HP Vectra XU 6/XXX Optimization Manual page 42

Optimized Timings
Data is transferred with
faster IDE devices at the
maximum rate supported
1 Your PC's Performance Features
Making the Most of Your PC's IDE Channels
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.
36 English
Different transfer rates are used for
IDE devices of different capabilities
connected on the same IDE channel
Lower data
transfer rates
are used for
slower IDE
devices such as
CD-ROM drives