Path: utzoo!attcan!uunet!inmet!gjs
From: gjs@inmet.inmet.com
Newsgroups: comp.sys.ibm.pc
Subject: Re: DOS 640K barrier?
Message-ID: <31300012@inmet>
Date: 6 Apr 90 17:26:00 GMT
References: <78829@tut.cis.ohio-state.edu>
Lines: 40
Nf-ID: #R:tut.cis.ohio-state.edu:78829:inmet:31300012:000:1965
Nf-From: inmet.inmet.com!gjs    Apr  6 13:26:00 1990


>       We reccently got an IBM PS/2 486 machine and I have been
> switched back to programming on the IBM after a lapse of 2 years.  Can
> anyone please tell me if the DOS 640 K limit has been abolished?  We
> have DOS 4.01 and from what I have read so far, that limit is still
> there.

The February and March issues of BYTE have several articles on getting
past the 640K limit.  For running applications, the major kinds of tools
are:

    Expanded memory (special boards, with LIM drivers), which can be
    used as data space by many programs such as 123, Paradox 3,
    Framework III, ...

    Programs such as QEMM and 386-Max, which can make extended memory
    (above 1 Meg) look like expanded memory, and can load some device
    drivers, TSRs, and (in some cases) DOS FILES and BUFFERS into holes
    between 640K and 1M, leaving more application space.

    Application switchers, such as Headroom and Software Carousel, which
    allow you to swap applications out to expanded memory, extended
    memory, or disk, and later restore their state with a "hot key."

    Multitasking DOS systems, such as DESQview, which allow applications
    to run concurrently, each with a "virtual" 500K or so.  I don't know
    whether DESQview must directly support an application to run it
    concurrently, or whether there are "classes" of programs it can or
    cannot handle.

    Disk caching programs (See February PC World) and RAM disks which
    use expanded or extended memory.  These don't save space directly,
    but can significantly speed up database operations, compiling and
    linking, frequently invoked batch files, etc.  With some programs
    that have code in an overlay file (notably Framework), you can
    minimize the size of the overlay buffer to effectively keep the
    overlay code in high memory.

-- George Snyder           uunet!inmet!gjs      (from usenet)
-- Intermetrics, Inc.      gjs@inmet.inmet.com  (from internet/MILnet)