I always suggest that those who are trying to overcome a hard disk size barrier, first
attempt to correct the problem through a free BIOS
upgrade, if possible. If that's not an option for whatever reason, however, you will
have a key decision to make in choosing between the other alternatives I am presenting: do
you want to spend money on a hardware solution, or go with a "free" software
solution?
For those who can afford to do so, I strongly recommend a hardware solution, such as an
expansion BIOS card, an add-in controller card, or a third-party (not free) BIOS upgrade.
The reason is simple: these solutions get around the hard disk barrier at a very low level
within the system, and in doing so ensure that you will have few problems using your new
hard disk on your old system. There are not likely to be any software issues with such a
solution.
If you cannot spend funds on a hardware solution (or simply don't want to for whatever
reason) then your alternative to allow access to the full capacity of your hard disk is
the use of a software translation driver, also called a dynamic drive overlay
or DDO. These usually go by names like Disk Manager, EZ-Drive and the like. The
idea behind one of these programs is pretty simple: they override in software some of the
BIOS code in your motherboard or hard disk controller, allowing access to the full size of
a new hard disk on an older system. The software must be loaded immediately when the
machine is booted, to ensure that the driver is in place before any other piece of
software tries to access the disk. Otherwise, the disk will not work properly. To ensure
that they are always loaded immediately at boot time, the installer for this sort of
program modifies the boot disk's master boot record
and installs the driver at the beginning of the disk.
When you buy a new hard disk at retail, the drive manufacturer will often include a
copy of one of these driver programs, "free", with the drive. (You can often
download them for free from the drive maker's web site too.) These are normally a
specially modified version of something like Ontrack's
Disk Manager that is customized for that manufacturer's drives; these utilities
normally have proprietary names as part of the licensing agreement between the drive maker
and the company that writes the overlay. Drive manufacturers provide these as a
convenience for those whose machines don't have real hardware BIOS support for larger
disks, and using them is a viable option.
However, do not believe these manufacturers when they sometimes say that using
these software drivers is as good as proper BIOS support. It isn't. There are numerous
problems associated with using these drivers for large disk support, which is why I do not
recommend their use. Here are just a few:
- Compatibility Problems: When you use one of these drivers they essentially set up
their own logical disk volumes using a non-standard format. This means you are not using
your disks the standard way. This isn't usually a problem in and of itself, since most
operating systems know about these drivers, but the potential for incompatibility exists.
- Reduced Drive Interoperability: The drivers that come with the various
manufacturers' drives are normally customized for that manufacturer's equipment only. This
means that if you put a Quantum disk in your PC and later want to add a Seagate, for
example, you may have a bit of a problem. You will have to at this point probably purchase
the full version of something like Disk Manager, and for the extra cost you will be better
off buying an add-in hard disk controller.
- Problems Removing the Driver: Some of these overlays can be very difficult to
remove from the disk, and require you to use uninstall facilities that come with the
driver, if you want to get rid of them. When you do remove the driver, say because you
have upgraded to a PC that supports large drives, you may have to repartition and reformat
the disks (though this may not be required).
- Floppy Disk Booting Complications: Because the driver is located on the hard
disk, you must boot from the hard disk to load it. If you boot from a floppy, your
hard disk may seem to "disappear" because the overlay wasn't loaded. The driver
will allow you to boot from a floppy, but you must do it by booting the hard disk, waiting
for the overlay to load and a message to be displayed that says "To boot from a
floppy disk, press the space bar", and then put the floppy into the drive and press
the space bar.
- Operating System Installation Issues: The drive overlay located on the hard disk
can cause problems when using alternative operating systems, attempting to set up a
multiple-OS system, and so on. You must verify that every operating system that you
install is capable of handling the driver you are using.
Again, most of the time these drivers will work OK, especially if you are not doing
anything too unusual with your PC. With so many people upgrading older systems and running
into size barriers, they are becoming more prevalent than ever. I just think that they are
not the best way to deal with BIOS translation, given that much more reliable, and
relatively inexpensive, hardware solutions exist. It's all a matter of your priorities,
really.
Next: Disk Size Reduction Jumpers
