553 lines
10 KiB
Plaintext
553 lines
10 KiB
Plaintext
# Copyright: Public domain.
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# Filename: TPI_SEARCH.agc
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# Purpose: Part of the source code for Colossus 2A, AKA Comanche 055.
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# It is part of the source code for the Command Module's (CM)
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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: 551-561
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# Mod history: 2009-05-15 RSB Adapted from the Colossus249/ file of the
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# same name, using Comanche055 page images.
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# 2009-05-20 RSB Corrections: On p. 551, "SETLOC P17S" -> P17S1.
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#
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# This source code has been transcribed or otherwise adapted from digitized
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# images of a hardcopy from the MIT Museum. The digitization was performed
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# by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many
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# thanks to both. The images (with suitable reduction in storage size and
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# consequent reduction in image quality as well) are available online at
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# www.ibiblio.org/apollo. If for some reason you find that the images are
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# illegible, contact me at info@sandroid.org about getting access to the
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# (much) higher-quality images which Paul 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 055 of AGC program Comanche by NASA
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# 2021113-051. 10:28 APR. 1, 1969
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#
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# This AGC program shall also be referred to as
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# Colossus 2A
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# Page 551
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# TPI SEARCH
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# PROGRAM DESCRIPTION S17.1 AND S17.2
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# FUNCTIONAL DESCRIPTION
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# THE TPI SEARCH ROUTINE DETERMINES THE MINIMUM TOTAL VELOCITY TRANSFER TRAJECTORY FROM A GIVEN TPI
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# MANEUVER TIME WITHIN THE CONSTRAINT OF A SAFE PERICENTER. THIS VELOCITY IS THE SUM OF THE IMPULSIVE VELOCITIES
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# FOR THE TPI AND TPF MANEUVERS.
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# THE S17.1 ROUTINE EXTRAPOLATES THE STATE VECTORS OF BOTH VEHICLES TO THE TPI TIME AND COMPUTES THE
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# RELATIVE PHASE ANGLE BETWEEN THE VEHICLES, THE ALTITUDE DIFFERENCE(I.E. THE MAGNITUDE DIFFERENCE OF THE
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# POSITION VECTORS) AND SELECTS A SEARCH SECTOR BASED ON THE SIGN OF THE ALTITUDE DIFFERENCE.
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# THE S17.2 ROUTINE FURTHER DEFINES THE SEARCH SECTOR BY COMPUTING ANGULAR LIMITS AND USES THE TIME THETA
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# SUBROUTINE TO COMPUTE THE SEARCH START AND END TIMES. THE SEARCH IS THEN MADE IN AN ITERATIVE LOOP USING THE
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# LAMBERT SUBROUTINE TO COMPUTE THE VELOCITIES REQUIRED AT TPI TIME AND AT TPF TIME. EXIT FROM THE SEARCH LOOP
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# IS MADE WHEN SOLUTION CRITERIA ARE MET (NORMAL EXIT) OR AS SOON AS IT IS EVIDENT THAT NO SOLUTION EXISTS IN
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# THE SECTOR SEARCHED.
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# CALLING SEQUENCE
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# BOTH ROUTINES ARE CALLED IN INTERPRETIVE CODE AND RETURN VIA QPRET. S17.1 HAS ONLY A NORMAL EXIT.
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# S17.2 RETURNS VIA QPRET FOR NORMAL EXIT AND TO ALARUMS FOR ERROR EXIT.
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# SUBROUTINES CALLED
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#
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# CSMCONIC
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# LEMCONIC
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# TIMETHET
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# INITVEL
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BANK 36
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SETLOC P17S1
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BANK
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COUNT 36/TPI
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EBANK= RACT3
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# **** TEMPORARY ****
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HPE 2DEC 157420.0 B-29 # EARTH'S MIN. PERICENTER ALTITUDE 85 N.M.
