Autor: Andrzej Karpinski (KARPIO_at_golem.umcs.lublin.pl)
Data: Sun 26 Mar 1995 - 21:24:34 MET DST
WARP VS CHICAGO: A Decision Maker's Guide to 32-bit Operating
System Technology
EXECUTIVE SUMMARY
=================
This document is designed to provide the corporate decision maker
with benefits of OS/2 and important information about critical
weaknesses in Microsoft's forthcoming Chicago operating system.
At the heart of the discussion are key architectural,
operational, and strategic flaws in the Chicago OS design and
strategy - flaws that Microsoft has either downplayed or ignored
in its efforts to market Chicago as the "next generation" Windows
desktop platform.
For example, you'll learn:
Why OS/2's ability to isolate individual 16-bit Windows
applications into their own separate VDMs provides a level of
inter-application protection that is unavailable under Windows
3.1 or Chicago.
How this same isolation also allows OS/2 to preemptively multitask
existing 16-bit Windows applications, with no impact on native
application performance
Why having a comprehensive System Object Model (SOM) is important,
and how OS/2's SOM implementation acts as the "glue" to the
WorkPlace Shell interface.
Ways in which OS/2's Virtual DOS Machine implementation is more
flexible than Chicago's.
Major topics include:
Architectural flaws that compromise Chicago's stability when
running 16-bit Windows applications.
How these same flaws also limit Chicago's multitasking
capabilities with a mixture of application types.
Why the lack of a System Object Model makes the Chicago interface
"fragile."
Ways in which Chicago's DOS heritage render the product inflexible
when dealing with 16-bit DOS device drivers.
At the end of each section, a direct comparison is made between
the Chicago implementation of a particular subsystem or
feature/function, and that of the leader in 32-bit desktop
operating systems, IBM's Operating System/2.
The material is based on an in-depth analysis of Microsoft's
public statements regarding Chicago's design characteristics and
various presentations given at trade shows by industry
consultants.
OS/2 - THE RIGHT SOLUTION
Choosing the right operating system. In many ways it's the most
important personal computer technology decision you'll make in
this century. Choose wisely and you'll reap the benefits for
years. Choose poorly and you may find yourself in a quagmire of
under-performing software and inadequate computing power.
So just what constitutes a wise choice in today's confusing PC
marketplace? Simple: the product that does the best job of
preserving your existing investments while opening the door to
the future. In a nutshell, the wise choice is Operating
System/2.
OS/2 - THE WORLD'S MOST POPULAR 32-BIT OPERATING SYSTEM FOR IBM
AND IBM COMPATIBLE PC's
Why OS/2? Because it represents the most logical upgrade path
for today's PC users. OS/2 preserves your investment in 16-bit
DOS and Windows applications while providing access to a new
world of 32-bit, object-oriented technology.
Upgrading to OS/2 is a win-win proposition. Just ask any of the
more than seven-million OS/2 users - over 17 times as many users as
Microsoft's current 32-bit offering, Windows NT. These are
people just like you who have outgrown their existing DOS or
Windows environments and who are looking for more - more power,
more functionality, more stability.
With OS/2 they've found a powerful mix of backward-compatibility,
32-bit processing power, and ease of use, along with the kind of
rock-solid reliability that only a mature, established operating
system platform can deliver. With the release of V3, OS/2 is
entering in its 3rd generation, and the product's reputation for
reliability and price/performance is unmatched in the PC
industry.
BUT WHAT ABOUT CHICAGO?
This is the question that perplexes both corporate decision
makers and end users alike. With all of the media hype
surrounding this "next generation" of Microsoft Windows, many
customers feel paralyzed when making operating system purchasing
decisions. The fear of "missing-out" on Chicago is overwhelming
for some.
But as experience with the initial beta release of Chicago has
demonstrated, Microsoft's "next generation" of Windows is far
less compelling than they would lead you to believe. In fact,
the core of Windows 4.0 is probably running on a PC near you:
it's called Microsoft Windows 3.1.
ARCHITECTURE
============
CHICAGO - SAME CODE, DIFFERENT PACKAGING
"How can that be? It looks so different!"
Looks can be deceiving. While Chicago indeed sports a radically
different user interface (more on that later), as you peel-away
the layers of GUI and packaging you'll discover a product that
looks remarkably like Windows 3.1. In fact, Chicago retains so
much of its original DOS/Windows heritage that it retains the
latter's most notorious operational characteristic: instability.
