The BBC Micro has, built into it, a hardware interface called the User Port. This port allows the computer to communicate with such things as mouse controllers, EPROM programmers and robots. The Electron, due to its lower specification, has no such port.

Project Expansions have filled this large gap by developing a user port which fits into the Plus 1. The port comes in the form of a standard cartridge with a connecting socket jutting out of the back. This means that the cartridge must go in the rear socket of the Plus 1. This, in turn, causes problems for Cumana disc users and for Advanced Computer Products' Plus 4 users, as both these cartridges must also go in the rear socket.

If the companies who produce these add-ons had any sense, they would put the connectors on the top of the cartridge. This may make them seem a little untidy, but at least then you would be able to use them in conjunction.

Supplied with the user port is a manual giving details on the technical specification. This includes a diagram of the various lines in and out of the port. The information is sufficient for anyone who wants to embark on a hardware project. In addition to this are instructions for building an electronic LED display.

The Electron User Port differs from the Beeb's only in the addressing. This is very important to remember as this means that no software written for the Beeb User Port will work on the Electron without (minor) alterations. In some software, such as AMX Art, these alterations are being done by Project Expansions themselves. Other programs written in Basic can be altered by the user. Details on changes to software are included in the manual.

Project Expansions have converted an art program called Mouse Paint by Wigmore House for use with the port. This allows the use of a mouse to control the on-screen cursor when drawing graphics. The program is responsive and gives pleasing results once you have familiarised yourself with the menu system. The mouse I used was the original AMX mouse and it performed perfectly. Any mouse or controller which works on the Beeb will work on the Electron.

I tried various other pieces of hardware but each time the software was incompatible. Being in machine code I could not easily find and alter the offending addresses in the programs. The problem will have to be overcome by the software writers themselves in subsequent versions if they want to sell to an even wider market.

This product opens the way to a lot of exciting and useful products being available on the Electron in the future. At the moment there are not many products converted for use on the Electron but, with a bit of effort, they can be encouraged to do so. When Project Expansions have finished converting AMX Art for the Electron, I will have a look at it and let you know how it performs.