This is the original GEC 4080 Sales Brochure dating from 1973. The 4080 was very advanced for its time. Most particularly its Nucleus hardware executive, which later won GEC Computers the Queen's Award for Technology, was a unique concept in processor design, and remains so even 25 years later. Careful reading shows that the 4080 was designed from the beginning as a multi-processor system with 4-ported store system for up to 4 processors. However, this was only used for additional I/O processors initially, not actually for additional CPUs for some 14 years.

Forward references:
Architecture - the CPU, I/O, and Store systems
Programming Languages - Babbage, Fortran IV, Coral 66 (many more came later)
Nucleus - the hardware executive
Operating System Software - COS and DOS (OS4000 came later)
Peripherals - Paper tape, Teleprinter, Lineprinter, Thermal console, Discs, Terminals
Specifications - System sizing, Timings, Register widths, Store, I/O, etc.


GEC 4080

a new dimension in computing for the real-time control and automation market

Is the automation world waiting for a break-through in basic system capability?

Is it reasonable to expect one?

The breaks come few and far between nowadays; real progress is only gained at the expense of increasing effort and greater talent and experience. However, significant steps forward are still made, generally spurred by an urgent requirement.

Here is a major new development that gives you an opportunity to bring your medium to large-scale systems thinking right up-to-date. Check your problems against those listed below; see how 4080 tackles them, and then ask yourself these questions again.

System Development risks

How many system risks do you take to get a contract? Of course, you use modular software - we all do - but how well can you control the software interfaces? How much help do you get from the basic system? How worried are you about system integration? - software PDS? How long will that system bug stay hidden?

Now we have built a system that sets out to help you - monitors your implementers - organises your interfaces - structures your system for you. Prevents inter-process corruption, both now and when you go on-line. Traces inter-process messages.

On-line commissioning

When you get to site, how long will it take to bring the system in? Are your control algorithms good enough? How long will it take to localise the problem?

4080 offers a powerful, modular means of simulating plant interfaces. Changing from simulated to actual plant transducers is as easy as plugging in an exchange hardware module - without the slightest disturbance to the system structure.

General purpose operating systems

The hallmark of the G.P. operating system is flexibility - ability to adapt to all extremes of load that might be applied to the system, even at the expense of average efficiencies as low as 20-30%. This is no good to the real-time man - he must use as much as 80% of the potential system capability, yet guarantee that the system will still cope with limiting conditions.

In 4080 you get all the basic essentials of a quick-responding, safe real-time system - built into the hardware for maximum performance - plus a system structure within which you can safely tailor your own highly efficient operating environment. And there are many on-line facilities to help you provide additional software features like data management, job scheduling, store management, and so on.

Response times

How long are you prepared to take to service an interrupt? Or to reschedule? How do you handle multiple asynchronous events? The real-time systems man will recognise these as the limiting factors in real-time performance, and will look carefully at how his prospective system handles each matter.

In 4080 he will find these problems administered by micro-program stored on bipolar read-only memory, which uses special hardware built into the central processor. He knows nobody can do better than that! Look carefully at our operation times.

Critical functions

But the system can still lack top performance if it takes a multitude of instructions to perform the functions you require.

4080 has five different address formats for store reference instructions - including three for arrays - and others for literals, register and control operations. Fixed and floating point arithmetic operations are available on a wide range of data formats. Bit and byte string manipulation may be performed. Speed and efficient use of store are both enhanced by this powerful set of operations.

Cost

Does this sound to you like a price tag of £¼M? £100K? £50K? - You'd be surprised- you might find yourself able to use this powerful system for a lot smaller applications than you think!

Architecture

The GEC 4080 is specifically designed to provide a major advance in the rapidly developing medium to large-scale automation system field. It comprises a range of basic units providing central processor, store and input/output facilities extending over a wide range of system size; other processors may be added to provide major standard or special input/output extensions, or to extend the general purpose processing capability of the system.

The minimum configuration contains one module of store (either 32 or 64 kilobytes) and one central processor with its built-in input-output multiplexer capable of accommodating up to 256 fully autonomous peripheral devices. Control teleprinter and paper tape equipment are also required. This configuration will occupy a standard 6ft. rack with room to spare.

Larger configurations may contain up to 256 kilobytes of store, magnetic discs, line printer, magnetic tape, communications peripherals, etc.

The Central Processor

The CENTRAL PROCESSOR of 4080 provides extensive logical, integer and floating point manipulation facilities in a high speed multiple register hardware system. Data formats provided are:-

BYTE 8 bits
HALF-WORD 16 bits
FULLWORD 32 bits
FLOATING POINT 24 bits fraction, 7 bits exponent
FLOATING POINT 56 bits fraction, 7 bits exponent

Modern, MSI hardware techniques enable 4080 to provide directly interpreted hardware instructions operating on all these formats.

