Original Apollo 11 Guidance Computer (AGC) source code for the command and lunar modules. Tracking the original at upload https://github.com/chrislgarry/Apollo-11
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# Copyright: Public domain.
# Filename: TVCINITIALIZE.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: Jim Lawton <jim.lawton@gmail.com>.
# Website: www.ibiblio.org/apollo.
# Pages: 936-944
# Mod history: 2009-05-11 JVL Adapted from the Colossus249/ file
# of the same name, using Comanche055 page
# images.
# 2009-05-20 RSB Corrections: +80 -> +8D, added 4 missing
# lines in TVCINIT1, changed the capitalization
# of a couple of the "Page N" comments,
# corrected a couple of lines in LOADCOEFF.
# 2009-05-22 RSB In LOADCOEF, DXCH N10 +14D corrected to
# TS N10 +14D. Also, various comment-marks
# were added to comments following this
# change.
#
# 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 937
# NAME TVCDAPON (TVC DAP INITIALIZATION AND STARTUP CALL)
# LOG SECTION...TVCINITIALIZE SUBROUTINE...DAPCSM
# MODIFIED BY SCHLUNDT 21 OCTOBER 1968
# FUNCTIONAL DESCRIPTION
# PERFORMS TVCDAP INITIALIZATION (GAINS, TIMING PARAMETERS, FILTER VARIABLES, ETC.)
# COMPUTES STEERING (S40.8) GAIN KPRIMEDT, AND ZEROES PASTDELV,+1 VARIABLE
# MAKES INITIALIZATION CALL TO "NEEDLER" FOR TVC DAP NEEDLES-SETUP
# PERFORMS INITIALIZATION FOR ROLL DAP
# CALLS TVCEXECUTIVE AT TVCEXEC, VIA WAITLIST
# CALLS TVCDAP CDU-RATE INITIALIZATION PKG AT DAPINIT VIA T5
# PROVIDES FOR LOADING OF LOW-BANDWIDTH COEFFS AND GAINS AT SWICHOVR
# CALLING SEQUENCE - T5LOC=2CADR(TVCDAPON,EBANK=BZERO), T5=.6SECT5
# IN PARTICULAR, CALLED BY "DOTVCON" IN P40
# MRCLEAN AND TVCINIT4 ARE POSSIBLE TVC-RESTART ENTRY POINTS
# NORMAL EXIT MODE
# TCF RESUME
# SUBROUTINES CALLED
# NEEDLER, MASSPROP
# ALARM OR ABORT EXIT MODES
# NONE
# ERASABLE INITIALIZATION REQUIRED
# CSMMASS, LEMMASS, DAPDATR1 (FOR MASSPROP SUBROUTINE)
# TVC PAD LOADS (SEE EBANK6 IN ERASABLE ASSIGNMENTS)
# PACTOFF, YACTOFF, CDUX
# TVCPHASE AND THE T5 BITS OF FLAGWRD6 (SET AT DOTVCON IN P40)
# OUTPUT
# ALL TVC AND ROLL DAP ERASABLES, FLAGWRD6 (BITS 13,14), T5, WAITLIST
# DEBRIS
# NONE
COUNT* $$/INIT
BANK 17
SETLOC DAPS7
BANK
EBANK= BZERO
TVCDAPON LXCH BANKRUPT # T5 RUPT ARRIVAL (CALL BY DOTVCON - P40)
EXTEND # SAVE Q REQUIRED IN RESTART (MRCLEAN AND
QXCH QRUPT # TVCINIT4 ARE ENTRIES)
MRCLEAN CAF NZERO # NUMBER TO ZERO, LESS ONE (MUST BE ODD)
# TVC RESTARTS ENTER HERE (NEW BANK)
+1 CCS A
TS CNTR
CAF ZERO
TS L
INDEX CNTR
DXCH OMEGAYC # FIRST (LAST) TWO LOCATIONS
CCS CNTR
TCF MRCLEAN +1
# Page 938
EXTEND # SET UP ANOTHER T5 RUPT TO CONTINUE
DCA INITLOC2 # INITIALIZATION AT TVCINIT1
DXCH T5LOC # THE PHSCHK2 ENTRY (REDOTVC) AT TVCDAPON
CAF POSMAX # +3 IS IN ANOTHER BANK. MUST RESET
TS TIME5 # BBCON TOO (FULL 2CADR), FOR THAT
ENDMRC TCF RESUME # ENTRY.
