### FILE="Main.annotation"

## Copyright: Public domain.

## Filename: P61-P67.agc

## Purpose: Part of the source code for Colossus, build 249.

## It is part of the source code for the Command Module's (CM)

## Apollo Guidance Computer (AGC), for Apollo 9.

## Assembler: yaYUL

## Reference: pp. 743-772.

## Contact: Ron Burkey <info@sandroid.org>.

## Website: www.ibiblio.org/apollo.

## Mod history: 08/17/04 RSB. Began transcribing.

## 2010-10-24 JL Indentation fixes.

## 2010-10-24 JL Fixed a pseudo-label on p751.

## 2010-10-25 JL Fixed page number.

## 2011-05-07 JL Flagged SBANK= workarounds for future removal.

## Fixed garbled lines.

## 2017-01-06 RSB Page numbers now agree with those on the

## original harcopy, as opposed to the PDF page

## numbers in 1701.pdf.

## 2017-01-18 RSB Cross-diff'd comment text (not whitespace)

## vs the already-proofed corresponding Colossus

## 237 and Comanche 55 source-code files

## and corrected errors found.

## 2017-02-08 RSB Fixed comment-text errors noted while diff'ing

## vs Artemis 72.

##

## The contents of the "Colossus249" files, in general, are transcribed

## from a scanned copy of the program listing. Notations on this

## document read, in part:

##

## Assemble revision 249 of AGC program Colossus by NASA

## 2021111-041. October 28, 1968.

##

## This AGC program shall also be referred to as

## Colossus 1A

##

## Prepared by

## Massachusetts Institute of Technology

## 75 Cambridge Parkway

## Cambridge, Massachusetts

## under NASA contract NAS 9-4065.

##

## Refer directly to the online document mentioned above for further information.

## Please report any errors (relative to the scanned pages) to info@sandroid.org.

##

## In some cases, where the source code for Luminary 131 overlaps that of

## Colossus 249, this code is instead copied from the corresponding Luminary 131

## source file, and then is proofed to incorporate any changes.

## Page 743

# PROGRAM: P61

# MOD NO.: 0 MAR. 13, 1967

# MOD BY: R. HIRSCHKOP

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 22 JUN 67 RESTARTS.

# MOD NO: 2 MOD BY: RR BAIRNSFATHER DATE: 17 JAN 68 COLOSSUS GSOP CHANGES.

# MOD NO: 3 MOD BY: RR BAIRNSFATHER DATE: 8 MAY 68 DELETE CMSM MANEUVER (PCR 50)

# FUNCTION: TO CALCULATE AND DISPLAY EMS INITIALIZATION DATA

# CALLING SEQUENCE- BY V37

# EXIT- TO P62

# SUBROUTINE CALLS- S61.1, S61.3, GOFLASH, FLAGUP, R02BOTH

# ERASABLE INITIALIZATION:

# EMSALT (-29) M .05G ALTITUDE ABOVE FISCHER ELLIPSOID PAD LOADED.

# ALFAPAD /180 HYPERSONIC CM TRIM ANGLE OF ATTACK PAD LOADED

# OUTPUT: THE FOLLOWING REGISTERS ARE WRITTEN IN FOR USE BY DISPLAYS

# GMAX 100 GMAX (-14) G,S MAXIMUM ACCELERATION

# VPRED (-7) M/CS PREDICTED VELOCITY AT 400K FT

# GAMMAEI GAMMA/360 PREDICTED GAMMA AT 400K FT

# RTGO THETAH/360 RANGE ANGLE TO SPLASH FROM EMSALT EMSALT IS PAD LOADED

# VIO (-7) M/CS INERTIAL VELOCITY AT EMSALT EMSALT IS PAD LOADED

# TTE (-28) CS TIME TO EMSALT EMSALT IS PAD LOADED

# LAT(SPL) /360 TARGET LOCATION LEFT BY DSKY

# LNG(SPL) /360 TARGET LOCATION LEFT BY DSKY

# HEADSUP (0) +1 = LIFT DOWN, -1 = LIFT UP LEFT BY DSKY

# DEBRIS: SEE SUBROUTINES.

BANK 26

SETLOC P60S

BANK

EBANK= AOG

COUNT* $$/P61

P61 CA BIT14 # EXTENDED VERB SHOULD BE FREE THIS CLOSE

TS EXTVBACT # TO V37

# LOCK OUT EXTENDED VERBS SO CAN USE TFF

# ROUTINES. EXT VERB ERASE IS USED

CS ONE # REMOVE IF HEADSUP EVER ON UPLINK DATA

TS HEADSUP # PRELOAD

TC S61.1 # CHECK STATE VECTOR AND IMU ORIENTATION

# RV 60GENRET. DOES PHASCHNG, GROUP 4.

CA V06N61 # LAT(SPL) LNG(SPL) HEADSUP

# XXX.XX DEG XXX.XX DEG XXXXX.

TC BANKCALL

CADR GOFLASHR

TC GOTOPOOH

## Page 744

TC P61.4

TC -5

P61.3 TC PHASCHNG

OCT 00014

TC ENDOFJOB

P61.4 ZL

CCS HEADSUP # C(HEADSUP)= +1/-1

CA BIT14 # IF HEADSUP POS,ROLLC =180 DEG.(LIFT DWN)

NOOP # IF HEADSUP NEG,ROLLC =0 (LIFT UP)

DXCH ROLLC # ROLLC IS USED BY S62.3: GIM ANG AT .05G

TC INTPRET

NEWRNVN DLOAD

PIPTIME # SAVE TIME OF RN,VN TO DETERMINE IF AN

STCALL MM # UPDATE HAS OCCURRED

STARTEN1 # INITIALIZE

VLOAD

RN

STORE RONE

UNIT

STOVL URONE

VN

STORE VONE

VXV UNIT

URONE

STORE UNI

DUMPP61 DLOAD DSU

MM # INITIAL VALUE OF PIPTIME

PIPTIME

BMN CALRB

NEWRNVN # UPDATED... GO TRY AGAIN

S61.2 # GET DISPLAY DATA FOR N60 AND N63

# AND RETURN IN BASIC, BELOW.

P61.1 TC CLEARMRK

CA V06N60 # GMAX VPRED GAMMAEI

# XXX.XX G XXXXX. FPS XXX.XX DEG

TC BANKCALL

CADR GOFLASH

TC GOTOPOOH

TC P61.2 # PROCEED

TC -5

P61.2 TC INTPRET # CORRECT TTE FOR TIME LAPSE DURING

# ABOVE DISPLAY.

RTB DSU

LOADTIME # CURRENT TIME.

