Re: TIB: Lets Beat a horse

To: ti-basic@lists.ticalc.org
Subject: Re: TIB: Lets Beat a horse
From: gussie@alaska.net (Grant Stockly)
Date: Thu, 12 Feb 1998 16:34:47 -0700
Reply-To: ti-basic@lists.ticalc.org

:)  same...prooves that you should do your homework before entering a debate...

>I for one appreciate the beating!--D
>
>Rosyna wrote:
>
>> Sorry to beat a dead horse but...
>>
>> --- begin forwarded text
>>
>> Here's an article I picked up recently regarding DOS in Windows 95:
>>
>> Windows 95 is DOS 7 + Windows 4. Thats it. Nothing more to it. I don't
>> see why people would need to debate that. Its not like it's a bad thing.
>>
>> As an example: When Windows 95 boots press F8 to get the screen where you
>> can boot it in DOS-prompt only mode. Do that, and then go into your
>> Windows 3.11 directory. Type WIN and, hey presto! your running Windows
>> 3.11. Exit Windows 3.11 and go to the root. type Win, and your starting
>> Windows 95. Then do select Shutdown and select "Restart the computer in
>> MS-DOS mode". Does the computer restart? Nope, it exits Windows. No
>> restart whatsoever.
>>
>> Not really. The difference really boils down to Win95 handles more things
>> with VxD's than Win3 did. The architecture is about the same. It has to
>> be...otherwise you would not be able to load DOS drivers and TSR's before
>> Windows and have them appear in all DOS sessions. OS/2 can run DOS
>> drivers and TSR's, but they only appear in the session in which they are
>> loaded because there is no "underlying" DOS.
>>
>> Windows 3+ has always run DOS in V86 mode, and could always run multiple
>> DOS sessions. The multitasking wasn't very good, but it could run
>> multiple DOS sessions if you had patience.
>>
>> You're right, DOS is not used for all that much under Win95... but it
>> wasn't under Windows for Workgroups either if you had 32-bit file access
>> enabled.
>>
>> MS is following a strategy of gradual evolution. With each release of
>> Windows, DOS becomes less important. But Win95 is not "all new". It
>> relies quite heavily on 16-bit Windows 3 code, even for 32-bit programs.
>> Many functions in USER32 and GDI32 are "thunked" down to the USER16 and
>> GDI16. That's the origin of the "Win16MutEx" sema- phore that protects
>> such code from being reentered. All programs, even 32-bit ones, get a DOS
>> PSP structure. Which makes sense, as the old 16-bit Windows code relies
>> on having that.
>>
>> Frankly, with all the thunking, the long interrupt handler chains, the
>> mode transitions, etc, I am amazed that it performs as well as it does.
>> But maybe it's not all that great...
>>
>> One article in Windows/DOS Journal this month is a study comparing the
>> context-switch performance of '95 and NT. One would think that '95 would
>> be faster, as it is Intel-specific and assembler-optimized, while NT is
>> portable and written in C and C++.
>>
>> One would be wrong. According to the article, NT context-switches about
>> twice as fast. The author speculates that it is all the thunking and such
>> that kills performance. He points out that '95 has to go all the way down
>> to DOS to context-switch, because it has to switch DOS PSP's. Going "down
>> to DOS" involves quite a large number of traps and mode transitions, a
>> lot of overhead.
>>
>> Conclusion is that if you are targeting Win95, you should think carefully
>> before using threads. Using too many might make your application much
>> slower than it would be otherwise.
>>
>> So, if DOS isn't used, why is all this thunking going on? Why are they
>> giving each program a PSP, and switching PSP's on a context switch?
>> Answer--DOS _is_ still being used for crucial functions. Whether this is
>> good or bad is a different argument.
>>
>> To unsubscribe, send a message to: listmaster@marlowe.net and include the
>> following in the body of the message:
>> leave macmarines your_email_address
>>
>> (substitute the email address you used when joining for "youremailaddress")
>>
>> --- end forwarded text
>>
>> ---
>> I pledge allegiance to the Mac of Apple Computer Incorporated, and to the
>> developers for which it stands, one platform, under Guy, indestructible,
>> with creativity and multimedia for all.
>
>
>
>--
>
>Douglas S. Oliver
>Department of Anthropology
>University of California
>Riverside, CA 92521
>e-mail: douglaso@citrus.ucr.edu
>    or: dsoliver@earthlink.net