Elements of Bus Design

Bus Types
Bus lines can be separated into two generic types: dedicated and multiplexed.

A dedicated bus line is permanently assigned either to one function or to physical subset of computer components.

The use of the same lines for multiple purposes is known as Multiplexing.

Bus Width
The width of the data bus has an impact on the system performance

The wider the data bus, the greater the number of bits can be transferred at one time.

The width of the address bus has an impact on the system capacity.

The wider the address bus, the greater the range of locations that can be referenced.

Method of Arbitration
Arbitration is the process for resolution of disputes: the process of resolving disputes between people or groups by referring them to a third party, either agreed on by them provided by law, who makes a judgment.

In a centralized scheme, a single hardware device, referred to as a bus controller or arbiter, is responsible for allocating time on the bus. In distributed scheme, there is no central controller. Rather each module contains access control logic and the modules act together to share the bus.

Timing
Refers to the way in which events are coordinated on the bus.

With synchronous timing, the occurrence of events on the bus is determined by clock.

With asynchronous timing, the occurrence of one event on a bus follows and depends on the occurrence of a previous event.

Data Transfer Type
Read
Write
Read-modify-write
Read-after-write
Block