The main difference between address bus and data bus is that the address bus helps to transfer memory addresses while the data bus helps to send and receive data. That is, the address bus is used to specify a physical address in the memory while the data bus is used to transmit data among components in both directions. Therefore, the address bus is unidirectional while the data bus is bidirectional.
There are three major components in a computer system. They are the Central Processing Unit (CPU), Memory and Input, Output devices. The CPU is the major unit that process data. Memory holds data required for processing. The input and output devices allow the users to communicate with the computer. The mechanism for each of the components to communicate with each other is the bus architecture. It is an electronic communication system, which carries information through electronic pathways called circuit lines. The system bus is divided into three types called address bus, data bus and control bus.
Key Areas Covered
Address Bus, Data Bus, Computer Architecture, Operating System
What is Address Bus
The address bus helps to identify the particular location in the memory. Assume that the CPU needs to read data from memory. Then, the address bus helps to identify that specific location. Furthermore, each IO device has a unique ID, and it is the address of that component. The address bus helps to transfer memory addresses of data and IO.
The width of the address bus determines the amount of memory the system can address. When there are ‘n’ address lines, it can directly address 2n memory locations. For example, an 8085 microprocessor has address bus of 16 bits. Therefore, it can access 2 16 = 65536 different memory locations.
What is Data Bus
Data bus helps to transfer data between various components. It includes the related hardware components such as wires and optical fiber. The data bus consists of 8, 32,64, etc. separate lines. The number of lines refers to the width of the data bus. This bus width helps to determine the data transferring rate. Therefore, the data bus width determines the system performance, but it is expensive to increase the number of lines.
The other bus besides the address bus and data bus is the control bus. It is bidirectional and transmits control signals from one component to another.
Difference Between Address Bus and Data Bus
The address bus is a computer bus that is used to specify a physical address in the memory. The data bus is a computer bus that is used to transmit data among components.
The address bus is unidirectional while the data bus is bidirectional.
Address bus helps to transfer memory addresses of data and IO. Data bus helps to send and receive data. This is the main difference between address bus and data bus.
Width of the Bus
The width of the address bus determines the amount of memory a system can address. The width of the data bus determines the data transferring rate.
A bus is a communication pathway connecting two or more devices. The system bus is divided into address bus, data bus and control bus. The difference between address bus and data bus is that the address bus helps to transfer memory addresses while the data bus helps to send and receive data. The control bus helps to send control signals among the devices.
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1. “Computer system bus” By W Nowicki – Own work, based on a diagram on page 36 of The Essentials of Computer Organization and Architecture By Linda Null, Julia Lobur (CC BY-SA 3.0) via Commons Wikimedia