HP Vectra XU 6/XXX Optimization Manual page 25

Your PC's integrated IDE controller can be configured as either a PCI master or a PCI slave.
As a PCI master, the IDE controller will give a significantly improved performance for data
transfers on the PCI bus. Typical PCI transfer rates are greater than 15 MB per second (with a
maximum of 16.7 MB/s) when operating as a PCI master, compared with up to 5 MB per
second as a PCI slave.
When configured as a PCI master, your PC's IDE controller helps to improve the overall
performance of your PC in two ways:
• PCI masters can begin and interrupt their PCI data transfers according to the demands of
other PCI data traffic. As a PCI master, your PC's IDE controller works with other PCI
devices to give maximum PCI bandwidth.
• As a PCI master, the IDE controller can transfer data to and from memory without
intervention from your PC's processor. This means that the processor is free to continue
with other work.
You can configure your PC's IDE controller as a PCI master through the IDE driver used by
your operating system. For more information on your operating system's IDE driver, refer to the
manual supplied with your operating system.
Optimized Timings
Different IDE devices have different data transfer capabilities. The latest IDE hard disk drives
support PIO Mode 4 and DMA Mode 2 timings, but older hard disk drives and CD-ROM drives
will typically support only the lower modes.
To give maximum performance with any combination of IDE devices, your PC's IDE controller
supports split-mode timing on both IDE channels. This means that it is able to transfer data at
different rates with different devices on the same IDE channel. Split mode timing enables you
to gain all the performance advantage from the latest generation IDE devices, without
compromising your ability to connect slower devices.