HARDWAREPERIPHERIQUES ★ TV - INTERFACES TELETEXT ADAPTOR AND TUNER|AMSTRAD ACTION) ★

Tv - Interfaces Teletext Adaptor And Tuner|Amstrad Action)Hardware Peripheriques
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Microtext has made it possible for you to page Oracle and Ceefax without the need of a television or remote control unit. Indeed, all you need is your Amstrad CPC. a couple of black boxes and an aerial You may think It odd having this facility on your Amstrad. but the monitor is ideal for displaying Teletext frames, ana it's a lot cheaper than buying a special Teletext-receiving television.

The Teletext Adaptor has been available for almost a year. To tune into the Teletext services (with only the adaptor) you need a video recorder. A lead is connected between the adaptor and the Video Out or AV of the video Video Out is normally used for recording from one video to another, but carries all the correct signals for tapping into Teletext Recently another box has joined Microtext's system - the Teletext tuner You no longer need a video to assist in picking up Teletext because the tuner does that. Cost of upgrading is £48.80.

Using a video recorder and adaptor to receive Teletext allows you to use the setup anywhere in the world - assuming that the country you're in has such a service. Currently most of Europe. Australia. South Africa, Malaysia and a host of other countries have Teletext on offer. If you use the tuner you probably won't be able to use it in other countries.

If you're lucky enough to possess a satellite dish then you may tune into SkyText and similar services from abroad.


The life and times

Teletext, a British invention, was first introduced to the public back in 1976. During its development period the BBC and IBA went their separate ways, but it was eventually agreed that two heads are better than one - indeed. BBCs Ceefax and ITVs Oracle hit the air waves at the same time

Most countries in Europe, and for that matter the rest of the world, use the Teletext system invented in the UK Two exceptions being France and America The States are way behind in this method of information transmission apparently US advertisers would rather television viewers sit through commercial breaks than flick through frames of news, sport, weather reports and so on. Understandable really

Teletext is available during normal broadcasting hours. It is free; the BBCs service being financed by the licence fee and the Oracle service on ITV and Channel 4 from advertising News stones are updated as they come in. share prices every day and other features once a week Generally there are a handful of people working full-time keying in pages and making sure everything goes smoothly. Most of the work is done on a freelance basis, journalists around the UK sending news and articles direct to the Ceefax and Oracle offices


Digital tuning

The Teletext adaptor fits neatly into the expansion port at the back of the computer. If you're using a video then a lead (supplied) is connected between adaptor and video recorder Alternatively a cable (also supplied), with plugs of the 5-pin din variety at each end. is placed between the adaptor and tuner. The tuner requires external power, which it gets from a 12V power pack An aerial is necessary A loft or indoor aerial may work in your area, but to avoid any uncertainty connect to a roof antenna If you intend using the tuner to receive teletext then special software must be run This automatically scans the television frequencies in your area to find out which are being used. If you've connected everything successfully then you should get a message PI00 SEARCHING. If the tuner is not plugged in. or the power not turned on. then you won't get such a message When the software encounters a signal, you'll know it because the fust line of the Teletext frame will be displayed, then you may save this channel setting to a key (between 0-9 and A-F). Alter that the software continues its search, letting you save channel settings when found, until the whole TV band has been scanned (which takes about 90 seconds).

Telesoftware

Both Ceefax and Oracle have small sections devoted to micro users Computing and Telesoltware can be found on Ceefax pages 700 to 737 (BBC 2) Unfortunately the BBC's service is geared to wards BBC computer owners, there aren't any programs lor CPC users, but the news pages are interesting Within Oracle (Channel 4) is a section called 4-Tel This offers BBC and Amstrad users the opportunity to download listings Starts at page 460. 


During the signal tracing you can identity from which broadcasting house the Teletext frames are coming as either CEEFAX (BBC) or ORACLE (ITV) appear

CEEFAX 134 Wed 14 Oct 11:23/03 - BBC J
CEEFAX 221 Wed 14 Oct 11 34/26 - BBC 2
ORACLE 173 Wed24 Oct ITV 1144:35 - ITV
ORACLE 556 Wed24 Oct C4 1152:11 - Ch 4

You can distinguish between BBC 1 and BBC 2 frames by the frame number in the 100's and 300's for BBC 1 and 200 s. 300's and 700's for BBC 2 It is simpler to spot an ITV or Channel 4 page as either ITV or C4 is displayed at the top of the frame

There is no need to go through this procedure if you are using the video and adaptor as the video is already tuned in to the correct channels.