For example, under Windows 3.1 all applications, as well as the
operating system code itself, share a single memory address
space. While such a memory management model breeds performance,
it also means that an error in any single application can
potentially crash the entire operating system.
This crashing phenomena is often referred to as a General
Protection Fault or "GPF," and has been the bane of Windows users
since version 3.0. It is because of this inherent architectural
weakness that Windows 3.1 has gained a well-deserved reputation
of being an unstable, unreliable operating environment.
Under Chicago, this same single address space model (referred to
as the "System Virtual Machine") is retained, along with the
inherent weakness of leaving key portions of the operating system
code exposed to potentially buggy applications. Thus the same
application failures that crashed Windows 3.1 can potentially
bring down the entire Chicago operating system.
To their credit Microsoft has made great strides in "cleaning-up"
many of the bugs in the original Windows 3.1 code while
preparing it for inclusion with Chicago. However they cannot
avoid the inherent architectural flaws that the Windows 3.1
single System VM model introduces. There will always remain the
possibility of an errant application causing a disastrous system
crash.
OS/2 - SAME CODE, BETTER IMPLEMENTATION
OS/2 eliminates the Single System VM stability problem by letting
you run Windows applications in their own separate sessions, or
"VDMs" (Virtual DOS Machines). Thus if an application fails
under OS/2, the effect of the failure is limited to the
individual session. Other applications, as well as the operating
system itself, remain unaffected.
And by retaining much of the original Windows 3.1 code base,
OS/2's environment remains highly backward compatible with
Windows 3.1 applications and device drivers.
MULTITASKING
============
CHICAGO - A "SEMI-PREEMPTIVE" TASK SWITCHER?
One of Microsoft's biggest selling points for Chicago has been
the promise of a new breed of 32-bit Windows applications. These
applications are to be preemptively multitasked by the Chicago
operating system, and will have access to advanced performance
enhancing techniques like multi- threading.
Let's define the difference between preemptive and cooperative
multitasking. Preemption is an involuntary loss of control which
the application must handle. Cooperative multitasking is where
the application is given control and it is the application's
responsibility to give up control so that other applications may
execute.
The move to a preemptive multitasking model represents a a
significant departure from Windows 3.1. Under that environment
applications must "cooperate" in order for multitasking to occur.
Each program "yields" to the operating system so that it can
switch control of the PC's CPU to a different application (this
is often referred to as "cooperative multitasking" or
"task-switching").
It is a well know fact that the Windows "cooperative
multitasking" model is inefficient. It also forces programmers to
code their applications in a way that adds complexity and hinders
performance. So it comes as no surprise that Microsoft's promise
of preemptive multitasking in Chicago has been heralded as one of
the new platform's most important features.
But the truth is that Microsoft isn't telling the whole story
when it comes to Chicago's multitasking architecture. In
reality, unless you work exclusively with 32-bit "Win32"
applications, you won't reap the benefits of true preemptive
multitasking.
Why? Because of Chicago's heavy reliance on 16-bit, Windows
3.1-era code. Under Chicago, both 16-bit and 32-bit applications
rely on 16-bit code structures that reside within the System VM -
code that has been brought over from Windows 3.1.
While the "bitness" of the code itself isn't significant, the
environment from which it hails is. Windows 3.1 was written as a
cooperative, not preemptive, multitasking environment. When you
introduce portions of its code into a preemptive setting, where
more than one task may be vying for its services at any given
time, the code breaks.
To safeguard against this sort of "code breakdown," Microsoft has
serialized access to key portions of the Chicago infrastructure -
most notably the USER (window management) and GDI (graphics
device interface) subsystems. In technical terms, this is
referred to as a "non-reentrant" design, meaning that only one
application may execute within these modules at any given time.
While such an approach works with Win32 applications - which can
be preempted at any point during their execution - it breaks down
once a 16-bit Windows (Win16) application begins to execute. As
it stands, currently shipping Win16 applications cannot be
reliably preempted during execution. Attempting to do so while
such an application is calling on a non-reentrant, 16-bit code
module can cause the entire operating system to crash.
To avoid this latter scenario, and thus retain some semblance of
multitasking, Microsoft has implemented a special locking
mechanism. Dubbed "Win16LOCK," this mechanism denies access to
the older code when a 16-bit application has called on its
services. Thus only the currently running Win16 application has
access to the 16-bit code - all other applications, including
Win32 applications, are "blocked" from executing until the 16-bit
application has finished and the environment has been made safe
for the next task.
