Microprocessor that makes up your personal computer’s central processing unit, or CPU, is the computer’s brains, messenger, ringmaster, and boss. All the other components—RAM, disk drives, the monitor—exist only to bridge the gap between you and the processor. They take your data and turn it over to the processor to manipulate; then they display the results. The CPU isn’t the only microprocessor in PCs. Coprocessors on graphics, 3-D accelerator, and sound cards juggle display and sound data to relieve the CPU of part of its burden. And special processors, such as the one inside your keyboard that handles the signals generated whenever you press a key, perform specialized tasks designed to get data into or out of the CPU.

 The current standard for high-performance processors is Intel’s Pentium II chip design. On two combined chips that together are less than a couple of square inches, the Pentium II holds 7.5 million transistors, or tiny electronic switches. All the operations of the Pentium are performed by signals turning on or off different combinations of those switches. In computers, transistors are used to represent zeros and ones, the two numerals that make up the binary number system. These zeros and ones are commonly known as bits. Various groupings of these transistors make up the subcomponents within the Pentium, as well as those in coprocessors, memory chips, and other forms of digital silicon.

 Many of the components of the original Pentium II are designed to get data in and out of the chip quickly and to make sure that the parts of the Pentium that do the actual data manipulation never have to go into idle because they’re waiting on more data or instructions. These compo­nents have to handle the flow of data and instructions through the processor, interpret the instruc­tions so they can be executed by the processor, and send the results back to the PC’s memory.

 The Pentium family of processors—including the Pentium MMX, Pentium Pro, Pentium II, Celeron and Xeon—has several improvements over its predecessor (Intel’s 80486 processor) that help ensure that data and code move through the Pentium as fast as possible. One of the most im­portant changes is in the arithmetic logic unit (ALU). Just think of the ALU as sort of a brain within the brains. The ALU handles all the data juggling that involves integers, or whole numbers, such as 1, 23, 610, or 234. The Pentium is the first Intel processor to have two ALUs so that it can crunch two sets of numbers at the same time. Like the 486, the Pentium has a separate calculation unit that’s optimized for handling floating-point numbers, or numbers with decimal fractions, such as 1.2 or 35.8942.

 Another significant difference over the 486 is that the Pentium can take in data 64 bits at a time, compared to the 32-bit data path of the 486. Where the 486 has one storage area called a cache that holds 8 kilobytes at a time, the Pentium II has multiple caches totaling more than 5 12K. They’re designed to make sure the ALU is constantly supplied with the data and instructions it needs to do its job.