## Page 745

MM # PIPTIME FOR RONE & VONE.

DAD

TTE1 # NEGATIVE OF FREE FALL TIME.

STORE TTE # DECREMENTED

EXIT

CA V06N63 # RTGO VIO TTE

# XXXX.X NM XXXXX. FPS XXBXX M,S

TC BANKCALL

CADR GOFLASH

TC GOTOPOOH

TC +2

TC P61.2 # REDO

# .... THEN FALL INTO P62

## Page 746

# PROGRAM- P62

# MOD NO.- 0 MAR. 13, 1967

# MOD BY- R. HIRSCHKOP

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 21 MAR 67

# MOD NO: 2 MOD BY: RR BAIRNSFATHER DATE: 22 JUN 67 RESTARTS.

# MOD NO: 3 MOD BY: RR BAIRNSFATHER DATE: 17 JAN 68 COLOSSUS GSOP CHANGES.

# MOD NO: 4 MOD BY: RR BAIRNSFATHER DATE: 8 MAY 68 MOVE START OF DESIRED GIMBAL CALC.

# FUNCTION- 1) TO NOTIFY CREW WHEN GNC SYSTEM IS PREPARED FOR CM/SM SEPARATION

# 2) TO ORIENT THE CM TO THE CORRECT ATTITUDE FOR ATMOSPHERIC ENTRY

# CALLING SEQUENCE- BY V37 OR DIRECTLY FROM P61

# EXIT- TO P63

# ERASABLE INITIALIZATION:

# ALFAPAD LEFT BY PAD LOAD

# LADPAD LEFT BY PAD LOAD

# LODPAD LEFT BY PAD LOAD

# LAT(SPL) (MAY BE CHANGED BELOW) LEFT BY DSKY, VIA P61

# LNG(SPL) (MAY BE CHANGED BELOW) LEFT BY DSKY, VIA P61

# HEADSUP (MAY BE CHANGED BELOW) LEFT BY DSKY, VIA P61

# SUBROUTINE CALLS: NEWMODEX, S61.1, CM/DAPIC, CM/DAPON, R02BOTH, GOPERF1, GOFLASH, GODSPR

COUNT* $$/P62

TC NEWMODEX # MODE CHANGE IF CAME FROM P61.

MM 62 # MODE CHANGE AUTOMATIC VIA V 37.

CA ONE

TS DNLSTCOD

P62 TC S61.1 # CHECK STATE VECTOR AND IMU ORIENTATION.

TC INTPRET

SSP RTB

POSEXIT

P62.3 # CALCULATE DESIRED .05G GIMBAL ANGLES,

# WITHOUT DISPLAY.

CM/DAPIC # START CM/POSE AND BODY RATE CALC

# DOES 2PHSCHNG, OCT 40116, OCT 05024, OCT 13000.

# CM/DAPIC SETS EBANK = EBAOG

# AND RETURNS IN BASIC TO P62.2.

P62.2 EXTEND

DCA POSECADR # CONTINUE WITH CM/POSE AFTER AV G.

DXCH AVEGEXIT

CAF OCT41 # REQUEST SEPARATION

TC BANKCALL

CADR GOPERF1R

TC GOTOPOOH

TC +3 # PROCEED

## Page 747

# NOTE: NODOFLAG WILL BE SET IN CM/DAPON. <<<

TC -5 # ENTER

TC P61.3 # FOR PHASCHNG AND ENDOFJOB.

+3 TC POSTJUMP

CADR CM/DAPON # DISABLE RCS DAP, ENABLE ENTRY DAP AND

# DO ATTITUDE HOLD.

# WILL IDLE UNTIL CM/POSE DOES ONE UPDATE.

# CM/DAPON DOES NO PHASCHNG.

P62.1 CA V06N61 # LAT(SPL) LNG(SPL) HEADSUP

# XXX.XX DEG XXX.XX DEG 0000X.

# TERMINATE ATTITUDE HOLD. SET UP COMMANDS:

# ROLLC, ALFACOM, BETACOM. BEGIN MANUVER TO

# ENTRY ATTITUDE.

TC BANKCALL

CADR GOFLASH

TC -3

TC +2

TC -5

TC PHASCHNG

OCT 04024 # USE ENTRYVN FOR DISPLAY BELOW.

# EBANK WAS SET IN CM/DAPON TO EBAOG

CCS HEADSUP # C(HEADSUP) = +/- 1

CA BIT14 # IF HEADSUP POS, ROLLC=180 DEG (LIFT DWN)

NOOP # IF HEADSUP NEG, ROLLC=0 DEG (LIFT UP)

TS ROLLC

CA ALFAPAD # NOMINAL ALFATRIM PAD LOADED, NEG. NO.

ZL

DXCH ALFACOM # SET ALFACOM = ALFA TRIM, BETACOM=0

CA ONE # PERMITS EXDAP2 TO CHANGE FLAG TO +0

TS P63FLAG # AS INDICATOR. STARTS UP P63.

CA V06N22 # SET UP DISPLAY FOR CDU DESIRED VALUES

TS ENTRYVN # FROM ENTRY ATTITUDE CALC, THAT IS

# ALREADY GOING.

TC UPFLAG # TURN ON ENTRY DISPLAY

ADRES ENTRYDSP # ENTRYDSP = 92D BIT 13 FLAG 6

# SKIP

## Page 748

CS CMDAPMOD # GO DIRECTLY TO P63 IF BODY ATTITUDE

MASK ONE # IS SUCH THAT THE DELAY TASK: WAKEP62

EXTEND # WILL BE OMITTED.