TVCINIT1 LXCH BANKRUPT
EXTEND
QXCH QRUPT
TC IBNKCALL # UPDATE IXX, IAVG/TLX FOR DAP GAINS (R03
CADR MASSPROP # OR NOUNS 46 AND 47 MUST BE CORRECT)
CAE EMDOT # SPS FLOW RATE, SCALED B+3 KG/CS
EXTEND
MP ONETHOU
TS TENMDOT # 10-SEC MASS LOSS B+16 KG
COM
AD CSMMASS
TS MASSTMP # DECREMENT FOR FIRST 10 SEC OF BURN
CAE DAPDATR1 # CHECK LEM-ON/OFF
MASK BIT14
CCS A
CAF BIT1 # LEM-ON (BIT1)
TS CNTR # LEM-OFF (ZERO)
INDEX CNTR # LOAD THE FILTER COEFFICIENTS
CAF CSMCFADR
TS COEFFADR
TC LOADCOEF
INDEX CNTR # PICK UP LM-OFF,-ON KTLX/I
CAE EKTLX/I # SCALED AT 1/(8 ASCREV) OF ACTUAL VALUE
TS KTLX/I
TCR S40.15 # COMPUTE 1/CONACC, VARK
TVCINIT2 CS CNTR # PICK LM-OFF,-ON VALUE FOR FILTER PERIOD
INDEX A # DETERMINATION:
CAF BIT2 # BIT2 FOR CSM ONLY 40MS FILTER
TS KPRIMEDT # BIT3 FOR CSM/LM 80MS FILTER
COM # PREPARE T5TVCDT
AD POSMAX
AD BIT1
TS T5TVCDT
CS BIT15 # RESET SWTOVER FLAG
# Page 939
MASK FLAGWRD9
TS FLAGWRD9
INDEX CNTR # PICK UP LEM-OFF,-ON KPRIME
CAE EKPRIME # SCALED (100 PI)/16
EXTEND
MP KPRIMEDT # (TVCDT/2, SC.AT B+14 CS)
LXCH A # SC.AT PI/8 (DIMENSIONLESS)
DXCH KPRIMEDT
INDEX CNTR # PICK UP LEM-OFF,-ON REPFRAC
CAE EREPFRAC
TS REPFRAC
INDEX CNTR # PICK UP ONE-SHOT CORRECTION TIME
CAF TCORR
TS CNTR
CAF NEGONE # PREVENT STROKE TEST UNTIL CALLED
TS STRKTIME
CAF NINETEEN # SET VCNTR FOR VARIABLE-GAIN UPDATES IN
TS VCNTR # 10 SECONDS (TVCEXEC 1/2 SEC RATE)
TS V97VCNTR # FOR ENGFAIL (R41) LOGIC
TVCINIT3 CAE PACTOFF # TRIM VALUES TO TRIM-TRACKERS, OUTPUT
TS PDELOFF # TRACKERS, OFFSET-UPDATES, AND
TS PCMD # OFFSET-TRACKER FILTERS
TS DELPBAR # NOTE, LO-ORDER DELOFF,DELBAR ZEROED
CAE YACTOFF
TS YDELOFF
TS YCMD
TS DELYBAR
ATTINIT CAE DAPDATR1 # ATTITUDE-ERROR INITIALIZATION LOGIC
MASK BIT13 # TEST FOR CSM OR CSM/LM
EXTEND
BZF NEEDLEIN # BYPASS INITIALIZATION FOR CSM/LM
CAF BIT1 # SET UP TEMPORARY COUNTER
+5 TS TTMP1
INDEX TTMP1
CA ERRBTMP # ERRBTMP CONTAINS RCS ATTITUDE ERRORS
EXTEND # ERRORY & ERRORZ (P40 AT DOTVCON)
MP 1/ATTLIM # .007325(ERROR) = 0 IF ERROR < 1.5 DEG
EXTEND
BZF +8D # |ERROR| LESS THAN 1.5 DEG
EXTEND
# Page 940
BZMF +3 # |ERROR| > 1.5 DEG, AND NEG
CA ATTLIM # |ERROR| > 1.5 DEG, AND POS
TCF +2
+3 CS ATTLIM
+2 INDEX TTMP1
TS ERRBTMP
+8 CCS TTMP1 # TEST TEMPORARY COUNTER
TCF ATTINIT +5 # BACK TO REPEAT FOR PITCH ERROR
CA ERRBTMP # ERRORS ESTABLISHED AND LIMITED
TS PERRB
CA ERRBTMP +1
TS YERRB
NEEDLEIN CS RCSFLAGS # SET BIT 3 FOR INITIALIZATION PASS AND GO
MASK BIT3 # TO NEEDLER. WILL CLEAR FOR TVC DAP
ADS RCSFLAGS # (RETURNS AFTER CADR)
TC IBNKCALL
CADR NEEDLER
TVCINIT4 CAF ZERO # SET TVCPHASE TO INDICATE TVCDAPON-THRU-
TS TVCPHASE # NEEDLEIN INITIALIZATION FINISHED.
