CASE HISTORY # 6
          by the Disk Doctor


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Copyright (C) 1987,  the Disk Doctor.

First published in the Rochester (PC)^3 News:
   Picture City PC Programming Club
   PO BOX 20342
   Rochester, NY 14602
The Disk Doctor may be contacted at this
address, or via CIS [73147,414].

This material may be reproduced for internal
use by other not-for-profit groups, provided
this copyright notice is included.
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9:25am
"Doc, it's good to see you again.  Thanks
for coming over."
 
I had stopped by the Purchasing department
to help my friend, TW, with a problem.
 
"Remember how we used to have that shoebox
full of diskettes?" TW pointed to the
empty cardboard container in the waste
basket.  "Well, we finally took your
recommendation and bought ourselves a
hard-card.  It came in just yesterday.
Amazing little bugger.  Imagine, 10
MegaBytes in a single slot."
 
"Did you have a problem installing it?"
 
"No. Installation was a cinch.  I just
popped it in to an empty slot.  No, the
problem showed up after I began to copy
our files over to drive C:.  All of a
sudden it won't take anymore."
 
"You mean the disk is full?"
 
"I don't think so.  When I do a DIR, it
says 8.9 MB free.  The error message is
something about 'file creation error'."
 
"You'd better show me what you've got."
 
 
9:30am
I verified the problem for myself.  It was
just as he said.  Next, I did a TREE
command to list all his directories.  "Oh
boy.  You've got all these programs in the
root directory!"
 
"Huh?  What do you mean, rude erectomy?"
 
"No, R-O-O-T directory.  It's the root of
the directory hierarchy."
 
TW looked at me with a smirk.  "I don't
understand any of this stuff, but I'm glad
you got to the 'root' of the problem."
 
I shook my head.  I try to ignore bad puns
(unless they're my own).  "Here, take a
seat while I explain directories to you.
 
 
9:37am
"The hard disk can hold millions of files,
more files that anyone can easily keep
track of.  So, the operating system
provides the ability to group related
files into separate sub-directories."
 
"Why did they have to make this more
complicated than it already was?"
 
"For a couple reasons.  When you do a
DIRectory command, and there are 100
files, what do you do?"
 
"I use one of those DIR tricks you showed
me, either DIR/W to show the files wide
across the screen, or else DIR/P so it
pauses every 22 files."
 
"Right.  Think what it would be like to
find one file in a list 5,000 files long."
 
"Geez.  It would take all day."
 
"Exactly.  That's why DOS provides sub-
directories, to group files in logical
subsets.  When you use DOS commands like
DIR or COPY, they work on only one sub-
directory at a time.  DOS remembers the
current directory, just as it remembers
the default disk drive."
 
 
9:39am
I continued. "These directories are set up
in a hierarchical arrangement like a tree.
At the top of the tree is the root
directory."
 
"Boy somebody got that backwards."
 
"Maybe so, but we're stuck with that
terminology.  On a 10 MB hard disk, the
root directory is allocated a fixed 32
sectors.  That limits us to no more than
512 files in the root directory.  So what
we have to do now is to copy all your
files into different sub-directories."
 
"You mean each directory is limited to 512
files?"
 
"No, only the root directory has that
restriction.  The root directory has to
occupy a certain place on the disk, and
its size is fixed.  But sub-directories
are just like files.  They can be created
anywhere on the disk, and may be any
length."
 
"You said DOS only works in one directory
at a time, right?"
 
"Right."
 
"Does that mean I have to make copies of
those DOS programs I use all the time,
like CHKDSK, FORMAT, and so on?"
 
"No. That's where the DOS PATH facility
comes in.  Your PATH-link lets DOS find
executable programs or batch files in
another directory.  Most people set up one
master DOS directory.  Here let me show
you.  Use the MKDIR command to create
directories...
 
 
10:15am
"There," I said as he copied the last file
into the newly created directory
structure.  "Now you should be all set."
 
"Wait a minute, Doc.  You've been such a
big help this morning, I'm going to create
one more directory, in your honor."  He
typed in MD \HICKORY.
 
"I don't understand.  That's not my name.
What does the 'hickory' stand for?"
 
"Come now.  Surely you've heard of HICKORY
Directory, Doc!"