English translation — EAI Report Nr. 016 — Mitteilungsblatt der Electronic Associates GmbH

This document is an English translation of the original German-language EAI Report Nr. 016, published by Electronic Associates GmbH, Aachen, May–June 1969 (5th year of publication). The original is a scanned image PDF with no text layer.

Cover Page

EAI — Report

Newsletter of Electronic Associates GmbH 51 Aachen — Bergdriesch 37 May 1969 – June 1969 · No. 016 · 5th Year

Clevite / Brush Recorder — Mark 280, 6-channel Portable. Low cost-per-channel.

Clevite Brush — Recording Systems

Brush Instruments USA, one of the twelve subsidiaries of Clevite Corporation USA, was founded in 1921 by Charles F. Brush, son of the inventor of the arc lamp.

Brush Instruments has rendered fundamental achievements in the development of piezoelectric, acoustic, and ultrasonic devices — for example, the first practical wire recorder, the first magnetic shaker motor, the first magnetic device for entertainment purposes.

In recent years, Brush has concentrated on the development and manufacture of writing measuring devices, has specialized in this field, and holds a leading position in this area.

One of the most rapidly advancing innovations presented at the most recent IEEE is the new high-speed dot printer “DATAPOINT,” designated in this area as a “revolutionary innovation in strip chart recorder development.”

At its main plant in Cleveland, Ohio, USA, Brush Instruments manufactures in modern facilities all types of Brush recorder programs and maintains its own print shop for branded Brush registration paper. Brush sales and service organizations are present in all parts of the world. The European Brush general representative is located in Antwerp, Belgium, and carries full responsibility for all Brush activities in sales, service, and application. The Brush office in Antwerp supplies all European Brush representatives with instruments, accessories, paper, and spare parts.

EAI-GmbH in Aachen has been the authorized German representative for Brush Instruments since 1965, and maintains, alongside the sales department (with spare parts warehouse), a flexible service department that works to quickly resolve any deficiencies and at all times can supply the customer with the best possible instrument.

Enclosed, the reader will find our Brush brochure package, including information about the Brush Mark 280 6-channel recorder, a product description of the Brush 2-channel recorder Mark 220, and a reply card.

On the following pages, the reader will find a report on several Brush instruments and their applications. The reader is invited to contact EAI.

Application Areas for Brush Strip Chart Recorders and Cathode-Ray Oscillographs

Since EAI’s Brush recording instruments are in a position to solve most emerging measurement and recording problems, the following list of typical Brush applications is provided to help the reader find the right path to the solution of a specific problem:

Industrial Applications:

Displacement, Differential pressure, Pressure, Acceleration, Shock, Vibration, Ballistic pressure, Force, Torsion
Temperature, Voltage and deformation, Torque, Weight, Speed, Speed of rotation, Power, Electrical voltage/current
Telemetry: FM, PDM, PCM

Scientific Applications:

Recording of outputs from analog computers
Stability measurements and drift measurements on DC amplifiers and networks
Recording of results from bridges and measuring instruments: differential voltmeters, vibration analyzers, frequency response analyzers, electronic filters, measuring amplifiers, oscillographs, etc.

Chemical Applications:

Process control, recording of control behavior
Mass spectrometer — signal output
pH and conductivity controls
Low DC potential levels

Clevite Brush DATAPOINT — “New” (Specifications)

Operating modes:

Multipoint: Samples 1 to 8 channels at speeds of 20 points/sec to 2 sec/point. Points are distributed equally across the selected channels.
Intensive: Channel 1 (selectable) or 1 other preferred channel is printed out; remaining active channels less often.
Continuous: 1 channel (selectable) is recorded continuously (not pointwise); the remaining channels at 0.5 Hz over the full chart width. Electrical channel switching via pushbutton.

