System Bus: The System bus is a communication path between the microprocessor and peripherals. It is nothing but a group of wires to
carry bits.

Address Bus: The address bus consists of 16, 20, 24 or 32 parallel signal lines. On these lines the CPU sends out the address of the memory location that is to be written to or read from. The number of address lines determines the number of memory locations that the CPU can address. If the CPU has N address lines, then it can directly address 2^N memory locations. Simply, we can say that Address Bus is used to carry the address of memory location.

Example: if there are 16 lines then it can address 2^16 = 64 KB memory location.

Data Bus: The data bus consists of 8, 16, or 32 parallel signal lines. The data bus lines are bidirectional. This means that the CPU can read data in from memory or from a port on these lines, or it can send data out to memory or to a port on these lines. Simply we can say that data bus is used to carry the data.

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