Hello!

The following is my understanding of the registry structure. I hope others
will quickly correct me if I falter in my explanations.

1. Regedit does indeed include all the data within the system.dat and the
(loaded) user.dat files. You will have a different regedit if you have
enabled multiple users on your computer (a different user.dat is included
depending on who logs on).

2. The difference in file sized is due to the fact that the exported file
(*.reg) is a text file; therefore, it is not in the same file format as the
*.dat files (which I assume store the data more efficiently). I do not
believe any other configuration files are included.

3. When you export the regedit from the My computer level, it creates the
*.reg file which is the complete and unsullied dat files from your computer.
Double clicking on the .reg file will restore the user.dat and system.dat
files. You are correct that a reboot must occur to actually have the
restored files in memory. You can copy the user.dat and system.dat files to
a different folder (or copy and rename them in the same /Windows folder to
system.old and user.old). Double clicking on copies of these files will not
restore them. You must rename them back to system.dat and user.dat and they
must be in the /Windows folder.

4. The two io.* files are used as beginning boot files. When you start the
computer, after the POST process, the file Msdos.sys is accessed (there is a
menu that you can get to appear by pressing (I believe) F8 just before the
windows splash screen comes up). This file "chooses" which operating system
to load: by default Windows 9x or real mode DOS (perhaps you have an old DOS
game you still enjoy playing or you need to be in DOS for diagnostic
purposes). If you choose the default route, io.sys is loaded which starts
loading the rest of the Windows operating system. If real mode DOS is
chosen, io.sys is renamed to io.win(?) and io.dos is renamed to io.sys. This
file loads the real mode DOS operating system: the c:/> prompt. Do not
delete either file.

I hope this helps!

Will Stephenson
Call Center Manager
Prexar
mailto:[log in to unmask]

-----Original Message-----
From: PCSOFT - Personal Computer software discussion list
[mailto:[log in to unmask]]On Behalf Of don penlington
Sent: Saturday, June 10, 2000 4:02 AM
To: [log in to unmask]
Subject: [PCSOFT] Some questions for the registry experts.


This is not a problem, I'm just seeking enlightenment.

1. When I open Regedit, am I looking at ALL the data contained in both
User.dat and System.dat?

2. If I export "My computer" using Regedit, is this identical to making
copies of User.dat and System.dat?  There must be some other stuff as well,
because if I do this, the Regedit export is larger than the sum of these 2
files, in my case by .5 Mb.  Which files are represented by this extra
data?  The config and ini files seem too small to account for this missing
mass.

Perhaps this is the "missing mass" that cosmologists have been searching
for, that holds the Universe together?  If so, Bill Gates may be closer to
God than we had supposed.

3.  Could I just make a copy of those files, rename them with a .reg
extension, and restore the complete registry by double-clicking?  If the
answer is yes, I assume that the restoration won't be effective until the
next reboot, as I believe that all this data is loaded into memory at
bootup. I guess that's why a substantial portion of memory is used just to
keep Windows running.

4. In Win 95B, I have 2 files in my root directory--io.dos and io.sys. Is
this normal? Both are identical size.  Although they are in binary form,
the contents appear at a glance to be identical.  Are they both necessary?
If not, which should I delete?

Don Penlington
Visit my Web pages: http://members.xoom.com/donpen.1/
A horrible mixture of fractals, poetry, and free icons.

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