Information Technology Reference
In-Depth Information
student Dan Bricklin released their program, called VisiCalc, for the Apple II. VisiCalc's
labor-saving potential was obvious to businesses. After a slow start, it quickly became
one of the most popular application programs for personal computers. Sales of the Apple
II computer increased significantly after the introduction of VisiCalc.
The second development was the release of the IBM PC in 1981. The IBM name
exuded reliability and respectability, making it easier for companies to make the move
to desktop systems for their employees. As the saying went, “Nobody ever got fired for
buying from IBM.” In contrast to the approach taken by Apple Computer, IBM decided
to make its PC an open architecture, meaning the system was built from off-the-shelf
parts and other companies could manufacture “clones” with the same functionality. This
decision helped to make the IBM PC the dominant personal computer architecture.
The success of IBM-compatible PCs fueled the growth of Microsoft. In 1980 IBM
contracted with Microsoft to provide the DOS operating system for the IBM PC.
Microsoft let IBM have DOS for practically nothing, but in return IBM gave Microsoft
the right to collect royalties from other companies manufacturing PC-compatible com-
puters. Microsoft profited handsomely from this arrangement when PC-compatibles
manufactured by other companies gained more than 80 percent of the PC market [26].
In the early nineteenth century, the United States fell far behind Europe in network-
ing technology. The French had begun constructing a network of telegraph towers in
the 1790s, and forty years later there were towers all over the European continent (Fig-
ure 1.11). At the top of each tower was a pair of semaphores. Operators raised and
lowered the semaphores; each pattern corresponded to a letter or symbol. A message
initiated at one tower would be seen by another tower within viewing distance. The re-
ceiving tower would then repeat the message for the next tower in the network, and so
on. This optical telegraph system could transmit messages at the impressive rate of about
350 miles per hour when skies were clear.
In 1837 Congress asked for proposals to create a telegraph system between New
York and New Orleans. It received one proposal based on proven European technology.
Samuel Morse submitted a radically different proposal. He suggested constructing a
telegraph system that used electricity to communicate the signals. Let's step back and
review some of the key discoveries and inventions that enabled Morse to make his
dramatic proposal.
Amber is a hard, translucent, yellowish-brown fossil resin often used to make beads and
other ornamental items. About 2,600 years ago the Greeks discovered that if you rub
amber, it becomes charged with a force enabling it to attract light objects such as feathers
and dried leaves. The Greek word for amber is
ηλκτρων
(electron). Our word “electric”