BZF P63.1 # DISABLE GRP 4, GO TO ENDOFJOB.

# (IE, CONTINUE IF CMDAPMOD = -1, OR +0)

TC P63

# PUT JOB TO SLEEP UNTIL VEHICLE MANUVER HAS

# REDUCED ALFA TO +/-45 DEG. CONSIDER REMAINING

# 65 DEG (25 DEG IF ALFA NEG) TO ALFA TRIM TO

# OCCUR AT 3 DEG/SEC, AND TERMINATE P62 AT THAT

# TIME.

# TASK WAKEP62 IS CALLED FROM ENTRY DAP.

WAKEP62 CA PRIO13

TC NOVAC

EBANK= AOG

2CADR P63

TC TASKOVER

P62.3CAD CADR P62.3

# EACH 2 SEC, CALCULATE GIMBAL ANGLES FOR ENTRY CON-

# DITIONS THAT WILL HOLD IF REORIENTATION WERE MADE

# AT PRESENT RN, VN. COME HERE FROM CM/POSE AND ALSO

# IN KEPLER PHASE OF ENTRY.

P62.3 SSP GOTO # SET RETURN ADDRESS SO THAT ROUTINE

QPRET # GOES DIRECTLY TO ENTRY GUIDANCE EXIT

ENDEXIT # THAT DOES ENTRY DISPLAY, GRP 5.

S62.3 # PUT DESIRED CDU VALUES IN CPHI'S FOR

# N22 DISPLAY.

## Page 749

# P63

# PROGRAM- P63

# MOD NO.- 0 MAR. 13, 1967

# MOD BY- R. HIRSCHKOP

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 22 JIN 67 RESTARTS.

# MOD NO: 2 MOD BY: RR BAIRNSFATHER DATE: 14 JUL 67 REVISED RESTARTS

# FUNCTION- 1) TO INITIALIZE THE ENTRY EQUATIONS

# 2) TO CONTINUE TO HOLD THE CM TO THE CORRECT ATTITUDE WITH RESPECT TO THE ATMOSPHERE FOR

# THE ONSET OF ENTRY DECELERATION. ROLL ANGLE IS LIFT UP/DOWN AS SPECIFIED BY HEADSUP.

# 3) TO SENSE .05 G

# CALLING SEQUENCE- DIRECTLY FROM P62

# EXIT- TO ENDOFJOB

# SUBROUTINE CALLS- NEWMODEX, GODSPR

COUNT* $$/P63

P63 TC NEWMODEX

MM 63

TC BANKCALL # FLUSH N22 DISPLAY, IF ON. (ONIT DISP

CADR CLEANDSP # DURING STARTENT PASS.)

# ARRIVE WITH EBANK = AOG.

CA ENTCADR # CONTINUE AT STARTENT AFTER CM/POSE.

# AT END OF STARTENT, CHANGE ADDRESS IN GOTOADDR

# TO CONTINUE AT SCALEPOP THEREAFTER.

TS POSEXIT

CA V06N64 # G VI R TO SPLSH

# XXX.XX G XXXXX. FPS XXXX.X NM

TS ENTRYVN # FOR DISPLAY CALL IN OVERNOUT.

CS ONE # IN CASE FLAG IS LEFT AT +1 BY DAP. THE

TS P63FLAG # -1 ASSURES THAT EXO-ATM DAP WILL NOT

# CALL P63 OUT OF SEQUENCE IN P66.

P63.1 TC PHASCHNG

OCT 00004 # DISABLE. DISPLAY RESTARTED VIA ENTRY.

TC ENDOFJOB

V06N60 VN 0660

V06N61 VN 0661

V06N63 VN 0663

V06N64 VN 0664

ENTCADR CADR STARTENT

## Page 750

EBANK= RTINIT # TO CARY OVER INTO ENTRY STEERING.

POSECADR 2CADR CM/POSE

## Page 751

# PROGRAM- P64

# MOD NO.- 1 SEPT. 19, 1967

# MOD BY- R. HIRSCHKOP

# MOD NO: 2 MOD BY: RR BAIRNSFATHER DATE: 8 MAY 68 REVISED COMMENTS FOR COLOSSUS

# FUNCTION- 1. TO START ENTRY GUIDANCE AT .05G SELECTING ROLL ATTITUDE, CONSTANT DRAG LEVEL, AND

# DRAG THRESHOLD, KA, WHICH ARE KEYED TO THE .05G POINT.

# 2. SELECT FINAL PHASE P67 IF V < 27000 FPS WHEN .2G OCCURS.

# 3. ITERATE FOR UP-CONTROL SOLUTION P65 IF V > 27000 FPS AND IF ALTITUDE RATE AND DRAG

# LEVEL CONDITIONS ARE SATISFIED. ENTER P65 WHEN CONSTANT DRAG CONTROLLER HAS BROUGHT RANGE

# AS PREDICTED TO WITHIN 25 NM OF DESIRED RANGE.

# 4. SELECT FINAL PHASE P67 IF NO UP-CONTROL SOLUTION EXISTS WITH VL > 18000 FPS.

# CALLING SEQUENCE- BY RTB FROM REENTRY CONTROL

# EXIT- BACK TO REENTRY CONTROL

# SUBROUTINE CALLS- NEWMODEX

BANK 25

SETLOC P60S1

BANK

# THIS DISPLAY IS CALLED EACH PASS THROUGH STEERING. RESTART PROTECTION IS VIA STEERING.

COUNT* $$/P64

P64 TC NEWMODEX # ENTER VIA RTB WHEN .05G IS EXCEEDED.

MM 64

CA V06N68 # ROLLC VI HDOT

# XXX.XX DEG XXXXX. FPS XXXXX. FPS

TS ENTRYVN # DISPLAY VIA OVERNOUT.