Index registers and special address mapping logic also result in fast and extremely flexible address structuring. There are five formats for store reference, including three specifically designed for accessing arrays of varying complexity, as well as formats for register to register, literal and branch instructions.

These features result in a processor which is not only fast by any standards, but also which can save considerable amounts of time and store-space by performing in one operation tasks that would take other computers many instructions. For instance, 4080 may scan through an array of characters packed in store until any of a number of pre-specified characters are found - in one instruction!

And to ensure that maximum advantage is obtained from all resources in the system, store accesses are interleved to optimise store utilisation.

Input/Output

Built into this central processor unit is the BASIC MULTIPLEXOR CHANNEL which time-shares peripheral transfers from any of up to 256 devices on to the store highway. This is a completely autonomous operation and involves the central processor only at the beginning and end of each operation.

The basic multiplexor communicates with peripherals via NORMAL INTERFACE. This is a fully asynchronous interface with up to sixteen data lines. Equipment may be connected to it by plugging a controller or other interface board into one of the SLOTS provided in the central processor unit. Eight such slots are available, and are used not only for connecting to peripherals, but also to modules of store. Connecting cables are plugged into connectors provided along the top edge of the interface board for this purpose.

Should the eight slots be insufficient for the store/peripheral configurations required further slots are made available by adding one or more EXTENSION UNITS. These are standard units, common to all GEC 2000 and 4000 equipment, and provide a further thirteen slots each.

The Store

The main STORE of 4080 is a modular 2½D core system of advanced design. The nominal cycle time is 550 nano-seconds, and modules of 32 and 64 kilobytes are available. Up to four modules may be fitted, making a maximum of 256 kilobytes.

In order to facilitate connection of additional processors, each store module has four ports built into it. Thus four separate 'highways' may be connected to each store module. The scheduling of demands on the store from these highways is handled by the STORE ACCESS DIRECTOR. This is, of course, also a built-in feature.

Programming Languages

Babbage

A system providing the wide range of operations and addressing modes of 4080 must, we well appreciate, pose something of a problem at the machine-code programming level. This is why we have introduced a new concept in the high-level assembler for 4080, which we have called BABBAGE. It has all the clarity and power of expression of a high-level language, yet is specifically designed in conjunction with the structure of 4080 to provide explicit control of the machine-code. Algorithms are provided for automatic allocation of registers, but where machine-code must be fully optimised for a specific requirement, the programmer may use BABBAGE to define how he wants the registers used.

Thus the programmer may exploit all the complex facilities available on 4080, yet operate in a medium which looks very much like a conventional high-level language.

Other Languages

Of course, many specialist industrial and military application areas have already standardised on an appropriate standard high-level language. 4080 will support these areas by providing the appropriate compilers. These include:-

FORTRAN IV

CORAL 66

Nucleus

Possibly the most critical aspect of the larger real-time system is the structure of the operating system. Use of a ready-made, proven-purpose system involves overheads that are frequently unacceptable; starting from scratch for each project maximises the work - and the risks.

4080 provides a unique compromise; the operating system software concentrates on providing a development structure within which you can quickly and safely construct your own operating system, while special hardware provides those critical features upon which all real-time systems depend - and provides them with ten times the performance of their software counterparts. This hardware we call NUCLEUS.

Protection

Special hardware registers in the central processor are used by NUCLEUS to surround each segment of program or data with inviolable boundaries to protect it from corruption resulting from errors in other parts of the system, or vice-versa. Attempts by any part of the system to cross these boundaries will be prevented - throughout the working life of the system.

Communication

But isolated programs cannot be used to construct a real-time system without some means of communication. NUCLEUS provides a fully asynchronous message-handling system, not only for passing messages between programs or processes but also between processes and peripherals. Thus the user may retain considerable flexibility in structuring his system for both the off-line and on-line phases of his project.

Scheduling

In the real-time environment the sequence of events within the computer is dictated millisecond by millisecond by events in the world outside. The ability of the system to respond quickly is thus another critical factor. NUCLEUS is responsible for responding to all interrupts, passing messages to the appropriate process and deciding whether this enables a higher priority process to run. If it does NUCLEUS will activate the relevant process, dumping and reloading registers in the central processor as required. It will also schedule in a lower priority process when this higher priority process terminates.

And remember, this all happens at bipolar logic speed!

The Operating System Software

While NUCLEUS provides the fundamental system features requiring a fast response, extensive software is available, designed to add optional features to the system as required by the application. In providing these features first consideration has been given to two criteria:- That the minimal core-resident system should be small. It is, in fact, less than 8 kilobytes! The rest of core is occupied by program you choose.

That maximum support should be given to the system analyst to structure and control his software system during development. In addition to the normal features, special command languages and real-time monitor facilities are provided.

