Processors (CPUs)

Processors, or Central Processing Units (CPUs), are the chips that are at the core of the computer system and process instructions and direct information between all of the other chips, memory, and storage systems on the computer.

For the A+ Essentials 2006 exam, you will need to know common 32-bit and 64-bit processors and how they work. There are two main CPU manufacturers: Intel and AMD. Each has a full line of 32-bit and 64-bit processors. There are other CPU manufacturers such as IBM, Motorola, and VIA, but each of these is small market share or specialized for a specific purpose (e.g. IBM/Motorola PowerPC in the old PPC line of Macintosh computers). VIA (Cyrix) makes Intel-compatible chips, but is a small player compared to Intel and AMD.

32-bit Processors

Most computers built in the last decade, and a majority of those being built today, use a 32-bit processor. The Intel compatible 32-bit chips are often referred to as “32-bit x86 architectures.” Intel licensed early 32-bit chips to other manufacturers but declined to license the Pentium models, so AMD and Cyrix began designing their own 32-bit chips.

64-bit Processors

AMD introduced the first 32-bit backwards compatible architecture, the AMD64, in September 2003. Intel subsequently released their version of x86-64 chips and 64-bit chips were brought to the Windows desktop. The AMD and Intel chips can run 32-bit software, but Microsoft, Apple, and Linux has Operating Systems written to run in native 64-bit code. Microsoft calls their OSes Windows XP 64-bit edition and Windows Vista x64. One of the big differences between the 64-bit edition and 32-bit edition is the use of device drivers. The 64-bit editions of the Windows OS required native 64-bit signed device drivers to recognize and properly use hardware. If you are running a system with hardware with no 64-bit drivers, you may run into problems.

Multi-Core Processors

If you wanted to increase the speed of a computer, you could install multiple processors. Running multiple processors is an expensive proposition and required you to have a motherboard designed for it. Additionally, if you have a one processor machine and add a second processor, you will need to reinstall the Operating System for the system to function properly. Please Note: you are almost guaranteed to see a question about this: I have on multiple CompTIA certification exams. If you want to upgrade your computer to dual processors, you must reinstall Windows as the HAL is based on the number of processors you have in your machine.

Microprocessor manufacturers wanted to get more performance out of their chips so they began designing chips with multiple microprocessors in one chip. By 2007, it is very common to see desktops, laptops and servers with a dual-core processor – one which has two microprocessing cores in it. Quad-core, or chips with four processors, are becoming increasingly common in datacenters and specialized workstations.

Some high end manufacturers, such as Sun Microsystems, build systems with 8-core CPUs.

RISC versus CISC

You should be familiar with the two general terms for processors: RISC and CISC. Originally, most processors began as CISC chips – Complex Instruction Set Computer – while high end systems had RISC chips – Reduced Instruction Set Computer. RISC chips were designed to required a fewer number of instructions to do tasks which resulted in faster speeds.

Over time, CISC has been able to catch up in terms of speed to RISC chips. The PowerPC is an example of a desktop RISC chip – used in older Apple Macintoshes. Apple has since moved their platform to a 64-bit Intel core.