Further Data:

Sampling rate: 20 pts./sec to 2 sec/pt., continuously adjustable
Channel identification: each channel is briefly interrupted as a paper number appears; identification via pushbutton “IDENT”
Writing method: fiber-tip writer, capillary reservoir with ink from a tank
Paper: continuous, internal storage, length 23 m, width 15 cm, channel width 11.5 cm, 50-scale divisions, lightly readable
Paper speeds: 12 selectable speeds: 0.02; 0.05; 0.1; 0.2; 0.5; 1 inch/min; 1 inch/sec
Paper drive: over gear wheels, automatic stop when paper runs out
Non-linearity: less than 0.5%, achieved through contactless servo system
Input: ±2.5 V; 5 kΩ impedance, compatible with all Brush preamplifiers and coupler amplifiers

Additional Inputs: Amplifiers with automatic zero-point compensation for thermocouples, gain adjustment, and zero suppression; Sensitivity: 5 mV full scale; 1 kΩ impedance; Several inputs for thermocouples with mixer from preamplifier-signals.

Markers/Event markers: available additionally.

Control: Network, Paper-Paper-Scroll switch, Stop; 0.02; 0.05; 0.1; plus MIN/SEC switching, factor 10.

Operating mode: Network, analog filter, selection of the number of sampling points, continuously required. Stop: switches continuous operation to the next active channel (40-Hz filter — 30 ms); Single: single scan for channel selection, Input switch channel 1 to 8; All print channels illuminated.

Mains connection: 230 V/50 Hz, 100 W; Other connection options on request.

Dimensions: 23 cm wide, 37 cm high, 30.5 cm deep.

Order number: Model 13-6617-40

Typical DATAPOINT Applications:

Temperature distribution, Extent and speed of temperature changes
Pressure distribution in ship hulls, Structural force analysis
Process monitoring, Chemical analyses, Machine and vehicle dynamics
Monitoring of biological functions

EAI — Maintenance — Mail-in Services

Subject: New arrangements in the maintenance area of EAI-GmbH Aachen

Dear Sirs,

EAI-GmbH, Aachen intends to immediately offer all its customers a new maintenance system. In addition to existing maintenance services, a so-called “MAIL-IN-SERVICE” is to be established — an idea that several of EAI’s customers have already raised with EAI.

The new maintenance system is to be structured as follows:

For the maintenance of EAI instruments, EAI-GmbH, Aachen will offer the customer a contract that runs for 1 year, with a fixed fee that varies according to the number and size of the instruments to be maintained. This fee is payable only upon conclusion of the contract.

The contract partner now has the option of sending all instruments or individual components to Aachen for repair. All repairs are carried out within the framework of the contract, regardless of the number of working hours and spare parts required. Naturally excluded are self-caused consumable materials such as batteries, writing pens, ink, paper, etc., as well as instruments damaged by improper handling, such as broken patchfields and connector leads, and instruments damaged by improper transport.

EAI believes that the new maintenance system will be of interest to the reader. Please send a brief note so that EAI can then present the reader with a corresponding offer.

With friendly greetings, EAI-ELECTRONIC ASSOCIATES GMBH Customer Service Department

(Ing. D. Schwarz) Department Manager

Description of Stochastic Time Functions by Means of the Autocorrelation Function

By Prof. Dr.-Ing. Dr. E.h. Walther Wegener F.T.I. and Dipl.-Ing. Günter Feier

Correlation analysis is an important method of signal processing. It is particularly well suited for the following two broadly applicable application areas:

For the detection of periodic signals in noise and for the analysis of signal or noise frequency bands.
For the comparison of two signals, both of which may be disturbed by noise or other signal frequencies. In this case, the degree of “relationship” between the two signals can be determined.

In the first case, the so-called autocorrelation function is used; in the second case, the cross-correlation function.

The autocorrelation function is conventionally given in the unnormalized form:

K(τ) = (1/T) ∫ x(t) · x(t+τ) dt

The following briefly addresses several properties that the time function x(t) under examination reflects in the autocorrelation function, and what influence each has on the course of the autocorrelation function.

The autocorrelation function of a strictly periodic time function contains all the frequency components of the frequency spectrum, but all phase information is lost. This peculiarity means that the course of the autocorrelation function in no way corresponds to the course of the signal functions. However, the wavelengths of periodic components contained in the signal x(t) can be determined from the course of the autocorrelation function.

