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Unformatted text preview: thmetic logic and control functions, the core activities of all computers, on a
single chip. Hence it became possible to build a complete computer with a
microprocessor, a few additional primary storage chips, and other support circuitry. It
started a new social revolution - the personal computer (PC) revolution. Overnight
computers became incredibly compact. They became inexpensive 4o make and suddenly
it became possible for anyone and everyone to own a computer. During the fourthgeneration period a large number of personal computers were deployed in both offices and homes, which changed the work culture of most organizations. By 1978, the
dominant personal computers were the Apple II from Apple Computer Inc. and the TRS80 model from the Radio Shack Division of Tandy Corporation. In 1980, IBM realized
that the personal computer market was too promising to ignore and came out with its own
PC in 1981, popularly known as IBM PC. Apple's and IBM's PCs became very popular
during the fourth generation. Several other manufacturers used IBM's specification and
designed their own PCs, which were popularly known as IBM compatible PCs or clones.
The IBM PC and its clones became a popular standard for the PC industry during the
During the fourth generation, magnetic core memories were replaced by semiconductor
memories. This allowed computer manufacturers to provide large random access
memories with very fast access time. Typical memory sizes were of the order of 16
Megabytes with access time of 200 nano seconds. On the other hand, hard disks became
cheaper, smaller in size, and larger in capacity. Hence they became the standard in-built
secondary storage device for all types of computer systems. Typical hard disk storage
sizes in those days were of the order of few hundred of megabytes of data per disk drive.
Parallely, in addition to magnetic tapes, floppy disks became very popular as a portable
medium for porting programs and data from one computer system to another.
In addition to the proliferation of PCs, during the fourth g...
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- Spring '14