When it launched the Electron in 1984, Acorn made the ambitious promise that owners would one day be able to add on all the facilities available as standard on the BBC Micro. Little did we realise that Acorn would soon lose interest in the machine. But the Elk proved to be a reliable micro with loads of potential, which is slowly but surely being fulfilled by independent manufacturers.

With the Elk capable of running at BBC speed via Sloger's Turbo board or the PMS second processor, and a choice of inexpensive disc interfaces and drives, user ports and Sideways RAM now available, the machine's lack of a Mode 7 has become the only significant BBC feature not available to Elk users.

Mode 7 is important and useful for several reasons. It offers text and limited block graphics in any colour. It uses only 1K - far less memory than any other mode - to display the teletext graphics used for e-mail and teletext, and it has by far the most attractive character set.

However, the omission of Mode 7 was not just a case of Acorn being awkward. Modes 0 to 6 are basically variations on a theme, and the circuitry fits on to a single chip in the Elk, but Mode 7 requires a chip unto itself and so is comparatively expensive to install.

Jafa is a small company run by the man who was the brains behind the excellent second processor now marketed by PMS. Its Mode 7 adaptor is about the size, shape and colour of an Acorn Plus 1 or Slogger Rombox; it plugs in and bolts on to the back of the Elk in the same way. With the adaptor in place, Mode 7 can be called with the command *MODE7ON, followed by a standard BREAK. A thoughtful provision is the new command *HELP BARS. This gives a seven-colour bar display, which proved very useful for adjusting brightness, colour and contrast.

The BBC's *TV n, where n is used to specify the number of blank lines to be shown at the top of a TV screen, is also implemented. The adaptor has its own BREAK key on top - functionally it replaces the Elk's own BREAK key, and Mode 7 is just as accessible from your programs as Modes 0 to 6.

Users also now have the option of BBC or Elk-style function keys. Few Elk owners would concede that their function keys are inferior to the Beeb's, so I'm not sure the adaptor should default to Beeb settings as it does.

Given the right hardware, the Elk will now run ROMs such as the BBC's Wordwise Plus, and existing Elk ROMs such as View, Viewsheet and Lisp in Mode 7. My Plus 1 and Master RAM Board continued to work perfectly and BBC Mode 7 adventure games ran without complaint.

As Mode 7 is the teletext mode, teletext control codes and graphics are now available. As the adaptor contains the same Mode 7 display chips as the BBC Micro, programming with the unit is just like using Mode 7 on the Beeb. Seven colours plus black are available, as are different backgrounds, double height letters and flashing characters. Chunky and limited teletext graphics are possible, if you have the patience to use them.

Unfortunately, Jafa's User Guide gives only a perfunctory description of these facilities, preferring to refer readers to chapter 28 of the BBC User Guide. Those without access to a Beeb might do better to buy a beginner's guide.

Electron users have been able to use electronic mail for some time, but a teletext mode, plus a bit more hardware, makes Prestel almost as accessible as on a Beeb.

The adaptor costs a lot because it contains much of the display circuitry that is inside a BBC Micro, plus a few other chips too. At £89, the Mode 7 adaptor represents a serious financial investment. Is it worth it? Well, it all depends. For the average games player, probably not - but if you have a yen for Prestel, or have a need for BBC compatibility, for an extra 7K memory, or just can't do without that beautiful Mode 7 character set, go on, spoil youreslf.

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