Many readers of Beebug might be familiar with the name of GIS - they are the makers of the Red Box home security system (reviewed in Beebug Vol. 5 No. 7). Over the past year they have been developing the Advanced Teletext Receiver (ATR) for BBC microcomputers, which has now been officially approved by the BBC, replacing the old Acorn system.

The ATR consists of a cream-coloured injection moulded case measuring 8.5 by 4.25 by 1.25 inches, and for some reason a wall mounting bracket is supplied. Emerging from the base is a thick one metre cable with two plugs on the end: one attaches to the User Port on a model B or Master 128, the other to the auxiliary power supply output. The only other connector is a socket for an aerial lead at one side. If you are already using the power-out socket on the computer, a splitter will be needed. Such a device can be supplied by Beebug.

Software to control the unit is supplied in the form of the Advanced Teletext System Plus (ATS+) ROM. This is a version of the ATS ROM produced by BBC Soft, which is now the standard software for all teletext adaptors on BBC computers. The ROM can either be fitted internally, put in a cartridge on a Master 128, or transferred to disc and loaded into sideways RAM when needed. Full instructions are supplied with the system.

Just like a television set, the ATR needs to be tuned into your local transmitter. The ATR uses digital synthesised tuning which is completely automated - no more twiddling tuning wheels as with the old Acorn system. The software scans through all the TV channels, stopping when a recognisable signal is received. Details of this channel can then be stored and the next one programmed, if you so wish.

Details of the frequencies are stored in an EEPROM (Electrically Erasable Programmable Read-Only Memory) device in the ATR. Thus, once you have tuned all the channels the details are remembered, even if the power is disconnected.

Teletext Terminal mode is entered by typing the command *TELETEXT, which makes the computer behave just like a Teletext Television. The top line shows the name of the Teletext Service (i.e. CEEFAX or ORACLE); the page number indicator of each page number as it is updated; and the date and time. To select a page, its number is entered, and when that page is transmitted it will be loaded into the computer and displayed. The ATS+ software uses the function keys to perform tasks such as: tuning the ATR, selecting the channel to view, hold, reveal, load page, and save page.

At the bottom of the screen there may be a series of coloured boxes followed by page numbers or 'keywords'. These are called links, and are designed to allow fast access to pages related to the current one. By pressing the appropriate function key, the page pointed to by a link will be loaded automatically. This is analogous to the routing of pages on Prestel, and is a feature not normally found on teletext TVs, except the new 'FastText' systems.

Because of the serial nature of teletext transmission, it can take up to a minute for the page you request to be received and displayed. To speed things up, the ATS+ software has a page grabber that keeps a list of up to twenty pages, and loads them as soon as they are transmitted. If you try and access a page that has been grabbed it will be displayed instantly. The software normally decides for you which pages to grab, on the basis of the last few pages looked at, and the links from the current page.

It is however possible to override this, and decide for yourself which pages you want to catch as they come around. By pressing Return from within Terminal Mode the Terminal Status page can be displayed. This displays details of the current page, 'links' from it, and the pages in the Page Grabber. Alongside the numbers of the pages in the Grabber are a series of flags showing their individual status: page not yet found; found; updating; revealed; held; and kept. It is quite fascinating to watch as the flags are updated as the pages are transmitted.

For those who wish to control the ATR directly from within application languages this can be achieved through a number of star commands and low-level OSWORD routines.

For example, if you want to display the contents of Page 700 on BBC2, here is a simple Basic program to achieve this.

10 MODE 7 20 *TTXON 30 *BBC2 40 *PAGE 700 50 *TRANSFER 7000 60 *DISPLAY 7000 70 *TTXOFF

More useful programs could be written, for example, to read the pages containing the FT share prices and tell you how much your portfolio is worth. Full details of all the commands are given in the manual.

One of the main advantages of a teletext adaptor connected to a computer over a teletext TV is the ability to download data and programs. The ATS+ system makes downloading very easy; all that is needed is to select the channel and press f5. The ATS+ then searches for and displays a special page giving details of all the programs that may be currently downloaded. It is then a simple matter of moving a highlight over the file required and pressing Return.

Due to the way teletext works, the time taken to download a file can be quite long. It has been known for some really BIG files to take over one-and-a-half hours to download! Fortunately this is the exception rather than the rule.

On BBC2, all pages starting with a 7, for example 701, are for telesoftware and computer related services: computing news; forthcoming events; and details of current and future telesoftware. Many useful programs are available to download including ones to make use of the ATS software, such as an interactive personal portfolio manager and a frame grabber and printing utility. There are also downloadable teacher's notes for many schools programs, and of course everything is free.

In use the ATR behaved impeccably. Compared to the original Teletext Receiver, the ATR is a worthy successor. It took me under five minutes to set it up and begin receiving data - the automatic tuning was very impressive compared with other receivers, and the Page Grabber facility was most useful.

Documentation came in the form of a 118 page A5 manual. As it was the first issue, I spotted a number of mistakes and (minor) omissions, but these should be tidied up for the second issue. Nevertheless, it is still perfectly adequate for the average user.

All in all a most impressive piece of kit which I would have no hesitation in recommending.

Product: Advanced Teletext Receiver
Supplier: General Information Systems Ltd, Croxton Park, Croxton, Cambridgeshire PE19 4SY. Tel: (0480) 87464
Price: £149