Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!yale!think!snorkelwacker!mit-eddie!bu.edu!mirror!prism!rob
From: rob@prism.TMC.COM
Newsgroups: comp.sys.ibm.pc
Subject: Re: Brain-dead 286 - summary
Message-ID: <206900171@prism>
Date: 9 Mar 90 15:47:00 GMT
References: <8681@rosevax.Rosemount.COM>
Lines: 111
Nf-ID: #R:rosevax.Rosemount.COM:-868100:prism:206900171:000:5273
Nf-From: prism.TMC.COM!rob    Mar  9 10:47:00 1990


phil@pepsi.UUCP writes: 

>In article <8681@rosevax.Rosemount.COM> marknew@rosevax.UUCP (Mark Newman) 
>writes:
>|From Raymond Chen (raymond@math.berkeley.edu):
>|   There is no way to switch from protceted mode to real mode on a 286.

>Of course not. What good is a protected mode if a random program
>can violate it?

  This can't be a serious question. Obviously, the means for switching
would be via a priviledged instruction, as on the 386/486. The operating
system hardly counts as a 'random program'.

  In fairness, the 286 was designed before anyone knew that DOS compatibility
(the main reason for desiring a two-way real <-> protected mode mechanism)
would be vital. 

>|From Dean William Wallwey (wallwey@snoopy.colorado.edu):
>|   The 386 and 386SX both have very powerful memory mapping powers which
>|   are used by the new operating systems.

>What new operating systems are you thinking of? Unix, perhaps?

  Also the various DOS multitaskers like Windows 386, VM/386, and so on.
There are also numerous 386 DOS extenders. Plus OS/2 version 2, if it ever 
becomes available (an open question, I'll grant). 

>|   calls Virtual 86 mode so you can multitask DOS programs using Windows
>|   or DesqView for the 386. The small amount of money you save by buying

>I still don't believe the DV386 uses virtual 86 mode. Does anyone have
>any definitive data? Maybe I'll ask QD.

   I'd be interested in knowing for sure, also. The fact that DV386 can 
virtualize screen access (even running programs that do direct video access)
suggests that it _is_ using the V86 mode, but it does seem less stable than 
I'd expect for a program that uses V86. Still, early versions of Windows 386,
which uses V86, were none too stable either. V86 mode makes safe multitasking
of DOS applications possible, but not easy.

>|   The new software that is coming around the bend really
>|   needs large flat memory spaces (EVEN the NEW 386 version of OS/2
>|   later this year will take advantage of the 386's powers and really
>|   shine!)

>It doesn't seem to me that there is very much software for OS/2.
>I know of Excel and Pagemaker. That's about it.

>Windows, on the other hand, has a lot of software. And when 3.0
>comes out, it will run in protected mode, allowing 16 megabytes of
>memory, ON A 286.

   It will still run better (offering multitasking of DOS applications
and better virtual memory support) on a 386.


>|   The 286 is not really brain dead. The problem is that nobody has
>|   ever properly taken advantage of its capabilities. The chip has
>|   available what is called protected mode, which allows advanced
>|   memory handling and multitasking. Chances are slim that you can ever
>|   find a useful DOS application to use this mode.

>At last, someone who knows what he's talking about.

   There's a lot of truth to the above paragraph; the 286 has seen use 
mostly as a fast 8088, which hardly does the chip justice. That's not why 
people disparage it, though. The problem is that 286 protected mode is far 
less versatile and powerful than 386 protected mode. That's why there's 
more 386-specific software around than 286-specific software, despite the 
fact that the 286 has been around years longer. I agree it's unfortunate 
that the 286 hasn't been used more fully, but at this point, that's not 
very relevant.

>With Windows 3.0, which does run in protected mode on a 286, due to
>come out early this summer, you should consider exactly what the
>extra cost of a 386 will buy you.

   Again, Windows 3.0 will support the 386, offering capabilities not
available under the 286 version. And the extra cost of a 386, especially
if you're willing to buy a non-name brand, is pretty marginal.

>Also realize that 10 or 20 million 286 machines constitutes a powerful
>reason for software companies to support the 286.

   Agreed. A similar argument can be made for the 8086/8.


>Certainly Unix is one program that benefits from a 386. But users
>don't buy PCs to run Unix, they buy PCs to run applications, and
>Unix is one of the worst systems to try to buy applications for.
>What kind of spreadsheets can you get? Anything that comes even
>close to Excel? I hear you can finally get MS Word 5.0 on Unix.
>A character based application, when DOS has Word for Windows. If
>you've got the Unix religion, I guess you'll get a 386. But if
>you want to get work done, you'll stay away from Unix.

   You're right about Unix, but you can benefit from a 386 even if you're 
not running Unix, and that degree of benefit will only increase with time.

   The 286 does offer a great price/performance ratio, and as a fast 8088, 
which is all many people need, it's tough to beat. And when you realize that 
it was designed a decade ago, its flaws become more understandable, though 
no less annoying. Obviously there's no sense buying a 386 or 486 just to have
the latest toy, and someone who really feels that a 286 will address their 
short and long term needs can buy one with a clean conscience. But the
benefits of a 386 are real even today, and will be far moreso in the future.
Given the narrowing cost difference between 286 and 386 machines, the group 
of tasks for which the 286 is the CPU of choice is shrinking, and will
continue to do so.