computers. RAM capacities increased from 8,000 to 64,000 words in commercially
available machines by the 1960’s, with access times of 2 to 3 MS (Milliseconds).
These machines were very expensive to purchase or even to rent and were
particularly expensive to operate because of the cost of expanding programming.
Such computers were mostly found in large computer centers operated by industry,
government, and private laboratories — staffed with many programmers and
support personnel. This situation led to modes of operation enabling the sharing
of the high potential available. During this time, another important
development was the move from machine language to assembly language, also known
as symbolic languages. Assembly languages use abbreviations for instructions
rather than numbers. This made programming a computer a lot easier.
After the implementation of assembly languages came high-level languages.
The first language to be universally accepted was a language by the name of
FORTRAN, developed in the mid 50’s as an engineering, mathematical, and
scientific language. Then, in 1959, COBOL was developed for business
programming usage. Both languages, still being used today, are more English
like than assembly. Higher level languages allow programmers to give more
attention to solving problems rather than coping with the minute details of the
machines themselves. Disk storage complimented magnetic tape systems and
enabled users to have rapid access to data required.
All these new developments made the second generation computers easier
and less costly to operate. This began a surge of growth in computer systems,
although computers were being mostly used by business, university, and
government establishments. They had not yet been passed down to the general
public. The real part of the computer revolution was about to begin.
One of the most abundant elements in the earth is silicon; a non-metal
substance found in sand as well as in most rocks and clay. The element has
given rise to the name ?Silicon Valley? for Santa Clara County, about 50 km
south of San Francisco. In 1965, Silicon valley became the principle site of
the computer industry, making the so-called silicon chip.
An integrated circuit is a complete electronic circuit on a small chip
of silicon. The chip may be less than 3mm square and contain hundreds to
thousands of electronic components. Beginning in 1965, the integrated circuit
began to replace the transistor in machines was now called third-generation
computers. An Integrated Circuit was able to replace an entire circuit board of
transistors with one chip of silicon much smaller than one transistor. Silicon
is used because it is a semiconductor. It is a crystalline substance that will
conduct electric current when it has been doped with chemical impurities shot
onto the structure of the crystal. A cylinder of silicon is sliced into wafers,
each about 76mm in diameter. The wafer is then etched repeatedly with a pattern
of electrical circuitry. Up to ten layers may be etched onto a single wafer.
The wafer is then divided into several hundred chips, each with a circuit so
small it is half the size of a fingernail; yet under a microscope, it is complex
as a railroad yard. A chip 1 centimeter square it is so powerful that it can
hold 10,000 words, about the size of an average newspaper.
Integrated circuits entered the market with the simultaneous
announcement in 1959 by Texas Instruments and Fairchild Semiconductor that they
had each independently produced chips containing several complete electronic
circuits. The chips were hailed as a generational breakthrough because they had
four desirable characteristics. ? Reliability – They could be used over and over
again without failure, whereas vacuum tubes failed ever fifteen minutes. Chips
rarely failed — perhaps one in 33 million hours of operation. This reliability
was due not only to the fact that they had no moving parts but also that
semiconductor firms gave them a rigid work/not work test. ? Compactness -
Circuitry packed into a small space reduces equipment size. The machine
speed is increased because circuits are closer together, thereby reducing the
travel time for the electricity. ? Low Cost – Mass-production techniques has
made possible the manufacture of inexpensive integrated circuits. That is,
miniaturization has allowed manufacturers to produce many chips inexpensively. ?
Low power use — Miniaturization of integrated circuits has meant that less
power is required for computer use than was required in previous generations.
In an energy-conscious time, this was important.
The Microprocessor
Throught the 1970’s, computers gained dramatically in speed, reliability,
and storage capacity, but entry into the fourth generation was evolutionary
rather than revolutionary. The fourth generation was, in fact, furthering the
progress of the third generation. Early in the first part of the third
generation, specialized chips were developed for memory and logic. Therefore,
all parts were in place for the next technological development, the
microprocessor, or a general purpose processor on a chip. Ted Hoff of Intel
developed the chip in 1969, and the microprocessor became commercially available
in 1971.
Nowadays microprocessors are everywhere. From watches, calculatores and
computers, processors can be found in virtually every machine in the home or
business. Environments for computers have changed, with no more need for
climate-controlled rooms and most models of microcomputers can be placed almost
anywhere.
New Stuff
After the technological improvements in the 60’s and the 70’s, computers
haven’t gotten much different, aside from being faster, smaller and more user
friendly. The base architecture of the computer itself is fundementally the
same. New improvements from the 80’s on have been more ?Comfort Stuff?, those
being sound cards (For hi-quality sound and music), CD-ROMs (large storage
capicity disks), bigger monitors and faster video cards. Computers have come a
long way, but there has not really been alot of vast technological improvements,
architecture-wise.
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