The CPU

The CPU

1. Memory

   • RAM (Random Access Memory)
     • Primary Storage

2. Hard Drive

   • Secondary Storage (non-volatile)

3. CPU

   • Central Processing Unit
   • Fetch, Decode, Execute Cycle
     • The CPU fetches the data from the main memory.
       • The internal temporary memory areas are called the registers.
         • The viral hardware path is called the address bus.
           • The other bus is called the data bus.
             • The process for the CPU to make sense of the instructions is called 'decode'.
               • These set of commands that understands a specific set of commands is called the instruction set.
                 • The CPU then executes the instructions. This is where the actual processing takes place.
   • This is often described as the brain of the computer.
     • The purpose of the CPU is to process data.
       • It is where all the searching, sorting, calculating and decision making take place.

4. The Control Unit

   • Inputs and Outputs
   • Control Unit
     • There are three things that the control unit does. It controls and monitors the hardware attached to the system to make sure the commands are used, it controls the input and output of data so that the signals og ot the right place at the right time and it controls the flow of data within the CPU - which is the Fetch-Execute cycle
   • Immediate Access Store
     • The CPU stores the data and programs into the IAS's memory. It need to do this because Backing Storage is way too slow to run programs directly
   • ALU (Arithmetic and Logic Unit)
     • There are two parts to the ALU. One is the arithmetic part, which performs the calculations on the data, and the other one is the logic part which deals with logic and comparisons
   • Backing Storage

5. Clock Speed

   • Computers can only process one thing at a time, so clock speed is used to process the data with each tick. Clock speed is measured in cycles per second. For example, if a computer was running at 3GHz, it would carry out the instructions three thousand million times a second. The only downside is that it runs hotter and comsumes more power. There is also a term called overclocking. Overclocking means adjusting the clock to run faster than the CPU was normally intended for.