Fact Sheet IBM Computer Will Direct Saturn Orbital Test Flight

8/6/2019 Fact Sheet IBM Computer Will Direct Saturn Orbital Test Flight

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For Release:(:( ,&;

c I . ' International Business Machines CorporationFederal Systems Division326 East Montgulnery AvenueHockville, Maryland 20850

For f urt her information contact:In Rockville: E. B. Evans301 424-6700In Houston: A. J . Cella713 HU 8-3300 , E d . 371In Owego: F. C. Smith6 0 7 MU 7-2121

FACT SHEET:IBM COMPUTER WILL DIRECT

SATURN ORBITAL TEST FLIGHT

An IBM digital computer will direct today's orbital mission of the Saturn LB,ano ther st ep toward putting an Amer ican on the mclon by 1 9 7 0 .

The computer will digest data on velocity, position, attitude and time andissue steer ing signals 25 times a second to keep the launch vehicle on co urse to orbit .

Then, through four orbits, the computer will control a series of tests designedto evaluate the Saturn's dbility to atop and restart its second stag e engines on futuremanned missio ns and maneuver into position a s a launching platform for the mannedApollo spa cecr . After sepa rat ion , the Apollo will continue on to the moon alone.


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In addition to the computer, the IBM Federa l sys tem s Division's Electron icsSys tem s Center in Owego, New York, under co ntract to the National Aeronautics andSpace Administration's George C . Marsha ll Space Flight Center, has developed thefactory-field te st equipment called Aerospace System T est and Evaluation Complex(ASTEC).

IBM, through FSD's Space Sys tems Center at Huntsville, Alabama, als o hasthe responsibility for the fabrication, assem bly and tes t of the Saturn launch vehicle'sinstrument unit (IU). The IU is a three-foot, 21. 7-foot d iameter s tage located betweenthe S-IVB propulsion stage and the payload. The computer and data adapter a re pa rtof the IU1s guidance sy st em .

WHAT THE COMPUTER DOESBefore launch, the computer fi rs t checks out the entir e guidance sys tem , then

run s a complete miss ion simulation. Once the 1.3-million-pound launch vehicle liftsoff, the comp uter is su es navigation commands for the two-stage booste r.

During a typical launch-to-earth-orbit flight segment, changes in speed andattitude a r e sensed bytsuch instruments as accelerome ters and gyros. A data adapter

j47 gathers the signals and translates them into computer language.uter pro ces ses the data and, using information stored in its memory,orrection sig nals. These signals a r e sent back through the data

flight control computer which dir ec ts the thr us t of gimbaled rockett the launch vehicle st ays on the most efficient co urse to ea rth orbit.


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Even should one of the Satu rn' s engines fai l, the*computer would iss ue sig nal sord erin g the oth er engines to change th ei r direction of thru st to compensate for thelos s in power.

After navigating Saturn into orbit, the computer ch ecks out the third stagepropulsion syst em and sends te st res ults to the ground for analysis. (On mannedflights, the computer will calculate the tran sfe r trajecto ry and issue signals re sta rtin gthe th ird stage to s end the Apollo on to the moon.)

UNIQUE SYSTEM FEATURESr e four unique design concepts developed by IBM to mee t the str ingentbility requirem ents of the Saturn guidance sys tem :

* Duplex Memory System - Two separa te memory syste msJ

operating simultaneously during the mos t cri tic al portions ofthe missi on. This reduces the possibility of a system failurecaused by transient er ro rs in the memory. One memory corr ectsthe other in the event of i ntermit tent failur e.

+

J "pe Modular Redundancy - The first computer application ini 01 which all ci rcu its vital to the accura te operation of the computerh

/ (and data adapter) a r e triplicate d, the ir output fed to "voting"circ uit s, and a two-out-of-three majori ty rul e established.


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b * Unit Logic Devices - Microminiature circuit technology resultingin a s mal l and light-weight computer that has seven times a smany components and is thre e times faste r, electronically,than many earlier computers.

f/ * Magnesium-Lithium Structure - A light-weight, high-strengthstructure that serves a s its own 'fcold-plate" to carry offpotentially damaging heat generated by el ectron ic circui ts.It offers a 65-pound saving in weight over conventional alwninun~structure designs.

