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INFLIGHT_ALIGNMENT_ROUTINES.s
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INFLIGHT_ALIGNMENT_ROUTINES.s
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# Copyright: Public domain.
# Filename: INFLIGHT_ALIGNMENT_ROUTINES.agc
# Purpose: Part of the source code for Colossus 2A, AKA Comanche 055.
# It is part of the source code for the Command Module's (CM)
# Apollo Guidance Computer (AGC), for Apollo 11.
# Assembler: yaYUL
# Contact: Ron Burkey <info@sandroid.org>.
# Website: www.ibiblio.org/apollo.
# Pages: 1355-1364
# Mod history: 2009-05-14 RSB Adapted from the Colossus249/ file of the
# same name, using Comanche055 page images.
#
# This source code has been transcribed or otherwise adapted from digitized
# images of a hardcopy from the MIT Museum. The digitization was performed
# by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many
# thanks to both. The images (with suitable reduction in storage size and
# consequent reduction in image quality as well) are available online at
# www.ibiblio.org/apollo. If for some reason you find that the images are
# illegible, contact me at info@sandroid.org about getting access to the
# (much) higher-quality images which Paul actually created.
#
# Notations on the hardcopy document read, in part:
#
# Assemble revision 055 of AGC program Comanche by NASA
# 2021113-051. 10:28 APR. 1, 1969
#
# This AGC program shall also be referred to as
# Colossus 2A
# Page 1355
BANK 22
SETLOC INFLIGHT
BANK
EBANK= XSM
# CALCGTA COMPUTES THE GYRO TORQUE ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
#
# THE INPUT IS THE DESIRED STABLE MEMBER COORDINATES REFERRED TO PRESENT STABLE MEMBER COORDINATES. THE THREE
# HALF-UNIT VECTORS ARE STORED AT XDC, YDC, AND ZDC.
#
# THE OUTPUTS ARE THE THREE GYRO TORQUE ANGLES TO BE APPLIED TO THE Y, Z, AND X GYROS AND ARE STORED DP AT IGC,
# MGC, AND OGC RESPECTIVELY.
COUNT 23/INFLT
CALCGTA ITA DLOAD # PUSHDOWN 00-03, 16D-27D, 34D-37D
S2 # XDC = (XD1 XD2 XD3)
XDC # YDC = (YD1 YD2 YD3)
PDDL PDDL # ZDC = (ZD1 ZD2 ZD3)
HI6ZEROS
XDC +4
DCOMP VDEF
UNIT
STODL ZPRIME # ZP = UNIT(-XD3 0 XD1) = (ZP1 ZP2 ZP3)
ZPRIME
SR1
STODL SINTH # SIN(IGC) = ZP1
ZPRIME +4
SR1
STCALL COSTH # COS(IGC) = ZP3
ARCTRIG
STODL IGC # Y GYRO TORQUING ANGLE FRACTION OF REV.
XDC +2
SR1
STODL SINTH # SIN(MGC) = XD2
ZPRIME
DMP PDDL
XDC +4 # PD00 = (ZP1)(XD3)
ZPRIME +4
DMP DSU
XDC # MPAC = (ZP3)(XD1)
STADR
STCALL COSTH # COS(MGC) = MPAC - PD00
ARCTRIG
# Page 1356
STOVL MGC # Z GYRO TORQUING ANGLE FRACTION OF REV.
ZPRIME
DOT
ZDC
STOVL COSTH # COS(OGC) = ZP . ZDC
ZPRIME
DOT
YDC
STCALL SINTH # SIN(OGC) = ZP . YDC
ARCTRIG
STCALL OGC # X GYRO TORQUING ANGLE FRACTION OF REV.
S2
# Page 1357
# ARCTRIG COMPUTES AN ANGLE GIVEN THE SINE AND COSINE OF THIS ANGLE.
#
# THE INPUTS ARE SIN/4 AND COS/4 STORED DP AT SINTH AND COSTH.
#
# THE OUTPUT IS THE CALCULATED ANGLE BETWEEN +.5 AND -.5 REVOLUTIONS AND STORED AT THETA. THE OUTPUT IS ALSO
# AVAILABLE AT MPAC.
ARCTRIG DLOAD ABS # PUSHDOWN 16D-21D
SINTH
DSU BMN
QTSN45 # ABS(SIN/4) - SIN(45)/4
TRIG1 # IF (-45,45) OR (135,-135)
DLOAD SL1 # (45,135) OR (-135,-45)
COSTH
ACOS SIGN
SINTH
STORE THETA # X = ARCCOS(COS) WITH SIGN(SIN)
RVQ
TRIG1 DLOAD SL1 # (-45,45) OR (135,-135)
SINTH
ASIN
STODL THETA # X = ARCSIN(SIN) WITH SIGN(SIN)
COSTH
BMN
TRIG2 # IF (135,-135)
DLOAD RVQ
THETA # X = ARCSIN(SIN) (-45,45)
TRIG2 DLOAD SIGN # (135,-135)
HIDPHALF
SINTH
DSU
THETA
STORE THETA # X = .5 WITH SIGN(SIN) - ARCSIN(SIN)
RVQ # (+) - (+) OR (-) - (-)