TC DANZIG # ... AND CONTINUE IN INITROLL ...

V06N68 VN 0668

## Page 752

# PROGRAM: P65

# MOD NO: 0 MOD BY: RR BAIRNSFATHER DATE: 17 JAN 68 COLOSSUS GSOP ADDITION.

# FUNCTION: TO CONTINUE ENTRY GUIDANCE, USING THE UP-CONTROL PHASE TO STEER TO A CONTROLLED EXIT

# CONDITION. THIS PHASE TERMINATES A) IF D < Q7 FPSS, GO TO P66 ,

# B) IF RDOT NEG, AND IF V < VL +500 FPS, GO TO P67.

# CALLING SEQUENCE: BY RTB FROM REENTRY CONTROL

# EXIT: BACK TO REENTRY CONTROL, OR TO ENDOFJOB.

# SUBROUTINE CALLS: NEWMODEX

COUNT* $$/P65

P65 TC NEWMODEX # ENTER VIA RTB WHEN RANGE < 25 N M OF

MM 65 # TARGET.

CA PRIO13

TC NOVAC

EBANK= ENTRYVN

2CADR P65.1

TC 2PHSCHNG # 2 PHASE CHG REQUIRED TO PREVENT RE-

OCT 00554 # STARTING FLASHING DISPLAY TWICE.

OCT 10035 # 4.55 SPOT AND SERVICER, HERE.

TC INTPRET

SSP RTB

GOTOADDR # CHANGE ENTRY MODE TO UPCONTRL.

UPCONTRL

REFAZE10 # GO HERE TO REESTABLISH ENTRY SEQUENCER.

# AND CONTINUE AT UPCONTRL...

P65.1 TC DOWNFLAG

ADRES ENTRYDSP # ENTRYDSP = 92D BIT 13 FLAG 6

CA V16N69 # ROLLC DL (Q7) VL

TC BANKCALL # XXX.XX DEG XXX.XX G XXXXX. FPS

CADR GOFLASHR

TC -3 # NODOFLAG IS SET ..

TC +3

TC -5

TC P61.3 # EST. GRP 4 FOR DSPLAY AND DO ENDOFJOB

# IF PROCEED, CONTINUE.

TC UPFLAG

ADRES ENTRYDSP # ENTRYDSP = 92D BIT 13 FLAG 6

TC P63.1 # DISABLE GRP 4, START UP ENTRY DISPLAY

# N06V68 VIA OVERNOUT, AS USED IN P64.

V16N69 VN 1669

## Page 753

# PROGRAM: P66

# MOD NO: 0 MOD BY: RR BAIRNSFATHER DATE: 17 JAN 68 COLOSSUS GSOP ADDITIONS.

# FUNCTION: KEEP CM ATTITUDE IN TRIM TO THE RELATIVE VELOCITY VECTOR. ENTRY GUIDANCE STOPS GENERATING

# ROLL COMMANDS UNTIL DRAG BUILDS UP TO Q7+0.5 FPSS.

# CALLING SEQUENCE: VIA RTB FROM REENTRY CONTROL.

# EXIT: BACK TO REENTRY CONTROL.

# SUBROUTINE CALLS: NEWMODEX

COUNT* $$/P66

P66 TC NEWMODEX # ENTER VIA RTB WHEN D < Q7 FPSS

MM 66

CA V06N22 # OGA IGA MGA

# XXX.XX DEG XXX.XX DEG XXX.XX DEG

TC P66END # IN CASE CAME FROM P65, GO DISABLE GRP 4,

# AND SET ENTRYDSP TO DO DISPLAY VIA

# OVERNOUT.

# ... AND CONTINUE AT KEP2

## Page 754

# P67

# PROGRAM- P67

# MOD NO.- 0 MAR. 16, 1967

# MOD BY- R. HIRSCHKOP

# FUNCTION- TO TERMINATE STEERING WHEN THE CM VELOCITY WRT EARTH = 1000 FT/SEC

# CALLING SEQUENCE-

# EXIT- TO POOH

# SUBROUTINE CALLS- GOFLASH

# THIS DISPLAY IS CALLED EACH PASS THROUGH STEERING. RESTART PROTECTION IS VIA STEERING.

COUNT* $$/P67

P67 TC NEWMODEX # ENTER VIA RTB

MM 67

CA V06N66 # ROLLC XRNGERR DNRNGERR

# XXX.XX DEG XXXX.X NM XXXX.X NM

P66END TS ENTRYVN # DISPLAY VIA OVERNOUT.

TC UPFLAG # (IN CASE CAME FROM P65. ENTRY DISPLAY

ADRES ENTRYDSP # WILL FLUSH FLASHING DISP. IF STILL ON)

# BIT 13 FLAG 6

KILLGRP4 TC PHASCHNG # DISABLE GRP4, IN CASE CAME FROM HUNTEST.

OCT 00004 # (COME TO KILLGRP4 VIA RTB, RET TO CALLER)

TC DANZIG # ... AND CONTINUE AT PREDICT3 ...

V06N66 VN 0666

BANK 26

SETLOC P60S2

BANK

P67.1 CA V16N67 # RTOGO LAT LONG

# XXXX.X NM XXX.XX DEG XXX.XX DEG

TC BANKCALL

CADR GOFLASH

TC +3 # EFFECTIVE GOTOPOOH

TC +2

TC P67.1 # REDO

CS THREE # TURN OFF ENTRY DAP

INHINT

MASK CM/FLAGS # CM/DSTBY, GAMDIFSW

TS CM/FLAGS

RELINT

EXTEND

DCA SERVCAD2

## Page 755

DXCH AVEGEXIT

TCF GOTOPOOH

## Page 756

P67.2 VLOAD CLEAR # CALC PRESENT LAT, LONG, ALT.

RN

ERADFLAG # USE PAD RAD FOR ALT. (NOT SEEN ANYWAY)

STODL ALPHAV

PIPTIME # USE TIME OF RN

CLEAR CALL

LUNAFLAG

LAT-LONG

P67.3 RTB # ENTRY EXIT THAT OMITS DISPLAY.

