Analog Computers

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EAI Newsletter / Circular — September/October 1966, No. 009

This is an English translation of the original German document (EAI Electronic Associates GmbH, Aachen, September–October 1966, Report No. 009).

EAI — Bulletin for Customers and Friends of EAI Electronic Associates GmbH — Aachen, Bergdriesch 37

September–October 1966 | No. 009

electronica 66 — Munich, 20–26 October 1966 — WE ARE EXHIBITING

Dear Sirs,

EAI Electronic Associates GmbH takes the liberty of inviting you to visit Stand No. 2116 / 2118 / 2120, Hall 2, at the electronica 66 trade fair.

From the product range, the following will be on display in addition to the analog computing systems of types TR-20 and TR-48/SS (with electronic mode control): the digital Logic Expansion System, type DES-30, as well as the EAI-PDS-1020 Digital Computer.

EAI – Electronic Associates Inc., European Division, Brussels, will for the first time in the Federal Republic of Germany be showing the new EAI Analog/Hybrid Computer, type 680.

Visitors will also be able to examine and operate the EAI X-Y recorders VARIPLOTTER series 1110, 1120, 1125, 1130, 1133, and the Digital Voltmeters of the Series 6000, as well as standard plug-in units for data processing, Series MDP-200, at the stands.

Additionally, for the first time, EAI displacement, force, and pressure TRANSDUCERS will be shown.

The following companies represented by EAI in the Federal Republic of Germany and West Berlin will also exhibit their products at the above-mentioned stands:

  • BRUSH INSTRUMENTS, USA (multi-channel recorders)
  • AUGUST FISCHER KG, Göttingen (evaluation equipment)
  • JOSEF HEINZINGER, Munich (transistorized low- and high-voltage power supply units)
  • MULTI-COMACT AG, Switzerland (patch cords)

EAI looks forward to welcoming visitors at the ELECTRONICA 66 stand.

Respectfully, EAI – ELECTRONIC ASSOCIATES GMBH Henk W.A. Jungbauer, Managing Director

EAI EVENT CALENDAR

  1. Physiker-Tagung 1966 (Physicists’ Conference) — Munich, 17–21 October 1966
  2. Electronica 66 — Munich, 20–26 October 1966
  3. EAI Symposium — Aachen, 3–4 November 1966
  4. EAI Analog Computing Course — 8–11 November 1966
  5. EAI Symposium — Rhine/Main, Frankfurt/Main, 24–25 November 1966
  6. EAI Lecture Series — Göttingen, 13 December 1966

EAI CLASS B EQUIPMENT AND SYSTEMS

The following Class B systems are currently available for offer:

EAI PACE Equipment:

  • 1 unit: EAI PACE Analog Computer, RMC, type TR-48
  • 1 unit: EAI PACE Analog Computer, type TR-20
  • 1 unit: Dataplotter, type 3110
  • 1 unit: Dataplotter, type 3120

Note: Class B equipment refers to units that have been used for a period in one of the computing centers in the USA and Europe, and are offered at reduced prices under normal warranty and delivery conditions.

NEW EAI PUBLICATIONS

  1. Price list EAI-TR-48/58 — P004, August 1966
  2. Price list EAI X-Y Recorders / Recorder VAR-REC-P002, September 1966
  3. Price list EAI Data-Processing Systems P001, September 1966
  4. Brochure: “EAI Maintenance Conditions”

All Solid-State VARIPLOTTER Series 1133

The new EAI VARIPLOTTER 1133 M is a coordinate recorder in a compact design. Its external dimensions are only slightly larger than its recording area, which measures 28 × 43 cm. In contrast to the VARIPLOTTER 1130 M, it lacks cost-increasing extra features such as a built-in time base. This made it possible to offer a cost-effective instrument that nonetheless equals the other well-known EAI VARIPLOTTERs in precision and reliability.

Accuracy is ±0.2% of full writing width, with each individual range calibratable to ±0.1%; the slewing speed is 50 cm/sec. The instrument is fully transistorized; the reference voltage is formed independently for each axis by separate Zener systems. The zero point is set with a multi-turn potentiometer and can be suppressed across the full writing width. The inputs are floating; input impedance is at least 1 MΩ and is not affected by the choice of scale factor.

Particularly noteworthy is the attractive appearance of this instrument and the clear arrangement of its controls. A novel feature is scale factor selection via pushbuttons; 10 setting ranges from 250 mV/cm to 10 V/cm are available for each axis.

Accessories included: 2 pens, 24 different-colored ink cartridges, a dust cover, and 100 sheets of recording paper. Ink cartridges are available in red, green, and black. Recording paper is manufactured to special tolerances prescribed by EAI; printing and cutting are performed under strict quality control to meet the highest accuracy requirements.

To extend the range of applications of this recorder, an accessory unit has been created that makes it possible to use the new AC and Log input modules developed for the larger VARIPLOTTER 1110 also with the 1125 M, 1130 M, 1131 M, 1132 M, and 1133 M recorders. The expansion unit consists of a pre-wired housing containing the necessary power supply.

Price ex-stock Aachen:

  • Undutiable: DM 6,255.–
  • Dutiable: DM 7,370.–

NEW INPUT MODULES FOR VARIPLOTTER 1110

Two new input modules have been developed for the well-known EAI VARIPLOTTER 1110: a logarithmic and an AC voltage module.