For the signal function x(t) = A · sin(ωt + φ), the autocorrelation function is:

K(τ) = (A²/2) · cos(ωτ)

In this way, τ and t can be assigned to one another by scaling.

If the periodic function x(t) is assumed to be a mixture of harmonic oscillations with x(t) = Σ_n + Σ_k A_k · sin(ω_k·t + φ_k), the autocorrelation function becomes:

K(τ) = Σ_k (A_k²/2) · cos(ω_k · τ)

A band-limited noise signal has an autocorrelation function described by the function (sin x)/x.

A catalog of such mappings allows the analysis of even more complex signals.

Signal functions and their autocorrelation functions:

Square wave → oscillating damped function
Sawtooth pulse → smooth function
Broadband noise → sharp narrow peak
Narrowband noise → oscillating damped function

Although autocorrelation analysis has undeniable advantages, it is still relatively rarely used in practice. This is due to the fact that suitable correlation computers are generally not available. In principle, however, any computer that allows the mathematical operations of the above-mentioned definition equation is suitable. The analog computer appears to be particularly favorable for autocorrelation analysis.

The electronic analog computer allows the operations of multiplication and integration required by the definition equation, whereby about 1% accuracy of the multiplication is required. The integration should be carried out as precisely as possible to minimize integration computation errors particularly influencing the correlation result.

An essential component for autocorrelation analysis is the time delay device, which delays the signal x(t) by a correlation displacement τ. This delay was previously realized via a magnetic tape loop and was very prone to failure due to unavoidable wear. Today the time delay can be achieved by a purely electronic working device. The electronic delay device LCZ operates in hybrid mode and can delay signals up to 1000 seconds.

Since the time delay can be influenced by an external clock, control by a closed-loop analog-hybrid computer (e.g. EAI-380) is possible. This hybrid computer can also carry out the arithmetic operations for determining the autocorrelation function and display the result either as a printout (VARIPLOTTER) or in digital form.

Block diagram for autocorrelation analysis: x(t) → [LCZ time delay] → [MULT. multiplier] → Output

If a stationary signal source can be assumed, the computation can be connected directly to the signal source. This case is particularly interesting for simulations on the hybrid computer when working with noise signals. If the signal to be examined is a measurement signal, then pre-storage on a magnetic tape makes sense, i.e., the stationarity of the signal is only approximately assumed when the playback speed corresponds to that of the signal.

A comparison of the autocorrelation function of the measurement signal with the autocorrelation function of the simulation experiment allows a deep insight into the regularities of the phenomena to be captured by simulation.

Application areas for autocorrelation analysis:

The production processes in textile technology are generally very complex, where many relationships have hitherto been essentially intuitively grasped and only slowly made accessible through large research efforts for accurate recording and description. The arrangement of individual fibers along a fiber band is subject to many coincidences. In individual production passages, the non-uniformity of the fiber band increases continuously. As a result, an uneven appearance of the fiber band increases. In addition, through faulty machine elements, periodic disturbances can appear which reduce the fiber surface uniformity of the fiber band in further processing.

Through the use of autocorrelation analysis, it was possible to detect these periodicities and explain their origin. A very important application concerns the comparison of various products or various manufacturers’ products. Here too, the autocorrelation analysis allows interesting statements about the non-uniformity.

The examined characteristic can be either the optical diameter or the mass per unit length. This requires only different measuring transducers.

Autocorrelation analysis allows fundamental statements about regularities and correlations in many other areas. For example, acoustics, pneumatics, hydraulics, meteorology, investigation of vehicle driving behavior, hovercraft-glide investigations, etc. can be mentioned. The list of applications can be extended to almost any field. Wherever stochastic processes appear in measurement and simulation technology, correlation analysis can reveal essential and often fundamental regularities.

The EAI 430 DATAPLOTTER

The EAI 430 DATAPLOTTER provides automatic conversion of computer-generated data, either on-line or off-line, into graphic form quickly… accurately… reliably… and efficiently.

