"Now without any additional effort, you can overcome the limitations of BASIC and give your Spectrum real power-faster programs, more powerful graphic commands, realistic explosions, fast screen scrolling, great sounds and much more! This book will help you to develop programs of professional quality- not only will your programs look better, run faster, and be more spectacular- but you will also be able to develop them in a fraction of the time you would expect it to take. One of the most spectacular examples of extending the Spectrum is a routine that allows you to reproduce your voice and play it back from within your own programs! No knowledge of machine language is required, as all the routines have been fully written and can be directly entered into your Spectrum. The routines in this book will also allow you to renumber your BASIC programs (including all GOTOs and GOSUBs!), deletes lines, and trace BASIC programs by showing the line number of each line as it executes. David Webb also includes the most discussion of all the Spectrum's system variables yet published. If you are already familair with machine language, then this book will be an invaluable aid to writing your own programs- here are over 50 ready-made and debugged routines, with clear and detailed comment, that use the full power of the Spectrum Z80A and its special features. So whether you are a beginner Spectrum user or an experienced programmer, Supercharge your Spectrum is a book you cannot be without."