# (POSSIBLE TVC-RESTART ENTRY)
CAE CDUX # PREPARE ROLL DAP
TS OGANOW
CAF BIT13 # IF ENGINE IS ALREADY OFF, ENGINOFF HAS
EXTEND # ALREADY ESTABLISHED THE POST-BURN
RAND DSALMOUT # CSMMASS (MASSBACK DOES IT). DON'T
EXTEND # TOUCH CSMMASS. IF ENGINE IS ON,
BZF +3 # THEN IT'S OK TO DO THE COPYCYCLE
# EVEN BURNS LESS THAN 0.4 SEC ARE AOK
CAE MASSTMP # COPYCYCLE
TS CSMMASS
+3 CAF .5SEC # CALL TVCEXECUTIVE (ROLLDAP CALL, ETC)
TC WAITLIST
EBANK= BZERO
2CADR TVCEXEC
EXTEND # CALL FOR DAPINIT
DCA DAPINIT5
DXCH T5LOC
CAE T5TVCDT # (ALLOW TIME FOR RESTART COMPUTATIONS)
TS TIME5
# Page 941
ENDTVCIN TCF RESUME
PRESWTCH TCR SWICHOVR # ENTRY FROM V46
TC POSTJUMP # THIS PROVIDES AN EXIT FROM SWITCH-OVER
CADR PINBRNCH # (PINBRNCH DOES A RELINT)
SWICHOVR INHINT
CA TVCPHASE # SAVE TVCPHASE
TS PHASETMP
CS BIT2 # SET TVCPHASE = -2 (INDICATES SWITCH-OVER
TS TVCPHASE # TO RESTART LOGIC)
+5 EXTEND # SAVE Q FOR RETURN (RESTART ENTRY POINT,
QXCH RTRNLOC # TVCPHASE AND PHASETMP ALREADY SET)