The amount of computer data in computing centers increases from year to year with the number of installed computing systems. It therefore placed the demand on one device that can present this data in graphic form as quickly as possible. EAI-Electronic Associates Inc., with its 20-year experience in building X-Y plotters, presented the VARIPLOTTER, DATAPLOTTER, etc. in its latest development, with great success at the Hannover trade fair.

The EAI 430 can, depending on the user’s requirements, be configured in various ways. From the configuration diagrams it can be seen that a fully functional basic system already consists of only the control console, a magnetic tape unit (or interface), a drawing table, and an automatic paper advance. The other units serve as extensions or alternatives.

The EAI 430 can be used in off-line or on-line mode. As media, 7- or 9-track magnetic tapes are available. For the common drawing sizes, two drawing tables are available: 31 × 36” (78 × 91 cm) and 54 × 76” (137 × 193 cm). The control console itself contains only the drive system electronics, while the remaining electronics is housed in the table. The EAI 430 uses an analog-digital servo system with high drawing speed and simultaneously the high precision of a digital servo system. The high-performance analog servo motors move the arm and the spring of the plotter, with a feedback encoder (Desired Position Register) coupled for each 0.001” (0.025 mm) of movement at all drawing speeds. This provides the possibility of comparing the feedback register with the position register (Feedback Register), so that both are compared until the digital error of the mechanism is zero, so that no displacement of the curve or line results from entry of a missed point.

Maximum drawing speed for straight lines: 20”/sec (50 cm/sec); for curves: 16”/sec (40 cm/sec). The DATAPLOTTER draws itself at maximum speed regardless of quality and accuracy of the servo drive.

The EAI 430 DATAPLOTTER control console is available in 2 versions for programming: BASIC and RAPID. BASIC contains the electronics for the operating modes Point, Line, Free Run, and Scribe; RAPID additionally includes the RAPID-Betriebsart (Rapid Accurate Polynomial Interpolation Device).

Point Mode: The data are plotted as a sequence of points or symbols at any angle.

Line Mode: Straight lines of any length can be drawn between any start and end point. Speed: up to 20”/sec (50 cm/sec).

Scribe Mode: In this mode, alphanumeric characters of any size are written in a Schnellschreiber font. 48 alphanumeric characters are printed with typewriter quality.

Print Mode: This mode is used in conjunction with the symbol printer; 48 alphanumeric characters are printed with typewriter quality.

Free Run Mode: This mode is used to draw smooth curves at constant speed, whereby the data for a series along a curve are simultaneously not precisely quantized and a small, continuously variable speed generator controls the DATAPLOTTER. The Free Run mode is an outstanding mode for drawing contours. The other data is generally only approximately quantized and a smooth interpolation of the curve is desirable.

RAPID Mode (Rapid Accurate Polynomial Interpolation Device): With RAPID mode, curves are computed exactly through discrete data points. RAPID interpolation uses a polynomial of nth order and achieves thereby a better approximation of the curve. The RAPID computation additionally calculates the optimum speed at which the mechanics may continuously draw the curve. This results in each curve section being run at maximum speed, so that even small curvatures in a curve section are drawn very rapidly.

Comparison of EAI-430 with conventional incremental plotters:

Drawing	EAI-430	Comparably priced incremental plotter	Substantially more expensive incremental plotter
Drawing a 75 cm straight line	0.06” magnetic tape required	56” magnetic tape required	10” magnetic tape required
Drawing a 75 cm diameter circle	0.4” magnetic tape required	175” magnetic tape required	31.5” magnetic tape required

An important advantage of the system is the simplification of the software. For example, only 2 data points are needed to draw a straight line in any orientation and length up to 20”/sec (50 cm/sec). These operational plotter capabilities substantially simplify the drawing of curves, i.e., when operating in this mode, symbols such as a point or an ellipse can be transferred from the computer to the plotter with only 40 data points to draw an ellipse of 50 cm circumference, and only 4 points are needed to define a 2.5 cm circle.

All programs are written in FORTRAN IV.

