The system BIOS is the set of core routines that provides the primary interface between
the main hardware of the system and the software that runs upon it. It plays a critical
role in the functioning of any PC.
The BIOS affects hard disk performance in two distinct ways. The first is that the BIOS
itself was traditionally used for access to hard disks, and thus the BIOS's routines had
an impact on overall performance. Most of today's operating systems now "bypass"
the BIOS to access the hard disks directly, reducing this influence greatly. See this section for a discussion of how the BIOS relates
to the hard disk in a general way.
The second is related to the way most systems are designed. In a typical
"regular" PC, the motherboard contains an integrated IDE/ATA system controller.
Since it is part of the motherboard, it is configured and controlled using code in the
system BIOS. This means that the BIOS must provide support for increased capacity when
larger drives come out--to avoid BIOS capacity barrier
problems--and also support for performance-enhancing features like higher-speed transfer modes, block mode, etc. If your system is a few years
old, its BIOS may need to be updated or you could find the performance of newer hard
drives restricted.
Next: Operating System and Controller Disk Caching