In practice, the performance hit associated with this locking
phenomena is minimal when running 32-bit applications
exclusively. However, when you introduce a mixture of 16 and
32-bit applications - the most likely scenario given the
projected lack of available Win32 products - Win16LOCK becomes a
major problem.
Most 16-bit Windows applications are notorious for failing to
yield properly under Windows 3.1, and until they do so under
Chicago, all other applications will be blocked from accessing
USER and/or GDI (in reality, only 50% of GDI calls are affected -
but these are the most common functions so the net result is the
same).
Taken as a whole, these two compromises - the serialization of
subsystem access and Win16LOCK - create what would best be
described as a "semi-preemptive" multitasking environment. And
while the resulting "hourglass" is expected under a cooperatively
multitasked environment, it seems out of place in a "next
generation" Windows that supposedly "preemptively multitasks"
native Win32 applications.
OS/2 - TRUE PREEMPTION FOR BETTER PERFORMANCE
OS/2 has featured true preemptive multitasking of native
applications since day one. Regardless of the mixture of
application types, OS/2 can continue to smoothly multitask dozens
of concurrent programs, and its reentrant subsystems allow it to
service multiple concurrent requests without the overhead of a
"Win16LOCK" implementation.
And thanks to its ability to run them in separate VDMs, OS/2 can
also preemptively multitask existing 16-bit Windows applications
which Chicago can not. Thus you can have DOS, Windows, and OS/2
applications running concurrently, side-by-side, without any
performance penalties and all preemptively multitasked. This is
a feature that Chicago will be unable to match without underlying
architecture changes, and a welcome addition to any power-user's
arsenal.
INTERFACE
=========
CHICAGO - BEAUTY THAT'S ONLY SKIN-DEEP
Another major feature of Chicago, and one that has drawn
considerable attention from the industry press, is its new user
interface. Terms like "object-oriented" and "desktop metaphor"
are often used to describe this radically different Windows look.
But as with most of Chicago's underpinnings, the actual
foundation underneath the product's user interface is nothing
more than an extension to what already existed in Windows 3.1.
Unlike a true object-oriented environment - where links between
individual objects are "live" and updated automatically - the
Chicago GUI is static. "Objects" on the Chicago desktop are
merely pointers to files on the disk. "Properties" for these
objects are stored in .INI files (for Windows applications) or
.PIF files (for DOS applications), and links between them (called
"shortcuts" under Chicago) are equally static.
For example, if you create a shortcut to an executable file and
place it on the Chicago desktop, then rename the original
executable, the shortcut will essentially be severed. To
re-establish it you'll have to re-create the shortcut from
scratch.
In a true object-oriented environment, all shortcut-like links to
the executable would have been updated automatically by the
underlying object management model. Chicago has no such
underpinnings, so links are easily broken by novice users who are
unfamiliar with the crudeness of the Chicago interface.
Going hand-in-hand with Chicago's shortcut mechanism is the
product's support for long file and directory names on FAT
volumes. Microsoft is emphasizing Chicago's ability to
automatically convert long file/directory names into 8.3
character abbreviations for compatibility with existing DOS and
Windows applications. What they seem to be ignoring, however, is
the fact that promoting the use of long names can be disastrous
when there is no underlying object model.
Take, for example, the novice user who, upon discovering long
filenames, decides to "reorganize" their hard disk. They
gleefully rename directories at will, unaware that they are
severing shortcut after shortcut in the process. Suddenly none
of their applications work, and I/S is called in to undo the
damage (which in some cases may mean reinstalling both operating
system and applications).
The Chicago desktop itself is not an OLE 2.0 object. This
statement in itself has no ramifications until you start
understanding what type of integration is lost due to this lack
of object technology. This deficiency in the product, means that
an application is not well integrated with the desktop and does
not inherit any of the advantages like Drag 'n' Drop support.
Heralded by Microsoft as one of Chicago's key selling points, the
new Windows interface may in the end prove to be one of its
biggest flaws. Without an underlying system object model to tie
everything together, this new "shell" may prove to be an I/S
support nightmare.
OS/2 - TRUE OBJECT-ORIENTATION
OS/2's WorkPlace Shell is a true object-oriented interface. The
underlying System Object Model (SOM) provides complete
object-tracking so simple operations like dragging a directory to
another directory won't invalidate links and other interface
structures. Thus it's easier on both novices and IS support
staff alike.
SOM also allows applications to fully manipulate the WorkPlace
Shell interface. A good example is cc:Mail for OS/2, which uses
SOM to seamlessly integrate its in/outbox interfaces with the
WorkPlace Shell desktop. This level of integration isn't
possible under Chicago since its shell is itself not an object.
