Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!FSUCS.CS.FSU.EDU!peterson
From: peterson@FSUCS.CS.FSU.EDU (Eric J. Peterson)
Newsgroups: comp.sys.amiga
Subject: Re: Return of the processor wars, part II
Message-ID: <9001132323.AA14496@fsucs.cs.fsu.edu>
Date: 13 Jan 90 23:23:45 GMT
References: <1646@bnr-rsc.UUCP> <90010.202827YTHPRGDB@MTUS5.BITNET>
Sender: daemon@ucbvax.BERKELEY.EDU
Followup-To: comp.sys.ibm.pc
Organization: Florida State University Computer Science Department
Lines: 49

In article <1652@bnr-rsc.UUCP>:
| In article <90010.202827YTHPRGDB@MTUS5.BITNET> YTHPRGDB@MTUS5.BITNET writes:
| >Granted, Intel did a very nice thing in giving us the "virtual 8086"
| >mode to allow multiple 8086-based programs (DOS-based?) to execute
| >concurrently.  This seems to be an excellent idea, but why then
| >does OS/2 only allow one DOS task (in the compatibility box)?
| 
| I assume this is a limitation of OS/2 that is designed to force users
| to migrate to "true" OS/2 applications.

DISCLAIMER:  I know virutally nothing about OS/2.  What follows is
	     speculation only.

More likely, this limitation is due to the inability of DOS to multitask
(without packages such as ConcurrentDOS and DoubleDOS).  DOS does not have
any way to lock resources to individual processes the way that a
multitasking OS does.  This paves the way to race conditions and all sorts
of classical Op sys problems.

Suppose OS/2 supported multiple Compatibility Boxes.  Suppose that an
application in one Box configures and uses the serial port.  Suppose that
another Box tries to access and configure the same port.  When it changed
any of the port settings, one or both programs would crash or operate
erroneously.

Of course, Microsoft could have added resource sharing controls to its
Compatibility Boxes.  But this has the potential to introduce compatibility
problems; i.e., using a Compatibility Box-compatible program in one Box
while using a non-compliant program in another.  But if you're adding all
of these things, why not just make it into a new spectacular version on
DOS?  Two reasons as far as I can tell:

(1) Development Time.  It's easier to implement something that already
    exists than it is to go out and make something new from scratch.  The
    important thing was getting OS/2 out on the market.

(2) Lack of Necessity.  DOS 4.0 has all sorts of great new features in it,
    yet the public has virtually ignored it.  Plus, if you're going to do
    things in DOS such as resource locking and so forth, why not just use
    OS/2?

Followups directed to comp.sys.ibm.pc.

Eric
-- 
  . |~~
 _O_)            Eric J. Peterson ... peterson@{nu,fsucs}.cs.fsu.edu
( X   FSU CS Technician // 011 Love // Work: 904-644-2296 // Home: 904-576-3318
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