13. Cpu Chip

Most personal computers today use CPU chips (microprocessors) of two kinds—those made by Intel and those by Motorola—although that situation may be changing. Workstations generally use RISC chips.

Intel makes chips for IBM and IBM-com­patible computers such as Compaq, Dell, Gateway, Tandy, Toshiba, and Zenith. Variations of Intel chips are made by other companies—-for exam­ple, Advanced Micro Devices (AMD), Cyrix, and Chips and Technologies.

Intel has identified its chips by numbers—8086, 8088, 80286, 80386, 80486—and is now marketing its newest chips under the names Pentium and Pentium Pro. The higher the number, the newer and more powerful the chip and the faster the processing speed, which means that software runs more efficiently. The chips are commonly referred to by their last three digits, such as '386 and '486.

Some chips have different versions—for example, "386SX" or "486DX." SX chips are usually less expensive than DX chips and run more slowly. Thus, they are more appropriate for home use, whereas DX chips are more appropriate for business use. SL chips are designed to reduce power con­sumption and so are used in portable computers. DX2 and DX4 chips are usually used for heavy-duty information processing.

Macintosh computers. These chip numbers include the 68000, 68020, 68030, and 68040. In 1994, Motorola joined forces with IBM and Apple and produced the PowerPC chip.

Sun Microsystems, Hewlett-Packard, and Digital Equipment use RISC chips in their desktop workstations, although the technology is also showing up in some portables.

RISC stands for reduced instruction set computing. With RISC chips a great many needless instructions are eliminated. Thus, a RISC computer system operates with fewer instructions than those required in conven­tional computer systems. RISC-equipped workstations have been found to work 10 times faster than conventional computers. A problem, however, is that software has to be modified to work with them.

14. Ports are of five types.

* A parallel port allows lines to be connected that will enable 8 bits to be transmitted simultaneously, like cars on an eight-lane highway. Parallel lines move information faster than serial lines do, but they can transmit information efficiently only up to 15 feet. Thus, paral­lel ports are used principally for connecting printers.

* A serial port, or RS-232 port, enables a line to be connected that will send bits one after the other on a single line, like cars on a one-lane highway. Serial ports are used principally for communications lines, modems, and mice. (They are frequently labeled "COM" for communica­tions.)

* Video adapter ports are used to connect the video display monitor outside the computer to the video adapter card inside the system unit. Monitors may have either a 9-pin plug or a 15-pin plug. The plug must be compatible with the number of holes in the video adapter card.

* SCSI port Pronounced "scuzzy" (and short for Small Computer System Interface), a SCSI port provides an interface for transferring data at high speeds for up to eight SCSI-compatible devices. These devices include exter­nal hard-disk drives, CD-ROM drives, and magnetic-tape backup units.

* Game ports allow you to attach a joystick or similar game-playing device to the system unit.

Why are so many ports needed? Why can't plugging peripherals into a com­puter be as easy as plugging in a lamp in your living room? The reason, says an Intel engineer, is that "The PC industry has evolved ad hoc. We were : always adding one more piece of equipment." As a result, connecting a new device, such as a scanner or a second printer, "is about as straightforward as triple-bypass surgery," says one writer. In. many cases, it involves opening the computer and inserting a circuit board, installing or modifying pertinent software, and fiddling with little switches.