GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc
### FILE="Main.annotation"
## Copyright: Public domain.
## Filename: GROUND_TRACKING_DETERMINATION_PROGRAM_-_P21.agc
## Purpose: A section of Luminary revision 210.
## It is part of the source code for the Lunar Module's (LM)
## Apollo Guidance Computer (AGC) for Apollo 15-17.
## This file is intended to be a faithful transcription, except
## that the code format has been changed to conform to the
## requirements of the yaYUL assembler rather than the
## original YUL assembler.
## Reference: pp. 657-660
## Assembler: yaYUL
## Contact: Ron Burkey <info@sandroid.org>.
## Website: www.ibiblio.org/apollo/index.html
## Mod history: 2016-11-17 JL Created from Luminary131 version.
## 2016-11-29 RRB Updated from Luminary210 source.
## 2016-11-30 HG fix operand GOTOPOOH -> GOTOP00H
## 2016-12-07 HG unfix and revert P00 -> POO
## 2016-12-25 RSB Comment-text proofed using ProoferComments
## and corrected errors found.
## Page 657
# GROUND TRACKING DETERMINATION PROGRAM P21
#
# PROGRAM DESCRIPTION
# MOD NO - 1
# MOD BY - N. M. NEVILLE
# FUNCTIONAL DECRIPTION -
#
# TO PROVIDE THE ASTRONAUT DETAILS OF THE LM OR CSM GROUND TRACK WITHOUT
# THE NEED FOR GROUND COMMUNICATION (REQUESTED BY DSKY).
# CALLING SEQUENCE -
#
# ASTRONAUT REQUEST THROUGH DSKY V37E21E
# SUBROUTINES CALLED -
# GOPERF4
# GOFLASH
# THISPREC
# OTHPREC
# LAT-LONG
# NORMAL EXIT MODES -
#
# ASTRONAUT REQUEST TROUGH DSKY TO TERMINATE PROGRAM V34E
# ALARM OR ABORT EXIT MODES -
#
# NONE
# OUTPUT -
#
# OCTAL DISPLAY OF OPTION CODE AND VEHICLE WHOSE GROUND TRACK IS TO BE
# COMPUTED
# OPTION CODE 00002
# THIS 00001
# OTHER 00002
# DECIMAL DISPLAY OF TIME TO BE INTEGRATED TO HOURS, MINUTES, SECONDS
# DECIMAL DISPLAY OF LAT,LONG,ALT
# ERASABLE INITIALIZATION REQUIRED
# AX0 2DEC 4.652459653 E-5 RADIANS %68-69 CONSTANTS"
# -AY0 2DEC 2.147535898 E-5 RADIANS
# AZ0 2DEC .7753206164 REVOLUTIONS
# FOR LUNAR ORBITS 504LM VECTOR IS NEEDED
# 504LM 2DEC -2.700340600 E-5 RADIANS
## Should _2 and _4 be +2 and +4? Value has _ instead of -, I think this is a typo — RRB
# 504LM _2 2DEC -7.514128400 E-4 RADIANS
# 504LM _4 2DEC _2.553198641 E-4 RADIANS
#
# NONE
# DEBRIS
## Page 658
#
# CENTRALS-A,Q,L
# OTHER-THOSE USED BY THE ABOVE LISTED SUBROUTINES
# SEE LEMPREC,LAT-LONG
SBANK= LOWSUPER # FOR LOW 2CADR'S.
BANK 33
SETLOC P20S
BANK
EBANK= P21TIME
COUNT* $$/P21
PROG21 CAF ONE
TS OPTION2 # ASSUMED VEHICLE IS LM, R2 = 00001
CAF BIT2 # OPTION 2
TC BANKCALL
CADR GOPERF4
TC GOTOPOOH # TERMINATE
TC +2 # PROCEED VALUE OF ASSUMED VEHICLE OK
TC -5 # R2 LOADED THROUGH DSKY
CAF ZERO # INITIAL TIME = PRESENT TIME
TS DSPTEM1
TS DSPTEM1 +1
P21PROG1 CAF V6N34 # LOAD DESIRED TIME OF LAT-LONG.
TC BANKCALL
CADR GOFLASH
TC GOTOPOOH # TERM
TC +2 # PROCEED VALUES OK
TC -5 # TIME LOADED THROUGH DSKY
TC INTPRET
DLOAD BZE
DSPTEM1
P21PRTM
P21PROG2 STCALL TDEC1 # INTEG TO TIME SPECIFIED IN TDEC1
INTSTALL
BON CLEAR
P21FLAG
P21CONT # ON---RECYCLE USING BASE VECTOR
VINTFLAG # OFF--1ST PASS CALL BASE VECTOR
SLOAD SR1
OPTION2
BHIZ SET
+2 # ZERO--THIS VEHICLE (LM)
VINTFLAG # ONE--OTHER VEHICLE (CM)
CLEAR CLEAR
DIM0FLAG
INTYPFLG # PRECISION
CALL
INTEGRV # CALCULATE
GOTO # -AND
## Page 659
P21VSAVE # -SAVE BASE VECTOR
P21CONT VLOAD
P21BASER # RECYCLE -- INTEG FROM BASE VECTOR
STOVL RCV # --POS
P21BASEV
STODL VCV # --VEL
P21TIME
STORE TET # --TIME
CLEAR CLEAR
DIM0FLAG
MOONFLAG
SLOAD BZE
P21ORIG
+3 # ZERO=EARTH
SET # ---2=MOON
MOONFLAG
+3 CLEAR CALL
INTYPFLG
INTEGRVS
P21VSAVE DLOAD # SAVE CURRENT BASE VECTOR
TAT
STOVL P21TIME # --TIME
RATT1
STOVL P21BASER # --POS B-29 OR B-27
VATT1
STORE P21BASEV # --VEL B-07 OR B-05
ABVAL SL*
0,2
STOVL P21VEL # VEL/ FOR N91 DISP
RATT
UNIT DOT
VATT # U(R).V
DDV ASIN # U(R).U(V)
P21VEL
STORE P21GAM # SIN-1 U(R).U(V) , -90 TO &90
SXA,2 SLOAD
P21ORIG # 0 = EARTH
OPTION2
SR1 BHIZ
+3
GOTO
+4
+3 BON
SURFFLAG
P21DSP
+4 SET
P21FLAG
P21DSP CLEAR SLOAD # GENERATE DISPLAY DATA
LUNAFLAG
X2
## Page 660
BZE SET
+2 # 0 = EARTH
LUNAFLAG
VLOAD
RATT
STODL ALPHAV
TAT
CLEAR CALL
ERADFLAG
LAT-LONG
DMP # MPAC = ALT, METERS B-29
K.01
STORE P21ALT # ALT/100 FOR N91 DISP
EXIT
CAF V06N43 # DISPLAY LAT, LONG, ALT
TC BANKCALL # LAT, LONG = 1/2 REVS B0
CADR GOFLASH # ALT = KM B14
TC GOTOPOOH # TERM
TC GOTOPOOH
TC INTPRET # V32E RECYCLE
DLOAD DAD
P21TIME
600SEC # 600 SECONDS OR 10 MIN
STORE DSPTEM1
RTB
P21PROG1
P21PRTM RTB GOTO
LOADTIME
P21PROG2
600SEC 2DEC 60000 # 10 MIN
V06N43 VN 00643
V6N34 VN 00634
K.01 2DEC .01
