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From: ralph@computing-maths.cardiff.ac.uk (Ralph Martin)
Newsgroups: comp.sys.mac,comp.windows.misc
Subject: Re: Preemptive and Nonpreemptive Multitasking
Message-ID: <234@cf-cm.UUCP>
Date: 21 Mar 88 10:39:31 GMT
References: <4129@hoptoad.uucp> <283@rhesus.primate.wisc.edu> <1710@ssc-vax.UUCP> <9829@steinmetz.steinmetz.UUCP> <7593@apple.Apple.Com> <3609@bloom-beacon.MIT.EDU> <7658@apple.Apple.Com> <1174@cpocd2.UUCP> <7720@apple.Apple.Com>
Organization: Univ. Coll. Cardiff, Cardiff, WALES, UK.
Lines: 25
In-reply-to: dwb@Apple.COM's message of 17 Mar 88 06:54:25 GMT

Posting-Front-End: GNU Emacs 18.47.1 of Mon Nov 23 1987 on v1 (berkeley-unix)


I'm afraid you guys at apple have shot your self in the foot.

By saying that applications such as excel POLL for events during long 
calcultions, you have hit the real nub of the matter. 

In a "real" multitasking operating system, the operating system takes care of
events via interrupts, and deals with them accordingly - even while other
things are going on.

A second thing the OS does is to handle memory management. On the mac, the poor
programmer has to worry about handles, and relocation blowing him away.

Lets face it, the Mac is a machine with a brilliant user interface, but no real
operating system worthy of the name. I much prefer to use my mac to my sun, but
I LOATHE programming it. On the sun, part of the OS (the notifier) takes care
of events and calls the bits of code I want in response to the events. On the
Mac, I have to ask all the time what is going on, figure out if I want it, 
and give it back to the system if I dont, and so on, as well as looking after
memory management too. This has two serious upshots (1) Mac programs are much
more likely to crash - there is no overall way of ensuring programmers 
manage memory in a sensible way, (2) If programs don't both to poll, they
screw the user up if he wants to switch (juggle), and so on. In my opinion,
much of this garbage should be pushed out of the control of the programmer,
for the benefit of all concerned. I can well believe the rumours that the Mac
OS is being written.