[Ham-Computers] RE: DOS Question

[Hsu, Aaron (NBC Universal)]

Duane,

In a true "DOS" environment (meaning booting from a DOS boot disk, be it
MS-DOS or a bootable Win9x disk), filenames are converted uppercase only
before being written to the directory.  In fact, if a filename is
somehow modified with a lower-case letter or other "special" character
(such as via a disk editor), then you wouldn't be able to access the
file via normal DOS methods.

Enter Windows 95 (and 98 and ME) with Long File Name (L-F-N) support.
With LFN, at least two entries are made in the directory - an 8.3
upper-case name for DOS compatibility and a second entry that holds the
filename as entered in Windows.  If you boot with a DOS disk, you would
see the uppercase 8.3 name which consists of the first 6 characters of
the LFN (in uppercase) plus ~x (tilde x) where x is a number (usually 1
- sequentially higher if the first 8 characters of a filename are the
same as another file).  There is an exception to the tilde - details to
follow.

Note: If you create a file in a DOS prompt while in Windows, then the
file is created with LFN support and is treated as if Windows created
the file with a LFN.


Viewing the filename in Windows is where it gets tricky.  There are
three basic scenarios:

1. If the file was created in DOS (booted into DOS), then Windows shows
you the 8.3 filename with the first character in uppercase and the rest
of the filename in lowercase.

2. If the file was created in Windows, then Windows would show you the
filename as you typed it when it was created except in one certain case
- see #3.

3. If the file was created in Windows in all uppercase with 8 characters
or less and a 3 character extension (or less) - aka an 8.3 name - then
Windows created a true 8.3 DOS filename without a ~x and rule #1
applies.

Windows 2000 and XP still follow rule 1 and 2, but no longer create a
true 8.3 filename.  I believe it's possible to enable scenario #3 via a
policy or registry change, but not many people do this.

Depending on where the file file was originally created (DOS or Windows)
and in what OS you're in when viewing the filename, you can get
different results.  Suffice it to say, in Windows 2000 and XP, filenames
created in DOS are shown with an uppercase first letter and the rest in
lowercase.  All other filenames are shown as when they were created.

So, if you booted from a DOS disk, the filenames you see should *ALWAYS*
be in uppercase.  It's only in a Windows environment (including a
full-screen DOS prompt in Windows) where you would be able to see
lowercase filenames.

73 and Merry Christmas,

  - Aaron, NN6O


p.s.   Yes, I know that other op systems also support lowercase, but
Duane doesn't have anything than DOS and Windows (and TI OS/99).


-----Original Message-----
Sent: Sunday, December 24, 2006 3:45 PM
Subject: [Ham-Computers] DOS Question




Hi All,

The blind dude is having a problem in determing upper and lower case
when 
viewing a C:\ DOS screen.

I saved a file as "weekly.txt" When I examine the file name in the 
directory, it appears to be all in upper case. Yet it was in lower case
when 
I saved it. What gives?

Unfortunately there is now way I know of to determine upper from lower
case 
letters on a DOS screen listing. In a program, yes, typing, yes, but not

when doing a dir/b etc.

So gentlemen, if I am using a DOS word processing program, running in
DOS 
from boot up, not in a DOS window, and save a file using all ower case 
letters, does it come out on the HD as all upper case or all lower case?

Thanks!

Duane Fischer, W8DBF
dfischer at usol.com
HHI: Halligan's Hallicrafters International http://www.w9wze.net
HHRP: Historic Halligan Radio Project
http://hhrp.w9wze.net