Newsgroups: comp.sys.ibm.pc
Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!umich!srvr1!willow.engin.umich.edu!bdlepla
From: bdlepla@caen.engin.umich.edu (Bryan Dennis Lepla)
Subject: Re: Why use MS-window ?
Message-ID: <1990Jun1.183342.8164@caen.engin.umich.edu>
Sender: news@caen.engin.umich.edu (CAEN Netnews)
Organization: The University of Michigan, Ann Arbor
References: <404@newave.UUCP> <10509@ingr.com> <54985@microsoft.UUCP>
Date: Fri, 1 Jun 90 18:33:42 GMT

In article <54985@microsoft.UUCP>, derekho@microsoft.UUCP (Derek HOIEM) writes:
> In article <10509@ingr.com> fordke@ingr.com (Keith Ford x8614) writes:
> >in article <404@newave.UUCP>, john@newave.UUCP (John A. Weeks III) says:
> >> 
> >> In <10699@medusa.cs.purdue.edu> wjin@cs.purdue.EDU (Woochang Jin) writes:
> >>> According to the discussions, windows for 88/86/286 machines cannot do
> >>> muti-tasking. Then my question is why use windows if multi-tasking is
> >>> impossible ? Anyway you start one job and wait until it is done.
> >> 
> >> Windows (at least 2.x) is multi-tasking.  Things can be done in the
> >> back-ground when the machine has extra cycles.  Some "experts" say
> >> windows is not true "pre-emptive" multi-tasking.  If this means anything
> >> to you, then you might want to investige further.
> >
> >As I thought I read in BYTE, the multi-tasking is only available on 386
> >machines.  286's can only program switch.  Is this clarification correct?
> >-- 
> >| fordke@ingr.com,  ...!uunet!ingr!fordke,  sysop@f12.n373.z1.fidonet.org
> >| Micro Magic BBS (1:373/12 - 205/830-2362) IBM/Apple2/Trackstar/Echoes/News
> >| "...and the Trees are all kept equal by hatchet, axe, and saw." -Rush
> 
> Well kind of.  Windows does "timeslicing", which appears to be multitasking.
> Windows timeslices on 286 and 386 machines.  Windows basically divides the
> microprocessor's time into milliseconds which are assigned to each job.
> Windows 286/Windows 3.0 real mode can timeslice between Windows applications,
> but cannot for DOS applications.  For example, if I was running Crosstalk
> for Windows in Win 3.0 real mode, I could be working in Excel while Crosstalk
> diligently downloads a file.  Thus, you appear to be multitasking.  But if
> I was running WordPerfect under Win 3.0 real mode, Windows would suspend
> all jobs and assign all of the processor's time to WordPerfect.
> 
> Now if I'm using a 386 or 386SX with Windows in protected mode (enhanced),
> it will timeslice even between DOS applications.  For example I could be
> editing in WordPerfect,  recalulating in Lotus 1-2-3, and telecommunicating in
> Works all at the same time.  In actuality, however, Windows is just updating
> each application every X number of milliseconds.  You will notice that each
> application will be running a little slower than normal.  That is because
> they have to share the processor's time amongst each other.
> 
> OS/2 is the operating system capable of *real* multitasking.  OS/2 has
> "threads" which are processes that can be happening at the same time.  For
> example, I can be formatting a floppy disk and downloading a file without
> noticeable system degradation in speed.   Pagemaker for OS/2 is a great
> example of how threads can be utilized for real multitasking.

OS/2's *real* multitasking is no different than windows 3.0 in the enhanced
mode.  OS/2's threads also use timeslices.  There is no possible way for the
threads to *happen* at the same time on a one cpu machine.