Operating systems may be based on a core-resident system or on a disc system. These are known as Core Operating System (COS) and Disc Operating System (DOS).

Core Operating System

This operating system is primarily intended for use in the development and operation of custom real time systems. The use of COS is particularly appropriate where the application is of sufficient complexity to benefit from the program structuring, protection and asynchronous communication facilities of the 4080 Nucleus. It will include the following components:-

Program Preparation
Text Editor
Macro Generator
Link Editor
Tailor
Babbage Assembler
Fortran Compiler
Coral 66 Compiler
Program Development
Interactive Diagnosis System
Post Mortem Dumps
Message Monitor
Diagnosis Trace System

Communications Software
Operating System
Initial Program Load from Paper Tape
Initial Program Load from Magnetic Tape
Command Process
Command Analysis
Process Controller
Process Loader
Core Space Allocation
Error Reporter
System Error Process
Timer Routines
System Generation
Tailor
System Description Analyser
Nucleus Table Generator
Initial Program Generator
System Generation from High Level
Controls
Data Management
Radix Conversion
Comment Generation
Data Marshalling
Device Selection
Device Routines for:-
Teleprinter/Thermal Printer
Paper Tape Punch
Paper Tape Reader
Magnetic Tape
Line Printer
Paper Tape Utilities
Magnetic Tape Utilities
Magnetic Tape Filing System
Mathematical Routines
Numerical
Trigonometric
Hyperbolic
Complex Numbers

Disc Operating System

This operating system is intended to be used in the development of custom real time systems. The use of DOS is particularly appropriate when the computer is committed to a real time application which needs the overlay and filing systems. DOS is also appropriate where the computer is being used for the commissioning of a complete real time system which may ultimately be run under COS.

The primary functions of DOS are the set up of real time systems in a safe orderly, and controlled manner; and the operation of and the provision of services to such systems in real time, with full

It will include the following components:-

Program Preparation
Text Editor
Macro Generator
Link Editor
Tailor
Babbage Assembler
Fortran Compiler
Coral 66 Compiler


Program Development

Interactive Diagnosis System
Post Mortem Dumps
Message Monitor
Diagnosis Trace System
Communication Software
Operating System
Initial Program Load from Paper Tape
Initial Program Load from Disc
Initial Program Load from Magnetic Tape
Command Process
Command Analysis
Process Controller
Process Loader
Core Space Allocation
Overlay System
Error Reporter
System Error Process
Timer Routines
System Generation
Tailor
System Description Analyser
Nucleus Table Generator
Initial Program Generator
System Generation from High Level
Controls
Data Management
Radix Conversion
Comment Generation
Data Marshalling
Device Selection
Device Routines for:-
Teleprinter/Thermal Printer
Paper Tape Punch
Paper Tape Reader
Magnetic Tape
Line Printer
Cartridge Disc
Head per Track Disc
Card Reader
Paper Tape Utilities
Disc Utilities
Magnetic Tape Utilities
Disc Filing System
Magnetic Tape Filing System


Mathematical Routines
Numerical
Trigonometric
Hyperbolic
Complex Numbers

Miscellaneous
Plotter
Character Display
Digital I/O

Peripherals

4080 is supported by a wide range of standard peripherals. The following 3000 range peripherals may be fitted to 4080 via the NORMAL INTERFACE.

These include:-

High performance reader (500 ch/sec) and high performance punch (110 ch/sec)

These peripherals have a designed performance compatible with the requirements of a typical 4080 system. They are based on high quality mechanisms of proven performance.

The control teleprinter normally supplied is ASR 33, but if the tape system is not required the KSR 33 is also available. ASR 35 is offered for systems requiring maximum availability. MODEL 390 has additional styling features which considerably reduce the noise level.

LINE PRINTER (300 or 600 l.p.m.)

Two speeds of line printer are offered for bulk output. The maximum line-length is 136 characters.

THERMAL PRINTER

This printer has a speed of up to 30 characters/sec and has a character set of 64 symbols of good legibility. It is very quiet in operation.

line printerthermal console

CARTRIDGE DISC 2.4 or 4.8 megabyte

This moving head disc represents a most cost effective way of purchasing bulk rotating storage. Mechanisms are available with either a single 2.4 megabyte removable cartridge or a 2.4 megabyte removable cartridge plus 2.4 megabytes of fixed disc storage on the same spindle.

HEAD PER TRACK DISC 1 megabyte

This fixed head disc is used to supplement or replace the cartridge disc where faster access times are important.

DISPLAY TERMINALS

A range of video terminals from a simple teletype replacement to full graphics capability.

COMMUNICATION CONTROLLERS -
SINGLE ASYNCHRONOUS
SINGLE SYNCHRONOUS
MULTIPLE ASYNCHRONOUS

All these units are based on the V24 ½-duplex line standard (full duplex uses two modules), all are CCITT and GPO compatible, offering cost-effective means of inter facing to a wide range of line standards and transmission speeds.

