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From: joonsong@tornado.Berkeley.EDU (Suk-Hyun Song)
Newsgroups: comp.windows.ms
Subject: Re: Non-windows application problems
Message-ID: <1990Aug9.001052.5248@agate.berkeley.edu>
Date: 9 Aug 90 00:10:52 GMT
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Reply-To: joonsong@tornado.Berkeley.EDU (Joon Song)
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In article <4325@buff3.UUCP> krotz@motcid.UUCP (Scott A. Krotz) writes:
.
[stuff deleted]
.
>This is untrue.. I have Paging=no so that virtual memory is turned off.
>Thats why I start up with 1400k free instead of 4000k.  My question, however,
>still remains..  Why can't I start up another dos box when windows says I have
>800k free?  I have created a "small" dos box that only uses about 200k when I
>start it, but I can't call up more than two or three of those.  Windows says I
>have insufficient memory to start up a fourth, even though it reports about
>600k free.  If I am running out of memory because windows is using it to save
>screen info or virtual 86 system info or something, that is fine... but then
>why does it report 600k free?  That should be plenty of room to start up a
>200k dos box, right?  I even have trouble starting up normal windows
>applications, like the paint program after I have opened up three of these
>"small" dos windows.... Insufficient memory again.  I HAVE 600K FREE,
>THOUGH!!!  I remember when 16k was a lot of memory, and windows can't start up
>an application with 600k?  I know that the paint program does not use 600k....
>What is going on here?  Is there an incompatability with my system? Is anyone
>else with a 2meg system having this kind of a problem??  There almost seems to
>be a limit at about 530k that I cannot cross in the 386 enhanced mode, but in
>the standard mode I can start up as many apps as I want, and get the free
>memory down to 200k and below...(My head hurts)
>
>Many thanks for advice in advance..
>Scott Krotz

Sorry, I misunderstood your original post.

Windows reports the amount of free memory available.  It does this by adding
up all of the individual blocks of memory available.  However, even when 
Windows reports 800k of memory available, the largest block of contiguous
memory may be less than 200k.  But programs require a certain amount of 
contiguous memory to load.  So when you try to run even a 200k program, 
Windows will report insufficient memory if the largest block of contiguous 
memory is less than 200k.  

Memory in 386 enhanced mode is highly fragmented.  With paging=on, this is
not a problem.  However with paging=off, you are stuck.

DOS windows are still stuck at 640K-DOS-overhead ~=~ 530K.

    Joon Song
    joonsong@ocf.berkeley.edu