The Concept

What is Videodisc?

Videodisc is an audio-visual delivery medium which offers a wide range of totally new communications opportunities in the field of teaching, training, learning, marketing and general information distribution.

Because it is a replay medium it has a dense storage capacity for exceptionally high quality pictures and sound.

Because it is a disc — encoded in a spiral form — very fast random access can be gained to any part of the material.

Because special codes can be pressed into the disc a high degree of control can be exercised by the programme designer which affect the way the disc is used.

Together these offer a new opportunity — interactivity.

What is Interactivity?

In an interactive programme the otherwise passive viewer becomes an active participant — a user. He controls the message, he progresses at his own pace, absorbing and learning unhindered by others.

The programme maker can design the programme material in such a way that choices made by the user direct him along the most appropriate path.

For the first time the user feels that he is in charge, and for the first time the programme designer knows that his message is being tailored to that user’s needs.

Why Interactivity?

There is already substantial evidence that interactive video is the most effective tool for delivering a complex message — simply and clearly.

Because the interactive programme cannot progress without the user’s active participation fie is more inclined to pay particular attention to the information he is being asked to absorb. Systems can be designed to examine the user on his reactions and understanding, and he can be accurately directed to the most appropriate next step.

Why Interactive Videodisc?

Adding computer control is simple — and even small micro computers can add a new dimension to interactive programming.

The only way to grasp the potential of Interactive Videodisc is to experience it. Only a demonstration can do justice to this powerful tool.

The videodisc has an unparalleled capacity for storing information. Sixty minutes of video material can be packed into one side of a to inch VHD disc together with two audio tracks. Two complementary commentaries, different comprehension levels, question and answer, second languages – all are immediately possible on one disc. A capacity of 45,000 still pictures, each with its own unique address, turns videodisc into a database of immense density. And these capabilities can be coupled on one disc, with one videodisc player performing all the required access and replay functions.

PETER MORLEY OBE – Controller of Programmes
ALASTAIR BOWES – General Manager

The Service


In Commerce, in Industry, in Institutions — whatever the applications — interactive video is only as good as its software.

That is why THORN EMI VIDEODISC is making available a comprehensive service you can draw on, ranging from the development of the initial idea right through to the delivery of the system — and beyond.


Consideration of a videodisc system may involve major investment decisions by a company. Careful planning of both software and hardware requirements is needed.

THORN EMI Videodisc can provide it full consultancy and advisory’ service to translate these needs into decisions, and then actions.

Programme Design

THORN EMI has the videodisc design experience. This experience is available to your team to assist in the development and design of your interactive programmes. Help can be given with the new conceptual approach, flow-charting and with technical requirements.


Our Software Advice Centre is available to work with your own in-house video or film unit, or with your chosen production and facility companies, keeping a close liaison with both creative and technical teams.

Post Production

We will monitor progress during this important phase and ensure that the programme design, programme material and videodisc technical capabilities are correctly integrated.


We will supervise this final post-production stage where the video and audio information is committed to 1″C Format video tape.

Our associate company THORN EMI Video Facilities is able to quote favourable rates for this stage of the work. They are one of London’s leading video facilities companies and have gained unique experience in videodisc pre-mastering.

Making the Disc

Our own factory at Swindon is dedicated to the mastering and pressing of VHD videodiscs for the commercial, industrial and institutional markets.


The VHD videodisc players will be delivered and installed by trained THORN EMI personnel. Demonstrations will be given to familiarise staff with the system.

The Service Continues

Apart from maintenance and warranty arrangements, we offer to monitor — with the user — the effectiveness of this new form of communication and will advise on future applications.


Disc Manufacturing

JIM JOHNSTON – VHD Manager, Swindon


The THORN EMI Videodisc factory at Swindon was purpose built to master and press VHD Videodiscs.

This is where the new technology takes over. Videodisc manufacture involves a blend of old and new technologies — and from the old demands higher standards than ever before.

The factory itself is a building within a building. The mastering and manufacturing processes all take place in an environmentally controlled series of clean rooms. The standard demanded throughout is not less than Class 10,000 and in the most sensitive areas is better than Class 100 — fewer than 100 microscopic particles in every cubic foot of air.


Programme material from virtually any source can be considered for videodisc. The final stage of post-production is to edit all the material onto a broadcast standard 1″ C format videotape in the order in which it is required on the final disc.

All audio must also be recorded in the correct places on the correct tracks.

During this process the exact location of each of the special VHD control signals is determined. These signals identify chapters, time code, page addresses, autostops, and automatic audio switching.

The finished videotape is called the PREMASTER TAPE.

Videodisc Mastering

In the VHD videodisc plant the Glass Master is prepared. This is an optically perfect glass disc which has been cleaned, coated with a photo-resist solution and baked to harden the coating. After careful checking it is placed in the Laser Cutter.

The Premaster Tape is played back to the Laser Cutter which encodes the signals into a form which drives the powerful laser. A complex series of optics condense and shape the laser beam and focus it onto the Glass Master to create the latent image of the microscopic pits in the surface.

The Glass Master is then developed, checked for flaws and after thorough cleaning is ready for the next stage in the process.

Swindon U.K.

