Home Computer: The Lord helps them that go 'on-line': Rupert Goodwins lays down the law on how to get the most out of modems

IN A GREEN and rainy suburb of Plymouth my father, the archetypical West Country vicar, tends his flock by computer. I am not sure that the 1662 Book of Common Prayer has many intercessions for MS-Dos failure: floods, war and plague are covered but this modern pestilence remains beyond the theological pale.

But it remains true that the bugs of the father are visited on the son and while I have no doubt the biblical duty of honouring my father includes solving his computer problems, it would be most useful if he could tap into the resources available 'on-line' - information in electronic databases that can be accessed by connecting the computer to the telephone network.

Thousands of people regularly exchange tips and information via 'bulletin boards' - electronic 'pinboards' where messages can be displayed or read by anyone who has the board's telephone number and password. Commercial information services such as Cix and CompuServe and the many hobbyist bulletin boards are readily available to him, if he had a modem, the piece of equipment that converts computer-readable information into a form that can be trasmitted over the telephone line.

Buying a modem is no task for the unworldly. Bargains are rarely what they seem and there are many ways to be led astray by the incompetent and the deceptive. All this in a market where there are more standards - technical specifications which define what can and cannot be done - than apples on the Tree of Knowledge.

Yet with faith in standards and a little knowledge it is possible to get a good deal. First, find out what standards are used by the services or other users you are interested in communicating with and make absolutely sure that your intended purchase matches them to the letter.

A fast modem is always to be preferred; they generate smaller telephone bills. You also have to decide whether you want your modem to be able to send and receive faxes as well as data. Since almost all new modems can handle fax and the price difference is only a few pounds, there is no real dilemma.

Deciding on a technical specification for your ideal modem is one thing, but the next choice is more interesting: do you want to break the law? In data communications, crime most definitely seems to pay. The law says that only modems which conform to a certain set of electrical standards - it should say BABT approved on it - may legally be plugged into the telephone.

But the market says that unapproved imported modems cost much less than the lawful kind and the laws of physics could not care less: an approved modem will chatter amicably to similarly equipped members of the criminal classes. But as the penalties for using an unapproved modem include total disconnection from the telephone system this is not a risk many people - most certainly not West Country vicars - would be prepared to take.

But the temptation is strong. An unapproved acceptably fast fax modem can be bought perfectly legally for about pounds 200; a similarly specified approved device will cost between pounds 350 and pounds 600. For that premium, you will get the sticker on the modem proclaiming its innocence and the knowledge that it has been designed for and tested on British telephone lines. You will also know that the modem company has at least some technical staff in the country to help you if things go wrong.

Perversely, it does not follow that an approved modem will be any easier to use. Most communications programs provide on-screen lists of modems - by picking your model from the list, the software can automatically set itself up to work most efficiently. Since most software is American, it follows that most of the modems in the lists will be of similar provenance; there is a chance that you will be able to get the resolutely unapproved SupraFaxModem going without tears rather than the thoroughly approved Eclipse 144, for example. This is not a hard-and-fast rule since some software is properly customised for the UK and most modems will work adequately with programs set up for the lingua franca of data communications, 'Hayes compatibility' - the codes used by the Hayes range of modems.

As always, you spend more for the assurance of a really famous name. Two of the most recognisable brands are Hayes and US Robotics, both of which produce modems which can be relied upon to work and be recognised by almost every piece of communications software written.

But Hayes has been slow in updating its product range in the UK - there is still no fax modem - and US Robotics has only just introduced a 'low-cost' model, the pounds 399 Sportster. This is competitively priced, has fax and is otherwise well specified, but comes with a poor manual and a worse standard 'set-up' procedure.

Those prepared to import direct from the US can get keener prices. But the safest option is to buy the same modem as your most patient and technically competent friend. For the price of a bottle of decent wine, the chances of everything working perfectly in the end can be considerably enhanced. A few pounds here and there will in any case soon be swamped by the increased telephone bill; whatever model you choose, making it work may be the most expensive mistake of all.

Jargon buster

Modems are made to work at different speeds which are not easily decipherable from the technical descriptions. Essential terms include:

Bits per second (bps): the speed of transmission also known, usually incorrectly, as baud. Divide by 10 to get a rough idea of bytes (roughly equivalent to characters) per second.

V22bis: 2,400bps. Old, universal and cheap.

V32: 9,600bps. Newer, rather uncommon by itself and in decline.

V32bis: 14,400bps. The current standard of choice. Twice the price of V22bis. V Terbo: 19,200bps. New and uncommon.

V Fast: 28,800bps. Not available yet. Unsuitable for vicars.

V42: Error correction standard. Ensures a clean connection.

V42bis: Data compression standard. Removes repetitions from data during transmission to boost speeds for text and pictures by between two and three times.