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From: amf@ecs.soton.ac.uk (Andrew Fountain)
Newsgroups: comp.windows.ms
Subject: Re: MS windows "true" multi-tasking?
Message-ID: <2400@ecs.soton.ac.uk>
Date: 19 Feb 90 09:39:53 GMT
References: <51@dynasys.UUCP> <15962@orstcs.CS.ORST.EDU>
Organization: University of Southampton, UK
Lines: 27

abukarb@prism.cs.orst.edu (Bassam A. Abu-Karroum) writes:

>In article <51@dynasys.UUCP> jessea@dynasys.UUCP (Jesse W. Asher) writes:
>>I was wondering if MS Windows gives you a true multi-tasking environment?
>>I don't know much about MS Windows and I was wondering if there were any
>>advantages/disadvantages to running MS Windows versus running a unix
>>environment with virtual terminals.  Thanx in advance.
>>
>If you mean Windows/286 then the answer is no. Windows/286 uses memory 
>swapping/banking to simulate multitasking. What this means is that once
>an application is in the background it is suspended until it is brought
>back into the foreground as the active application. Besides Windows/286
>cannot regain control of the CPU if the application is busy.

The above is only true for non-windows tasks.  Windows uses
non-preemptive or cooperative multitasking whereas unix and os/2 use
pre-emptive (time-sliced) multitasking.  This means that a well behaved
Windows program will regularly give control back to the system, and
reasonably successful multitasking can be done.  (How do you think the
spooler program works.) The memory management is not directly linked to
multitasking, although it makes it faster when lots of programs are
loaded.  Petzold's book gives a good explanation of this. 

amf@ecs.soton.ac.uk                  Andrew Fountain
Tel: +44 703 592831                  Dept of Electronics and Computer Science
Fax: +44 703 593045                  University of Southampton
Telex: 47661 SOTONU G                Southampton  SO9 5NH  England