The Central Processing Unit

The Central Processing Unit

1. Purpose of a CPU

   • The CPU is the brain of the Computer. The CPU processes Data, this is where the searching, sorting, calculating and decision making takes place.
   • Every piece of information that is stored or processed on a computer goes through the CPU at some point. A CPU executes programs stored on a computer. It takes in instructions and puts out data.

2. Control Unit

   • 1. This controls the hardware attached to the system to make sure that every command given to it by the application software are used.
   • 2. It controls the input and output signals to make sure that everything goes to the right place at the right time.
   • 3. It controls the flow of data within the CPU.

3. Immediate Access Store

   • The CPU reads data and programs kept of the Backing storage. It then stores it on the IAS’s memory. The CPU does this because the Backing storage (the hard disk) is too slow to be able to run applications directly.

4. Arithmetic and Logic Unit

   • The Arithmetic part does exactly what you think it should; it performs the calculations like 7 + 3 = 10. The Logic part deals with the logic and comparisons, like if one value is greater than the other.

5. Clock Speed

   • The computer can only handle one thing at a time; it’s just because the machine is so fast, to you, that everything seems to be happening simultaneously.
   • A CPU clock speed is measured in cycles per second. 1 cycle per second is also known as 1 hertz. A computer running at 1GHz can carry out a thousand million instructions per second.

6. What can affect a CPU’s performance?

   • 1. Clock frequency - The higher the Hertz the faster your processor will run. This works both ways.
   • 2. Instruction per cycle - The number of instructions per cycle is an approximate indicator of the likely performance of the processor. If you have a lower number of instructions per cycle then your processor performance will be lower. There are many, many more factors!

7. What can improve the speed of a CPU?

   • 1. Clock frequency - The higher the Hertz the faster your processor will run. This works both ways.
   • 2. Overclocking - If your computer isn’t fast enough for you, you can overclock it and improve the performance, this is risky if you don’t have extra cooling fans as your computer will overheat and the processor could break.