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From: UH2@psuvm.psu.edu (Lee Sailer)
Newsgroups: comp.sys.amiga
Subject: Re: Multifinder - Just the Facts, man.
Message-ID: <90122.102429UH2@psuvm.psu.edu>
Date: 2 May 90 14:24:29 GMT
Organization: Penn State University
Lines: 34

Multifinder has been around, but it offers a more limited flavor of
multitasking than Amiga users are used to.

1.  Amiga multi-tasking is "preemptive."  This means that the OS can
interrupt any program and start another.  So, all programs are automatically
multi-tasking (unless the programmer foes out of his way to make it
otherwise).  Multi-finder is "cooperative".  This means that the programmer
must insert statements into the code that say "OK.  Give some other program
a chance now".  When this happens, if there are any others around, they'll get
a turn.  This means that older programs are very likely to hog the whole
machine.

2.  Mac multi-tasking requires much more memory, typically 2MB or more.
Amiga multi-tasking is quite usable with 1MB.  This is because, since the
Amiga was designed with MT in mind from day one, there is a lot more
sharing of memory resources.  For example, two Mac programs in memory
would each have there own complete copy of the window resizing code, while
on the Amiga all programs would share that code.

3.  The Amiga has more asynchronous processes (due to more custom chips).
On the Mac, when info is being drawn to the screen, no other process can
be executing because drawing is done by the main cpu.  On the Amiga, when
a task requests that something be drawn on the screen, a custom chip does
part of the work, allowing the cpu to switch to some other task and do a little
computing in the meanwhile.  This is also true for I/O, printing, sound, voice,
etc etc etc.

In short, Multifinder is a great effort to tack something sort of like
real  multitasking onto a system that is basically a single-tasker,
while Amiga multitasking is designed in from day one.

Also, point out that while multifinder is "available," the vast majority
of Macs don't have it installed.  ALL Amigas have multitasking installed.
So, though there are a few more Macs, there are more multitasking Amigas.