True BBC Micro disc compatibility at long last! The little box of tricks will allow you to use any 3.5" or 5.25" disc drive and will handle any Acorn DFS disc.

Originally only the 3.5" format was available through the Acorn Plus 3. More recently, Solidisk has provided DFS and ADFS compatibility with the Electron Filing System interface. Cumana provide their own CDFS and transfer software on disc with their interface. The Advanced Plus 4 cuts out the need for such converters.

The physical housing of the Plus 4 is better than the Cumana or Solidisk interface in that it is smaller and feels much more solid in the Plus 1 slot. The cable to the disc drive does not have to bend double as on the Cumana design. The Cumana and Plus 4 both have default PAGE settings of &E00 but the Plus 3 lacks the battery-backed RAM of the Cumana interface.

With the Plus 4 you can also fit an ADFS chip and have full compatibility with the BBC B+ and Master Series ADFS discs. As a further alternative you could use the ACP Sideways RAM Cartridge and load up an image of the ADFS which works just as well. Indeed, any 1770 based filing system should plug in and run.

The DFS which is supplied with the Plus 4 is a fairly standard Acorn lookalike. There are some nice touches however, such as an extra parameter with the FORMAT command to allow automatic formatting of two sides of a disc. If you fit the Advanced Disc Toolkit ROM into the spare socket then you are in total command of any filing system you care to install. An ideal combination.

In conclusion the Plus 4 is a very neat and well-built interface which will best serve the needs of anyone wanting to upgrade to discs. The full BBC compatibility is more than just a bonus since a healthy percentage of BBC BASIC and even machine code programs will run on the Electron Plus 4. Anything written for the BBC Micro Model B with DFS, even in Mode 7, stands a good chance of transferring to an Electron with PAGE set at &E00. This setting will also aid and abet the transfer of tape-based software, an important point in these days of tape-only games houses and handsome collections of Electron games software.

The Plus 4 costs £79.98. Details from ACP on 0276 76545 or from Advanced Computer Products, 6 Ava House, High Street, Chobham, Surrey GU24 8LZ.

Matthew FifieldMark Webb