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From: buffa@kish.inria.fr (Michel Buffa)
Newsgroups: comp.sys.amiga.games
Subject: Re: Sniffle, Sniffle no memory was (FAUG demo of Powermonger by E.A.)
Message-ID: <9459@mirsa.inria.fr>
Date: 17 Dec 90 11:01:03 GMT
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In article <22187@well.sf.ca.us>, farren@well.sf.ca.us (Mike Farren) writes:
> buffa@kish.inria.fr (Michel Buffa) writes:
> >Try X-OUT, R-TYPE, BATTLE SQUADRON, SILKWORM, TURRICAN, LOTUS ESPRIT TURBO,
> >and you'll understand quite easily why these games don't multitask.
> 
> I've tried TURRICAN and LOTUS, and don't understand why they don't at all.
> Perhaps it's time for a challenge round here:  Buffa, explain to us all,
> in correct technical terms, just why it is impossible for these games to
> multitask (or at least, to leave the system intact while they run).  I'd
> really be interested to know, but, frankly, don't think you have the
> technical expertise to even begin to make such a statement.  Better yet,
> grab a plane flight to the Bay Area when I talk about how to do all of this
> at a BADGE meeting (coming soon, don't know exactly which one yet), and
> I guarantee you'll get a chance to rebut my assertions.  I'll even 
> provide a free meal or two if you do.

Ok, I'm not a professional programmer, but wrote some little demos, studied
the code of Menace when it was published, read programmer's interviews, and
what I can say is that most of the arcade games I love have 60Hz animation.
It's often written in the advertising pages, so it exists !!!!!!!  Why 60 Hz ?
because the main loop is executed at each VBL interrupt, while the video beam
comes from the bottom of the screen to the top in order to draw a new screen.
The main adventage is that the joystick will be read each 1/60 seconds, the
screen will be redrawn at a given and regular period -> instantaneous
reactions all the time, not depending on the number of objects on screen, on
the other tasks running in the background. Of course, the game should be
designed so that all the animation can be done in 1/60 second (or in 1/30 if
it is done one time out of two). I wrote some demos (like the demos done by
the european crackers, but I'm not one of them), and this technique works very
well. And my demos, didn't nuke the system, restored all the memory... In some
games, like in menace, only the scrolling the joystick reading was done in the
VBL interrupt, the Bobs animnation was done in a background loop, but the
programmer Dave Jones explained that it was only an error because he didn't
mastered the amiga very well at this time. The bitmap brothers who did ST
ports until now (And their ST ports were excellent games: XENON 1 and 2,
SPEEDBALL), promised a 60 HZ animation for SPEEDBALL 2, their first game with
a pecific amiga version.

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Michel Buffa:       Projet Robotvis, INRIA, France

    Internet:       buffa@sardaigne.inria.fr
Surface Mail:       Michel BUFFA, INRIA - Sophia Antipolis, 
                    2004, route des Lucioles, 06565 Valbonne Cedex -- FRANCE
 Voice phone:       (33) 93.65.78.39, Fax: (33) 93 65 77 65
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