Today, we have personal computers that are based on many different microprocessors and operating systems. A microprocessor is a single integrated circuit chip that contains all the control unit and arithmetic/logic unit electronic circuitry that comprise the CPU. Early microprocessors condensed the CPU circuitry down to five chips; then, in the early 1970s, it was shrunk onto a single chip. The two most popular microprocessors are made by Intel, notably for the PC-compatibles and PS/2s, and Motorola, for Macintoshes.
Yet one thing almost all microprocessors have in common is the manner in which they process instructions. Complex-instruction-set computing(CISC) is a microprocessor or CPU architecture and operating system design that allows it to recognize 100 or more instructions, enough to carry out most computations. CISC is the most prevalent architecture today; virtually all popular personal computers use CISC. Most people feel CISC computers are adequate for our computing needs; besides, all our application software is based on the CISC instruction set and operating system.
Reduced-instruction-set computing (RISC) is a microprocessor or CPU architecture that uses a condensed set of instructions for its operating system. RISC microprocessors have the advantage of simplicity and elegance over CISC microprocessors. They are also extremely fast. The increased performance and lower price of RISC microprocessors have had a profound effect on the computer industry, prompting companies such as IBM (which created RISC technology) to introduce an entire line of RISC workstations. For that reason, more and more workstations are based on RISC microprocessors.
In the 1980s, four companies became well known for their workstations: Sun Microsystems, Hewlett-Packard (H-P), Apollo Computer (now part of H-P), and Digital Equipment Corporation. These companies manufacture their own proprietary microprocessors. Proprietary means the chip is made exclusively by or for a certain manufacturer. A RISC microprocessor that shows great promise for the 1990s is Digital's Alpha.
The Interface. Workstations were the first computers to make the friendly human-computer interface of prime importance. The human-computer interface is the point of meeting between the person using the computer and the computer itself. The interface was intended to make it as easy as possible for users to get their work done, rather than having to spend time manipulating the computer system. A research report published in 1981 said, "the interface of the integrated workstation is meant to represent a natural technological extension of a person's mind. It comes the closest to setting the pace for future information systems."
Multitasking. Multitasking is the ability of the computer to run two or more applications at the same time. Using a conventional computer, the operating system must first be loaded, then the application software is loaded. When the knowledge worker wants to change work—say from word processing to the spreadsheet — the first application must be exited, down to the operating system, then the second application is loaded.
Multitasking permits loading and running multiple applications. Each appears in its own area of the screen, often called a window, which can be opened, closed, made larger or smaller, and moved around the screen. In addition, multitasking permits taking portions of one application's file and copying them into another—for example, the spreadsheet data can be inserted in a word processing report. The workstation also makes it possible to have a small multi user computer that can be shared by others. These were significant benefits that, over time, have led to new and innovative ways for people to utilize computers.
