Competition is never a bad thing but in some ways the duplication of material in the two Cambridge produced BASIC ROM guides is an unhappy event. This one is obviously from the same family as the Advanced User Guide and looks very much the same, spiral-bound with blue and yellow colouring.

The contents is a very straightforward presentation of the facts about BASIC routines grouped into Integers, Floating Point, Conversions, Mathematical Functions and Random Numbers. Here we are given subroutine name, function, addresses for BASICs 1 and 2, entry conditions, exit status and typical timing (there is subsequently a chapter on timings and a listing for a microsecond timer).

The author takes it upon himself to supply a quick guide to binary and hex numbering before launching into the routines and this will be appreciated by the inexperienced. Each grouping is given some explanation before the data is presented, page by page, routine on routine. There's similar information as in the Adder publication about locations, stacks, buffers and tokens. There is more detail about action tables and where they reside.

The timings are interesting and the program might find other uses when testing software but the most useful chapters follow, one on writing replacement trigonometrical (or trigonometical as the guide has it) routines. Drawing a circle is taken as a main example and various methods explored. This is interesting stuff and reduces your confidence in the speed of the BBC somewhat.

The Advanced Guide is not "advanced" compared with the Adder publication but does approach the subject in an entirely different fashion. The last chapter on building large machine code programs, including dealing with inter and intra module problems, is very sound instruction.

The Adder publication looks at BASIC with enthusiastic interest and tries to demonstrate how it can be put to new uses. The Cambridge Computing Centre edition takes what is useful in BASIC for the programmer and suggests how to get round the limitations of some of its routines. There is much duplicated material between the books, but I am forced to suggest that you at least take a look at both and probably buy both if you fall into the category of BBC user described in the final paragraph of the last review.