Late 1960s - Early 1970s: Third Generation Computers One of the most important advances in the development of computer hardware in the late 1960s and early 1970s was the invention of the integrated circuit, a solid-state device containing hundreds of transistors, diodes, and resistors on a tiny silicon chip. It made possible the production of large-scale computers (mainframes) of higher operating speeds, capacity, and reliability at significantly lower costs. Another type of computer developed at the time was the minicomputer. It profited from the progresses in microelectronics and was considerably smaller than the standard mainframe, but, for instance, powerful enough to control the instruments of an entire scientific laboratory. Furthermore operating systems, that allowed machines to run many different programs at once with a central program that monitored and coordinated the computer's memory, attained widespread use.

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Expert system Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to artificial intelligence. The three main elements of expert systems are: (1) an interface which allows interaction between the system and the user, (2) a database (also called the knowledge base) which consists of axioms and rules, and (3) the inference engine, a computer program that executes the inference-making process. The disadvantage of rule-based expert systems is that they cannot handle unanticipated events, as every condition that may be encountered must be described by a rule. They also remain limited to narrow problem domains such as troubleshooting malfunctioning equipment or medical image interpretation, but still have the advantage of being much lower in costs compared with paying an expert or a team of specialists.

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