Analog Computers

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Dornier 960 Simulation System — System Description

This document is a full English translation of the original German-language brochure/system description “Simulationssystem Dornier 960 — Do 960 Systembeschreibung”, published by Dornier System GmbH.

Do 960 — System Description

Table of Contents

  1. Introduction
  2. System Architecture
  3. Do 960 Bus
  4. Microprocessor + Software
  5. Operation and Use
  6. Do 960 Module
  7. Do 960 Computing Elements
    • 7.1 Integrator
    • 7.2 Summer
    • 7.3 Multiplier
    • 7.4 Digital Potentiometer
    • 7.5 Digitally Adjustable Function Generator
    • 7.6 Fixed-Setting Function Generator
    • 7.7 Limiter
    • 7.8 Comparator and Electronic Switch
    • 7.9 External Interconnection Lines
  8. Logic Extension

1. Introduction

The DORNIER 960 combines analog and digital computing techniques in a single system. The functions and states of the analog components are controlled and monitored by a central processor. Operation of the system is normally performed via a terminal with screen and keyboard. In addition, further peripherals can be connected as desired.

The present system description is intended to give a brief introduction to the main features and characteristics of the DORNIER 960.

2. System Architecture

Figure 1 provides an overview of the system architecture. The analog computing elements are arranged in up to 16 modules, each of which is connected via a bus (the Do 960 Bus) and controlled and monitored by it. This bus is driven by a CAMAC system, whose core is a microprocessor (µP).

Analog Computing Elements

In response to inputs at the terminal or to the operator-supplied program, the microprocessor controls the coupling components via the Do 960 Bus and thus the analog computing elements.

3. Do 960 Bus

The Do 960 Bus carries the following signals:

  • 16 data write lines: These lines handle data transfer from the processor to the Do 960 modules.
  • 16 data read lines: These lines handle data transfer from the Do 960 modules to the processor.
  • 4 function lines: These lines cause the module to execute the desired function (encoded).
  • 16 address lines for modules: These lines handle addressing of a module for slot selection.
  • 16 address lines for digital potentiometer groups: These lines handle addressing of a digital potentiometer group within a slot.
  • 1 strobe: On the rising edge of the strobe, the desired function is executed. The strobe output quits the executed function and optionally starts an amplifier.
  • 1 strobe answer: This signal shows the status of the strobe.
  • 1 alarm signal: This signal shows the overloading of one or more integrators.
  • 1 reset signal: This signal is simultaneously sent to all modules connected on the bus.
  • 1 analog sampling line: This line carries the instantaneous output voltage of the currently addressed computing element.

The Do 960 Bus will be supplied with two CAMAC modules: the “Digital Output Do 200-2711” module for driving the 32 address lines and the “Input/Output” module for the remaining bus signals.

4. Microprocessor and Software

The controller (slots 23 to 25 of the CAMAC frame) controls all Do 960 modules. Its core is an INTEL 8080 microprocessor, with the following memory configuration:

  • 18 K RAM
  • 12 K PROM

In PROM is stored the basic operating system SAS (Stand Alone System) and the BASIC interpreter.

The PROM memory can be further expanded by an additional CAMAC PROM module with up to 64 K bytes. This PROM module stores all further program packages, such as the Monitor Program for operating the Do 960 system, the 8080 assembler (which runs itself on the bus), the 8080 editor for creating individual assembly programs, and the BASIC interpreter. The BASIC interpreter supplements the normal BASIC instruction set with logical and CAMAC functions.

Programs are executed in Overlay Technique: each part of the program is loaded into RAM from PROM and executed there, so that the user program is not interrupted.

To simplify operation of the Do 960 system, a MONITOR program is provided that allows dialogue interaction via the terminal (Figure 4) to trigger standard functions.

5. Operation and Use

Every function within the CAMAC frame and thus (via the coupling modules) within the Do 960 modules can be performed in BASIC or in assembler programs.

For simpler operation there is a MONITOR program that allows dialogue via the terminal (Figure 4) to trigger standard functions.

After starting the MONITOR, the startup distributor awaits the entry of a character from the terminal keyboard. Depending on the entry (valid = falls), a sub-program for execution of the desired function is jumped to. After execution, the program returns to the startup distributor. Thus the user’s own program written using BASIC can be appended. Combining the comfort of the MONITOR and the user’s own BASIC routines is thereby possible.

Valid inputs to the startup distributor:

InputFunction
AAll integrators take operating mode AB
RAll integrators take operating mode R
HAll integrators take operating mode HT
TAll integrators enter a common time-constant mode
CTRL AAddress the computing elements
CTRL DGroup mode: dump computing elements
CTRL FSet function generator
CTRL LSet limiter (limiter)
CTRL PSet potentiometer
CTRL TTime-constant control (individual)
CTRL UJump to user program
XAlignment
CBus control / external control
ISet alarm mask
ESCExit from MONITOR

CTRL X means that first the CTRL key is pressed and then the X key is pressed simultaneously.

CTRL A causes an address-and-display sub-program to appear at the right side of the terminal display, showing both the address and digital voltmeter readout. The input address there shown (if valid) is displayed; the display of the output address remains valid until another computing element is addressed.

6. Do 960 Module

The Do 960 module (Figure 6) serves to accommodate computing elements. At the same time it acts as the interconnecting link between the computing elements and the Do 960 Bus.

The module carries two sockets on the rear side: the “Process socket” designated in Figure 6 is for connecting the computing elements, and the “Bus socket” is for the Do 960 Bus connection.

The upper part of the module carries the panel with five digital potentiometers, which can accommodate handpotentiometers, digitally adjustable function generators, integration capacitors, etc.

At the rear of the module are six external connection lines that are accessible from the process socket side and that normally serve to connect external equipment. Three of the lines (TO bis T2) are addressable.