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HPL 2DEC 10668.0213 B-29 # MOON:S MIN. PERICENTER ALTITUDE 35000FT
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CDSEC 2DEC 40000
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CLSEC 2DEC 15000
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PIINVERS 2DEC .3183098862
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SEC1THET 2DEC .1944444444
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# Page 552
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SEC2THET 2DEC .9166666667
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MANYFEET 2DEC -1.0 B-2
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LIMVEL 2DEC .6096 E-2 B-7 # 2FPS
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DFTMOON 2DEC .1524 E3 B-29 # 500 FEET
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DP-.002 2DEC 0.002
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SETLOC P17S
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BANK
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S17.1 STQ DLOAD
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NORMEX
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TTPI
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STCALL TDEC1 # ADVANCE PASSIVE VEHICLE TO TPI
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LEMCONIC
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CALL
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LEMSTORE
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DLOAD
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TTPI
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STCALL TDEC1 # ADVANCE ACTIVE VEHICLE TO TPI
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CSMCONIC
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CALL
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CSMSTORE
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VLOAD
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RACT3
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ABVAL PDVL # /RA/ 0D PL 2D
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RPASS3
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UNIT PDDL # UNIT RP 0D PL 6D
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BDSU SET
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36D # /RP/ -/RA/
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KFLAG # OFF = +
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BMN CLEAR
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+2
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KFLAG # ON = -
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STOVL DELHITE
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0D
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VXV UNIT
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VPASS3
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STOVL E2 # ALMOST IT SAVE FOR 17.2
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RACT3
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PUSH VPROJ
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E2
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VSL2 BVSU # RPA
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UNIT DOT
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0D
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SL1 ACOS
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PDVL
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VXV DOT
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# Page 553
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RACT3
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E2
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PDDL SIGN
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STADR
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STODL THETZERO # CENTRAL ANGLE
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X1
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STCALL XRS # SAVE INDICES FOR FURTHER USE
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NORMEX # += ACTIVE AHEAD -= ACTIVE BEHIND
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S17.2 STQ VLOAD # COMPUTE SEARCH SECTOR LIMITS
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QTEMP
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RACT3
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UNIT DOT
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E2
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ABS SQRT
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SL1 DAD
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DP-.002 # ADD .002 RADIANS TO IT
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BON DCOMP # GIVES CORRECT SINE, COSINE MUST BE
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KFLAG # COMP. ADD .5 FOR ANGLE
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+1
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# PHI(0)=180-(-(THETAZERO +K5IT)), PHI(I)=180-(-THETAZERO+K2IT))
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# SIN(180-ALPHA)=SIN(ALPHA) ETC
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DMP SETPD
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PIINVERS # REVOLUTIONARY HERES TWO IT
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0D
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PUSH DSU
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THETZERO
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STORE IT # PHI(I) , -(THETZERO + K2IT)
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PDDL PUSH
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SR1 DAD
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DAD PUSH # PHI(0) , -(THETZERO + K5IT)
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SIN SET
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RVSW
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STODL SNTH
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COS BMN
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+2
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DCOMP
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STODL CSTH
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XRS
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STOVL X1
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RPASS3
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VSR*
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0,2
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STOVL RVEC
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VPASS3
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VSR*
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0,2
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STCALL VVEC
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TIMETHET
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DLOAD # SAVE START TIME AND GET END TIME
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T
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# Page 554
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STORE TF
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STODL TFO
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IT
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PUSH SIN
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STODL SNTH
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COS BMN
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+2
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DCOMP
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STORE CSTH
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LXA,1 CALL
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XRS
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TIMETHET
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# INITIALIZE LOOP
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DLOAD CLEAR
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T
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ITSWICH
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STODL TFI # SAVE TIME FOR LOOP TEST
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DPPOSMAX
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STODL DELVEE
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MANYFEET
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STODL HP
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SEC1THET # 70 DEGREES
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BON DLOAD
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KFLAG
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+2
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SEC2THET # 330 DEGREES
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STCALL THETL
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CONCAUL
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BIS DLOAD SR1
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CSTH
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STODL COSTH
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SNTH
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SR1
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STCALL SINTH # GET 4 QUADRANT THETA
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ARCTRIG
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BPL DAD
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+2
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DPPOSMAX # PUT THETA BETWEEN 0,1
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BDSU PDDL
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THETL
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TF
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DSU SIGN # FAST TIMES
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TFI
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BMN
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RNGETEST # TIME MUST HAVE A STOP
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# ADVANCE PASSIVE FOR TARGET VECTOR
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CONCAUL DLOAD
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TTPI
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DAD BON
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TF
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# Page 555
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AVFLAG
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ADVCSM
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STCALL TDEC1
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LEMCONIC
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GOTO
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JUNCT3
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ADVCSM STCALL TDEC1
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CSMCONIC
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# SAVE BACK VALUES OF HP AND DELVEE
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JUNCT3 VLOAD
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VATT
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STOVL VPASS4