APPLICATION SUPPORT
===================
CHICAGO - STILL DOS AFTER ALL THESE YEARS
"Chicago eliminates the need for DOS. It is a true operating
system..."
This is one of the more colorful myths surrounding Microsoft's
Chicago operating environment. Microsoft claims that Chicago
eliminates the need for DOS - that DOS and Windows are now
completely integrated and that all the old restrictions that DOS
brought to the table have been eliminated.
While it is true that you will no longer have to purchase a
separate DOS product in order to install and use Chicago, this in
no way constitutes the eradication of DOS as a part of the
Windows operating system equation. DOS is still there, lurking
in the shadows. It's just been cleverly disguised by a different
Windows GUI. And though much of its functionality - including
file system access - has been replaced by 32-bit Chicago VxDs
(Virtual Device Drivers), there are still ways in which DOS can
hinder the Windows environment.
Take real-mode device drivers, for example. Under DOS/Windows
3.1 you were forced to load all DOS device drivers at DOS
boot-time via the CONFIG.SYS file. These drivers would then
occupy all DOS sessions under Windows' 386 Enhanced Mode,
impacting their available conventional memory and limiting the
overall configurability of the Windows VDM architecture.
Chicago suffers from this very same limitation. Any real-mode
DOS device drivers that you wish to access from within Chicago
must be loaded via CONFIG.SYS at boot-time. Thus, if you want
access to a particular resource, and this resource requires a DOS
device driver, you'll be forced to pay a penalty in terms of lost
conventional memory and potential compatibility problems across
all Chicago VDMs.
And what about troublesome applications like games? Chicago
features a special DOS session - the "Single MS-DOS Application
Mode" - that allows such applications to execute unencumbered by
the confines of a traditional Virtual DOS Machine (virtual I/O,
video memory, etc.). What Microsoft doesn't publicize, however,
is the fact that, in order to invoke this mode, you must
essentially shut-down Chicago. All running applications close,
and the Chicago GUI itself is paged to disk. This entire process
can take up to a minute depending on the speed of the hardware in
use and the number of open applications - quite a disruption,
especially when you're trying to finish that last minute memo or
download a large file from a host system.
OS/2 - A BETTER DOS THAN DOS (OR CHICAGO)
OS/2 really does eliminate the need for DOS. It's VDMs are
completely configurable, allowing you to create individual
CONFIG.SYS and AUTOEXEC.BAT files for each DOS session. This is
an important option in those situations where a single device
driver or TSR configuration for all VDMs would be inadequate.
OS/2's VDMs are also highly backward-compatible and can also be
configured to allow direct hardware access for applications that
require it. And if an application truly refuses to run under
OS/2 you can use the "dual-boot" option to run real DOS in about
the same amount of time it takes you to invoke Chicago's "Single
MS-DOS Application Mode."
INDEPENDENT SOFTWARE VENDOR COMMITMENTS
=======================================
CHICAGO: AN ISV HEADACHE
One area where Microsoft continues to be uncertain is on the
subject of API standards. Independent Software Vendors (ISVs)
have been fighting an uphill battle in their efforts to pin-down
Microsoft's overall API strategy. This is especially true of the
native Chicago API, Win32c, which is itself a subset of the full
Win32 API published nearly two years ago and implemented on
Windows NT.
Further exacerbating the situation is Microsoft's continual
updating of the Win32c specification. New APIs emerge almost
monthly, many of which extend Win32 in ways that tie applications
to the Chicago platform. This has aggravated ISVs who wish to
write cross-platform applications for Windows, Windows NT, and
Chicago. The only way these ISV's can write cross-platform
applications, because of the different APIs support, is to poll
the Kernel, determine which API is available and write dual or
triple path code. With the APIs still in a state of flux there is
no guarantee that the multiple path code will work.
What this means to the 32-bit operating system customer is a
potential delay in the release of Chicago-compatible Win32
applications. Given the architectural limitations of Chicago's
Win16 application support - especially when multitasking and
stability are major considerations - lack of Win32 applications
could represent a serious obstacle to the platform's widespread
adoption. Chicago needs Win32 applications before it even begins
to make sense as a replacement for Windows 3.1. But given the
confusion and frustration in the ISV community it may be some
time before we see a substantial selection of Win32 titles.
