OUT OF THE MOUTHS OF 10-YEAR OLDS

By Bob Maunder, published by Linsac. £7.95

Ten-year-old A. D. Lindsay of Frodsham sent us in his review of a number of ZX books, and we include the review here, word for word as we received it.

A couple of days ago a few packages dropped through my letterbox. They did (surprise, surprise) all contain books.

It is amazing what books can do. They re-awaken interest in the black shelled object, which just happens to be called ZX81. There are lots of ZX81s lying neglected in their boxes because, frankly, there is nothing else to be done with them.

You do, however, have to be careful with books; some of the programs do not work. All of the ones that I tried worked first time - or were quite easy to modify.

The first book which came under my scrutiny was called 49 Explosive Games for a ZX81. This book does not (as you will have gathered from the title) pretend to teach you programming; it just has page after page of great programs. Some are real oldies, like 'NIM' but some are completely new, like an adventure called 'Smugglers Bold' which fits in to 8K RAM '81.

The programs are chosen, I am told (it says on the back) to illustrate a certain programming skill. There is, however, a conversion table of PEEKs and POKEs from the old ZX80 ROM to the new 8K ROM. This is very useful when converting 27 ZX80 programs to run on the 81. Many of the programs need extra memory so I would advise people with only 1K RAM to leave this book alone.

The next one I examined was called Not Only 30 Programs for the Sinclair ZX81. This book is a collection of programs which show just how much can be crammed into Sinclair's tiny RAM chips. Most of the programs are games. The first one is a very basic pattern generator, though a 1K Draughts is available later in the book. The programmer, however, has to report to machine code for this game to fit into Clive's magic chips.

They are written by a few different programmers but are all set out in the same way. First there is a description of what happens when the program is run. After this, the structure or how the program is built - is explained. Then there are notes on running it and finally, the actual program.

The ZX81 Pocket Book is much better than its ZX80 counterpart. Trevor Toms has learnt from his mistakes and the book now has more space-saving hints and games. One very useful routine which he discovered was PAUSE 4E4. This means that the computer pauses until a key is pressed.

Getting Acquainted with your ZX81 is written by Tim Hartnell. This is probably the best ZX81 book around because it combines games with tips. It contains over 80 programs. Many of these are very short, but there are a few good games. If "PRINT PEEK 16396 + 256 * PEEK 16397 - 16509" is used as a direct command, it will print how many bytes of memory have been used in your program. This can be very useful if you have only 1K RAM to play with. There are a few graphics routines which show just what can be obtained with a six-line program. These are listed under titles such as Games and Data Files. For someone with only 1K it is a good investment. The book shows just how much can be squeezed into the 81's mini memory. If one has 16K, one would be critical of some of the games, though one could modify to make them even better.

Understanding Your ZX81 ROM aims to teach you how to program short machine code routines into your computer. It contains 26 basic programs and quite a few chapters. Chapter Six examines the 8K monitor in quite some detail. This is written by Dr. Logan and it is really for people with no previous machine code knowledge. Those who have will be very disappointed not to find a complete listing of the ROM in one place.

The ZX81 Companion is written for people with the 16K RAM pack. Without it, this book is of no use. It is not a "games" book but rather a learning book. Some of the chapters are about saving and loading machine code and the ZX81 as an educational tool.

Chapter Four deserves a special mention because it is very good - "Examining and using the Monitor" is its title and it contains an almost complete monitor listing.

(I shall give each book a star rating, out of five).

STARTING TO GET ACQUAINTED WITH THE SINCLAIR BOOK WORLD

Since the dawning of the ZX-80, hundreds of thousands of words have been written about it and its successor. Each month we will examine some of those words to see if they are of value to users. By Ron Coates.

Once you have your ZX-81, have set it up and worked your way through the manual provided, the obvious question arises - Where do I go from here?

For the Sinclair book, good of its kind, is still only a manufacturer's manual - a guide to the capabilities of the product. It will tell how to do things but is not concerned particularly with why the techniques it describes are useful, nor the best way of attacking a practical program, whether for household accounts or a game.