One module can accommodate the following components at most:

  • 2 integrators (also usable as open-loop amplifiers)
  • 2 summers
  • 1 multiplier/divider
  • 1 or 2 fixed function generators
  • 1 electronic switch
  • 5 digital potentiometers
  • 2 freely programmable resistance networks (1:1, 10, 10:1 SP)

Furthermore, a module provides the following connections:

  • 1 handpotentiometer (ungrounded)
  • 1 digitally adjustable function generator
  • 8 external connection lines (3 of them addressable)
  • 2 integrators
  • 2 summers
  • 1 function generator
  • 16 external connection lines

7. Do 960 Computing Elements

7.1 Integrator

The integrator can be used not only as an integrator but also as an open-loop amplifier. In the latter mode it is always available as a summer as well. Each module can take 1 Multiplexer, receiving the control signal from the bus from a single externally available summing point, through which the means of the freely programmable resistance networks (1:1, 10, 10:1) can be enhanced.

The control (operating mode, time constant, and external input) of the integrators is handled from the bus separately for each integrator. An integrator module accepts two integration capacitors at the patch panel.

Patch connections:

  • Internal time-constant control
  • Integration capacitor input

Further specifications:

  • Integration capacitors: 10 µF, 1 µF, 0.1 µF, 0.01 µF
  • Working balance:
    • Drift in HT (10 µF): 0.03% FS typ., and 0.1% FS for 0.1 µF and 0.01 µF
    • Drift in DR (1er input, 10 µF): < 30 µV/sec
    • Switch-over time (operating mode switch): ~1 µs

7.2 Summer

The summer can be used with or without various feedback resistors. The selection is done via short-circuit plug on the patch panel.

Schematic:

(Two-input summer with selectable feedback, with gain options 1, 10)

7.3 Multiplier/Divider

Each multiplier contains all the amplifiers required for operation, plus a standard multiplier. Two types are available:

  • Standard multiplier (0.5% FS error)
  • High-accuracy multiplier (0.05% FS error)

Schematic:

(Four-quadrant multiplier X)

Patch connections:

  • Signal bandwidth: > 200 kHz
  • Gain uniformity of inputs: 0.01% typ.

7.4 Digital Potentiometer

The digital potentiometers are Digital/Analog converters with a freely settable reference voltage input and a resolution of 14 bits. The setting range is −1.0000 to +1 LSB. The setting is done via the Do 960 Bus.

Each group of potentiometers (platine) that is installed in the module is gathered together.

Patch connections:

Further specifications:

  • Setting precision: 0.02% typ.
  • Signal bandwidth: > 100 kHz
  • Settling time: 1 µs

7.5 Digitally Adjustable Function Generator (DCFG)

The DCFG is a CAMAC component and occupies one slot within the CAMAC frame. It allows the approximation of arbitrary functions with any number of variables and with infinite slope.

Data is loaded into the RAM of the DCFG by the CAMAC data bus. The input variable X is digitized by the ADC, which is the RAM address information. The content of the addressed RAM location is then output by the DAC.

The look-up table function is generated via the CAMAC data bus. The input X (entering the ADC) is digitized; the RAM address information allows the content of the addressed RAM location to be output by the DAC.

The recalled function is generated from the Monitor Program by linear interpolation between stored set points and an operator-supplied program.

Patch connections:

Further specifications:

  • Number of set points: 1023
  • Resolution in X direction: 10 Bit (≙ ca. 20 mV)
  • Resolution in Y direction: 12 Bit (≙ ca. 5 mV)
  • Max. slope: —

7.6 Fixed-Setting Function Generator (FDFG)

The fixed set-point function generator supplements the multiplier to offer the following types:

  • X for positive input voltage
  • X² for negative input voltage
  • log X for positive input voltage
  • log X for negative input voltage

Dual sin/cos function generator (requires two multiplier slots)

On application of the multiplier slot with a dual sin/cos function generator using an adhesive film, the function generator gives the sin/cos output.

7.7 Limiter

The limiter limits the output voltage of an amplifier. Both the upper and lower limits are independently adjustable, over the range −1 bit to −(−1 LSB) above the Do 960 Bus.

Each time the upper trip value is preset, it can be set as “positive” (higher) or “lower” (negative) trip.

Patch connections:

Further specifications:

  • Resolution of the trip values: adjustable
  • Hysteresis: adjustable
  • Switching time (comparator → switch): < 2 µs

7.8 Comparator and Electronic Switch

Each comparator is coupled to an electronic switch. Without external patch connections the switch follows the comparator state. Over external patch connections the switch can have its own control signal.

The switch has a current output and must therefore be connected with the summing point of an amplifier.

Simple arrangement:

(Comparator with switch K0 and output S0)

Patch connections:

Further specifications:

  • Sensitivity of the comparator: < 3 mV
  • Hysteresis: adjustable
  • Switching time (comparator → switch): < 2 µs

7.9 External Interconnection Lines

At the base of each module section are six external connection lines accessible from the process socket side, normally used to interconnect external equipment. Three of the lines (TO bis T2) are addressable.

8. Logic Extension

In addition to the analog components in the Do 960, logic elements are also available. These logic elements are accommodated in a special Logic Module that can replace one analog module.

Each Logic Module reduces the number of maximally possible analog modules by one.

A Logic Module contains the following components:

  • 1 clock generator
  • 10 AND/NAND gates
  • 6 flip-flops
  • 2 4-bit counters
  • 2 monoflops

The outputs of the logic elements can be connected together using “WIRED AND”. Counters and monoflops are clocked by the bus, and likewise start/stop of the clock generator by the bus.

Publisher:

Dornier System GmbH Postfach 1360 7990 Friedrichshafen 1 Tel. 07545/81 — Telex 073210-0