Mumbai University > Electronics Engineering > Sem6 > Computer Organization

Marks: 5M

Year: June 2015, Dec 2015

1) In most programmed processor, an instruction fetch from memory is intercepted by a micro program stored in a single control memory.

2) In some microprogrammed processors the micro instructions are not directly used by the decoder to generate control signals.

3) They are second control memory called a nano control memory. There are two levels of control memories, a higher level control memory known as micro control memory and lower control memory known as nano-control memory.

4) The control memory stores micro instructions whereas nano control memory stores nano instructiobs. Fig. below shows that the decoder uses nano instruction from control memory to generate control signals.

Advantages of nano-programming:

1) Reduces total size of required control memory.

2) Greater flexibility.

Disadvantages:

1) Loss of speed due to extra memory access required.