Bus structure in Computer Organization

A Bus is a collection of wires that connects several devices. 

Buses are used to send control signals and data between the processor and other components

This is to achieve a  reasonable speed of operation. 

In computer system all the peripherals are connected to microprocessor through Bus.

Types of Bus structure:

  1. Address bus  
  2. Data bus 
  3. Control bus 

1. Address Bus:

  1. Address bus carry the memory address while reading from writing into memory.  
  2. Address bus caary I/O post address or device address from I/O port.  
  3. In uni-directional address bu only the CPU could  send address and other units could not address the microprocessor. 
  4. Now a days computers are haing bi-directional address bus. 

2. Data Bus:

  1. Data bus carry the data.
  2. Data bus is a bidirectional bus.
  3. Data bus fetch the instructions from memory.  
  4. Data bus used to store the result of an instruction into memory. 
  5. Data bus carry commands to an I/O device controller or port.  
  6. Data bus carry data from a device controller or port.
  7. Data bus issue data to a device controller or port.

3. Control Bus:

Different types of control signals are used in a bus:

  1. Memory Read: This signal, is issued by the CPU or DMA controller when performing  a read operation with the memory. 
  2. MemoryWrite: This signal isissued by the CPU or DMAcontroller when performing  a write operation with the memory. 
  3. I/O Read: This signal isissued by the CPU when it is reading from an input port.
  4. I/O Write: This signal is issued by the CPU when writing into an output port.
  5. Ready: The ready is an input signal to the CPU generated in order to synchronize the  show memory or I/O ports with the fast CPU.

system bus is a single computer bus that connects the major components of a computer system, combining the functions of a data bus to carry information, an address bus to determine where it should be sent, and a control bus to determine its operation.


Q1. Is USB a bus?

Ans. A USB is a fast serial bus, which connect an electronic device to a computer. It is mostly used on personal computers. USB is used with mobile phones, video games, etc.