Replay is a magical piece of equipment. Especially interesting for the specialist games player, it has certainly proved useful in reviving (in its literal sense) all sorts of software, dumping screen (some for A&B) and also in aiding and abetting assaults on high-score tables everywhere.

Of course taking on games with a gadget is not very ethical but when you know that you can complete the first fifteen screens without losing a life...

Replay allows you to save a game (or other program) in its entirety to disc. Thus, when you recall the disc file, the software will run from the point at which you saved it. And that's not all. Replay consists of a ROM which has its own socket. This plugs into a spare sideways socket. It's wired up to a couple of points on the BBC board, a link and one of the legs of IC89.

The Replay menu offers choices to format a Replay disc, to create a file, to delete a file, to display a screen. An "empty" file has to be created ready to receive the contents of BBC memory. This is done a file at a time, one in operation on each disc surface at any one time. You can use up to four disc surfaces.

A Replay file is reloaded by choosing the appropriate letter A,B,C etc from the disc menu display. The number of files per disc varies with the capacity of the filing system. You can have six on your Acorn DFS 80 track drive for instance.

You can reload to continue a game where you left off or you can use the screen load option to dump a screen.

Replay can be summoned at any time by pressing a small switch connected by cable to the ROM. This interrupts whatever is going on on screen. The CAPS LK LED flashes. Hitting function keys 0 to 3 sends the whole memory to the disc surface of your choice. Function key 6 will proceed with the program.

Replay deals with most games. Only special screen formats can cause problems. Some of the more recent are recognised and the correct data applied to the video controller. New games however won't be recognised and you may have to resort to the Edit option. This allows the easy editing of the registers of the video controller.

The manual does its best to explain but you'll need to go to an advanced guide on the 6854 to understand how to fiddle the registers to your needs. Barry Landsberg's article in A&B last autumn will tell you all you need to know.

As well as being great for pausing screens, saving them to go back to and dumping them, REPLAY is a useful tape to disc and disc to disc backup device. Programs saved in this way cannot be used on any other BBC system, even one with a Replay device installed.

Replay is a pretty marvellous device, more than a toy for those who have to document software, very useful if you can only buy a tape version of a program (it doesn't matter what nooks and crannies the code is packed into) and a good opportunity to have fun with the screens of your choice. A liberating piece of software and highly recommended.