This very impressive book is a bit more technical than its sci-fi cover suggests but this should not deter the Electron (and, I see no reason why not, unless Granada are going to come up with a BBC version, the BBC) adventurer from going straight out and buying it. If you bought Peter Killworth's Penguin/Acorn guide then don't worry. There is some overlap in subject matter, naturally, but with both you will be as clued up on the subject as most.

There's the obligatory history lesson, Standford Research versus Massachusetts Institute of Technology, Colossal Caves versus Dungeon. The latter's Infocom language is compared with Melbourne House's Inglish, found in The Hobbit. Language recognition is all part of the believabiliy of adventures.

Later in the book, chapter eight goes into the tokenising and crunching techniques needed to squeeze "language" into a micro adventure. This chapter presents some very interesting ideas and demonstrates them with a set of programs for encoding and decoding text/descriptions - similar methods, we are told, to those used by Level 9.

For those new to programming, there is a line by line analysis of each largish program. The method used is one of assigning character groups to ASCII codes above 127. A string analysis program lists the most common letter groupings and this information is used by the encoder.

Strings are stored above HIMEM in byte arrays and accessed with a pointer table. Electrons with only Mode 6 and not a lot of memory to play with, will especially benefit from this sort of crunching.

However, Adventure Games For The Electron is not just about the coding. The author deals with the creative side, the necessary elements to maintain interest, the plot, problems and clues. He also looks at planning, internal consistency and comprehensibility. Creating characters, keeping track of movement, not just of the player but other creatures, saving games, analysing player input; all these aspects and more are discussed with programming examples. Finally there is a chapter on limited use of sound and graphics.

It's fairly obvious that the author did not develop all his ideas on an Electron, or even a BBC. As an ardent adventurer, steeping in the American game, he reveals himself as an Apple owner. No matter. Even if he does use subroutines rather than procedures, Electron adventurers would not want to miss out on a wonderfully enthusiastic, breezily written and technically comprehensive manual on adventure writing.

Peter Mujtaba