Do not worry. Publishers are falling over each other to produce books which will aim, with varying degrees of success, to provide the answer for which the new ZX-81 owner is looking.

In the UK, there are at least 15 manuals generally - available for owners of all levels of experience and fields of interest, with new titles appearing almost weekly. That is at least comforting but it raises another problem, that of which to choose. The answer can really be provided by deciding the purpose for which you bought the machine in the first place.

The machine is just a tool. It is how you use it that counts - for enjoyment, for work or for education. The authors and publishers have had somewhat the same problems of trying to decide what information the ZX-81 user might want and how best to impart it.

The approaches generally can be divided into two - that the whole thing should be fun and that the reader should be taught or shown the techniques he needs to know for what he wants to do. Both frequently then leave you to get on with it.

Both are fair enough. The programming techniques learned in computer games are just as applicable to writing a household accounts program as those designed specifically to do so.

We aim to provide a rough guide to the books available, so that you can choose the approach to suit you. All the books assume that the reader has read the manual. Some may say that is not the case but all have to rely at one point or another on various pieces of information and the explanations in it.

That probably is unavoidable, for if any manual or book tried to explain all its terms and usages in comprehensive detail, it would be long, boring, tedious and, worst of all, very expensive.

The game approach to teaching computer programming has a long history. Many big computer companies and universities discovered that one of the best ways of teaching programming was for the students to design their own games and run them on a machine.

It was regarded by the teachers and students as a painless way of learning how to make the machine work and do what was required of it. When you think that the alternative was to read a number of manuals and then write programs to work out the VAT on any quantity of widgets, you can see way it became popular; it also worked.

That is the approach followed by one of the pioneer ZX-80 writers. Tim Hartnell, who has a number of titles to his credit of scaled degrees of difficulty. Getting acquainted with your ZX-81 starts at the lowest level.

It aims to have the reader start using the machine as soon as it can be hooked to the television. The explanatory text is held to a bare minimum, as are the other books. There is a page-and-a-half of introduction and Hartnell then expects you to key-in the first game to see how it works and enjoy it. Then he explains what has happened. Through the book games of greater complexity are listed, most to demonstrate a programming technique or facility of the machine - tricks with the screen, specialised functions in mathematics and so on.

His other book, Making the most of your ZX-80 and Stretching your ZX-81 or ZX-80 are continuations of increasing complexity and I found that stretching referred more to me than it really did to the computer.

The good point is that Hartnell makes the effort to make learning a pleasure and pushes the reader quickly to a point of confidence in programming ability and the ZX81.

The techniques and uses of the machine are indicated very well by the example programs. The disadvantages are that the books are all revisions of books for the ZX-80 and Hartnell has had neither the time nor resources to make it clear which listings of programs are for which machine.

His explanations are terse, occasionally to the verge of incomprehensibility, but he never says anything without reason and you can generally grasp the point with a little thought.

That may sound damning but on the whole the books are to be recommended because of the successful effort Hartnell has put into judging the level of information he presents in each.

A book which tries to cover much the same ground is The ZX81 Pocket Book by Trevor Toms. The author has made an effort to extend his explanation - for instance each line of programming code is explained if it is novel - and to do more than provide a series of listings to type into the machine.

It is not really for the absolute beginner but embraces most of the techniques dealt with by Hartnell's three books. Readers will probably find his explanations easier to follow. because of his step-by-step notation.

For the person who wishes to take the ZX-81 really seriously, The ZX-81 Companion is one of the better books. It is different in concept from the others reviewed. The author is an academic and his style, while not heavy-handed, shows it. Programs and examples are presented clearly but he is obviously addressing himself to the ZX-81 owner who wants to move as quickly as possible from the manual to using the machine for teaching, business or household accounting.

Next month we will look at more serious books and the delightful Peek, Poke, Byte and Ram.