# Page 1358
# SMNB, NBSM, AND AXISROT, WHICH USED TO APPEAR HERE, HAVE BEEN
# COMBINED IN A ROUTINE CALLED AX*SR*T, WHICH APPEARS AMONG THE POWERED
# FLIGHT SUBROUTINES.
# Page 1359
# CALCGA COMPUTES THE CDU DRIVING ANGLES REQUIRED TO BRING THE STABLE MEMBER INTO THE DESIRED ORIENTATION.
#
# THE INPUTS ARE 1) THE NAVIGATION BASE COORDINATES REFERRED TO ANY COORDINATE SYSTEM. THE THREE HALF-UNIT
# VECTORS ARE STORED AT XNB, YNB, AND ZNB. 2) THE DESIRED STABLE MEMBER COORDINATES REFERRED TO THE SAME
# COORDINATE SYSTEM ARE STORED AT XSM, YSM, AND ZSM.
#
# THE OUTPUTS ARE THE THREE CDU DRIVING ANGLES AND ARE STORED SP AT THETAD, THETAD +1, AND THETAD +2.
CALCGA SETPD # PUSHDOWN 00-05, 16D-21D, 34D-37D
0
VLOAD VXV
XNB # XNB = OGA (OUTER GIMBAL AXIS)
YSM # YSM = IGA (INNER GIMBAL AXIS)
UNIT PUSH # PD0 = UNIT(OGA X IGA) = MGA
DOT ITA
ZNB
S2
STOVL COSTH # COS(OG) = MGA . ZNB
0
DOT
YNB
STCALL SINTH # SIN(OG) = MGA . YNB
ARCTRIG
STOVL OGC
0
VXV DOT # PROVISION FOR MG ANGLE OF 90 DEGREES
XNB
YSM
SL1
STOVL COSTH # COS(MG) = IGA . (MGA X OGA)
YSM
DOT
XNB
STCALL SINTH # SIN(MG) = IGA . OGA
ARCTRIG
STORE MGC
ABS DSU
.166...
BPL
GIMLOCK1 # IF ANGLE GREATER THAN 60 DEGREES
CALCGA1 VLOAD DOT
ZSM
0
STOVL COSTH # COS(IG) = ZSM . MGA
XSM
# Page 1360
DOT STADR
STCALL SINTH # SIN(IG) = XSM . MGA
ARCTRIG
STOVL IGC
OGC
RTB BONCLR
V1STO2S
CPHIFLAG
S2
STCALL THETAD
S2
GIMLOCK1 EXIT
TC ALARM
OCT 00401
TC UPFLAG # GIMBAL LOCK HAS OCCURRED
ADRES GLOKFAIL
TC INTPRET
GOTO
CALCGA1
# Page 1361
# AXISGEN COMPUTES THE COORDINATES OF ONE COORDINATE SYSTEM REFERRED TO ANOTHER COORDINATE SYSTEM.
#
# THE INPUTS ARE 1) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM A STORED AT STARAD. 2) THE STAR2 VECTOR
# REFERRED TO COORDINATE SYSTEM A STORED AT STARAD +6. 3) THE STAR1 VECTOR REFERRED TO COORDINATE SYSTEM B STORED
# AT LOCATION 6 OF THE VAC AREA. 4) THE STAR2 VECTOR REFERRED TO COORDINATE SYSTEM B STORED AT LOCATION 12D OF
# THE VAC AREA.
#
# THE OUTPUT DEFINES COORDINATE SYSTEM A REFERRED TO COORDINATE SYSTEM B. THE THREE HALF-UNIT VECTORS ARE STORED
# AT LOCATIONS XDC, XDC +6, XDC +12D, AND STARAD, STARAD +6, STARAD +12D.
AXISGEN AXT,1 SSP # PUSHDOWN 00-30D, 34D-37D
STARAD +6
S1
STARAD -6
SETPD
0
AXISGEN1 VLOAD* VXV* # 06D UA = S1
STARAD +12D,1 # STARAD +00D UB = S1
STARAD +18D,1
UNIT # 12D VA = UNIT(S1 X S2)
STORE STARAD +18D,1 # STARAD +06D VB = UNIT(S1 X S2)
VLOAD*
STARAD +12D,1
VXV* VSL1
STARAD +18D,1 # 18D WA = UA X VA
STORE STARAD +24D,1 # STARAD +12D WB = UB X VB
TIX,1
AXISGEN1
AXC,1 SXA,1
6
30D
AXT,1 SSP
18D
S1
6
AXT,2 SSP
6
S2
2
AXISGEN2 XCHX,1 VLOAD*
30D # X1=-6 X2=+6 X1=-6 X2=+4 X1=-6 X2=+2
0,1
# Page 1362
VXSC* PDVL* # J=(UA)(UB1) J=(UA)(UB2) J=(UA)(UB3)
STARAD +6,2
6,1
VXSC*
STARAD +12D,2
STOVL* 24D # K=(VA)(VB1) J=(VA)(VB2) J=(VA)(VB3)
12D,1
VXSC* VAD
STARAD +18D,2 # L=(WA)(WB1) J=(WA)(WB2) J=(WA)(WB3)
VAD VSL1
24D
XCHX,1 UNIT
30D
STORE XDC +18D,1 # XDC = L+J+K YDC = L+J+K ZDC = L+J+K
TIX,1
AXISGEN3
AXISGEN3 TIX,2
AXISGEN2
VLOAD
XDC
STOVL STARAD
YDC
STOVL STARAD +6
ZDC
STORE STARAD +12D
RVQ
# Page 1363
QTSN45 2DEC .1768
.166... 2DEC .1666666667
# Page 1364 (empty page)