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From: connery@bnrmtv.UUCP (Glenn Connery)
Newsgroups: net.micro.pc
Subject: Re: Anyone know how to enlarge the PC-DOS default environment size?
Message-ID: <281@bnrmtv.UUCP>
Date: Wed, 12-Mar-86 14:15:11 EST
Article-I.D.: bnrmtv.281
Posted: Wed Mar 12 14:15:11 1986
Date-Received: Fri, 14-Mar-86 08:19:24 EST
References: <1007@unmvax.UUCP> <40@ur-tut.UUCP> <593@kontron.UUCP>
Distribution: net
Organization: Bell Northern Research, Mtn. View, CA
Lines: 52

Ok, listen up troops.  This has been posted before, and I don't want to
post it again.  You will probably need to know this at some point so if
you don't already copy this message someplace and save it for when you
do...

Dos 2.0-3.0 Environment size patch:

The allocation of memory for the OS copy of the environment is hard coded as:

    xxxx:0ece    BB 0A 00     MOV BX,000A
    xxxx:0ed1    B4 48        MOV AH,48
    xxxx:0ed3    CD 21        INT 21

The patch is:

    DEBUG COMMAND.COM
    S 100 L 7fff BB 0A 00 B4 48 CD 21         (search for the allocation call
    replace the 0A with how many paragraphs you want - 14 is 20 paragraphs
	      and so on. the algorithm used is size=(#+4)*16
    W
    Q

I'm told that dos2.1 has the fix at ECF and dos3.0 at F2B. The guy
that found it is using it so it seems to work. Doesn't work on DOS 3.1.

Dos 3.1 Environment size patch:

Here it is, snarfed from a  recent issue of the Boston Computer Society's
PC REPORT:

Debug Command.Com:
xxxx:0D11 0A
change the 0A to 1E for a 544 byte environment or 3C for a 1K size.
Then of course do a 'W' command to save the new version.

The best way to increase Environment space under DOS 3.1:

Forget the patch.  Just add the following into your CONFIG.SYS
file in your root directory:

    SHELL=C:\COMMAND.COM /P C:\ /E:xx

where xx is the number of paragraphs (which are 16 bytes each) to allocate
to the environment space.  If you don't have a fixed disk drive, then
change the drive specifications to A:\.  The /P switch means make
COMMAND.COM permanent (required switch).  No, it does not force the
non-resident portion of COMMAND.COM to be resident at all times.  The
second C:\ indicates the directory where AUTOEXEC.BAT can be found.
-- 

Glenn Connery, Bell Northern Research, Mountain View, CA
{hplabs,amdahl,3comvax}!bnrmtv!connery