It has taken nearly four years, but now here at last is a true Mode 7 Display Unit for the Electron. And very impressive it is too!

It's a hardware add-on which plugs directly into the back of the Electron and is about the same size as the Acorn Plus 1.

The pre-production prototype version I tried was not cased, so I can't say what it will look like when finished. Hopefully, it will match the colour and style of the Electron.

Acorn Plus 1, Plus 3 and Rombox owners needn't worry, as the edge connector is continued at the rear of the board and our Rombox+ and Cumana Disk Interface worked perfectly throughout the review.

There is a short monitor lead on the left side of the board which is not, as I first thought, for plugging into a monitor, but into the monitor socket on the Electron's side.

The TV output is taken from the Mode 7 Display Unit itself, not the Electron. There isn't a monitor output, and I hope this slight deficiency is rectified on production models.

There's really very little to it. You simply plug in, switch on, type *MODE7ON and tap the BREAK key. You now have Mode 7 in addition to the normal modes 0 to 6.

HIMEM is set at &7C00 so 5K extra RAM is available for your programs.

The Electron has a habit of clearing this on pressing BREAK (it still thinks this is the screen memory) so there's a special reset button which acts like a soft BREAK. However, the content of the extra RAM stays intact.

You can print all teletext characters, colours and graphics on the Mode 7 screen and you can even poke it directly if you wish.

As a test I borrowed half a dozen BBC discs from the Micro User team and booted them up on the Electron. They all worked.

In fact, no matter how they were written - legally or illegally - they produced a perfect display every time.

One of the toughest tests was Invasion from the February 1984 issue of The Micro User. This is a Mode 7 version of Space Invaders.

After adding two lines to stop the introductory music from playing it ran first time. It was every bit as good on the Electron as it is on the BBC Micro.

As a bonus, the unit also works with Slogger's TURBO BOARD (but not in 64K Shadow RAM mode), so now you can have the speed of the BBC Micro and Mode 7 as well.

With this combination quite a high proportion of (unprotected) BBC Micro software will run on the Electron. But you won't be able to run commercial software such as Acornsoft's Revs. There are many reasons why this won't work. One is simply that the software checks which micro it is running on while loading and will stop if it's an Electron.

You can turn the unit off at any time so the micro behaves as a normal Electron.

Several new commands have been added to the Electron's operating system. The Mode 7 display can be brought down the screen with *TV255 and the BBC Micro's red function keys are emulated on the Electron's keyboard.

On the BBC Micro you can press SHIFT, CTRL, or SHIFT-CTRL and a function key to obtain special effects.

This doesn't work on the Electron, but after *EFN and BREAK the bottom three rows of the keyboard emulate these keys when used with CAPS LK/FUNC.

At £79 the adapter costs as much as an Electron itself and must be considered a luxury rather than a necessity.

Remember, no matter what you add to an Electron, it will never be exactly the same as a BBC Micro, and you could end up paying out more.

However it does carry the Electron a long way down the road towards that great micro, and if money is no object then I can recommend it.

Roland Waddilove