3. Processing cores
A 'core' is a complete processing unit within the CPU - it has an ALU, a control unit and memory in the form of registers
Originally there was only one processing core in a CPU. Now it is common for a CPU chip to have two, four, eight cores or more. A cpu with two cores is called a 'dual core' and one with four cores is called a 'quad-core'.
Challenge see if you can find out one extra fact on this topic that we haven't already told you Click on this link: Multi-core parallel processing