EAI 430 Applications:

Production of weather maps
Flight and wind tunnel test drawings
Profile and construction drawings for road construction companies and architecture firms
Location plans, seismic analyses, etc. from oil companies — drawn in perspective, isometric, or 3-D view
Drawing of printed circuit schematics, integrated circuit schematics, etc.
General technical drawings

EAI 430 Series DATAPLOTTER system block diagram:

Control consoles: BASIC and RAPID
Magnetic tape units: 7-track 11 ips, 9-track 20 ips, 7-track 20 ips, 9-track 20 ips
File recognition units
Core memory unit
Drawing tables: 31 × 36” and 54 × 76”
Automatic paper advance
Single pen / Four pen
Symbol printer
On-line interface

MC Laboratory Materials

MC laboratory cables and connectors are available from EAI-GmbH. The product line includes:

MC Laboratory Cable 1 mm (Stecker-∅)

Brass, hard-silvered, highly flexible litz wire 0.25 mm²
9 colors, standard lengths 7.5, 15, 30, 45, 60 cm
Connector insulation: shrink tubing

MC Laboratory Cable 2.3 mm (Stecker-∅, 5 A)

Beryllium bronze, hard-gold-plated, highly flexible litz wire 0.5 mm²
9 colors and 5 standard lengths (7.5, 15, 30, 45, 60 cm)
Connector insulation: shrink tubing

MC Laboratory Cable A 4 mm (Stecker-∅, 10 A)

Beryllium bronze, hard-gold-plated, highly flexible litz wire 1 mm²
9 colors and 6 standard lengths (25, 50, 75, 100, 150, 200 cm)
Connector insulation: MC connector type A

MC Laboratory Cable B 4 mm (Stecker-∅, 10 A)

Beryllium bronze, hard-gold-plated, highly flexible litz wire 1 mm²
9 colors and 6 standard lengths (25, 50, 75, 100, 150, 200 cm)
Connector insulation: MC connector type B

MC Laboratory Plug LS 2.3

2.3 mm connector-∅, 5 A; Beryllium bronze, hard-gold-plated
Insulation in shrink tubing can be supplied on request

MC Laboratory Plug LS 4

Connector-∅ 4 mm, 10 A; Beryllium bronze, hard-gold-plated

MC Connector Type A — Material: Nylon, 9 colors

MC Connector Type B — Material: Polypropylene, 9 colors

MC Mini-Jacks — from 0.5 mm diameter, in all desired forms; Contact lamella of proven MC type used.

MC Laboratory Jack LB 4 for MC laboratory plug LS4

Brass, hard-gold-plated; Solder connection
Easy mounting: drill hole, countersink, and press jack in

MC Laboratory Jack LB-IF 4

Universal jack for all common rigid and spring 4 mm plugs (MC laboratory plug, banana plug, spring plug)
Solder connection; Insulation: Aculon

MC Laboratory Jack LB-I 4

For use only with spring 4 mm plugs; Solder connection; Insulation: Aculon

MC Short-Circuit Plug KS 4-19, 15 A

Plug spacing: 19 mm; For jacks of 3.9–4.2 mm ∅
From one piece beryllium bronze, hard-gold-plated; Insulation: soft PVC, black

MC Short-Circuit Plug KS 4-12, 15 A

Plug spacing: 12 mm; For jacks of 3.9–4.2 mm ∅
From one piece beryllium bronze, hard-gold-plated; Insulation: soft PVC, grey

MC Component Plug KP 4

Ideal for connecting small circuit elements
Combination of jack and plug, isolated from one another; 4 mm connector-∅, gold-plated
Material: beryllium bronze, hard-gold-plated; Insulation: MC connector type KP

MC Plug LS 4-KP — fits MC connector type KP; Beryllium bronze, hard-gold-plated

MC Connector Type KP — Material: transparent nylon

MC Laboratory Cable Holder — for approx. 150 laboratory cables 4 mm; Spacing between individual consoles adjustable; Iron profile, nickel-plated

