The first thing that strikes you about the Acorn Plus 1, the official hardware extension for the Electron, is that it looks neat. It fits on the back of the Electron, screwing firmly into place and immediately blends in with it, seeming to have always been there.

As a colleague and non-Electron fan said when he saw the combination, "That makes the Electron look like a proper micro". The guy's an ignorant yahoo, but I can see what he means. And it's not just the appearance of the Electron that the Acorn Plus 1 improves, it also expands its powers enormously.

It allows the Electron to use a printer, joysticks and (when there are some) ROM file cartridges.

To be more accurate, it's not just a joystick capacity that the Acorn Plus 1 gives the Electron, it gives it an analogue interface. This analogue port allows the Electron to measure smoothly varying electric currents and convert them to a numeric form that the Electron can handle.

What this means in practice is that all sorts of electrical devices can be attached to it, from heat and light sensors to heart rate monitors. Joysticks are, however, the most obvious use of the port.

As it is an analogue port, it's no surprise that the joysticks that are used with the Acorn Plus 1 are analogue joysticks. Most of the previous interfaces for the Electron have used the switched, Atari-style joysticks.

This leads to a problem in that, while the Acorn Plus 1 will allow the use of joysticks with Acornsoft games, games with a joystick option from other software manufacturers may not work. No doubt in time software houses will incorporate the Acorn Plus 1 joystick handling routines in their software. Until then it's a serious mark against the official add-on.

Having said that I got hold of a set of Voltmace analogue joysticks (excellent hardware) and used them with Acornsoft's Monsters and Starship Command.

Once I'd figured out how the joystick movements replaced the more familiar keys the difference was remarkable. Using joysticks really improves games.

The second major feature of the Acorn Plus 1 is its Centronics-compatible parallel interface which allows the Electron to use a wide range of printers. Working on Micro User and Electron User has meant that I've had a lot of experience using the BBC Micro's printer facility, which is excellent. The Acorn Plus 1 gives the Electron exactly the same capability. I attached the printer to my Acorn Plus 1 and the rest was plain sailing.

Normal print, italics, bold print, I could get them all, simply and easily. When I say it was just like using the BBC, you can take that as praise indeed.

The Acorn Plus 1 manual explains all the previously unlisted *FX calls that you need to know. The manual is clear, concise and useful, but newcomers to using a printer should be warned that the manuals that come with printers are usually pretty awful.

Any difficulties you may have using your Acorn Plus 1 for printing will almost certainly come from that area and not the hardware itself.

As to the Acorn Plus 1's ROM cartridge facility there's not a lot I can say. Despite the leaflet's promise that some were available, none came with the Acorn Plus 1 and Acorn's public relations firm couldn't supply me with any to test out. However, if the manual is to be believed, they sound quite promising.

The cartridges work in two ways. The first uses them as a sort of very fast read-only cassette system for entering games and applications software. This promises to be far quicker than the usual cassette filing system. The second method is for language cartridges such as Lisp. Here the language itself is used as an alternative to the Basic already in the Electron, leaving you the normal amount of memory space for programs in the new language. I look forward to that.

The Acorn Plus 1 has room for two of these cartridges at once, and when they arrive, they will significantly increase the Electron's potential as a serious micro.

Also, if hints that an RS423 Interface is being developed for the cartridge slots have a basis in fact, then the Acorn Plus 1 will allow the Electron to enter the growing world of computer communications.

However that's for the future. What Acorn Plus 1 owners get for their money now is the capability to use joystick (with Acornsoft games), hang peripherals on the analogue port, and use parallel printers. There's also the potential for using cartridge software when it becomes available.

By providing the analogue port and cartridge slots it opens up the Electron to the outside world, and I doubt if it will be long before enthusiasts and manufacturers take advantage of this.

All in all, it's a very good piece of hardware that takes the Electron into the same league as other, more expensive micros. While the lack of joystick-compatible software and the cartridges is a mark against it, I have little doubt that time will remedy this.

As it is, the Acorn Plus 1 has to be the most useful Electron expansion unit to come on the market.

Trevor Roberts