Longman have introduced a series of four books on the Commodore 64, all having the same format and price. Each one deals with a particular facet of the computer.

Turbocharge Your Commodore 64 contains 160 pages, each page is divided into two columns of text interspersed with diagrams and program listings. Unfortunately this format forces most program lines to wraparound which makes program development more difficult to follow. Each chapter finishes with several practical exercises.

The somewhat sensational title gives the impression that the book will enlighten the reader on the subject of Turbo loaders. This is not the case, the book is yet another guide to Commodore Basic, together with some techniques which help to speed up Basic programs.

The first part offers sound advice about planning your programs away from the computer, using structured techniques. The disadvantages of GOTO, and the advantages of GOSUB are discussed together with the merits on ON GOSUB over numerous IF THEN statements.

The various functions such as RND, SGN etc. are covered, and there's some good advice about storing exponents in look-up tables to increase processing speed. Interactive programming includes a detailed description of keyboard data entry, and a machine code routine to enable PRINTing AT any row or column.

Data entry leads onto information handling and arrays, although multi-dimensional arrays are not very well explained. The majority of the rest of the book is devoted to graphics, with only one character each on sound and interfacing.

Boolean operators (AND/OR) and explained logically (groan!), and are the key to the C64's sound and high resolution graphics. The concept of bank switching is only briefly covered. Multicolour and extended character mode are fully explained but multicolour bitmap mode is glossed over.

The chapter on sprites is comprehensive and includes the oft forgotten subject of collisions. The sections on Sound and Interfacing are short and not very exciting.

On the whole, the book is well written and informative and should help you write better, faster programs. However, like so many books on the C64, it is just average, and hardly warrants the £5.95 price tag. It is not a book for the faint hearted, the exercises must be worked at to gain full benefit from it. Average, with some good tips.