Difference between Single Bus Structure and Double Bus Structure

1. Single Bus Structure: In a single bus structure, one common bus is used to communicate between peripherals and microprocessors. It has disadvantages due to the use of one common bus. 

2. Double Bus Structure: In a double bus structure, one bus is used to fetch instructions while other is used to fetch data, required for execution. It is to overcome the bottleneck of a single bus structure.

Differences between Single Bus and Double Bus Structure :

S. No.	Single Bus Structure	Double Bus Structure
1.	The same bus is shared by three units (Memory, Processor, and I/O units).	The two independent buses link various units together.
2.	One common bus is used for communication between peripherals and processors.	Two buses are used, one for communication from peripherals and the other for the processor.
3.	The same memory address space is utilized by I/O units.	Here, the I/O bus is used to connect I/O units and processor and other one, memory bus is used to connect memory and processor.
4.	Instructions and data both are transferred in same bus.	Instructions and data both are transferred in different buses.
5.	Its performance is low.	Its performance is high.
6.	The cost of a single bus structure is low.	The cost of a double bus structure is high.
7.	Number of cycles for execution is more.	Number of cycles for execution is less.
8.	Execution of the process is slow.	Execution of the process is fast.
9.	Number of registers associated are less.	Number of registers associated are more.
10.	At a time single operand can be read from the bus.	At a time two operands can be read.
11.	Advantages-  Less expensive Simplicity	Advantages- Better performance Improves Efficiency