System Bus Design

• Bus is a communication channel.
• Characteristic of bus is shared transmission media.
• Limitation of a bus is only one transmission at a time.
• A bus which is used to provide the communication between the major components of a computer is called as System bus.

Computer:

System bus contains 3 categories of lines used to provide the communication between the CPU, memory and IO named as:

1. Address lines (AL)
2. Data lines (DL)
3. Control lines (CL) 

1. Address Lines:

• Used to carry the address to memory ad IO.
• Unidirectional.
• Based on width of a address bus we can determine the capacity of a main memory

Example:

2. Data Lines:

• Used to carry the binary data between the CPU, memory and IO.
• Bidirectional.
• Based on the width of a data bus we can determine the word length of a CPU.
• Based on the word length we can determine the performance of a CPU.

Example:

3. Control Lines:

• Used to carry the control signals and timing signals
• Control signals indicates type of operation.
• Timing Signals used to synchronize the memory and IO operations with a CPU clock.

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