SERVNOUT

V16N67 VN 1667

OCT41 = 33DEC

SERVCAD2 = SERVCAD1

## Page 757

# SUBROUTINE NAME: S61.1

# MOD NO: 0 DATE: 21 FEB 67

# MOD BY: RR BAIRNSFATHER LOG SECTION: P61-P67

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 22 JUN 67 RESTARTS.

#

# FUNCTIONAL DESCRIPTION: CALLED BY BOTH P61 AND P62

# FIRST, TEST TO SEE IF AVERAGEG IS ON. IF NOT, UPDATE THE STATE VECTOR TO PRESENT TIME + TOLERANCE

# AND TURN ON AVERAGEG AT THAT TIME, AND CONTINUE. OTHERWISE CONTINUE: SEE IF IMU Y AXIS IS

# WITHIN 30 DEG OF V*R. IF YES, EXIT SUBROUTINE S61.1. IF NO, SEE IF -Y AXIS OF IMU IS WITHIN

# 30 DEG OF V*R. IF YES, DISPLAY ALARM: 01427 IMU REVERSED.

# IF NO, DISPLAY ALARM: 01426 IMU UNSATISFACTORY.

# IN EITHER OF THESE LAST 2 CASES, WAIT 10 SEC AND THEN EXIT SUBROUTINE S61.1.

#

# REMARK: THERE WILL BE A SHORT 10 SEC DELAY IF AN ALARM EXIT IS TAKEN. THE DELAY FOR INTEGRATION IS

# AS SHORT AS CAN BE MADE, BUT IS ARBITRARY SINCE IT DEPENDS ON THE AGE OF THE STATE VECTOR.

#

# CALLING SEQUENCE: CALL

# S61.1

#

# C(MPAC) UNSPECIFIED

# PUSHLOC UNSPECIFIED

#

# SUBROUTINES CALLED: LOADTIME, CSMPREC, TPAGREE,

# WAITLIST, JOBSLEEP, JOBWAKE, PREREAD, ALARM, GODSPR, BANKCALL, DELAYJOB

#

# NORMAL EXIT MODES: RVQ

#

# ALARMS: 01426 IMU UNSATISFACTORY

# 01427 IMU REVERSED

#

# OUTPUT: POSSIBLE ALARMS

# POSSIBLY TDEC1, RATT, VATT, RN, VN

#

# ERASABLE INITIALIZATION REQUIRED:

# AVEGFLAG AVERAGEG ON OR OFF LEFT BY SERVICER

# PIPTIME (-28) CS TIME OF PIPA UPDATE LEFT BY READACCS

# RN (-29) M STATE VECTOR LEFT BY AVERAGEG

# VN (-7) M/CS STATE VECTOR LEFT BY AVERAGEG

# REFSMMAT (-1) .5 REF TO SM MATRIX LEFT BY LAST IMU ALIGNMENT

#

# DEBRIS: QPRET

# POSSIBLY PIPTIME1, RATT, VATT, TDEC1, RN1, VN1, QTEMP, X1 IF UPDATED

# PUSH LIST LOCS USED BY CSMPREC

EBANK= AOG # FOR 60GENRET, S61DT

BANK 26

SETLOC P60S3

BANK

COUNT* $$/S61.1

S61.1 EXTEND

QXCH 60GENRET # SAVE RET ADDR IN EB 6

TC BANKCALL

CADR R02BOTH

TC INTPRET

## Page 758

BON CALRB

AVEGFLAG # IS AVERAGEG ON

S61.1A # YES

MIDTOAV2 # GET FUTURE STATE VECTOR SOON AS CAN

CA MPAC +1 # RETURN INHINTED ***

TS S61DT # FOR RESTART.

TC WAITLIST

EBANK= DVCNTR

2CADR S61.1C

TC PHASCHNG

OCT 40434

TC ENDOFJOB

S61.1C CA PRIO13

TC FINDVAC

EBANK= AOG

2CADR S61.1A -1

EXTEND

DCA SERVCAD1 # HE WHO STARTS AVERAGEG MUST SERVICE

DXCH AVEGEXIT # THE EXIT.

TC 2PHSCHNG

OCT 00454

OCT 00415

CA EBENTRY # SET EB= 7 FOR PREREAD.

TS EBANK

TC POSTJUMP

CADR PREREAD # PREREAD DOES TC TASKOVER.

TC INTPRET

S61.1A BOVB VLOAD

TCDANZIG # TURN OFF OVFIND, IF ON

VN # VN (-7) M/CS

VXV MXV

RN # RN (-29) M

REFSMMAT # .5 UNIT MATRIX

UNIT DLOAD

MPAC +3 # GET COS(THETA)/2

BMN DAD

S61.1B # DO TEST ON -YSM

C(30)LIM # = 1.0 -.5 COS(30)

BOVB RTB

RETRN1

RETRN3

## Page 759

S61.1B DCOMP DAD

C(30)LIM # = 1.0 - .5 COS(30)

BOVB EXIT

RETRN2

RETRN3 TC ALARM

OCT 01426 # IMU UNSATISFACTORY

TC RETRN2 +2

RETRN2 TC ALARM

OCT 01427 # IMU REVERSED

+2 CAF V05N09

TC BANKCALL

CADR GODSPR # DO DISPLAY

CA 10SECS

TC BANKCALL

CADR DELAYJOB

RETRN1 TC 60GENRET

EBANK= DVCNTR

SERVCAD1 2CADR SERVEXIT

C(30)LIM 2DEC .566985 # = 1.0 - .5 COS(30)