OS/2 - A CONSISTENT MESSAGE
In contrast to Microsoft's "API du jour" strategy, IBM has stood
firm on its promises to support open standards and honor ISV
commitments. There is one 32-bit OS/2 Presentation Manager API
for both client and server systems. Applications written to that
API will work across OS/2 versions running on Intel-based PC's,
and will be easily portable to more advanced implementations in
the future (including OS/2 for PowerPC).
OS/2 currently boasts over 2000 native applications, all of which
tap into the superior multitasking and performance of the world's
most popular 32-bit operating system.
SUMMARY
=======
OS/2: THE RIGHT ANSWER
As you can see, Microsoft's Chicago operating system is long on
hype and somewhat short on technology. But if you've followed
their product offerings over the past few years, this revelation
should really come as no surprise. Microsoft has a track record
of delivering "cosmetically advanced" operating systems while
ignoring the more important issues like robustness, capacity, and
true object-orientation.
In contrast, IBM has a very different track record, one that
speaks of commitment to open standards and listening to customer
needs. This is the same company that has been developing cutting
edge OS technology for mainframe and minicomputer systems since
the dawn of the information age. With OS/2, IBM has laid the
foundation for a truly robust, high-capacity computing
environment that preserves your existing investments while
opening the door to the future.
You can see the difference in areas like the OS/2 user interface.
The WorkPlace Shell, in conjunction with the System Object Model
(SOM), provide a truly object-oriented computing environment, one
that thinks for you and doesn't break-down when you try to tap
into its power. Likewise, OS/2's multitasking represents a
no-compromises approach to bringing this powerful capability to
the masses. From native OS/2 applications to its robust Win-OS2
VDMs, it is an operating system that can juggle your most complex
tasks with ease.
So in the end, the wise choice is obvious: OS/2 has the backward
compatibility you want, the stability and reliability you need,
and the kind of rock-solid commitment to excellence you've come
to expect from the world's number one software company, IBM.
Chicago looks more and more like a warmed-over version of
yesterday's technology, not the "next generation Windows"
platform that Microsoft is advertising it to be.
So what about Chicago? Good question! With one foot still
buried in the DOS/Windows grave, Chicago is yesterday's
technology dressed-up to look like tomorrow's 32-bit OS. Why
wait for an impostor? OS/2 is here today, and represents the
real future in personal computer operating systems.
APPENDIX A: FEATURES CHARTS FOR OS/2 AND CHICAGO
================================================
The following charts provide a summary of OS/2 and Chicago
features, including multitasking characteristics, application
environments, and bundled productivity tools.
OS/2 VS CHICAGO ON ARCHITECTURE
WARP LAN
FEATURE WARP CLIENT CHICAGO
32-bit Window Management Yes Yes No (1)
32-bit Graphics Subsystem Yes Yes No (2)
32-bit Printing Subsystem Yes Yes No
32-bit Multimedia Subsystem Yes Yes Yes
32-bit Kernel Yes Yes Yes
Internet Access Tools Yes Yes No
FTP Yes Yes No
Telnet Yes Yes No
Gopher Yes Yes No
Newsreader Yes Yes No
WEB Explorer Yes Yes No
CompuServe Front-End Yes Yes No
Word Processor Yes Yes No (11)
Spreadsheet Yes Yes No
Database Yes Yes No
Charting Yes Yes No
Report Writer Yes Yes No
Electronic Mail Yes Yes Yes
Image Viewer Yes Yes No
FAX Yes Yes Yes
Phonebook Yes Yes No
Personal Information Mgr Yes Yes No
Sys Info Yes Yes No
VideoIn Yes Yes No
Video Conferencing Yes Yes No
(11) Chicago comes with a simple text editor, not a word processor
DISCLAIMER
==========
The information contained in this document represents the current view
of IBM Corporation on the issues discussed at the date of publication.
Because IBM must respond to changing market conditions, it should not
be interpreted to be a commitment on the part of IBM, and IBM cannot
guarantee the accuracy of any information presented after the date of
publication.
This document is for informational purposes only. IBM makes NO
WARRANTIES, EXPRESSED OR IMPLIED, IN THIS SUMMARY.
1994 IBM Corporation. All Rights Reserved. Printed in the United
States of America.
OS/2 is a registered trademark of International Business Machines
Corporation.
Microsoft is a registered trademark and Windows is a trademark of
Microsoft, Inc.
NetWare is a registered trademark of Novell, Inc.
To archiwum zostało wygenerowane przez hypermail 2.1.7 : Wed 19 May 2004 - 15:50:20 MET DST