The current trend in processors is to increase the number of tasks which a processor can run at once. A normal processor, known as a uni-core or single core, can only run one instruction at once. So in order to run more than one program at once the operating system needs to swap between the two programs. This is known as process scheduling and is covered in detail in A2.

Dual core processors have two cores. This effectively means that they have two sets of CU and ALU’s. As such, the operating system can run more than one program at once without the need to swap them in and out. As more and more programs are being run on a standard home PC, dual core processors are becoming increasing needed.

It is important not to get confused between multi-core and multiple processors. Multiple processors means that you will have more than one CPU in a system. A multi-core processor means that you have only one CPU which is capable of running more than one program at once.