The PCI bus is a local computer bus standard used to connect hardware devices inside a computer. It was developed in the early 1990s to standardize how expansion cards connected to the motherboard. Key features of PCI include plug and play capability, configuration ROMs that store device information, and interrupt request lines. During initialization, the configuration software reads the ROM on each device to determine its type and assign resources like addresses and interrupts.

1. BY TEAM 1:
PERIPHERAL COMPONENT
INTERCONNECT (PCI) BUS

2. INTRODUCTION:
❖ Peripheral Component Interconnect (PCI) is
a local compute bus for
attaching hardware devices in a computer and
is part of the PCI Local Bus standard.
❖ The PCI bus is a good example of a system
bus that grew out of the need for
standarization.
❖ An important feature that the PCI pioneered
is a plug and play capability for connection I/O
devices.

3. ❖ PCI slots are utilized to install sound cards,
Ethernet and remote cards and presently strong
state drives utilizing NVMe innovation to supply
SSD drive speeds that are numerous times
speedier than SATA SSD speeds. PCI openings too
permit discrete design cards to be included to a
computer as well.
❖ PCI openings (and their variations) permit you to
include expansion cards to a motherboard. The
extension cards increment the machines
capabilities past what the motherboard may create
alone, such as: upgraded illustrations, extended
sound, expanded USB and difficult drive controller,
and extra arrange interface options, to title a
couple of.

4. HISTORY OF PCI BUS:
❖ Work on PCI began at the Intel Architecture Labs (IAL, also
Architecture Development Lab) c. 1990. A team of primarily IAL
engineers defined the architecture and developed a proof of concept
chipset and platform (Saturn) partnering with teams in the company's
desktop PC systems and core logic product organizations.
❖ PCI was immediately put to use in servers, replacing Micro Channel
architecture (MCA) and Extended Industry Standard
Architecture (EISA) as the server expansion bus of choice. In
mainstream PCs, PCI was slower to replace VLB, and did not gain
significant market penetration until late 1994 in second-
generation Pentium PCs. By 1996, VLB was all but extinct, and
manufacturers had adopted PCI even for Intel 80486 (486)
computers.

8. Device Configuration
When an I/O device is connected to a computer, several
actions are needed to configure both the device and the
software that communicates with it. The software needs
to know the address of the device and also the device
characteristics , such as the speed of the transmission
link etc;
The PCI simplifies this process by incorporating a small
Configuration ROM memory that stores information
about that device in each I/O device interface.

9. Device Configuration in PCI Bus
❖ The PCI has a configuration ROM that stores
information about the device.
❖ The configuration ROMs of all devices are
accessible in the Configuration Address-Space.
❖ The PCI initialization software reads these ROMs
whenever the system is powered up or reset.
❖ In each case, it determines whether the device is a
printer, a keyboard or an Ethernet interface.
❖ Devices are assigned addresses during the
Initialization process.
❖ Hence Devices cannot be accessed based on their
address during the configuration process.

10. ❖ Each device has an input signal called Initialization
Device Select , IDSEL# .
❖ IDSEL# pin of each device is connected to one of
the upper 21 address lines(AD11 to AD31)
❖ During configuration operation ,
➢ A configuration command and an address is
issued.
➢ The corresponding AD line is set to 1 and the
remaining 20 lines are set to 0.
❖ The lower address lines , (AD10 to AD00) are used
to specify the type of operation and to access the
contents of Configuration ROM.

11. ❖ The configuration software scans all 21 locations.
❖ Each device may request an address in the I/O
space or Memory space.
❖ The PCI Bus has four interrupt request lines.
❖ The software instructs the device as to which of
these lines it can use to request an interrupt.
This process relieves the user from having
to be involved in the configuration process.The
user simply plugs in the interface board and turns
on the power.

12. Electrical Characteristics
❖ The PCI bus is defined for operation with either a
5V or 3.3V power supply.
❖ Motherboard is designed to operate with
signaling system.
❖ Connectors in the expansion board are designed
to ensure that they can be plugged only in a
compatible motherboard.