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From: keithd@cadovax.UUCP (Keith Doyle)
Newsgroups: net.micro.atari
Subject: Re: Atari 800XL superior to c64?
Message-ID: <340@cadovax.UUCP>
Date: Thu, 20-Dec-84 15:01:57 EST
Article-I.D.: cadovax.340
Posted: Thu Dec 20 15:01:57 1984
Date-Received: Sun, 23-Dec-84 01:22:03 EST
References: <212@eneevax.UUCP>
Organization: Contel Cado, Torrance, CA
Lines: 77


>I have noticed several comments in this newsgroup stating that
>the graphics on the atari is superior to the c64. I personally
>have a c64 although today the atari is a better buy. However, I
>always thought that the c64 had better graphics and sound
>hardware than the atari. I realize that for basic programming
>the atari graphics and sound is very easy to use since the
>keywords are built into basic. But for applications programs
>and games the c64 seems to have the edge. It has 16 colors in
>the hi res mode (limited to two different colors in any 8x8 block)
>vs only 2 shades for the atari. The sprites in the c64 can be
>moved in the x and y directions where as the player missiles
>in the atari can only be moved horizontally. The sound chip on
>the c64 is a real synthesizer with ADSR features, filtering, the
>ability to modulate one voice with another, and external input
>as compared with atari's more primitive distortion parameters.
>I have heard that the 800XL's have a newer antic chip that
>allows more graphics modes, but on the surface at least the
>c64 seems to have the edge. I am sure that there are some arguments
>for the atari that I may have missed and I would enjoy hearing
>more pro's and con's about the two machines.

Some of these features are hard to compare.  Your description of
the Commodore '16 colors in hi res' obviously has limitations,
(only 2 in any 8x8 etc.)  The Atari features are different and
may also have limitations.  True, the Atari technically only has
2 colors in hi-res, but with proper use of the display list, you
can have 128 colors (or is it 256?), limited to two different
shades on any raster line.  With the display list, you can mix
graphics and text modes on the screen like crazy, ie: a screen
with 1. four raster lines of hi-res, then 2. a text line, then
3. 20 pixel lines at medium res, etc. ad infinitum (or at least
until the bottom of the screen) The display list will also 
facilitate scrolling of all or part of the screen either
horizontally or vertically without moving any of the actual
data.  Display list interrupts can be used to divide the 4 (actually
5) players into seperate entities, provided they only move horizontally.
(actually you might even be able to do vertical movement like this with
some cute tricks).  In this way, each of the 5 players could be divided
into up to 192 individual horizontal moving 'sprites'.  Of course at
192, each sprite is 8 horizontal by 1 vertical.  Collision detection
is built in for player-player, player-background, etc. but I suppose
the Commodore may have this feature.  I've heard nothing about any
display-list type features in the C64.  If there are any, I'd like to
hear about them.

I must admit though, the Atari sound generators are not particularly
impressive.  The best feature is that there are 4 of them and you can
combine them for more sophisticated effects.  The worst feature is that
there is only 1 'tone' while there are 7 'noises'.  The 1 'tone' is
approximately a sine wave, so you don't have much control over timber.
You can change the clock rate to the generators in order to drop to
lower octaves (more bass!) and you can inter-combine them in some
odd ways that I haven't gotten around to experimenting with.  I don't
particularly miss an ADSR, as this is a slow enough function that it
can be 'simulated' with a clock interrupt routine.  (nice not to have
to do it that way though)  One feature however, is the volume-only
mode, where you turn off the sound generators, and use the volume
control as a 4 bit D/A.  S.A.M. uses this for it's speech synthesis
output, and does an excellent job, however, you have to turn off all
interrupts and DMA etc. because they affect the timing adversely.  This
means a blank screen when you use this sound feature.

I don't know much about the C64 except it has 32 sprites.  I guess it
just uses the T.I. 9918? (no display list or associated interrupts).
All I know about the sound generators is what was said in the above
referenced article.

I would like to know what versions of FORTH people are using on the
C64.  I use it exclusively for Atari programs, and would like to
know what the best commercially available C64 version is.


Keith Doyle
{ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd
"You'll PAY to know what you REALLY think!"