Dec 092017
Directions for patching all versions of DOS to allow 512 byte environments.

Full Description of File

Text file explaining how to patch COMMAND.COM
(DOS 6.2 and below) to generate 512 bytes of
ENVIRONMENT space. Another jewel from The

File 62ENVPAT.ZIP from The Programmer’s Corner in
Category Utilities for DOS and Windows Machines
Directions for patching all versions of DOS to allow 512 byte environments.
File Name File Size Zip Size Zip Type
DESC.SDI 146 130 deflated
FILE_ID.DIZ 146 130 deflated
HERMENV.TXT 2346 1157 deflated

Download File 62ENVPAT.ZIP Here

Contents of the HERMENV.TXT file

The Hermit's Hole
(703) (703)
328-0028 328-HRMT
[Public] [HST]


MODIFY COMMAND.COM for more environment!
(Updated for DOS 6.2)

If, like most of us fellow tinkerers, you like to have a HUGE DOS prompt
and a jillion PATHS and SET commands, you have probably already run upon
the dreaded "OUT OF ENVIRONMENT SPACE" message!

Now you can solve that problem PERMANENTLY without any tricks, or the useless
SHELL command supplied with DOS.

Simply follow the instructions below and you can patch COMMAND.COM to generate
512 bytes of precious ENVIRONMENT space rather than the puny little 256 bytes
it spits out in the "stock" version.

It's easy. For DOS 6.2, all you have to do is change the 10H byte at 1777H

to 20H (from sixteen 16-byte paragraphs to thirty-two).

Here's how:

1. First copy COMMAND.COM to COMMAND.WRK, or something like that, and edit
the WORK version only (just in case you screw up).

2. My version of COMMAND.COM had the READ ONLY attribute set, so you must
clear the attribute before you can edit. Type 'ATTRIB -R COMMAND.WRK'.


4. You'll get the DEBUG prompt which is simply a '-'.

5. Type 'E 1777 20'

6. Type 'W' to write the changes.

7. Type 'Q' to exit DEBUG.

8. SAVE your original copy of COMMAND.COM by renaming it something else.

9. Test your handy work by typing 'COMMAND' (the processor will be loaded
again, THIS time with the big environment).

10. Type 'EXIT' to return to the original.

11. If both 'COMMAND' and 'EXIT' work OK, then you've done it right!

12. Reboot your machine and enjoy the new space, cadets.

13. Send money to The Hermit (me).

The debug addresses for some other versions of DOS are:

MS-DOS 2.xx: 0ECF
MS-DOS 2.11: 0DF3
MS-DOS 3.00: 0F2C
MS-DOS 3.10: 0D
MS-DOS 3.2x: 0D4F
MS-DOS 3.30: 0EB8
COMPAQ 3.31: 0EB8
MS-DOS 5.00: 1666
MS-DOS 6.00: 1767
MS-DOS 6.20: 1777

 December 9, 2017  Add comments

 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>