STANDARD INTERFACES
MARCH 4

This interface provides access to a range of peripherals designed for the industrial control market. They include:-
DIGITAL I/O, ADC's, DAC's, LOGGERS, etc.

LABORATORY INTERFACE

Provides access to a range of devices providing low-cost ADC's, DAC's etc. for the smaller system.

LOCAL EXTERNAL INTERFACE

Enables users to replicate NORMAL INTERFACE in their own equipment up to 4 metres (14ft) away from the 4080.

SPECIAL INTERFACES

The flexibility of the NORMAL INTERFACE is such that customers can with confidence contemplate the design of an interface to his own equipment. Facilities to assist him in this process are available and may be used subject to discussion.

Maintenance

GEC Computers use the extensive facilities of the GEC Group of companies to offer maintenance and field support on a world-wide basis.

Maintenance of 4080 can be achieved by the use of exchange units. This minimises repair time when optimum performance and a low mean-time-to-repair (MTTR) are necessary.

For optimum system performance a comprehensive maintenance scheme can be adopted. However, alternative servicing arrangements can be offered and the schemes fall into the following categories:- Fully comprehensive service, on a 24 hour basis, to cover routine service visits, emergency on-call service and free replacements of all components and materials.

Fully comprehensive service as above but restricted to normal working hours (9 a.m. to 5 p.m.)

'On-call' emergency service, as a second line support to the customer's own maintenance team.

Spares supply to the customer's own maintenance team. Base workshop facilities for returned units.

Training

A well equipped Education Centre exists at Borehamwood and operates frequent "Standard Courses" covering the programming, engineering, and maintenance aspects of all products. These include introductory courses on 4080 and on BABBAGE.

Support

The expertise that designed 4080 also extends through a wide range of application areas as well; GEC Computers is hence able to offer you assistance at all levels; this may be a matter of discussion of configuration details, assistance with hardware or software design, joint development - up to our acceptance of complete system design responsibility. We will gladly discuss your requirements in these terms, and place our resources at your disposal.

Specification

SYSTEM PARAMETERS

Type Modular, multiprocessor with built-in multiprogramming facilities.
Max number of processors 4
Max number of store modules 4
Max size of store 256 kilobytes
Max number of processes per processor 256
Max number of protected segments per processor 4000

4000 NUCLEUS TIMES

(microseconds, typical)

Semaphore operations no program change - 4.95
program change - 35
Segment load - 7.5
Inter-chapter branch no segment change - 4.6
segment change - 9.1
Start input/output - 20.0
Interrupt no program change- 8.7
program change - 42
Inter-process message no program change - 35
program change - 55

CENTRAL PROCESSOR

Operations byte (8 bits), 16, 32, 64 bits - parallel.
Program accessible registers 8
Accumulator length 32 bits
Number representation integer, 2's complement
Floating-point format 7 bit exponent to base 16 24 or 56 bit mantissa + sign
Control Microprogram matrix, bipolar ROM

Operation times (microseconds, typical)

ADD 1.1
MULT 5.9
DIV 20.0
F.P. ADD 7.9
F.P MULT 10.9
F.P DIV 19.4
BRANCH 1.35
SHIFT (N bits) 2.6+ .07N
BYTE STRING (N bytes) 1.55 + 3N
REGISTER - REGISTER 1.8

STORE

2½D core system
Cycle time (nominal) 550 nanoseconds
Store width 16 data bits + 2 parity
Module sizes 32 and 64 kilobytes

INPUT/OUTPUT

Number of autonomous ways 256 per processor
Max number of interrupt levels 256
Number of interrupt sub-levels 16 per level

PHYSICAL DATA

Mounting method GPO 19" rack standard on telescopic runners
Width 534mm (21") overall
Depth 599mm (23¼") overall
(the above does not apply to certain peripherals)
Panel heights:-
Central Processor with power 495mm(17½")
Store - with power 445mm(15¾")
Extension Unit (integral power) 267mm (10½")

ELECTRICAL

Power supply to BEAMA class IA.
Voltage 220-250V±10%
Frequency 50 or 60 Hz±4%
Consumption 1.5 Kva (Processor and 64KB store)

ENVIRONMENTAL

Operating temperature 0ºC to +55ºC
Non-derangement -40ºC to +70ºC
Humidity 0% to 95% without condensation
Minimum atmospheric pressure operating 860 m bar
non-derangement 150 m bar

GEC 4080

opens up the way for major advances in the field of integrated control of complex systems

© GEC Computers Limited 1973


Reproduced with the kind permission of GPT Limited.

© 1997,2008 Andrew Gabriel. All Rights Reserved. / Last revision 3 February 2008