Stamper Production

The cleaned Glass Master is sprayed with silver nitrate and a reducing solution to create a thin coat of silver. It is then electro-plated with high grade nickel in a two stage process. This gives the metal form rigidity, and it can then be removed from the Glass Master. This is the Metal Master, a negative image.

After careful cleaning the Metal Master is used to ‘grow’ positive masters, or Mothers. This is another electro-forming process. A number of mothers can be made from one Metal Master.

Again after careful cleaning the positive Mother is used to create the Stampers – the final negative image from which the videodiscs are pressed.

Disc Pressing

A pair of Stampers (Side 1 and Side 2) are placed in the press. The electro-conductive plastic compound from which the disc is made is extruded in a semi-liquid state into a carefully regulated form, known as a Patty. This is transferred to the space between the stampers, and as the press closes. steam is injected.

When the Patty has spread out cold water replaces the steam — the compound solidifies, and a videodisc emerges.

The disc is edge-trimmed, proceeds through quality assurance, and is then placed into its protective plastic disc case.

The VHD Videodisc is housed in a plastic case. The VHD player removes the disc when the case is inserted and replaces it after use.

Why VHD?

The VHD system is extremely versatile and cost-effective.

As a ‘stand-alone’ player plugged into a television set it provides an interactive capability which will satisfy a wide range of applications.

Plug in a computer via the (optional) interface and any computer can upgrade the interactive capabilities. With a ‘genlock’ capable computer high resolution graphics overlay can provide another new dimension.

Any customer buying VHD will be able to acquire further options as and when he wishes to expand his system — but the basic player remains the same.

In the near future….. with an AHD adaptor you have Advanced High Density. This is the digital option offering a new range of abilities which include full digital audio, computer data storage, and digital still pictures with compressed audio. In the latter mode the disc will store 1500 high resolution images per side.

VHD and AHD separately or on the same disc — a unique communications system. It starts with a basic videodisc player which in itself is a revolution in interactive communications.


Advice Bureau, Airlines, Auction Galleries, Banking, Catalogue Shopping, Corporate Affairs, Community Health Centres, Computer Familiarisation, Car Showrooms, Customer Care Training, Conference Organisers, Dancing Schools, Defence Training, Demonstrators, Distance Learning, Departmental Stores, Exhibition Stands, Engineering Instructions, Evening Classes, Estate Agents, Factory Instruction, Further Education, Financial Communications, Furniture’ Showrooms, Government Departments, Health Organisations, Hospitals, Information Centres, Induction Courses, Juvenile Rehabilitation, Laboratories, Libraries, Local Government, Medical Schools, Museums, Military Training, Maintenance Instructors, Music Teaching, New Product Promotion, New Product Training, Open University, Office Training, Personnel Departments, Pension Groups, Public Relations, Publicity Departments, Public Services, Quantity Surveyors, Research Establishments, Sales Instruction, Schools, Sports Centres, Stock Control, Showrooms, Training Departments, Technical Training, Tax Offices, Tourist Offices, Travel Agents, Trade Union Communications, Universities, Video Displays, Visual Database, Water Boards, Youth Training Centres, Zoos.

THORN EMI Videodisc

THORN EMI Video Disc Manufacturing Limited
Metropolis House
39-45 Tottenham Court Road
London W1P 9PD
telephone 01-636 7694
telex 296539

VHD System Prices

THORN EMI Video Disc Manufacturing Limited
Metropolis House
39-45 Tottenham Court Road
London W1P 9PD
telephone 01-636 7694
telex 296539

Disc Mastering

One side with 60 minutes programme capacity£1,750.00
Two sides with 120 minutes programme capacity£3,500.00

Disc Pressing

Prices for one or two-sided videodiscs (PAL/NTSC compatible_ with cases inside plain jackets.

per disc
(Special pricing for volumes over 1000)

Repeat order

If a request is made for the Swindon Plant to retain the master disc materials, repeat orders can be accepted at a later stage without re-mastering. A charge of £300.00 per disc side will be made for this service at the time of re-ordering, in addition to disc pressing charges.

The VHD player

THORN EMI Videodisc Player MODEL 3D01 with infra-red Remote Control£395.00

The interface

THORN EMI Videodisc VHD Computer Interface MODEL 3D02£95.00

THORN EMI VIDEODISC equipment carries a twelve months warranty.
Prices are exclusive of VAT and are subject to change without prior notification.
Full terms and conditions available on application.

A THORN EMI company
Registered Office: THORN EMI House, Upper Saint Martin’s Lane, London WC2H 9ED. Registered in England No 673395

The Risk Business

It’s 1981 and BBC-1’s ‘The Risk Business’, a spin-off from ‘Tomorrow’s World’ looks at how we will be watching television in the 1980s. Most likely we will be watching it via sell-though videodiscs, replacing our £35 VHS/Beta cassettes with £10 12″ discs made by JVC-Thorn, RCA or Philips – all with mutually incompatible systems, two of them using a form of microgrooves and one read by a laser!

Which one will the consumer of the 1980s pick? And why is Sony strangely sitting the battle out, ploughing on with tape instead?

This programme has the front titles cut off on the original VHS and the end is clipped by the tape running out. We’ve added back the titles so that the makers get their credits.