Excellent though the Acorn Plus 1 is, I think there is still room for improvement, and this is shown by the superb add-ons that have been released in recent months.

When Acorn designed it they decided to include an analogue to digital converter.

Although this is almost identical to that built in to the BBC Micro, and may be used for a variety of purposes, probably the most common function is as a simple joystick port.

At the design stage it's difficult to predict exactly what niche a micro will occupy and it was thought that compatibility with the BBC Micro took precedence.

The Electron has turned out to be a superb games micro with some outstanding software.

Hardened arcade addicts demand the best from their equipment, and many prefer the positive feel of a switched joystick to the less precise analogue variety. A quick action and rapid fire button are essential if wave after wave of marauding aliens are to be wiped out.

Unfortunately, the Acorn Plus 1 was rather late on the scene, and many games either do not include a joystick option or are designed to use a different interface.

First Byte was the first company to produce a suitable joystick interface and although it does enable you to use the switched variety with many games, it doesn't allow you to plug in an Acorn Plus 1.

So you can't take advantage of the Acorn Plus 1's main advantages - the multipurpose cartridge sockets and Centronics printer port. Of course if this is not important then the interface is well recommended by many games players.

In addition, Slogger's own alternative to the Acorn Plus 1 - the Rombox+, does not have any form of joystick port at all!

Now they have come to the rescue with a cartridge that plugs into the Acorn Plus 1 or Rombox+ providing a 9 pin D socket for Atari-style switched joysticks.

The cartridge is the same size and shape as a View or Viewsheet cartridge and has the socket set into the top.

The Operating System ROM in the Acorn Plus 1 or Rombox+ must be replaced with a new chip provided by Slogger.

The Acorn Plus 1's is easily replaced but, the Rombox+ can't be opened and you must insert it through the cartridge slots. This is not easy and requires an L-shaped screwdriver.

The new Operating System works in a similar fashion to the old ROM but, in addition, provides three new functions: The micro always powers up in BASIC (normally it is only entered as a last resort), an extended printer buffer can be set up in Sideways RAM and the new joystick port is set up.

Unlike the Acorn Plus 1's ADC port, the Slogger version is programmable. The joystick's up, down, left, right and fire functions can be made to emulate any key on the keyboard. The joystick pretends to be five keys, for instance, A, Z, ?, and * for up, down, left and right with RETURN for fire - a common key combination.

The advantage of this system is that it can be used with software that does not have a joystick option.

It will work with all the games published in Electron User and a fair proportion of commercial software too.

Providing the program reads the keyboard in the Acorn approved manner, using INKEY or osbyte &81, you can use the joystick. Unfortunately though, not all games do.

For instance, Superior Software's Deathstar and Bug Byte's Plan B work perfectly using a joystick, yet Syncron ignored it and Audiogenic's Last Of The Free wouldn't even load!

To sum up, the joystick interface does not work with all software. I didn't expect it to.

However, it does work with enough to make it well worth saving up for. Bearing in mind these reservations, I can recommend it to all arcade addicts.

Roland Waddilove