Rom on

If you own a romboard then contact Goldmark Systems: the software for the Teletext adaptor and tuner is available on ROM for €17.25. The tuner software, when run for the first time, tunes itself in to the channels - the settings are then saved. Goldmark requires a copy of this tuned in software to place on ROM. More information from Goldmark at 51 Comet Rd. Hatfield, Herts. AL10 OSY or phone them on 07072 xxxxx.


Frame flyback

With the software running, frames can be displayed quickly and easily by tapping in a three digit number The number simply refers to the page you wish to access. But the fust thing you want to do is select a channel, press C followed by a number between 0 and 9 or letter from A to F to choose one of the previously defined channels. Apart from jumping between channels and calling up pages. Microtext s software gives you many other options to play with - things not normally available from a Teletext-receiving television All functions are selected by pressing one key:

N - Next page. Say you have selected page 203; by pressing N you will advance to the next page Each keypress moves you one page forward.

Teletext for techs

Television signals consist of 625 lines. The signals deliver information regarding brightness and colour of individual lines. When these lines are demodulated and subsequently displayed a complete picture is formed (this occurs ever/50th of a second) The first 22 lines of the signal are not used in the picture's makeup, Of those 22 lines, a total of 16 may be used for Teletext. In fact, only eight are currently employed (in the early days tins was lour) Data comes in at approximately seven megabits a second (7000 baud) - that's why there is little hanging around lor a frame to arrive You can see the Teletext data as a series of dancing dots on a badly adjusted television channel.


B - Moves you back a page

R - Reveal Certain pages have hidden sections, such as a puzzle or joke which can be shown by hitting this key

H - Hold Pages may take up several screens To avoid the screens updating too quickly the H key holds the current screen Any othei key resumes

S - Save. This saves the current screen image to cassette or disk. You will be prompted lor a filename

L Load. Simply loads a previously saved image

Frames may be dumped to a printer if you have one that accepts Epson codes. However. Microtext can supply you with a dump routine for other printer types. The manual contains a program that prints a Teletext frame without the graphics characters. It's much taster and works with daisy wheel printers.

The place to be

If you have problems receiving Teletext frames, lor example characters are missing 01 lines corrupt, don't blame the adaptor or tuner immediately If you are using a loop or indoor aerial then the signal may be too weak - try and use an external antenna. Problems will also occur if you are hidden away in a valley or there are tall buildings that won't let signals through In these cases you may have to reposition the outside aerial


Legal requirements

A law recently passed through Parliament that allows bona tide computer users to use a television (black and white or colour) without need of a licence. If it can be proved that you use the television for anything other than computing - and you don't hold a licence - you will be prosecuted

Dedicated computer monitors, such as those found on the CPC machines, have never required a television licence. However, you must have a valid licence (colour if you own a colour monitor) if you wish to use the adaptor to receive Teletext Don't panic though, remember you only need one licence per household: if there's a television in the house (and an accompanying licence) you won't need another.


The Teletext frames that are eventually displayed on your Amstiad monitor are of decent quality Microtext had the problem of displaying 16 colours with forty-columns of text They had to settle for 16 colours and squashed text. The result, although not of the same standard as that found on the television, is very high indeed and legible

Microtext has left the software in unprotected form and actively encourages you to inspect it. The manual explains what certain parts of the program do and suggests that you could re-write it to suit your own purposes. This means you could automatically download particular pages everyday to keep track of trends in the weather, the stock market, or even use it as a pools predictor.

If you need to got your hands on the latest news flash, sports results or weather report in a hurry and don't have a Teletext receiving television then Micro text's offering is a welcome alternative. The Teletext adaptor et al is priced just right when you consider what you get and what it does. A well thought out product that performs admirably.

AA

★ PUBLISHER: Microtext
★ YEAR: 1988
★ PRICE: £74.95 (adaptor), £114.80 (adaptor and tuner)

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L'Amstrad CPC est une machine 8 bits à base d'un Z80 à 4MHz. Le premier de la gamme fut le CPC 464 en 1984, équipé d'un lecteur de cassettes intégré il se plaçait en concurrent  du Commodore C64 beaucoup plus compliqué à utiliser et plus cher. Ce fut un réel succès et sorti cette même années le CPC 664 équipé d'un lecteur de disquettes trois pouces intégré. Sa vie fut de courte durée puisqu'en 1985 il fut remplacé par le CPC 6128 qui était plus compact, plus soigné et surtout qui avait 128Ko de RAM au lieu de 64Ko.