The most commonly used and important method of getting around the key 504 MiB barrier is through the use of an enhanced BIOS
that supports BIOS translation. This translation allows the BIOS
to break the 504 MiB barrier by translating between disk parameters that the disk
understands, and a different set that the BIOS understands. The main problem with BIOS
translation is that very old BIOSes don't support it. In some cases, a BIOS upgrade can
enable an older system to employ BIOS translation, and a system that supports flash BIOS upgrades can be updated to this support without even opening up the system case. The manufacturer of the system or motherboard is the place to start when considering a BIOS upgrade.
Similarly, since many of the later size barriers are due to limitations in BIOS code,
they can similarly be overcome by upgrading the BIOS with new code that can handle larger
drives. A new BIOS today will enable Int13h
extensions to get around the 8 GB size barrier, for
example. It will also address other BIOS code problems such as the one that causes the
so-called 32 GB size barrier.
A BIOS upgrade from the system or motherboard manufacturer is generally the best
solution to a hard disk size barrier problem, for two reasons. First, it is generally
free, if the upgrade has been provided by the original hardware maker. Second, it is the
simplest and most direct solution to the problem: you are replacing broken code with fixed
code, and once that is done your hard drives will work properly without any other work
being required. These two attributes make this solution far superior to the others I
discuss in this section, and I strongly advise that you look for a BIOS upgrade before you
consider the others.
Unfortunately, some BIOSes cannot be easily upgraded. This is usually because the
manufacturer has obsoleted the motherboard and has decided to no longer support it. (This
is understandable for very old machines, but occasionally manufacturers give up on
hardware as little as two years old, which I consider unacceptable--avoid such hardware.)
In some cases where this has happened, you may be able to purchase a third-party
BIOS upgrade. This is BIOS code that has been written by a company other than the one that
initially made your system or motherboard. This is a viable option, and retains the
advantage of being an elegant solution, but not the one about the upgrade being free! In
some cases these upgrades are $75 or more, and frankly, if all you want is updated hard
disk size support it's often not worth the money compared to other solutions. If you want
other features that can come with a BIOS upgrade then it may be worthwhile.
Next: Enhanced BIOS Expansion Cards
