Computer system PCI

٠ When the I/O devices in the distributed embedded subsystems are networked all can
communicate through a common parallel bus.

* PCI connects at high speed to other subsystems having a range of I/O devices at very short
distances (<25 cm) using a parallel bus without having to implement specific interface for
each I/O device.

PCI bus Applications Connects

_ display monitor,

_ printer,

_ character devices.

PCI Bus Feature

_ 32- bit data bus extendible to 64 bits.

_ PCI protocol specifies the ways of interaction between the different components of a
computer.

_A specification version 2.1-synchronous/asynchronous throughput is up to 132/ 528 MB/s
[33M

x 4/ 66Mx 8 Byte/s], operates on 3.3۷ to 5Vsignals.

_ PCI driver can access the hardware automatically as well as by the programmer assigned
addresses.

_ Automatically detects the interfacing systems and assigns new addresses

_ Thus, simplified addition and deletion(attachment and detachment) of the system
peripherals.

FIFO in PCI device/card

_ Each device may use a FIFO controller with a FIFO buffer for maximum throughput.
Identification Numbers

_ A device identifies its address space by three identification numbers, (i) I/O port (11)
Memory locations and (iii) Configuration registers of total 256Bwith a four 4-byte unique
ID. Each PCI device has address space allocation of256 bytes to access it by the host
Computer

PCI device identification

_A sixteen16-bit register in a PCI device identifies this number to let that device auto- detect
it.

_ Another sixteen16-bit register identifies a device ID number. These two numbers let allow

the device to carry out its auto-detection by its host computer.