Date   : Tue, 29 Oct 1991 20:34:05 GMT
From   : mcsun!uknet!ukc!mucs!lilleyc@uunet.uu.net (Chris Lilley)
Subject: Re: GSX for Amstrad PCW 8512

In article <MVH.91Oct28220638@lysator.isy.liu.se> mvh@lysator.isy.liu.se
(Martin V. Howard) writes:

>
>I have an Amstrad 8512 and on the Dr Logo disk there is a resident
>system extension file called GSX, which I have understood I can
>somehow use to make my programs produce graphic output...
>
>So, does anyone know how I add this to my programs?  Can I use it with
>Turbo Pascal?  Would I have to hack a MC interface?  How do I use the
>routines in the GSX?  What routines are there? etc., etc., etc.

Yes you can use it.  I did, about 1987 when I got my PCW 8512.
You can use it from Turbo pascal, assembler, C etc as long as you can do a
BDOS call (its an RSX, so you call it just like the rest of the operating
system.  Or, if you have CBASIC you get some cute bolted on keywords to do
it a bit more pleasantly.

My advice is - STEER CLEAR OF GSX !!!

It is ultra buggy. It was developed for Digital Research by anothe company,
way back when.  The other company never finished it. DR released it anyhow.
They later abandoned it and no applications are available other than the
original 2 - DR Graph (which is OK when it works) or DR Draw (which has
more bugs than a nest of cockroaches and falls over all the time).

GSX is a minimal implementation of GKS (the 2-D version) as of about 1982.
It is dependant on suitable drivers: Amstrad in their infinite wisdom
provided
teeny drivers that do nothing.  For example, there are no input devices - a
bit of a problem there.  And, doing a filled area on the screen gives
you... an outline. No filling supported.

To be fair, you get better drivers with the 2 aforementioned DR programs.
DR had to bundle drivers because the Amstrad versions were so poor that the
DR programs couldn't run with them.

Oh, and on a 2.8 MHz (effective...) Z80, software which does lots of
floating point maths and is written in a very old version of ratfor (!)
tends to be, how shall I put this, a bit slow.

It can't selectively update the screen, either, it has to redraw the lot.
The DR programs use it for all their user interface....

If this still hasn't put you off, go ahead !!

Some of the old magazines ran articles about using GSX - however I gave
away my old collection of PCW file, 8000 Plus, PCW user etc (dating back to
87) when I moved house ... sorry .

       Chris