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RATT
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STORE RPASS4
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STODL RTARG
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TF
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STODL DELLT4
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HP
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STODL HPO
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DELVEE
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STODL DELVEO
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# PREPARE FOR LAMBERT
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TTPI
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STODL INTIME
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XRS
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STODL RTX1
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HI6ZEROS
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SETPD PDDL
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0D
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EPSFOUR
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PDVL
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RACT3
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STOVL RINIT
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VACT3
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STCALL VINIT
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INITVEL
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# COMPUTE H ET CETERA
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VLOAD VSU
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VTPRIME
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VPASS4
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ABVAL PUSH
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STOVL RELDELV # /V2-VP(TPI+TF)/
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DELVEET3 # V1-VA
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ABVAL # /V1-VA/
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STORE MAGVTPI
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DAD STADR
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STODL DELVEE
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XRS
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STOVL X1
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VIPRIME
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# Page 556
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VSR*
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0,2
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STOVL VVEC
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RACT3
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VSR*
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0,2
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STCALL RVEC
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PERIAPO
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LXA,2 DLOAD
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XRS +1
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SL*
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0,2
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STORE HP
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# ITSWICH DENOTES INTERPOLATION--SOLUTION ACCEPTANCE IS FORCED
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BON DLOAD
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ITSWICH
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ENDEN
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HPERMIN
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DSU BMN
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HP
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HALFSAFE
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PDDL DSU # WAS PERICENTER ALT SAFE
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HPERMIN
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HPO
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BMN DSU # (HPLIM-HPO)-(HPLIM-HP)=HP-HPO
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INTERP # SOLUTION AT HAND
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BMN DLOAD
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ALARUMS # IT'S GETTING WORSE - SOUND THE ALARM
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CDSEC
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JUNCT1 BOFF DCOMP # OFF IS PLUS ON IS MINUS
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KFLAG
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+1
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STORE DELTEE
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JUNCT2 DLOAD DAD
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DELTEE
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TF
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STCALL TF
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BIS # RECYCLE
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INTERP SET DSU # HP-HPO
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ITSWICH
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NORM PDDL
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X1
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DFTMOON
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DAD DSU
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HPERMIN
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HP
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NORM SR1
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X2
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XSU,2 DDV
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X1
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# Page 557
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DMP SR*
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DELTEE
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0 -1,2
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STCALL DELTEE
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JUNCT2
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HALFSAFE PDDL DSU # SAVE HP-HPLIM FOR POSSIBLE
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DELVEE
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DELVEO # SAVE THIS TOO
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PUSH ABS
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DSU BMN
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LIMVEL # 2 FT PS
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ENDEN
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DLOAD DSU
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HPERMIN
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HPO
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PDDL
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BMN DLOAD
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LRGRDVO
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BPL DLOAD
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INTERP
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DELTEE
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SR1 DCOMP
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STCALL DELTEE
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JUNCT2
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LRGRDVO DLOAD
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BMN DLOAD
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JUNCT2
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CLSEC
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GOTO
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JUNCT1
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# TIME RAN OUT ASSUME SOLUTION IF SAVE PERICENTER
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RNGETEST DLOAD DSU
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HP
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HPERMIN
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BMN DLOAD
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ALARUMS
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TF
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DSU
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DELTEE
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STORE TF # TIME OF SOLUTION
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ENDEN VLOAD
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VTPRIME
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DOT PDDL # SG2 WITH MAGNITUDE
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RPASS4
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RELDELV
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SIGN STADR # NOW SIGN(RELDELV)=SIGN(SG2)
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STCALL RELDELV
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TRANSANG # COMPUTE OMEGA T , CENTRAL ANGLE
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VLOAD DOT
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RACT3
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# Page 558
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VIPRIME # SG1
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SIGN BPL # IF POSITIVE THEN SG1 = SG2 OTHERWISE
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RELDELV
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USEKAY # SIGN(SG2-SG1)=SIGN(SG2)=SIGN(RELDELV)
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SLOAD DCOMP
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DECTWO
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SIGN BPL
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RELDELV
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NEXUS
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DCOMP GOTO
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USEKAY +4
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USEKAY SLOAD BON
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DECTWO
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KFLAG
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NEXUS
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DSU
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P21ONENN
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NEXUS STODL NN1
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HP
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STCALL POSTTPI
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QTEMP
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BANK 07
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SETLOC XANG
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BANK
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COUNT 07/XANG
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# CENTRAL ANGLE SUBROUTINE
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# THIS SUBROUTINE COMPUTES THE CENTRAL ANGLE OF TRAVEL OF THE
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# PASSIVE VEHICLE DURING THE TRANSFER.