MC Anchor Rail — for cable holder; Iron strip, nickel-plated; Available in standard 30 cm length as well as custom lengths

MC Console — for cable holder; consists of plastic part, a screw, and a fixing plate; Consoles can be screwed directly to the wall without the MC anchor rail

MC Small Materials Stand — 6 plastic shells, divided into 4 compartments, connected with a stable base; Individual shells rotate

MC Plastic Shells — The shells are available to order; Available from EAI as well

EAI is ready to submit an offer for the various parts. Please call EAI at: 0241/26042

Hannover Trade Fair (Hannover-Messe) Report 1969

EAI’s participation in this year’s Hannover Trade Fair was a great success. For the first time outside the USA, EAI demonstrated two new developments, specifically:

The large hybrid computing system EAI 7945, which simulated a moon landing. On a moon surface display device, the visitors could observe how the lunar landing vehicle detaches itself from the parking orbit around the moon and sets down on the moon’s surface with all speed. After switching off the “automatic guidance,” hundreds of visitors could “manually control” the lunar vehicle on the moon’s surface. The lectures by Mr. SIM(ulation) on the display screens also found great interest and demonstrated the performance capability of the EAI-7945 hybrid computing system.
The new DATAPLOTTER EAI-430 attracted great attention and quickly became the “talk of the experts.” Hundreds of demonstrations were carried out, with the attractive demonstration drawing attracting great approval.

The photos shown should give the reader a small impression of EAI’s successful participation at the Hannover-Messe 1969.

The Pursuit Problem (Programming Exercise)

By Dipl.-Ing. W. Ewert

In ancient times, when nothing was yet known about “rendezvous maneuvers” and scientists knew nothing of pursuit problems, hunters thought about a problem: how can an attacker pursue a moving target? The attacker has a goal which is moving, and the attacker must pursue it and capture it. In most cases, it is necessary to adjust the speed as required.

The simplest strategy of the attacker is to run in such a direction that the target always approaches, i.e., the attacker always aims directly at the position of the target.

This would be, for example, the natural behavior of a dog chasing a hare. The dog runs at a constant speed v and sees the hare running from a corner at the opposite side of a square field.

Problem 1: Pursuit along a hedge

The dog is standing in a corner of a square field and sees the hare running at a constant speed along the opposite side toward the field hole.

The relative position of dog and hare, x and y, are linear functions of time. The equations of motion for p and q are linear and the equations for dog and hare are given in explicit form. The equations examine how p and q vary, and the boundary conditions and initial conditions for the dog’s speed are provided.

For the signal function x(t) = A·sin(ωt+φ), the autocorrelation function is given, and at the boundary of the hare, the following equations of motion describe the dog’s velocity:

(1) dp/dy = -dx/p-x [equation of motion] (2) dp/dt = -∂v/∂t·dx/dt [expanded form]

It is about the trajectory equation in explicit form. The equation for p and q are linear functions of time. The equations examine how p and q develop with different initial and boundary conditions for the dog’s speed.

Case 1: Pursuit along a hedge (Figure 2)

The dog sits in a corner of a square field and sees the hare running from the field hole at the opposite corner. The dog runs at constant speed k·v.

The equation of motion of the hare is:

(6) (dy/dt)² + (dx/dt)² = k²·v²

To solve the equations, a fourth equation is needed which determines the problem through four variables (p,q,x,y):

(7) dp/dt = -∂v/∂t·dx/dt

When the equations are resolved and for p reaches the value of 1, the equations are:

(8) p = 1 (9) q = q₀ - ∫₀ᵗ v dt (10) x = ∫₀ᵗ [(k(1-x)·v) / ((1-x)² + (q-y)²)^(1/2)] dt (11) y = ∫₀ᵗ [(k(q-y)·v) / ((1-x)² + (q-y)²)^(1/2)] dt

Here the dog starts at the coordinate origin. These equations are simple enough to program on an analog computer.

Case 2: Pursuit from the center of a circular field (Figure 3)

The circular field is considered. The hare runs at constant speed v along the circumference of the circle. The dog starts at the center of the circle with speed k·v. How large must k be so that the dog can catch the hare?

