Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!microsoft!philba
From: philba@microsoft.UUCP (Phil BARRETT)
Newsgroups: comp.windows.ms
Subject: Re: 386 enhanced mode
Message-ID: <58923@microsoft.UUCP>
Date: 8 Nov 90 18:09:42 GMT
References: <7017@hub.ucsb.edu>
Reply-To: philba@microsoft.UUCP (Phil BARRETT)
Distribution: comp.windows.ms
Organization: Microsoft Corp., Redmond WA
Lines: 59

There seems to be some confusion over what windows 3 wants to see in
order to run in the various modes.

In order to automatically run in 386 enhanced mode, windows needs:
	- a 386SX, 386DX or 486 processor
	- an installed XMS 2.0 driver (i.e. himem.sys, the one shipped
          with windows)
	- a minimum of 1024Kb extended memory (via XMS)

In order to automatically run in standard mode, windows needs:
	- a 286, 386SX, 386DX or 486 processor
	- an installed XMS 2.0 driver 
	- a minimum of 256Kb of extended memory (via XMS)

Windows prefers to default to enhanced.

The key word in all this is automatically.  You can override the default
via the command line (as pointed out in the mail).

Note that many 2Mb machines  (especially C&T based ones) only have
1024Kb extended memory with the remaining 384Kb given to shadow ram.
If you install a disk cache in extended memory (for example smartdrv),
this will reduce the amount of extended memory below the magic 1024K
number and you will get the observed effect.  Smartdrv has a feature
where windows can `borrow' memory from it.  The smartdrv command line
looks like this:
	device=smartdrv <max-mem> <min-mem>
the max-mem param indicated the amount of memory to start with and
the min-mem param defines the amount of memory that windows will leave
when it borrows memory.  This is documented in the WUG

In this case, I suspect that you are giving 512Kb to your cacher
(if it were smartdrv is would be device=smartdrv 512 512) and not allowing
for borrowing.  You have some choices:
	- use smartdrv and let windows borrow it to `zero'
	  (device=smartdrv.sys 512 0) if enhanced mode is important 
	  to you.
	- live with standard mode. Its pretty good if you dont run DOS apps.
	- get more memory.  Right now it costs about $50/Mb or less.
	  This is the option I'd take.
	- if you are lucky, you can take shadow ram and turn it into
	  extended memory.  not a high probability but worth a shot.


Phil Barrett
uunet!microsoft!philba
Yup, the above opinions are mine and are not
necessarily representative of my employers.

In article <7017@hub.ucsb.edu> 6600bori@ucsbuxa.ucsb.edu (Boris Burtin) writes:
>I'm running Windows 3.0 on my 25mhz 386 with 2 megs, and I had some 
>questions about this so-called enhanced mode.  When I type just "win"
>at the command prompt, Windows throws me into STANDARD mode with 907k
>RAM.  The manual says that with my configuration, it should default to
>enhanced.  After I created a 2-meg cache on my hard disk (the actual
>name of this procedure slips my mind at the moment) and typed "win /3"
>at the DOS prompt, it ran in enhanced mode with some 2.7 megs of RAM.
>Is it normal for Windows not to default to enhanced mode?  Thanks...
>				- Boris Burtin