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[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk BIOS and Capacity Factors | Overcoming BIOS Disk Size Barriers ]

BIOS Upgrades

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

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