Scor­pio News


July–September 1987 – Volume 1. Issue 3.

Page 57 of 67

Take, for specific instance, the selection of a suitable colour monitor for my new toy. In every case (I visited five shops) I had to explain to the salesman the difference between the dot pitch of the colour tube (an intrinsic feature of the tube) and the number of pixels (computer generated output) that the monitor was capable of displaying. In every case the assumption had been made that because ‘such and such’ graphics card was capable of generating 720 pixels per line, then there must be a matching 720 colour dots per line. Not true of course, the more dots the better, in fact a usable minimum should be better than two dot triads (a triad is one blue dot, one green dot and one red dot) per pixel, but tube manufacturers don’t measure dot pitch that way anyway. They give the dot pitch as being. ‘so many per millimetre’ or, more usually, ‘so many decimal fractions of a millimetre per dot’. The finer the dot pitch, the better: unfortunately, also the more expensive. I finally opted for a 12″ tube with ea dot pitch of 0.23mm. I think some of the salesmen thought I was slightly dotty myself for being so insistent.

How it might seem I am maligning some very competent and knowledgeable computer salesmen. Not a bit of it, it just seems to me that computer salesmen are on the whole useless. Those few (I haven’t found one yet) who are knowledgeable and competent will know who they are (and likely share my low regard for their compatriots), my advice to them is get out now, you’re probably more worthwhile somewhere else.

So having dismissed salesmen as a source of information, where to next. Well a number of friends have recently defected towards IBMism, usually along the clone route, but in the main they are as much in the dark as I am. A couple of them have had the time to tinker and therefore have sussed certain bits of interest to them, but for an overall knowledge, I haven’t found anyone yet. (If I did find the ‘Fount of all Wisdom’, I doubt that I would be able to afford the considerable amount of time required to absorb the information, and for that matter, I doubt that the ‘Fount of all Wisdom’ would have the time for li’ll ole me.)

Books and Colleges

That leaves the technical colleges and books. Well, I do the night school teacher bit at Paddington college (not a computer subject) and I know they don’t do short courses (or long ones either) on ‘The Innards of MS-DOS’, ‘8086 (et al) Assembler Programming’ and ‘IBM type Architecture’, which is what I need. The best they aspire to is to keep asking me if I’d like to take an introductory course on Z80 assembler, and I keep saying no! Slough Tech did send me a glossy leaflet on just those sorts of subjects, but the very expensive quality of the leaflet made me very cautious about the price before I enquired, and I found my caution justified. The courses were obviously aimed at business and were priced commensurately, quite up to the price of some of the private rip-off classes I see advertised in the computer mags. Anyway, colleges are out, they either don’t do the courses, or if they do, the charge is OTT, at least on a private interest basis.

Books, well books abound, ranging from good to Mickey Mouse. The choice is almost too much. These sort of technical books are expensive, but not as much as the college courses. They may be hard to get, except by mail order, or to those within easy reach of the Modern Book Shop in Praed Street, Paddington, but at least they are obtainable. I have acquired two or three which suffice for the software side, and I have the IBM AT Technical Manual coming which might go some way to answering some of the more obscure hardware permutation problems I’ve hit.

Of the books, “Programming the 8086/8088” assembler manual by Sybex suits for the internal structure of the 8086 family of processors with a full breakdown of what makes it tick, the instruction set and examples of little programs. The book covers the 8088 and 8086, being very similar processors, it doesn’t cover the cleverer and newer processors, the 80186, 80286 and 80386, but as the sort of things I’m called upon to write have to cover the whole gamut of IBM PC’s, XT’s, AT’s and all the various breeds of clone, I have to write things at the lowest level, so 8086 assembler suffices. For those who are not aware,

Page 57 of 67