10SECS DEC 1000 # 1000 CS

60SECDP 2DEC 6000 B-28 # 6000 CS

## Page 760

# PROGRAM NAME: S61.2 DATE: 14 FEB 67

# MOD NO: 1 LOG SECTION: P61-P67

# MOD BY: MORTH / BAIRNSFATHER

# MOD NO: 2 MOD BY: MORTH/BAIRNSFATHER DATE: 11 MAY 67 ADD 2ND ITER FOR ERAD AT 400K FT.

# MOD NO: 3 MOD BY: RR BAIRNSFATHER DATE: 21 NOV 67 VARIABLE MU ADDED.

# MOD NO: 4 MOD BY: RR BAIRNSFATHER DATE: 21 MAR 68 DIFFERENT EARTH/MOON SCALES IN TFF'S

#

# FUNCTIONAL DESCRIPTION: CALLED BY P61. PROVIDES DISPLAYS FOR NOUNS N60 AND N63.

# PROGRAM CALCULATES ENTRY DISPLAY OF MAXIMUM ACCELERATION EXPECTED (GMAX) AND ALSO THE EXPECTED

# INERTIAL VELOCITY (VPRED) AND ENTRY ANGLE (GAMMAEI) THAT WILL OBTAIN AT 400K FT ABOVE THE FISCHER

# ELLIPSOID. PROGRAM ALSO CALCULATES A SECOND DISPLAY RELATIVE TO THE EMSALT ABOVE FISCHER ELLIPSOID

# AND CONSISTS OF RANGE TO SPLASH FROM NOW (RTGO), PREDICTED INERTIAL VELOCITY (VIO), AND THE TIME TO

# GO FROM NOW (TTE) .

#

# CALLING SEQUENCE: CALL

# S61.2

# C(MPAC) UNSPECIFIED

# PUSHLOC WILL BE SET TO ZERO.

#

# SUBROUTINES CALLED: TFFCONIC, CALCTFF, TFF/TRIG, FISHCALC, GETERAD, VGAMCALC

#

# NORMAL EXIT MODES: RTB P61.1

#

# ALARMS: NONE

#

# OUTPUT: THE FOLLOWING REGISTERS ARE WRITTEN IN FOR USE BY DISPLAYS

# GMAX 100 GMAX (-14) G,S MAXIMUM ACCELERATION

# VPRED (-7) M/CS PREDICTED VELOCITY AT 400K FT

# GAMMAEI GAMMA/360 PREDICTED GAMMA AT 400K FT

# FOR TM, DP(GAMMAEI) = (GAMMAEI, RTGO) / 360

# RTGO THETAH/360 RANGE ANGLE TO SPLASH FROM EMSALT EMSALT IS PAD LOADED

# VIO (-7) M/CS INERTIAL VELOCITY AT EMSALT EMSALT IS PAD LOADED

# TTE (-28) CS TIME TO EMSALT EMSALT IS PAD LOADED

# PUSHLOC = 0

# CONIC PARAMETERS STORED IN VAC AREA (SEE TFF SUBROUTINES)

#

# ERASABLE INITIALIZATION REQUIRED:

# RONE (-29) M STATE VECTOR LEFT BY USER

# VONE (-7) M/CS STATE VECTOR LEFT BY USER

# URONE UR/2 LEFT BY USER

# UNI (-1) UNIT NORMAL V*R LEFT BY ENTRY / P61

# THETAH THETAH/360 RANGE ANGLE LEFT BY ENTRY / P61

# UNITW (0) UNIT POLAR VECTOR LEFT BY PAD LOAD

# EMSALT (-29) M EMS INTERFACE ALTITUDE LEFT BY PAD LOAD

# ORBITAL REENTRY: 284643 FT, LUNAR REENTRY: 297431 FT.

#

# DEBRIS: QPRET,

# ALL PDL LOCATIONS ABOVE 12D, INCLUDING X1,X2,S1,S2

# ALSO PDL+0 ... PDL+5, WHERE INITIAL PUSHLOC = PDL

## Page 761

# THE FOLLOWING PUSH LIST LOCATIONS HAVE BEEN RESERVED FOR TFF ROUTINES AND ARE REPEATED HERE FOR CONVENIENCE.

# OF COURSE FOR S61.2 USAGE, EARTH ORIGIN SCALING IS USED.

#

# BELOW E: IS USED FOR EARTH ORIGIN SCALE

# M: IS USED FOR MOON ORIGIN SCALE

#

# RTERM = 18D TERMINAL RADIUS M E: (-29) M: (-27)

# NRTERM = 16D TERMINAL RADIUS M E: (-29+NR)

# M: (-27+NR)

# RMAG1 = 12D PRESENT RADIUS M E: (-29) M: (-27)

# NRMAG = 32D PRESENT RADIUS M E: (-29+NR)

# M: (-27+NR)

# SDELF/2 SIN(THETA) / 2

# CDELF/2 = 14D COS(THETA) / 2

# TFFX = 34D X, ARGUMENT OF SERIES T(X).

# TFFTEM = 36D ARG FOR TRANSFER ANGLE CALCULATION.

# TFFNP = 28D LC P M E: (-38+2NR) M: (-36+2NR)

# TFF/RTMU= 30D 1/SQRT(MU) E: (17) M: (14)

# TFFVSQ = 20D -(VN.VN/MU) 1/M E: (20) M: (18)

## Page 762

BANK 34

SETLOC P60S2

BANK

COUNT* $$/S61.2

# PDL LEFT AT ZERO BY TARGETNG

S61.2 DLOAD DSU

EMSALT

290KFT

BPL DLOAD

LUNENT

1/RTMU # ESTABLISH MU FOR ORBITAL ENTRIES

CALLCON CALL

TFFCONIC # FILL VAC AREA WITH CONIC PARAMETERS

DLOAD CALL

RTRIAL # 1ST GUESS AT TERMINAL RADIUS (-29)

CALCTFF # SAVES MPAC IN RTERM (18D)

CALL # CALC SDELF/2, CDELF/2

TFF/TRIG # RETURN WITH S(THETA) IN MPAC

CALL # GET FISCHER RADIUS (-29) M

FISHCALC # ANS IN MPAC AND IN ERADM.

DAD CALL

EMSALT

CALCTFF # SAVES MPAC IN RTERM (18D)

DCOMP # NEGATIVE AS IN COUNTDOWN.

