Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!microsoft!derekho
From: derekho@microsoft.UUCP (Derek HOIEM)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Why use MS-window ?
Message-ID: <54985@microsoft.UUCP>
Date: 31 May 90 21:17:13 GMT
References: <404@newave.UUCP> <10509@ingr.com>
Reply-To: derekho@microsoft.UUCP (Derek HOIEM)
Organization: Microsoft Corp., Redmond WA
Lines: 43

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.