What is Address Bus, Data Bus & Control Bus in Computer?

If you’re reading this tutorial by skipping the previous tutorial then I strongly recommended to you to learn first previous tutorial. In the Previous tutorial, we had discussed the basic concept of Buses. We can also say that previous tutorial is introduction tutorial about buses…

Let’s come on topic…Today I am going too described Address Bus, Data Bus, and Control Bus.

What is the Address Bus?

The address bus is used by the CPU to send the address of the memory location or the input/output port that is to be accessed at the instant. It is a unidirectional bus i.e. the address can be transferred in one direction only and that is form CPU to the required port or location.

Whether it is a read operation or write operation the CPU calculates the address of the required data and sends it on the data bus for the execution of the required operation. The maximum number of memory locations that can be accessed in a system is determined by the number of lines of an address bus.

An address bus of n lines can be addressed at the most 2n locations directly. Thus a 16-bit address bus can allow access 2 16 bit or 64 K Byte of memory.

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What is Data Bus?

A data bus is used to carry the data and instructions from the CPU to memory and peripheral devices and vice versa. Thus it is a bidirectional bus. It is one of most important parts of the connections to the CPU because every program instruction and every byte of data must travel across the bus at some point.

The size of the data bus is measured in bits. The data bus size has much influence on the computer architecture because the important parameters of it like word size, the quantum of data etc. are determined and manipulated by the size of the data bus.

Generally, a microprocessor is called n-bit processors. Thus as the CPU became more advanced, the data bus grew in size. A 64-bit data bus can transfer 8 bytes in every bus cycle and thus its speed is much faster as compared to the 8-bit processor that can transfer one byte in every bus cycle.

What is a Control Bus?

A control bus contains various individual lines carrying synchronizing signals that are used to control. Various peripheral devices connected to the CPU. The common signals that are transferred to the control bus from CPU to devices and vice versa are memory read, memory writes, I/O read, I/O write etc.

Signals are designed, keeping in mind, the design philosophy of the microprocessor and the requirement of the various devices connected to the CPU. So different types of the microprocessor have different control signals. See Below for better understanding.

Image Source Book

Hopefully, you guys did still find this information is useful for you. If you have any doubt or question about this tutorial then let me know through your comment. And don’t forget to share with other computer lovers.
Have a Good Day!!!
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