STORE TTE1 # DECR TTE FROM BASE TTE1. (RESTART)

# DNLIST AND DSKY WILL USE TTE.

STCALL TTE # LET MISS CONTRL DECR BY ELAPSED TIME

# TTE= TIME FROM NOW TO EMSALT +FISCHER

TFF/TRIG # S(THETA) IN MPAC ON RETURNING

# AND THETA= RANGE FROM NOW TO EMSALT

CALL

FISHCALC

CALL

VRCALC

CALL

DISPTARG

CALL

DISPTARG

STCALL RTGO

## Page 763

VGAMCALC

DMP # MPAC = GAMMA

# PDL0 HAS VGAM.

BDDV DAD

VEMSCON # -HS D 180/PI (-14)

0 # VGAM FROM PDL0.

STODL VIO # PREDICTED VELOCITY AT EMSALT.

# GAMMA AND VGAM AT 300K FT ARE REQUIRED BY GMAX

# ALGORITHM.

ERADM # EARTH RADIUS FROM GETERAD (-29) M

# = FISCHER RADIUS (-29)

DAD

300KFT # M (-29)

STCALL RTERM # TERMINAL RADIUS M (-29)

PREVGAM # VGAMCALC WITH NEW RTERM

# VBAR = (V(FPS) - 36KF/S) / 20KF/S

# GMAX = (4/(1 + 4.8 VBARSQ))(GAM - 6.05 - 2.4 VBARSQ) - 10(L/D - .3) + 10 ASSUME L/D = 0.3, BANK =0.

# GMAXCALC

PDDL DSU # GAM TO PDL2

0 # VGAM IS IN PDL0 (-7)

36KFT/S # (-7) M/CS

DDV DSQ

20KFT/S # (-6) M/CS

STORE 0 # VBARSQ (-2) TO PDL0

DMP DAD

KR1

# GAM, POS DOWN, FROM PDL2

DAD DMP

-6.05DEG

KR2

PDDL # XCH PDL+0 FOR VBARSQ (-2)

DDV DAD

KR4

DP2(-4)

BDDV

# NUM FROM PDL+0

DAD BPL

KR3

+3

DLOAD

HI6ZEROS

STODL GMAX # 100 GMAX (-14)

## Page 764

# DISPLAY USES GMAX AS SP, SO LO WORD IS WRITTEN OVER BY VPRED.

ERADM # = FISCHER RADIUS (-29) M

DAD CALL # 2 ND ITERATION FOR FISCHER RADIUS

400KFT

CALCTFF # ESTABLISH TRANSFER ANGLE DATA.

CALL

TFF/TRIG # GET SIN, COS DELF

CALL

FISHCALC # GET CORRESPONDING FISCHER RADIUS.

DAD LXA,2 # SAVE HI-WORD FOR DOWNLIST.

400KFT # M (-29)

RTGO # (RANGE ANGLE FROM EMSALT) / 360

STCALL RTERM

PREVGAM # VGAMCALC WITH NEW RTERM

DCOMP SXA,2 # HI-WORD OF EACH ON DOWNLIST.

MPAC +1

STODL GAMMAEI # CONIC GAMMA/360 AT 400K FT. (HI-WORD)

# CONIC RTGO/360 FROM EMSALT (LOW-WORD)

# FOR TM, DP(GAMMAEI) = (GAMMA, RTGO) / 360

# VGAM FROM PDL+0 (-7)

STADR

STORE VPRED # CONIC VELOCITY AT 400K FT

RTB

P61.1

# PDL BACK TO ZERO.

LUNENT DLOAD GOTO

1/RTMUE # ESTABLISH MU FOR LUNAR TYPE ENTRIES

CALLCON

290KFT 2DEC 88392 B-29

KTETA1 2DEC* .421844723 E2 B-14* # 1100 2PI/16384(163.84)

36KFT/S 2DEC 109.728 B-7 # (-7) M/CS = 36 KFT/S (-7)

20KFT/S 2DEC 121.92 B-7 # (-6) M/CS = 2 20KFT/S (-7)

KR1 2DEC -.026666667 # = -2.4 4 / 360

-6.05DEG 2DEC -.016805556 # = -6.05 / 360

KR2 2DEC .54931641 # = (360/4) 100 (-14) = 9000 B-14

KR3 2DEC 1000 B-14 # = 100 (10.0) (-14) G,S

## Page 765

# ASSUMES L/D = 0.3, BANK =0.

RTRIAL 2DEC 6460097.16 B-29 # RPAD +284643 FT =21 194 545 FT

# RPAD DEFINED AS 20 909 901.57 FT =6 373 338 M

400KFT 2DEC 121920 B-29 # METERS

# 300KFT 2DEC 91440 B-29 (-29) M

# EMSALT 2DEC 86759.2 B-29 284643 FT (-29) M (ORBITAL REENTRY)

# EMSALT 2DEC 90657 B-29 297431 FT (-29) M (LUNAR REENTRY)

KR4 2DEC .833333333

300KFT EQUALS MINPERE

VEMSCON 2DEC -.0389676 B-14 # = -HS D / 2 PI (-14) M SQ / CS SQ

# = -16369 .05G 32.2 .3048 .3048/2 PI (-14)

## Page 766

# SUBROUTINE NAME: FISHCALC (USED BY S61.2) DATE: 01.21.67

# MOD NO: 0 LOG SECTION: P61-P67

# MOD BY: MORTH / BAIRNSFATHER

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 11 MAY 67 INCLUDE GETERAD CALL