DUPLEX MEMORY SYSTEMThe computer has a random ac cess magnetic cb re memory sy stem capable

of storing 920,000 data bi ts in eight plug-in modules. Each memory module hasself-contained electro nics and toroid stor age for 4096 28-bit computer wor ds. Sixof these modules, operating as pa ir s of duplex mem orie s, a r e sufficient to hold the

! planned Saturn IB missio n pro gram s. The computer occupies only 2.2 cubic feet,Ii eighs only 88 pounds, and req ui res 131 watts input power . However, two additionalmemory modules can be plugged into the computer for special m issio n requirementswithout incre asing the computer's siz e.

The unusual aspe ct of the Saturn guidance computer memory syste m is thatit is organized to operate eith er as a single memory o r as two identical memorie soperating in parallel.


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In the para lle l, or duplex, mode the output of only one memory i s used by

the computer, although both operate simultaneously on the sa me progra m. Shoulda tran sien t failu re occur, the failure would be detected by special e r r o r detectioncircu itry built into the system . Automatically and instantaneously, the computerwould switch to the memory tha t had not failed.

Should the second memory subsequently fail, the computer would switchback to the first. The mathematical probability that both memories would fail atthe sam e memory word address a t the same time is very sma ll. Moreover, shoulda tra nsien t malfunction occur in either mem ory, the cor rec t output from the workingmemory automatically cor rec ts the failed memory, thus achieving a self-correctingsystem.

TRIPLE MODULAR REDUNDANCYResides the duplex memory design , IBM engineers utilized a tripl e modular

redundancy (TMR) approach to achieve a high degree of reliability for the Saturncomputer and data adapte r. With TMR, the computer has thre e identical logic

/ channels ra th er than the single channel of a conventional computer. Each of the th ree$>

channels is subdivided into seven functional ffmodulesfTepresenting the most crit icali

sections of the compu ter. This approach provides thr ee identical modules for each4ivital function:I

problem is presen ted to one module, the sam e problem is presentedto its tripl ets and all th ree a ct on the problem together. The results ,


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/ ar ri ve d at independently, a re f ed to a m ajority rule lrvotT"ertrircuit. Any dissenting"voteT1s discarde d as an er ro r, and only identical signals release d by a t least two

I of the modules a r e pa ssed along by the voter circ uit.Since thes e c ritic al a re as of the computer (and data adapter) ar e not dependent

upon sing le modules f o r co rr ec t data, the failu re of one vital functional module cannotcau se failure of the whole sys tem. The re ar e 98 vote rs in the computer checking anaverage of 13 output signals from each module. The voting proc edure does notappreciably slow the computer . Worst-case delay is only 100 nanoseconds (billionths

The micromiriiature circ uit module fo r the IBM computer uses a hybridology. Called unit logic dev ices, these modules com pri se 90% oonce computer and data adapted.e mo re than 50 types of the ULD circuits and a total of 8918 ULD's

and data adap ter. The bas ic circu it contains up to 1 7 components.Pass ive components a ~ dlectrica l interconnection paths for each circuit a re silk-

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sc ree ne d onto both side s of wafer-like alumina subst rate s measuring 0.3-inch squ are8

by 0.0 28 -i nc ~ hick. The active elements a r e attached by solder reflow.1of th ese ULD circ uit s a r e then mounted on a 2.5- by 3-inch multi-ction board containing all ne ces sary signal and power connections.


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level for the syst em.

d MAGNESKM-L ITH IUM CIlASSISThe stru ctu re in which ULD pages and the memory a r e housed is made of

magnesium-lithium alloy - metal with one of the bes t weight-to-strength ra tios .The stru ctu re also s erv es a s it s own cold-plate. Precision holes a r e gun-

bored into the chas sis through which a methanol-water coolant circu lates to ca rr y offheat generated by the electronic subassemblies. Using magnesium-lithium, and

1 making the str uc tu re ser ve two functions, have saved 65 pounds compared with aconventional a inum structure with a cold-plate,

DATA ADAPT

The data adapter use s the sam e basic technology a s the computer, includingTMR rel iab ili ty concept. Within the 3.3-cubic foot, 190-poundx power supplies for the computer, memory and its own electrical

requirements, plus re gis ters and sampling circuits for 13 outputs and 32 inputs,6

te rr up t signals to the computer, digital-to-analog and analog-to-s and glass ultrasonic delay lines to s to re digital data for the com-ng circuits, and telemetry data converters.the data adapter is the gateway to the computer for all elements of

the complex Saturn guidance system.

Fact Sheet IBM Computer Will Direct Saturn Orbital Test Flight

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