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From: ckp@grebyn.com (Checkpoint Technologies)
Newsgroups: comp.sys.amiga
Subject: Re: Multitasking at home (Was Reality check: ....)
Message-ID: <24170@grebyn.com>
Date: 21 Dec 90 01:20:09 GMT
References: <1990Dec13.155848.8152@maytag.waterloo.edu> <1990Dec15.031131.17141@isc.rit.edu> <1990Dec18.002802.624@lavaca.uh.edu> <37101@cup.portal.com> <41689@ut-emx.uucp>
Reply-To: ckp@grebyn.UUCP (Checkpoint Technologies)
Organization: Grebyn Timesharing, Vienna, VA, USA
Lines: 38

In article <41689@ut-emx.uucp> awessels@ccwf.cc.utexas.edu (Allen Wessels) writes:
>OK, guys.  I've been following the group for a while since I've been thinking
>of getting a 500 or 2000.  Just exactly what does the Amiga's true multitasking
>let me do (other than formatting disks) that I can't do on my Mac?

Given the memory, you can choose any combination of applications and run
them concurrently.  It is like MultiFinder in that respect.  There are
some exceptions. Most games are written to prohibit multitasking, for
better performance.

Unlike Multi-Finder, the Exec controls the execution of tasks in a
pre-emptive fashion, meaning that one application doesn't have to
explicitly "give up" in order to run the next.

Tasks are given "priorities", so that higher priority tasks will take
precedence over lower priority tasks. This is used to good effect by
the user input tasks and Intuition, and provides superb input response.

Finally, IO operations (including keyboard, screen, serial, parallel,
floppy, HD, mouse, joystick, what have you) are not CPU-polled. Many
are DMA driven (floppy, HD, screen [blitter]), and all will signal
their task when they complete.  This allows tasks to Wait(), so that
they consume no CPU time while their IO operations are underway.

So what, in practice, does this mean?  Just overall better
performance and responsiveness.  There isn't any particular thing that
"true" multi-tasking, versus MultiFinder's co-operative multi-tasking,
offers besides this.  Yes, you can format a floppy and run programs, you
can format two floppies at the same time as well, for the same reason.
The Exec helps to make all the tasks as independent of each other as
they want to be, or to cooperate as much as they want to,  and you don't
find yourself asking silly rhetorical questions such as "WHY must I wait
for this to finish before I can... ?"
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