#

# FUNCTIONAL DESCRIPTION: GIVEN THE PRESENT POSITION, UNITR, CALCULATE A NEW UNITR THAT IS ROTATED THROUGH

# TRANSFER ANGLE, THETA, ALONG TRAJECTORY. THEN CALCULATE SIN(LAT) AND USE TO OBTAIN FISCHER RADIUS.

# SINCE FISHCALC USES UNI (LEFT BY ENTRY) EARTH SCALING IS ASSUMED. (WILL IMPROVE FOR SUITABLE TENNANT)

#

# CALLING SEQUENCE: CALL

# FISHCALC

# ENTER WITH .5 SIN(THETA) IN MPAC.

# PUSHLOC IS AT PDL+0, AN ARBITRARY BASE VALUE IF LEQ 8D

#

# SUBROUTINES CALLED: GET ERAD

#

# NORMAL EXIT MODE: RVQ

#

# EXIT MODES: NONE

#

# OUTPUT: ERADM (-29) M IN MPAC ON RETURNING

# NEW UNIT VECTOR NOT SAVED.

# SIN(LAT) NOT SAVED.

# PUSHLOC AT PDL+0

#

# ERASEABLE INITIALIZATION REQUIRED:

# SDELF/2 =SIN(THETA) / 2, IN MPAC LEFT BY TFF/TRIG

# CDELF/2 =COS(THETA) / 2, STORED IN PDL 14D LEFT BY TFF/TRIG

# RONE (-29) M LEFT BY USER

# VONE (-7) M/CS LEFT BY USER

# URONE UR/2 LEFT BY USER

# UNI .5 UNIT(V*R) LEFT BY ENTRY / P61

# UNITW UNIT NORTH POLE LEFT BY PAD LOAD

#

# DEBRIS: QPRET, PDL+0 ... PDL+5

# - - -

FISHCALC PDVL VXV # URPR = UR CDELF + UHOR SDELF

URONE

UNI

VXSC VSL1

# SIN(THETA) / 2 FROM PDL+0

PDVL VXSC # TO PDL+0, +5

URONE

CDELF/2 # COS(THETA) / 2

VAD STADR

STORE URH # FOR USE IN RTGO FROM EMS DISPLAY

DOT SL1

UNITW # FULL UNIT VECTOR UNIT NORTH

STORE ALPHAV +4 # = .5 SIN(LAT)

DUMPFISH GOTO

GETERAD # SAVES FISCHER RAD (-29) M IN ERADM AND

# IN MPAC. RETURNS TO CALLER VIQ QPRET.

## Page 767

# SUBROUTINE NAME: VGAMCALC (USED BY S61.2) DATE: 01.21.67

# MOD NO: 0 LOG SECTION: P61-P67

# MOD BY: MORTH / BAIRNSFATHER

# MOD NO: 1 MOD BY: RR BAIRNSFATHER DATE: 11 APR 67

# MOD NO: 2 MOD BY: RR BAIRNSFATHER DATE: 21 NOV 67 VARIABLE MU ADDED.

# MOD NO: 3 MOD BY: RR BAIRNSFATHER DATE: 21 MAR 68 ACCEPT DIFFERENT EARTH/MOON SCALE

#

# FUNCTIONAL DESCRIPTION: EARTH CENTERED VIS VIVA CALCULATION OF TERMINAL VELOCITY AND GAMMA (REL TO

# HORIZONTAL) GIVEN THE SCALAR QUANTITIES: PRESENT RADIUS AND VELOCITY AND THE TERMINAL RADIUS.

# THE USER MUST APPEND PROPER SIGN TO GAMMA, SINCE IT IS CALCULATED AS A POSITIVE NUMBER.

# THE EQUATIONS ARE

#

# VGAM = SQRT(VN VN/MU + 2(RN-RTERM)/(RN RTERM) ) RTMU

#

# COSGAM = H / RTERM VGAM = SQRT (LCP) / (RTERM VGAM/RTMU)

#

# VGAMCALC ASSUMES THAT THE TERMINAL RADIUS IS LESS THAN THE PRESENT RADIUS. BOTH CALCTFF AND CALCTPER

# MAKE THIS ASSUMPTION.

#

# CALLING SEQUENCE: CALL STCALL RTERM

# VGAMCALC PREVGAM

# PUSHLOC AT PDL+0, ARBITRARY IF LEQ 12D

# C(MPAC) UNSPECIFIED C(MPAC)=NEW RTERM

#

# SUBROUTINES CALLED: NONE

#

# NORMAL EXIT MODE: RVQ

#

# ALARMS: NONE

#

# OUTPUT: GAMMA / 360 IN MPAC, POSITIVE NUMBER

# VGAM E: (-7) M: (-5) M/CS IN PDL+0

# PUSHLOC AT PDL+2

#

# ERASABLE INITIALIZATION REQD:

# TFF/RTMU E: (17) M: (14) 1/SQRT(MU) LEFT BY TFFCONIC.

# RMAG1 E: (-29) M: (-27) M PRESENT RADIUS LENGTH LEFT BY TFFCONIC

# NRMAG E: (-29+NR) M NORM LENGTH OF PRESENT POSITION LEFT BY TFFCONIC

# M: (-27+NR)

# RTERM E: (-29) M: (-27) M TERMINAL RADIUS LENGTH LEFT BY CALCTFF

# NRTERM E: (-29+NR) M NORM LENGTH OF TERMINAL RADIUS LEFT BY CALCTFF

# M: (-27+NR)

# TFFVSQ E: (20) M: (18) 1/M -(V SQ/MU): PRESENT VELOCITY, NORM LEFT BY TFFCONIC

# TFFNP E: (-38+2NR) M LCP, SEMI-LATUS RECTUM, WEIGHT NR LEFT BY TFFCONIC

# M: (-36+2NR)

#

# DEBRIS: QPRET, PDL+0 ... PDL+3

# RTERM, NRTERM IF PREVGAM ENTERED.

## Page 768

PREVGAM SL* # ENTER WITH NEW RTERM IN MPAC

# E: (-29) M: (-27)

0,1 # X1 = -NR

STORE NRTERM # RTERM M E: (-29+NR) M: (-27+NR)

VGAMCALC DLOAD DMP

NRMAG # RMAG M E: (-29+NR) M: (-27+NR)

NRTERM # RTERM M E: (-29+NR) M: (-27+NR)