[comp.os.msdos.programmer] COMMAND.COM patch for bigger environments?

timur@seas.gwu.edu (The Time Traveler) (03/07/91)

Could someone re-post the patch for COMMAND.COM (PC-DOS 4.0x) that
enlarges the default environment size?  Thanx!


----------------------------------------------------------- The Time Traveler
Truth is after all a moving target                          a.k.a. Timur Tabi
Hairs to split, and pieces that don't fit        Internet: timur@seas.gwu.edu
How can anybody be enlightened                   Bitnet:         HE891C@GWUVM
Truth is after all so poorly lit        -- Rush

Timothy.Litton@comp.vuw.ac.nz (Tim Litton) (03/14/91)

In article <2835@sparko.gwu.edu>, timur@seas.gwu.edu (The Time Traveler)
writes:
|> 
|> Could someone re-post the patch for COMMAND.COM (PC-DOS 4.0x) that
|> enlarges the default environment size?  Thanx!
|> 
|> 


	Sorry, but am I missing something somewhere??

There was a time, when, back then, in order to increase the environment
size of command.com you included the line..

SHELL=[drive]:\[path]COMMAND.COM /P /E:[size]

in your config.sys????

I use the above line (DOS 3.3) in my config.sys to set the environment
size to 512 bytes, and believe me, I need them all!!!



Tim Litton.

jcmorris@mwunix.mitre.org (Joe Morris) (03/14/91)

Timothy.Litton@comp.vuw.ac.nz (Tim Litton) writes:

>In article <2835@sparko.gwu.edu>, timur@seas.gwu.edu (The Time Traveler)
>writes:
>|> Could someone re-post the patch for COMMAND.COM (PC-DOS 4.0x) that
>|> enlarges the default environment size?  Thanx!

>	Sorry, but am I missing something somewhere??

>There was a time, when, back then, in order to increase the environment
>size of command.com you included the line..
>SHELL=[drive]:\[path]COMMAND.COM /P /E:[size]
>in your config.sys????

The SHELL= line in CONFIG.SYS affects only the copy of COMMAND which is
loaded at boot time.  If you're running a program and spawn a DOS shell
the system will give you an environment space size equal to the currently
active space (i.e., the space occupied by current definitions) or 160 bytes,
whichever is larger.  Note that this means that if you are currently using
more than 160 bytes of environment space that your spawned shell will
have *no* available environment space beyond whatever is left in
the last 16-byte allocation block.

The problem can be bypassed if the program spawning the shell specifies
the /E:xxxx parameter to increase the default to a value larger than 160.
Unfortunately, I've never seen *any* program do this.

You can fix this by patching COMMAND.COM to increase the default value
above 160 bytes.  I don't run 4.anything so I can't help DOS4 users, but
you can change the PC-DOS 3.3 version by the following:

debug command.com
d eb4 eb9                 <--- See what you are about to change
e eb8 20                  <--- this byte has the number of 16-byte paragraphs
                               to be allocated.  Default value is hex 0A for
                               10 (decimal) 16-byte blocks, or 160 bytes.  
                               Using hex 20 allocates 512 bytes.
d eb4 eb9                 <--- see it again
w                         <--- write it out
q                         <--- vamos.

Joe Morris