The equations of motion of the hare are:

(18) p = cos·vt (19) q = sin·vt

The radius of the circle has value 1. The dog’s constant speed v is in units per second. When the dog always runs directly toward the hare, the equation holds:

(20) dp/dt = (p-x) / [(p-x)² + (q-y)²]^(1/2)

The speed s of the dog has components:

dx/dt and dy/dt

and:

(21) s² = (dx/dt)² + (dy/dt)²

By arranging equations (18) through (21), the result is:

(22) p = 1 - ∫ v·q·dt (23) q = ∫ vp dt (24) y = ∫ [(k(q-y)·v) / [(p-y)² + (q-y)²]^(1/2)] dt (25) x = ∫ [(k(p-x)·v) / [(p-x)² + (q-y)²]^(1/2)] dt

In this case, none of the four variables has a monotone, linear variation with time and therefore cannot be considered as an independent variable.

Experiments on the Computer

Case 1: Pursuit along a hedge

Figure 4 shows the analog circuit for Case 1 described in Figure 2. The circuit shows the arrangement of the problem variables x, y, p, q as monotone, linear time variables.

The dog starts at the coordinate zero point. On the computer this means: it is the set time, which with t=0 seconds is the state of the dog for a fixed set value of k written by the XY recorder. Repeat the calculation for different values of k = 2/5, 3/5, 4/5, 1, 6/5, and the initial conditions p = 1, q = 0, X = 2, Y = 0.

Examine the behavior for the initial conditions p = 1, q = 0, X = 2, Y = 1.

Write the function y = f(x) for the following k values: k = 2/5, 3/5, 4/5, 1, 6/5, and the initial conditions p = 1, q = 0, x = 0, y = 0 using the XY recorder.

Case 2: Pursuit of a circular field

Program the computer corresponding to Figure 5, so that the circuit shows the problem outlined in Figure 3. The speed v of the hare is set to 1.

Calculate for the circuit the set values for the following initial values: p = 1, q = 1, x = 1/2, y = 1/2, and verify the values appearing on the computer.

EAI Salutes Rusty Schweickart

Cold and rainy weather could not diminish the cordial reception that the residents of the New Jersey coast gave to the Apollo 9 astronaut Russell Schweickart. Among the well-wishers was also Fred Martinson, Vice President and General Manager of the Computer Division at EAI. Mr. Martinson presented Russell Schweickart with a scale model of the EAI 8900 hybrid system. This system was used successfully in the Apollo 9 mission for the simulation of space flight and docking maneuvers. Several thousand people were on hand to honor the hometown native.

During the flights of Apollo 9 and 10, the experience gained by NASA by July 1969 in the first people landing on the moon and bringing them back to earth was hoped for.

Fred Martinson, Vice President and General Manager of the Computer Division at EAI, presents the astronaut Russell Schweickart with a scale model of the hybrid system EAI 8900, which was used for simulation of the Apollo 9 — docking maneuver.

EAI — Products and Services

Trade-In Program

New!

Effective May 1, 1969, EAI-Europe offers its customers the possibility of already-existing EAI computer systems on a “Trade-In” basis as payment toward the purchase of a new, or larger, EAI computer.

Through this new procedure, the EAI customer is in a position to plan long-term the procurement of a “smaller” EAI computer as the path to a larger system.

The “Trade-In” price offered by EAI for the EAI computer to be traded in generally depends mainly on the following factors:

Age and technical condition of the computer to be traded in.
New procurement value of the computer to be traded in (unrestored, restored).
Respective sales possibilities for the traded-in computer in the European region.
Model and price class of the newly to be procured EAI computer.

EAI computers received as trade-in are placed in a “pool” at the EAI-European main administration in Brussels and brought to a technically sound condition through a specially established maintenance-service department (Overhaul-Center).

The refurbished units are then offered as used systems to the European EAI customer circle.

If the reader is interested in individual details, please send a notice to EAI so that EAI’s sales engineers can discuss all details.

