In computer systems a method is required to allow for interaction between the various sections of a the overall system. This mechanism is known as buses. They allow for data communication between, the memory, processing unit, I/O devices and any other circuits or devices.
There are number of forms of buses, in a computer system, the following is a general overview. It should also be remembered that the demand for speed will dictate how standards change with time.
The bus system allows for computer systems to be modular, expandable and multipurpose. The user is allowed to expand a system without having to redesign.
Computer Communication Buses
Address Bus
The address bus is connected in parallel, so all the information is sent a one time.
By sending information at one time the task of access of a device or process is much faster. This allows selectivity, i.e. to give a choice of what to communicate with. A process known as address decoding is used for this process.
The following are a few definitions associated with computer data communications.
Addressing
In order to access the many locations in a computer memory has shown in fig 1, there must be a way of identifying all the locations to which to read/write to. This identification is known as an address, and can be imagined just like the address of a house
Data Bus
The data bus is bi-directional, The data bus is configured to allow communication with one device only.
Control Bus
The control bus provides the link from the control unit to all parts of the computer system.
Bus Classifications.
Component
Back plane
System
Parallel and Serial l interface
8.2.1 Component
These are buses that link all the components mounted on a board. The board is usually a printed circuit board (PCB). The bus structure is built around the architecture of the microprocessor.
Backplane
The backplane bus, gives the computer a means of communicating with other boards/devices associated with the computer system. These PCBs plug into the backplane via a connector known as a edge connector. These boards are often referred to as daughter boards.
System Bus
The are a number of standards that exist :
S100
IBM bus
Multi bus
