how a processor works 5

Monday, March 23, 2009

Step 4: Push Key =

A
When you press the "=" key, the Prefetch Unit once again checks the Instruction Cache for an instruction for the new data, which it doesn't find.

B
The instruction for "=" comes into the microprocessor from the computer's main memory through the Bus Unit and gets stored in an Instruction Cache address as the code "Print Z."

C
The Prefetch Unit then asks the Instruction Cache for a copy of the code "Print Z" and sends it to the Decode Unit for further processing.

D
In the Decode Unit, the instruction "Print Z" is translated or decoded into a string of binary code that is sent off to the Control Unit to tell it what to do with the instruction.

E
Now that the value of Z has been computed, and is residing in register file entry #5, the print command has only to retrieve register 5's contents and display them to a screen so you can finally see the sum of 2+3. The microprocessor has completed its task for you.