EAI 380 Analog/Hybrid Scientific Computer System

The analog/hybrid computer EAI 380 is the most recent member of the series of analog computing systems by EAI-Electronic Associates.

The fully transistorized unit, which operates at a reference voltage of ±10 V, contains in addition to purely computing components also parallel logic. The fully pre-wired base can be installed in the plug-in construction principle and can take over some computing elements from the larger system EAI 580.

Normal configuration of the EAI 380 includes the following components:

10 summing integrators
28 summers
4 summers
4 Track/Store networks
4 Bipolar-multiplier
36 Coefficient potentiometers
4 Variable function generators
4 Sine/Cosine function generators
4 Log function generators
4 Comparators
8 Electronic switches
4 Function relays
Parallel logic with gates, 4-bit registers, presettable counters, differentiators, and function switches

The flexible design of the unit allows additional configurations; for example, up to 16 integrators can be installed in the EAI 380.

Particularly noteworthy are the newly developed multipliers. Two multiplication networks with 2 input inverters each for X- and Y-input are housed in one module. At full output ±10 V, the multipliers have a 4-way amplifier (54 amplifiers total).

The convenient adjustable variable diode function generators (both Knicktpunkt setting and slope is continuously adjustable with knobs) make the EAI 380 the equal in this component (linear components ±0.01%, parabolic multiplier ±0.025%), broadband computing amplifier (400 kHz) and the digital and logical control of the integrators (shortest computing time 1 ms) of the EAI 380 comparable to a precision sliding-ruler calculator.

The control panel is centrally arranged and contains all of the necessary operating controls: the control of the repeat timer, the component selection system, the analog computing time control, an analog operational control and logic display, an analog mode display. A fully color-coded, and self-obviously removable patchboard has a 3.5-digit digital voltmeter and a central override display added.

As output instruments, XY recorder, 4-channel recorder, and multichannel recorder are available.

As standard features, the possibility of parallel operation with several machines as well as coupling with other EAI 10 V computers is provided.

On request, EAI will send complete technical documentation on the EAI 380 system.

Back Cover: EAI — Products and Services

“Paper tigers aren’t photogenic, that’s why we took a picture of the real world of realtime computation.”

The world of EAI computers — digital, analog, and hybrid

The one thing EAI couldn’t take a picture of is their fully operational, fully integrated hybrid software. It’s busy at work in the EAI 640 digital computer in the foreground. It’s also busy at work in leading aerospace, chemical, and nuclear power companies in the United States, England, France, Sweden, Belgium, Italy, Canada — anywhere in the world scientists want real systems to solve real problems.

They get their results from the 640, a powerful 16-bit machine. The first to offer a 32-bit hardware floating point option that provides 3 to 1 time savings in programming and execution speed. The EAI 640 with the expanded range of real-time software including Scaled Fraction FORTRAN, function manipulation, and the HOI interactive language. Working software that has made it the choice of close to 100 scientific computing laboratories.

Right in back of the 640 is the exciting, new 100-volt computer from EAI, the 7800. The computer designed for simulation labs looking for the best price/performance ratio. And its mainframe design has been made flexible so it can continue to incorporate new computing techniques as they’re dreamed up. A modern, high throughput analog computer, it has borrowed little from the past except EAI’s experience. The experience of having built, and installed over 4000 scientific computers.

Now for some symbiosis. Interface the EAI 640 with the EAI 7800, using a proven, dependable EAI interface, of course. Add the element of proven, dependable EAI software. Not just hybrid packages, but a true hybrid operating system. You now have the industry’s best way to simulate dynamic problems. And isn’t that what the real world of computation is really all about?

Be convinced. Send for information today: Analog, Digital, Hybrid. All it takes is a single letter or a single call.

EAI — ELECTRONIC ASSOCIATES GMBH 51 Aachen — Bergdriesch 37 Tel. (0241) 29041/45 Telex: 832976 EAI Aachen Nr. 832976

EAI Report No. 016 — Newsletter of Electronic Associates GmbH (May–June 1969)