Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!agate!labrea!decwrl!sun!pitstop!sundc!seismo!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 640kb limit on DOS?
Message-ID: <12834@steinmetz.ge.com>
Date: 19 Dec 88 22:45:33 GMT
References: <8043@ihlpl.ATT.COM> <45900179@uxe.cso.uiuc.edu> <3545@nicmad.UUCP>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 31

In article <3545@nicmad.UUCP> brown@nicmad.UUCP (Vidiot (Vid-e-it)) writes:

| PC/MS-DOS will not, on its own, access 736K.  There are drivers out there
| to do it for you.  But, that 96K isn't really much, considering the Megs
| of memory that can be added to a 386 machine.
| 
| MS/PC-DOS is purposely written to stay within the 640K limit.  That is
| why they are producing OS/2.  Unfortunatly OS/2 will NOT run existing
| DOS applications (expect one in a DOS partition, true?).

  PC-DOS accesses 640k, because a PC or compatible may have devices
starting above that. The versions of MS-DOS designed for PC compatibles
also honor that limit. However, generaic versions of MS-DOS will run all
the memory you have, such as the version for the Tandy 2000 (I have 768k
when 512 was a big PC).

  Other versions, such as PC-PRO, which use a serial console option, can
use the whole MB if you pull out the memory mapped console code. A
terminal running at 38.4kb is pretty easy to take for non-graphic
applications, and I can write some HUGE applications.

  Today's trick: If you really need to run something big, take a little
assembler program and add the memory from 640k-704k to the free memory
list, use CTTY to change to a serial console, and use your CGA memory
for program execution. This is crude, but it works, and you can
sometimes get the stack segment in display memory and "watch" your
program run. Your milage may vary, I don't have the program handy - RTM.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me