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TRANSANG STQ SETPD
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SUBEXIT
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0
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LXA,1 LXA,2
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XRS
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XRS +1
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VLOAD VSR*
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VPASS4
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0,2
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STODL* VVEC
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MUTABLE +2,1
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PDVL VSR* # SQRT MU (+18 OR +15) 00D
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RPASS4
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0,2
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ABVAL PDDL* # MAGNITUDE OF R (+29 OR +27) 02D
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MUTABLE,1
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PDVL VSQ # 1/MU (+34 OR +28) 04D
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VVEC
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NORM DMPR # PUSH LIST AT 02D
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X1
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# Page 559
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DMP SRR*
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02D
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0 -3,1
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BDSU # R V**/MU (+6)
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D1/32
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NORM PDDL
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X1 # (2 - R V**/MU) (+6-N)
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SR1R DDV # MAGNITUDE OF R (+30 OR +28)
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SL* PUSH # R/(2 - R V**/MU) (+29 OR +27)02D
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0 -5,1
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SR1 SQRT
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DMP
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NORM PDDL # ASUBP*** 00D
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X1
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SR1 DDV
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DMP SL*
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TF
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0,1
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PDDL NORM
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2PISC
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X1
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PDDL DDV
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SL*
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0 -3,1 # CENTANG = (SQRT(MU/ASUP***)TF)
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STCALL CENTANG # IN REVOLUTIONS B-0
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SUBEXIT
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BANK 35
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SETLOC P17S1
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BANK
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COUNT 35/P17
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# TPI SEARCH DISPLAY ROUTNE
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P17 TC AVFLAGA # AVFLAG = CSM , SET TRACK + UPDATE FLAGS
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TC P17.1
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P77 TC AVFLAGP # AVFLAG = LEM , SET TRACK + UPDATE FLAGS
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P17.1 TC P20FLGON # SET UPDATE FLAG
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CAF V06N37 # DISPLAY TTPI TIME
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TC VNP00H
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TC INTPRET
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CLEAR CALL
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UPDATFLG
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S17.1 # UPDATE STATE VECTORS TO TTPI
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SET AXT,1
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UPDATFLG
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DEC 2 # DELTA H = 2 K POSITIVE , KFLAG OFF
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BOFF AXT,1
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KFLAG
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+2
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DEC 1 # DELTA H = 1 K NEGATIVE , KFLAG ON
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# Page 560
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SXA,1 EXIT
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OPTION2
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CAF V06N72 # DISPLAY PHI , DELTA H , SEARCH OPTION K
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TC VNCOMP17
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TC INTPRET
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CLEAR SET
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UPDATFLG
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KFLAG
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SLOAD DSU
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OPTION2 # RESET KFLAG ON FOR OPTION =1
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P21ONENN # OFF FOR OPTION =2
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BHIZ CLEAR
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+2
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KFLAG
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SLOAD BHIZ
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XRS +1
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+4
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DLOAD GOTO
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HPL
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P17.2
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DLOAD
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HPE
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P17.2 STCALL HPERMIN
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S17.2
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SET EXIT
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UPDATFLG
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P17.3 CAF V06N58 # DISPLAY DELTA VTPI , DELTA VTPF , AND H
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TC VNCOMP17
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CAF V06N55 # DISPLAY PERICENTER CODE AND CENTRAL ANG.
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TC BANKCALL
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CADR GOFLASHR
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TC GOTOPOOH # TERMINATE PROGRAM
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TC GOTOPOOH # END PROGRAM
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TC P17.1 # RECYCLE WITH NEW TTPI OR SEARCH OPTION
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CAF TWO # BLANK R2
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TC BLANKET
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TCF ENDOFJOB
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EBANK= RTRN
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VNCOMP17 EXTEND
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QXCH QSAVED
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TS VERBNOUN
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CA VERBNOUN
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TCR BANKCALL
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CADR GOFLASH
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TC -3 # TERMINATE ILLEGAL REDISPLAY
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TC QSAVED # PROCEED
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CS MPAC # RECYCLE WITH NEW TPI TIME
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AD BIT6 # OR PROCEED WITH NEW SEARCH OPTION
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EXTEND
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# Page 561
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BZF P17.1
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TC VNCOMP17 +3
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ALARUMS SET EXIT
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UPDATFLG
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TC ALARM
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OCT 00124 # NO SAFE PERICENTER IN THIS SECTOR
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CAF V05N09
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TC VNCOMP17
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TC GOTOPOOH # PROCEED ILLEGAL TERMINATE PROGRAM
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V06N72 VN 0672
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