Exploring FORTH

Personal Computer News

Bryan Skinner

'The Beginner's Guide to Forth' by David Johns, published by Interface Publications at £2.95 (paperback, 85pp). 'Exploring Forth' by Owen Bishop, published by Granada at £6.95 (paperback, 176pp). An introductory book on Forth should include illustrations showing how the stack can be used and affected by operations. It should have Forth definitions which are clearly explained and which can be used in your own programs. The Beginner's Guide to Forth has none of these. It's a slim volume, weighing in 85 pages, 26 of which are appendices, and these give only watered down and, in some cases, incomprehensible versions of the public domain vocabulary provided by the Forth Interest Group. There's little mention of word definitions comprising other words and array handling promised in the blurb doesn't materialise. There's virtually nothing of any use in the book for a novice or anyone else and beginners would do far better to consider spending twice the money for a book with ten times the information and clarity. One such might be Exploring Forth. The text is well-illustrated with flowcharts, tables and the like, making the code fragments easy to follow. The book begins by explaining how Forth differs from languages such as Basic and moves rapidly on to detail the stack, stack operations and so on. Graphics, arrays, control structures, sorting and even such complexities as bit-mapped logic are covered. A full index is included but only one appendix - a pity, since tables of ASCII codes, for example, are always useful. All the routines are adaptable to your own micro, but some may need some hard work as they're based on Acornsoft Forth for the BBC and Electron. There are some simple games but rather too few routines for the user to incorporate in their own programs. Most newcomers to Forth should find this a clear and useful introductory text, if not the best ever.