Pakistan study notes for Matric, Intermediate, B.A, B.COM BSC, M.A, BCS. Free Pakistani Urdu educational school, colleges and University notes.

Purposes of address bus, control bus and data bus

Q.4. Define the term bus in general. What are the purposes of address bus, control bus and data bus?


A bus is set of wires or connections that connect the different components together and through which signals travel.


A bus is a set of wires that is used as a communication path. The bus width determines the speed of data transmission.


There are three typos of buses

l. Address bus

2. Control bus

3. Data bus

There are local buses that connect elements within the CPU and buses, which connect the computer to external memory and peripherals.


Address bus is a collection of wires connecting the CPU with main memory. It is used to identify particular locations (address) in main memory where data is stored.


Address bus is connections between the CPU and memory which transmit the address from which the CPU will read or to which the CPU will write.

The number of hits in the address bus can determine the amount of memory the CPU can address.


Modern PCs have as many as 36 address hues or buses which enable them theoretically to access 64 GB of main memory. However, the actual amount of memory that can be accessed is usually much less than this theoretical limit due to the chipset and motherboard limitation.


Control bus is a physical connection between the CPU and other devices within the computer.


• It carries control information between the CPU and other devices within the computer.

• The control bus carries signals that report the status of various devices.


One line of the bus is used to indicate whether the CPU is currently reading or writing to main memory.


It is a communication route through which data can travel between the computers central processing unit, memory and peripherals.


The number of wires in data bus determine the speed at which data can travel between the hardware components, just as the number of lanes on a high way determine the number of vehicles reach their destinations at the same time.


Each wire transmits a single hit at time. So 8 hits bus can transfer 8-hits at a time. Similarly, 16 bits bus can transmit 16- hits simultaneously and so on.

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