Log Module, type L2.1384: This module enables the recording of functions available as DC or AC voltage in a ratio of 1:1000, on a logarithmic scale. The logarithmic axis spans 60 dB (3 decades). The input attenuator is calibrated in dB and can be switched between 0 and 40 dB in steps of 10 dB; scale factors are 2, 5, and 10 dB/cm. For DC voltages, the input range begins at ±3.16 mV; for AC voltages, at 1 mV/eff. Frequencies from 50 Hz to 20 kHz can be processed with an accuracy of ±0.5 dB.

Price ex-stock Aachen:

  • Undutiable: DM 1,915.–
  • Dutiable: DM 2,295.–

AC Voltage Module, type L2.1394: This module enables the recording of quantities available as AC voltage. The instrument generates a DC voltage proportional to the RMS value of the AC voltage. Nine ranges are available from 0.025 to 20 V eff. full-scale. Accuracy in the most sensitive range is 2% for frequencies from 20 Hz to 20 kHz, and 5% for frequencies up to 50 kHz. In other ranges, accuracy is 1% between 20 Hz and 50 kHz, and 2% between 50 kHz and 100 kHz.

Price ex-stock Aachen:

  • Undutiable: DM 2,160.–
  • Dutiable: DM 2,595.–

NEWS FROM EAI — European Division (Brussels): The EAI 680

A Hybrid Computer to Grow With

The computing industry generally distinguishes three classes of hybrid computing systems:

  1. The analog computer with a certain number of digital logic units for flexible, automatic control of the analog computer and its elements. This concept ranges from a small number of digital logic building blocks to an independent general-purpose digital computer. In this form of hybrid computing, the logic elements of the digital computer are not used for computation purposes.

  2. The analog computer with a certain number of digital logic units for computational cooperation, in which both analog components and digital logic elements are used in parallel.

  3. An analog computer and a general-purpose digital computer, coupled and controlled for solving a single complex problem.

In practice, various problems require various combinations of these three concepts.

The EAI 680 system fulfills all these requirements. Its expandability ranges from a basic hybrid configuration to a fully expanded hybrid system containing plug-in digital logic and a general-purpose digital computer. The basic system is completely pre-wired to accommodate the full spectrum of computing plug-in units; this allows expansion according to the needs of the user.

The EAI 680 was designed for a wide range of applications:

  • Process industry: simulation and development of both digital and analog process control systems; studies of complex dynamic reactor problems; design of heat exchangers; parameter optimization; nonlinear chemical kinetics studies; simulations involving long fixed or variable time delays; automatic curve fitting; simulation of process and control systems for training purposes; system studies in reactor engineering.

  • Higher education: as a tool for training students in programming and development of scientific computers; as a demonstration instrument to show students the behavior of a physical system; as a system for solving problems of varying scope in research tasks.

  • Medicine and biophysics: on-line operation for measured-value processing and data reduction, as required in ECG and EEG studies; simulation of physiological systems where the solution of partial differential equations is required (e.g., circulatory systems).

Technical Description

The basic configuration of the EAI 680 is designed for iterative hybrid computations and features programmable digital logic elements for controlling the analog simulation. The analog computing components, logic interface components, digital logic elements, and the interface to a digital computer are all brought out on a single patchboard with 4080 holes. All components are built in plug-in construction. The digital portion of the patchboard is clearly separated from the analog portion, and patch cords of different sizes prevent inadvertent connection of analog and digital signals.

The EAI 680 features a 10-volt reference system; this combines the dynamic characteristics of a fully transistorized 10-volt system with the now-achievable high static accuracy of 10-volt components (static accuracy of linear components: 0.01%; of multipliers: 0.015%). Selected resistors and integration capacitors eliminate the need for an oven for temperature stabilization. Since most computing components are arranged directly behind the patchboard, the EAI 680 forms a compact unit — 150 × 150 × 75 cm — that can be installed without difficulty in a medium-sized laboratory or computing room. No air conditioning is required, and its low power consumption (due to the 10-volt reference voltage) allows simple connection to a standard power outlet.

In a single console, a fully expanded EAI 680 contains up to 156 amplifiers, divided into combination amplifiers (integrators/summers), summers, and inverters, plus up to 120 servo and 12 manually set potentiometers. An expanded system also contains a complete set of nonlinear computing elements: multipliers, sin/cos function generators, exponential function generators, angle function generators, and limiters. Added to this is a coupling system and a large number of interconnecting lines for expanding the system by adding additional consoles.

To simplify the programming of hybrid problems, a comprehensive logical interface is provided. This includes individual control of integrator operating modes and time normalization, Track/Store units with logic control, fast electronic comparators with logic outputs, function relays, and electronic switches. The analog inputs and outputs of these elements appear at the analog plug-in units, and the logic inputs and outputs are brought out on the digital portion of the patchboard.

The programmable logic system features triggered flip-flops; this eliminates the possibility of erroneous operations due to random influences, and simplifies the programming and debugging of a logic program. The logic elements include up to six 4-bit registers, which can serve as shift registers, binary counters, parallel buffer registers, or four individual RST flip-flops. The logic elements also include an assortment of AND/NAND gates, up/down counters, monostable multivibrators, and logic differentiators.

In addition to the capabilities listed, the EAI 680 is designed for interconnection with a stored-program digital computer. The interconnection lines for fast data transfer and the control interface are provided within the system.

The EAI 680 represents the fourth generation of hybrid computers developed by EAI.

EAI Electronic Associates GmbH — 61 Aachen, Bergdriesch 37 — Tel. (0241) 26041/42 — Telex: EAI Aachen No. 852676