 1484
|
|
LOUPE CCS QRCNTR # HAVE BOTH AXES BEEN PROCESSED?
|
|
TCF GOQTRIMG # NO. DO Q AXIS NEXT.
|
|
|
|
CA SAVESR # RESTORE THE SR
|
|
TS SR
|
|
|
|
GOCLOSE EXTEND # TERMINATE THE JASK.
|
|
DCA CLOSEADR
|
|
DTCB
|
|
|
|
EBANK= AOSQ
|
|
CLOSEADR 2CADR CLOSEOUT # TERMINATE THE JASK.
|
|
|
|
TWELVE EQUALS OCT14
|
|
ROOTHALF OCTAL 26501 # SQUARE ROOT OF 1/2
|
|
GMBLBITA OCTAL 01400 # INDEXED WRT GMBLBITB DO NOT MOVE *******
|
|
OCT11276 OCTAL 11276 # POSMAX -- ROOTHALF
|
|
GMBLBITB OCTAL 06000 # INDEXED WRT GMBLBITA DO NOT MOVE *******
|
|
|
|
# SUBROUTINE ROOTCYCL: BY CRAIG WORK, 3 APRIL 68
|
|
#
|
|
# ROOTCYCL IS A SUBROUTINE WHICH EXECUTS ONE NEWTON SQUARE ALGORITHM ITERATION. THE INITIAL GUESS AT THE
|
|
# SQUARE ROOT IS PRESUMED TO BE IN THE A REGISTER AND ONE-HALF THE SQUARE IS TAKEN FROM HALFARG. THE NEW APPROXIMATION
|
|
# TO THE SQUARE ROOT IS RETURNED IN THE A REGISTER. DEBRIS: A, L, SR, SCRATCH. ROOTCYCL IS CALLED FROM
|
|
# LOCATION (LOC) BY A TC ROOTCYCL, AND RETURNS (TC Q) TO LOC +1.
|
|
#
|
|
# WARNING: IF THE INITIAL GUESS IS NOT GREATER THAN THE SQUARE, DIVIDE OR ADD OVERFLOW IS A REAL POSSIBILITY.
|
|
|
|
ROOTCYCL TS SCRATCH # STORE X
|
|
TS SR # X/2 NOW IN SR
|
|
CA HALFARG # ARG/2 IN THE A REG
|
|
ZL # PREPARE FOR DIVISION
|
|
EXTEND
|
|
DV SCRATCH # (ARG/X)/2
|
|
AD SR # (X + ARG/X)/2 IN THE A REG
|
|
TC Q
|
|
|
|
|