3Com 3C905-TX User Manual page 13

1-2 C 1: I
HAPTER NTRODUCTION
The master, or bus master, is a more intelligent device that
can conduct processing independently of the bus or other
devices. A bus master device shares the bus with the main
processor and targets. Bus mastering allows a peripheral
device to take control of the system bus and not rely on the
central processor. The 3C595 Fast EtherLink PCI adapter is a
bus master device.
The PCI specification supports the following:
High performance. The PCI bus runs at a clock speed of
33 MHz and employs a 32-bit data bus that supports
multiple peripheral components and add-on cards at a peak
bandwidth of 132 MBps, up to an order of magnitude greater
than that of other PC buses (ISA, EISA, or MCA).
Automatic configuration. A PCI adapter has configuration
specifications set in on-board memory and provides
installation information to the computer at start-up.
Shared slots. The PCI specification calls for "shared slots,"
which denotes the shared expansion backplate slot. This
shared backplate slot provides access to one of two types of
adapters: a PCI adapter and an ISA adapter, for example, or a
PCI adapter and an EISA adapter. Only one adapter at a time
can be installed in a shared slot. Manufacturers are currently
producing computers that support the PCI bus in
conjunction with conventional ISA and EISA buses in the
same chassis.
For detailed information about the PCI local bus, consult the
PCI specification.