Page 34 - UNI 101 Computer Science Handout.

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Figure 7 Basic CPU-Memory-I/O Pathway

A more realistic general bus interface configuration is shown in Figure below. The bus organization of a

PC, for example, often consists of the system bus, a video display bus, a PCI-Express and/or PCI bus, a

serial or parallel ATA bus for the disk drives, probably a Universal Serial Bus, and sometimes an ISA bus
or other buses. The system bus, which is the primary interface with the CPU, is sometimes referred to

as the front side bus (FSB). The bus interfaces are known by a variety of different names, including

expansion bus interfaces or bus bridges or bus controllers. Bus interfaces expand the flexibility of the
system bus architecture by converting the format of the bus signals from one bus to another so that

different types of buses can be used together.

These other bus types can then be used to connect to specific devices, such as disks or terminals. The

ability to interconnect buses makes it possible for the system designer to optimize each I/O function for
maximum speed and flexibility, as well as to maximize overall system performance. It also makes

possible the design and use of industry standard buses on equipment of different vendors. The use of

standard system buses generally simplifies the purchase, setup, and proper operation of peripherals

from multiple vendors by allowing the connection of I/O devices that have been standardized across a

wide range of equipment types and manufacturers. This is a major aspect of the concept of open
architectures.

34 Academic Year 2025/2026