INTRODUCTION TO DATA BUS AND ADDRESS BUS

INTRODUCTION TO DATA BUS AND ADDRESS BUS

Data bus is the most  common bus .It is used to carry data .It is an electrial paht that connects CPU,memory ,input/output  devices and seconday storage devices.The bus contains parallel set of lines.The number of lines affects the speed of data transfer between different components .A data bus with more lines can carry more data.A data bus with 16 lines can carrry 16 bits (2 bytes) of data. A data bus with 32 lines can carry 32 bits (4 bytes) of data.A bus is designed in such way that it can communicate with components efficiently .The buses in old computers could carry only one byte of data.The buses used today can carry multiple bytes at one time.It improves the speed and perfomarnce of computer system

Address bus is used to carry address information.It is a set of wires similar to data bus.It only connects central processing unit and memory.

    The following steps take place when CPU needs data from the memory

          CPU places the address of required data on address bus

           The address bus is carried to the memory

            The data from the requested address is fetched and placed on data bus

            The data bus carries the data to CPU

The number of lines in the address bus detemines the maximum bumber of memory addresses.If an address bus has 8 lines ,the maximum number of memory locations that can be addressed are 256 .The computers used today have 32 bit address lines .These computers can access 4GB of memory.