Kreisen 3 8 6 X / X E - Manual (Page 125)

The MD command is a short form of MKDIR. This internal
DOS command creates a subdirectory under the directory you
are currently in. Since your computer boots up in the hard disk
root directory, the command you just entered created a
subdirectory named DOS4 under the root directory.
Note
If you don’t understand the term “root directory” refer to
your MS-DOS User’s Guide, “Files and Directories.”
When the computer displays the C> prompt again, enter:
C>DIR
to see what you have done. You should see a directory listing
similar to the following:
COMMAND COM XXXXX X-XX-XX X:XXX
FORMAT
EXE XXXXX X-XX-XX X:XXX
DOS4 x - x x - x x x : x x x
X File(s) XXXXXXXX bytes free
c >
Just as MS-DOS commands usually look at the “current” disk
drive, they also look at the current directory. Since you can
change the current, “logged” disk drive, you would
expect to
be able to change the current, logged directory. You can, using
the CD (CHDIR) command. Enter the command series:
6-12 Using Your Hard Disk