CAF NZEROJR # ZEROING LOOP FOR FILTER STORAGE LOCS
+8 TS CNTRTMP
MCLEANJR CA ZERO
TS L
INDEX CNTRTMP
DXCH PTMP1 -1
CCS CNTRTMP
CCS A
TCF SWICHOVR +8D
CS FLAGWRD9 # SET SWITCHOVER FLAG FOR DOWNLINK
MASK BIT15
ADS FLAGWRD9
CAE EKTLX/I +2 # LOW BANDWIDTH GAINS - DAP
TS KTLX/I
TCR S40.15 +7
CAF FKPRIMDT # - STEERING
TS KPRIMEDT
CAF FREPFRAC # - TMC LOOP
TS REPFRAC
EXTEND # UPDATE TRIM ESTIMATES
DCA DELPBAR
DXCH PDELOFF
EXTEND
DCA DELYBAR
DXCH YDELOFF
CA LBCFADR
# Page 942
TS COEFFADR
TC LOADCOEF
CAE PHASETMP # RESTORE TVCPHASE
TS TVCPHASE
TC RTRNLOC # BACK TO PRESWTCH OR TVCRESTARTS
LOADCOEF EXTEND # LOAD DAP FILTER COEFFICIENTS
INDEX COEFFADR # FROM: ERASABLE FOR CSM/LM HB
DCA 0 # FIXED FOR CSM/LM LB
DXCH N10 # FIXED FOR CSM
EXTEND # NOTE: FOR CSM/LM, NORMAL COEFFICIENT
INDEX COEFFADR # LOAD WILL BE HIGH BANDWIDTH PAD LOAD
DCA 2 # ERASABLES. DURING CSM/LM SWITCHOVER,
DXCH N10 +2 # THIS LOGIC IS USED TO LOAD LOW BANDWIDTH
# COEFFICIENTS FROM FIXED MEMORY.
EXTEND
INDEX COEFFADR
DCA 4
DXCH N10 +4
EXTEND
INDEX COEFFADR
DCA 6
DXCH N10 +6
EXTEND
INDEX COEFFADR
DCA 8D
DXCH N10 +8D
EXTEND
INDEX COEFFADR
DCA 10D
DXCH N10 +10D
EXTEND
INDEX COEFFADR
DCA 12D
DXCH N10 +12D
INDEX COEFFADR
CA 14D
TS N10 +14D
TC Q
# Page 943
S40.15 CAE IXX # GAIN COMPUTATIONS (1/CONACC, VARK)
EXTEND # ENTERED FROM TVCINITIALIZE AND TVCEXEC
MP 2PI/M # 2PI/M SCALED 1/(B+8 N M)
DDOUBL # IXX SCALED B+20 KG-MSQ
DDOUBL
DDOUBL
TS 1/CONACC # SCALED B+9 SEC-SQ/REV
+7 CAE KTLX/I # ENTRY FROM CSM/LM V46 SWITCH-OVER
EXTEND # SCALED (B+3 ASCREV) 1/SECSQ
MP IAVG/TLX # SCALED B+2 SECSQ
DDOUBL
DDOUBL
TS VARK # SCALED (B+3 ASCREV)
TC Q
CSMN10 DEC .99999 # N10 CSM ONLY FILTER COEFFICIENTS
DEC -.2549 # N11/2
DEC .0588 # N12
DEC -.7620 # D11/2
DEC .7450 # D12
DEC .99999 # N20
DEC -.4852 # N21/2
DEC 0 # N22
DEC -.2692 # D22/2
DEC 0 # D22
LBN10 DEC +.99999 # N10 LOW BANDWIDTH FILTER COEFFICIENTS
DEC -.3285 # N11/2
DEC -.3301 #N12
DEC -.9101 #D11/2
DEC +.8460 #D12
DEC +.03125 #N20
DEC 0 #N21/2
DEC 0 #N22
DEC -.9101 #D21/2
DEC +.8460 #D22
DEC +.50000 #N30
DEC -.47115 #N31/2
DEC +.4749 #N32
DEC -.9558 #D31/2
DEC +.9372 #D32
CSMCFADR GENADR CSMN10 # CSM ONLY COEFFICIENTS ADDRESS
HBCFADR GENADR HBN10 # HIGH BANDWIDTH COEFFICIENTS ADDRESS
# Page 944
LBCFADR GENADR LBN10 # LOW BANDWIDTH COEFFICIENTS ADDRESS
NZERO DEC 51 # MUST BE ODD FOR MRCLEAN
NZEROJR DEC 23 # MUST BE ODD FOR MCLEANJR
ATTLIM DEC 0.00833 # INITIAL ATTITUDE EROR LIMIT (1.5 DEG)
1/ATTLIM DEC 0.007325 # .007325(ERROR) = 0 IF ERROR < 1.5 DEG
TCORR OCT 00005 # CSM
+1 OCT 00000 # CSM/LM (HB,LB)
FKPRIMDT DEC .0102 # CSM/LM (LB), (.05 X .08) SCALED AT PI/8
FREPFRAC DEC .0375 B-2 # CSM/LM (LB), 0.0375 SCALED AT B+2
NINETEEN = VD1
2PI/M DEC .00331017 B+8 # 2PI/M, SCALED AT 1/(B+8 N-M)
ONETHOU DEC 1000 B-13 # KG/CS B3 TO KG/10SEC B16 CONVERSION
EBANK= BZERO
DAPINIT5 2CADR DAPINIT
EBANK= BZERO
INITLOC2 2CADR TVCINIT1