Math co-processor

The math co-processor, also known as the Numeric Processing Unit (NPU), is the processor's sidekick. Systems that have math co-processors can well outperform systems that do not have math co-processors because the math co-processor takes some of the workload off the CPU. For example, it performs many of the large calculations that applications may require, such as floating point arithmetic. Overall system performance increases because the CPU can focus on logic functions while the math co-processor executes complicated mathematical functions.

If you have large spreadsheets or use large graphics applications, you may find that applications run very poorly or not at all on systems without a math co-processor. If you are running a system that does not have a math co-processor integrated into the CPU, then you can add one to the motherboard - or perhaps upgrade the main processor.

In earlier computers, the processor was one chip and the math co-processor was a separate chip on the motherboard. For example, years ago, a 386 computer used an 80386 chip on the motherboard as the processor, but you could add an 80387 chip to the board to act as the math co-processor. All processors since the 80486 computer, including Pentium-class systems, have a math co-processor integrated into the processor's chip, so you will not be adding a math coprocessor to the system.

Real-mode versus protected-mode

A real-mode processor is a processor that sees memory as a whole unit and deals with it as a single entity. In other words, if you have 512MB of RAM, the real-mode processor sees that as one block of memory. This is limiting because in order to run multiple programs at the same time, each program has to be assigned its own independent block of that 512MB - something that real-mode processors cannot do. As a result, real-mode processors don't have any multitasking capabilities - the capabilities to divide memory up into multiple parts and run different applications or tasks in each part.

Protected-mode processors support the segregation of system memory into different parts and assigning a different application to each part of memory. Therefore, protected-mode processors support multitasking and multitasking operating systems, such as Windows 2000 and Windows XP.

Protected-mode processors also support virtual memory, which is the process of using hard disk space as emulated memory. This means you could increase your 512MB of RAM by using 768MB of hard disk space as "pretend" RAM. In this case, as far as the applications that are running are concerned, the system has 1280MB of memory - the combination of true memory plus virtual memory.