80-Bus News

Cortesi is author of another book on CP/M, Inside CP/M. This is divided into a tutorial manual, giving quite a detailed description of CP/M, and an exploration of many of its features, though not to such a great extent as Dennon. The second part of this sizeable book is a reference manual, giving a detailed page by page description of all of CP/M’s facilities. The miscreant who has borrowed Miller from me suggests that Cortesi is too verbose in his tutorial section, but to give Cortesi his due, when we were having a problem with a SUBMIT file, we eventually found the answer here – and nowhere else! For your information, I note that a SUBMIT file does not like blank lines. It simply won’t run. Cortesi remarks (p132) that this bug has been reported several times, but no fix has yet appeared. In consequence of finding this piece of information, and sorting out the SUBMIT problem we were having, I feel very kindly towards Cortesi.

For our last CP/M book, we have Hughes’s System Programming under CP/M-80. This book surveys, briefly and succinctly, the standard facilities of CP/M, and proceeds to deal with the problems of interfacing Assembly Language routines to it. In the course of the book, he develops LIST, a file printing utility, XDIR, an extended directory facility, SYSGEN, which is similar to the SYSGEN supplied with CP/M, but now at least you know what is happening, and he then proceeds to introduce some of the problems of writing and implementing a BIOS. I’m quite fond of this book, as the description of the standard facilities is quite succinct.

The availability of three Colour Graphics boards for the 80-BUS at reasonable prices has turned my thoughts to books on Graphics. Using my usual rule of finding out what has been written on a subject before setting out to reinvent the wheel, I’ve found two good books on Computer Graphics. These are:

Fundamentals of Interactive Computer Graphics by Foley and van Dam, (664) published Addison Wesley

Principles of Interactive Computer Graphics by Newman and Sproull, (541) published in paperback by McGraw Hill.

Both of these books cover substantialy the same ground. They are concerned with the methods used in Graphics display terminals, either in BW or Colour, low or hi res, and the solution of problems such as representation in three dimensions, movement of shapes in real time, perspective control etc. Foley and van Dam is more lavishly illustrated in colour than Newman and Sproul, but they are both well illustrated by line drawings. All of their demo programs are given in Pascal, which will allow them to be readily translated to almost any language.

Threaded Interpretive Languages by Loeliger, (250p) published by BYTE/​McGraw Hill

Recent interest in Forth is reflected in this book, which contains substantially the entire code, in Z80 mnemonics, to allow implemention of a Forth Complier. I include it here as I recently discovered that the Graphics routines of the EPSON QX10 computer and some others have all been written in Threaded Interpretive Languages (Forth-type languages). Those who have seen the EPSON QX10 in action will realise that it’s graphics are very powerful. Perhaps it might be worth looking into the use of such a language for similar purposes on the 80-BUS. The ideas contained in it, of the threaded type language, are quite different to the more conventional method of language design.