UPGRADING REPAIRING PCs

Bus-Mastering Chipsets for IDE 109
Table 4.12 Ultra DMA/66 and UDMA/100 Requirements Continued
Item Features Notes
If motherboard can’t run drive at full
speed, you can add a UDMA/66 or
UDMA/100 PCI-based IDE interface
card from sources such as SIIG
(www.siig.com) or Promise
Technologies (www.promise.com).
Cable Cable must be 80-wire Connect blue end of UDMA/66 and
cable (40 data wires UDMA/100 data cable to motherseparated
by 40
ground wires).
board to ensure proper operation.
Any system that cannot run the drive at UDMA/66 or UDMA/100
can use the drive at the system’s maximum speed (UDMA/33, PIO
4, and so on).
See Figure 4.5 for a comparison of a standard IDE 40-wire cable
with an 80-wire cable required for UDMA/66 and UDMA/100 operation.
Figure 4.5 A standard 40-wire IDE cable (left) compared to an 80-wire
UDMA/66-100 IDE cable (right). Both cables use the same 40-pin connector.
The standard cable’s 40 wires give the cable a pronounced ridged appearance
when compared to the smaller and finer wires in the 80-wire cable.
Bus-Mastering Chipsets for IDE
Most late-model Pentium-class and higher motherboards can support
bus-mastering drivers for their IDE interfaces. The benefits of
bus-mastering include faster IDE data transfer for CD-ROM,
CD-R/CD-RW, and hard drives, and lower CPU utilization rates (the
percentage of total time the CPU spends handling a particular
task). Table 4.13 lists the major chipsets providing bus-mastering
features and where to get the driver. Be sure you install the correct
driver for your chipset.