|★ LITTÉRATURE ★ ENGLISH ★ ADVANCED AMSTRAD BASIC ★|
|Advanced Amstrad Basic|Amstrad Action)||Littérature English|
Has Melbourne House gone mad? How can a publisher have the audacity to charge £13 for such a book? Some of this author's previous efforts from the same press have been almost twice as thick for hardly half the price.
Apart from that outburst; I have only praise for this publication. It is written by a very talented man. Joe Pritchard's previous book, Ready-made Machine-Language Routines for the Amstrad, was one of my favorites, and most certainly helped me with my assembly-language programing.
Advanced Amstrad Basic assumes you have a fairly thorough knowledge of Basic, with a minimum amount assembler - which is only to be expected, otherwise it would have a different title!
Chapter 1 starts with graphics and animation. There an clear listings, showing you how to print characters of any size a any angle - even multicoloured. Each routine is clearly explained, encouraging the reader to take the bull by its horn and alter the programs to suit his or her requirements.
I was impressed with the graphics routines, which made use of 'transformations'. A shape can be transformed be carrying out mathematical operations on it. Here matrices com into play - I always wondered, while slaving away at my matths homework, what use they would be in the real world. The boo goes into just enough detail, giving plently of short routines without putting the reader to sleep.
Sound is the following chapter; this covers all the sound commands available to the user under Basic. Especially detailed are the sections covering tone (ENT) and volume (ENV envelopes. There is a section on playing music under interrupt using the ON SQ instruction. It is a pity this was not covered in greater detail - even a small section on how to produce the desired effect via machine-code would not have gone amiss.
Mr Pritchard has steered well away from generating sour, using machine-code. The reason for this is that Basic gives you so much control over the sound chip; even producing a sho buzzing noise in machine-code is a very tedious and drawn-out process.
Directly following is a large chapter devoted to explaining and using RSX routines (resident system extensions bar commands). Using this system, variables can easily be passe* to machine-code routines. There are a number of interesting programs for the user to type in and modify, including an enhanced catalogue, a pause facility and even a routine to inspect data from any roms you may happen to own all a used via RSXs and should really get you to grips with the use and control of them.
You are taken on a guided tour of the screen, with good examples on manipulating it. It is about time someone made decent attempt at unveiling the mysteries or rather complexities of the screen. A lot of effort has gone into this tiny informative chapter - included are notes on the CRTC (cathode ray tube controller) and the registers, what they do and whit happens when you alter their contents.
All in all, a very well written, easy-to-follow and enjoyable book. The effort the author has taken to put across ideas exceptional. I'm sure that after reading it many of you will has only too eager to jump into lower-level programming 1anguages. Thoroughly recommended!
AMSTRAD ACTION #15