Central Processing Unit (CPU)

Inside the computer case, hidden amongst all the wiring and gizmos, is a particularly important part of the computer known as the central processing unit (or CPU, for short). The CPU is also known as the computer chip (because that’s what it is) or the microprocessor (or processor, for short).

Some say the CPU is the brain of the computer while others describe it as the heart. In any case, it’s the thing that makes your computer a computer. The CPU does all the work: It calculates, it processes, it keeps things running smoothly. You might think of it as a talented stage manager. When it does its behind-the-scenes job well, you don’t notice it; you simply enjoy the performance.

Originally, CPUs were given wildly inventive names like Chip. Okay, maybe not. The names were actually based on numbers like 8088. The next few names in the series—the 286, the 386, and the 486—were actually just shortened names for 80286, 80386, and 80486. Then, what would have been the 586 was dubbed the Pentium. After that, the names became rather mysterious: Pentium Pro and Pentium MMX. Finally, the names returned to a semi-ordered numbering system (albeit a mix of Roman and Arabic numerals): Pentium 2, Pentium 3, and Pentium 4. And that’s where we are at the moment. Both the Pentium 3 and the Pentium 4 are still quite common.

Intel makes most CPUs. In fact, Intel is the company that came up with the name Pentium. However, AMD and VIA Technologies are two other well-known CPU manufacturers. Their CPUs are less expensive and use a different naming system (such as the AMD Athlon and the AMD Duron). Intel actually makes a less expensive version of the Pentium as well, which it calls the Celeron. The Celeron does what the Pentium does, but not as quickly.

Speaking of which, speed is what the CPU is all about, and each successive version of the CPU gets progressively faster. A CPU’s speed is measured in megahertz (MHz) or, for newer models, in gigahertz (GHz). A megahertz equals millions of cycles per second; a gigahertz equals billions of cycles per second. Higher numbers equate to higher speeds. You might see an Intel Pentium 4 at 3.06 GHz, a Pentium III at 1.40 GHz, and a Celeron at 2.20 GHz.

Another common measure of a CPU is how many bits it can handle at a time. A bit is the tiniest piece of information processed by a computer. Eight bits make up one byte, and one byte equals one character. Computers used to handle 8 or 16 bits; now they’re up to 32 and 64. at a time.

Table 2-1:Types of CPUs

· The CPU, or Central Processing Unit, is the computer‘s main chip. It calculates and processes information. CPU Speed is Measured In:

· Megahertz (MHz).

· Gigahertz (GHz).

Common CPUs Include:

· Intel Pentium III

· Intel Pentium 4

· Intel Celeron

· AMD Athlon

· AMD Duron