4/09/06 Fred Langa

What's On Those Old CDs?

Fred: I've looked on both Google and in the Plus archives and
couldn't find a program to help me detail information on about
100 CD ROMs. What I need is something that will look at the
contents of any CD I put in my drive (they are usually a group of
files backed up just by copying them to the CD - sort of like we
used to use floppy disks for) and add the content info to a
database with file name, path, any other info, and allow a place
for me to enter a description, and then assign a number or unique
name to the CD which I can write on it in order to keep track of
what files are on what CDs. Can you refer me to any program like
that?---Becki

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The keywords you need are "catalog" and "index." Searching with those terms
will turn up many, many tools that will catalog the contents of disks
(hard, floppy, CDs...) and store the information in a variety of formats.
And, just as you asked for, some will leave the master catalog on your main
system so you can look things up without having to load each CD: You can
look up a file and the catalog will tell you it's on CD #31 (or whatever).

Here's a collection of free cataloging tools:
http://www.nonags.com/nonags/diskcat.html

And there are lots more here:
http://tinyurl.com/s7bwu

Drive Size Limits

Dear Fred: Your recent articles about adding and upgrading hard
drives inspired me to do just that. Along the way, I came across
a question you hadn't addressed. A technical support person at my
PC's manufacturer (Gateway) told me that each of my PC's could
only recognize a specific maximum size of hard drive (most were
120GB, but an older machine would support only a 40GB drive).

They told me that this maximum size applied to each of the
internal drives (primary and secondary, master and slave). The
tech support person could not explain the reason for this
maximum, but I guessed it to be a characteristic of the disk
interface, on the motherboard. However, they then told me that
the limit also applied to external USB drives, and that really
has me stumped. Fred, please help me answer these questions: (a)
why do these limits exist, (b) do they also apply to external
drives (or to NAS drives accessed across a network), and (c) how
does one discover these limits (other than - as the tech support
person suggested - by installing a too-large, non-returnable
drive)? Thanks, Alun Whittaker

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Hard drive have two main size limitations: There's a hardware and a
software component.

First, the BIOS has to know what to do with the hard drive. When the first
PC hard drive came out, there was exactly one model: It had 312 cylinders,
4 heads and 17 sectors per track and was pre-configured to 10.9 MB (that's
MB, not GB) in capacity. That was the only choice, so those specs were hard-
wired into the BIOS.

Later, when a few other drives came out, each was then assigned a unique
identifier ("type 22," or some such). You'd enter the drive's identifier
into the BIOS, and the BIOS would then know how to talk to that specific
hard drive. After a few years, things got a little more automatic, but
still often relied on certain built-in assumptions about the maximum number
of heads, platters, and such a drive might have.

The drives available today were unthinkable in those days; and there's
literally no way to manually enter the parameters of, say, an 80 GB drive
into a system designed to handle maybe a 20 MB drive at most. Similarly,
today's drives can communicate to a modern BIOS much more directly, and
don't use simple, preset "type" identifiers. But an old system that needs
to be told, explicitly, what drive type to use simply won't know what to do
with a new drive.

Relatedly, there can be fundamental mathematic limitations on how much data
an old system can access: If a new hard drive has more data addresses than
the hardware can generate, it's not gonna work: Those higher addresses are
simply invisible to the hardware. This became a huge issue starting about
10 years ago (and is still an issue for some older hardware today): It's
known as "The 1024 Cylinder Barrier" or (same problem, different name) "The
528 MB Barrier." It's a mathematical limit in older systems imposed by the
number of software bits available for defining a drive's geometry--- the
number of heads, cylinders and sectors. In simple terms, a drive can be
simply too big for the BIOS to handle on its own.

That segues into software, which can have exactly the same kind of
mathematic limitations. The old DOS FAT12 system, with a 12-bit addressing
scheme, could only handle drives to 16.7MB in size; DOS3 brought this to
33.6MB; DOS4 to 134MB; Fat16 has a 2.15GB maximum; FAT32 a 32GB max; and so
on.

You also can run into problems with non-OS software: The Win98 Format tool,
for instance, maxes out at 64GB due to its own, separate internal limits.
OK, that's all fairly arcane, and I've compressed and simplified thing a
lot in the name of brevity. If you want the full, gory detail, see
http://www.dewassoc.com/kbase/hard_drives/hard_drive_size_barriers.htm and
http://www.google.com/search?q=maximum+hard+drive+size+windows .

What does it all mean for Alun, and readers like him? If the PC is very old-
-- and Alun, it sounds like yours may be--- it may need a BIOS update or
replacement to overcome fundamental limitations there (see
http://www.google.com/search?q=replace+bios ). Many drive makers also offer
"drive translation" or "dynamic drive overlay" software that can fool an
older BIOS so that it doesn't know it's talking to a drive larger than it
can handle on its own. Although this kind of software adds a level of
complexity to things, it's often the fastest way to get a new drive running
on an old PC. (See http://tinyurl.com/plsyy )

Other software limitations are more easily gotten around by replacing the
software with newer versions--- a new version of Windows, or Linux, or
whatever.

USB drives connect through the system BIOS and the OS, so they'll inherit
the same basic limitations as other drives on the system. But a shared
drive, including NAS drives ( http://langa.com/newsletters/2006/2006-04-
03.htm#1 ) is controlled by the hardware and software that's offering the
share, and not by those connecting to the share. So, a file server or
network attached storage or a large shared drive on another PC are all ways
to deliver large storage to limited, older PCs.

Here's another out: You can divvy up a larger drive into a number of
logical drives or partitions below whatever the system limit is, and the
system will be happy. For example, if your system will only "see" 40GB at a
time, you usually still can use a 120GB drive, as long as you format it as
three separate 40GB logical drives.

It's another reason why partitioning can be a good thing; and another
reason to grab a tool like "Partition Logic," which can operate outside
whatever limitations a given OS may have.

You know, this kind of problem seemed to go away for a while when XP came
out because XP will handle drives up to 2.2 terabytes in size. That seemed
pretty big at the time. But a terabyte isn't what it used to be. ( See
http://tinyurl.com/s5fuu ) So, some modest number of years from now, we'll
be bumping up against the 2.2TB limits, and will need 64-bit hardware and
software to raise the ceiling to the next level... on and on and on! <g>