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Thursday, January 12, 2012

computer classification

Classification of Computers !

1. Mainframe Computers
2. Minicomputers
3. Microcomputers
4. Supercomputers
Mainframe computers are very large, often filling an entire room. They can store enormous of information, can perform many tasks at the same time, can communicate with many users at the same time, and are very expensive. . The price of a mainframe computer frequently runs into the millions of dollars. Mainframe computers usually have many terminals connected to them. These terminals look like small computers but they are only devices used to send and receive information from the actual computer using wires. Terminals can be located in the same room with the mainframe computer, but they can also be in different rooms, buildings, or cities. Large businesses, government agencies, and universities usually use this type of computer.
Minicomputers are much smaller than mainframe computers and they are also much less expensive. The cost of these computers can vary from a few thousand dollars to several hundred thousand dollars. They possess most of the features found on mainframe computers, but on a more limited scale. They can still have many terminals, but not as many as the mainframes. They can store a tremendous amount of information, but again usually not as much as the mainframe. Medium and small businesses typically use these computers.
Microcomputers are the types of computers we are using in your classes at Floyd College. These computers are usually divided into desktop models and laptop models. They are terribly limited in what they can do when compared to the larger models discussed above because they can only be used by one person at a time, they are much slower than the larger computers, and they can not store nearly as much information, but they are excellent when used in small businesses, homes, and school classrooms. These computers are inexpensive and easy to use. They have become an indispensable part of modern life.

computer component

Basic Computer Components

Every computer Consists of the following basic components
  1. Computer Case - Where all of the components are stored.\
  2. 2.  CPU - It is basically the brain of your computer. The CPU is a used to process         everything from basic to complex functions in a computer.
    3.   RAM - RAM is memory that attaches to the motherboard. RAM is hardware used   to temporarily store and access data.
    4.Motherboard - A Motherboard is the most important component in a computer system. All of  the other hardware in a computer system connect to the motherboard.
   5.Power Supply - A Power Supply is the sends power to all of the other hardware so they can operate.
6.Hard Drive - A Hard Drive is used for permanently storing files and programs.
7.Disk Drives - Disk Drives can be a floppy drive, CD drive, DVD drive or other   possible file storage devices that are used in a computer.
8.Video Card - A Video Card is the part of a computer system that converts binary code from the CPU so you can view it on a monitor.
9.Monitor - The part of a computer that allows you to see what the computer is  processing.
10.Keyboard - A keyboard allows a computer user to enter text commands into a computer system.
11.Mouse - A mouse allows a computer user to use a point and click interface to enter commands.

computer history and generations

Short History of the Computer
(b.c. - 1993a.d.)
Jeremy Meyers
INFORMATION! Instead, check
Download this paper in PDF format
Note: Yes, a lot of this is from Groliers Encyclopaedia. Hey, I was young. I didn't know any better. Credit where credit is due. Also, this
information is only current as of the early 1990's (1993, to be exact), and no I'm not planning to add more information anytime soon.
Citing This Work
You are welcome to use this document as a reference in creating your own paper or research work on
the subject. Please don't just copy this paper verbatim and submit it as your own work, as I put a lot
of time and effort into it. Plus, it's bad karma.
If you would like to use this work, please use this citation in your bibliography:
Meyers, Jeremy, "A Short History of the Computer" [Online] Available
<http://www.softlord.com/comp/> <Date you accessed this page>
Table of Contents:
In The Beginning...
The history of computers starts out about 2000 years ago, at the birth of the
holding two horizontal wires with beads strung on them. When these beads are moved around,
according to
Another important invention around the same time was the
abacus, a wooden rackprogramming rules memorized by the user, all regular arithmetic problems can be done.Astrolabe, used for navigation.
Blaise Pascal
entered with dials and was made to help his father, a tax collector. In 1671, Gottfried Wilhelm von
is usually credited for building the first digital computer in 1642. It added numbersIn The Beginning... 5) The Modern "Stored Program"
Babbage 6) Advances in the 1950’s
Use of Punched Cards by Hollerith 7) Advances in the 1960’s
Electronic Digital Computers 8) Recent Advances
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around, multiply.
digits, and this is still being used.
The prototypes made by
a little more than a century later, when Thomas of Colmar (A.K.A. Charles Xavier Thomas) created the
first successful
desktop calculators by many inventors followed, so that by about 1890, the range of improvements
invented a computer that was built in 1694. It could add, and, after changing some thingsLeibniz invented a special stepped gear mechanism for introducing the addendPascal and Leibniz were not used in many places, and considered weird untilmechanical calculator that could add, subtract, multiply, and divide. A lot of improved
Accumulation of partial results
Storage and automatic reentry of past results (A memory function)
Each of these required manual installation. These improvements were mainly made for commercial
users, and not for the needs of science.
Printing of the results
While Thomas of Colmar was developing the
series of very interesting developments in computers was started in
Cambridge, England, by Charles
store "
desktop calculator, aBabbage (left, of which the computerBabbages" is named), a mathematics professor. In 1812, Babbage
realized that many long calculations, especially those needed to make
mathematical tables, were really a series of predictable actions that
were constantly repeated. From this he suspected that it should be
possible to do these automatically.
He began to design an automatic mechanical calculating machine,
which he called a
to demonstrate with. With financial help from the British government,
difference engine. By 1822, he had a working model
fully automatic, including the printing of the resulting tables, and commanded by a fixed instruction
The difference engine, although having limited adaptability and applicability, was really a great
he thought he had a
fully program-controlled, automatic mechanical digital computer.
started fabrication of a difference engine in 1823. It was intended to be steam powered andBabbage continued to work on it for the next 10 years, but in 1833 he lost interest becausebetter idea -- the construction of what would now be called a general purpose,Babbage called this idea an
Analytical Engine
appreciated until a full century later.
The plans for this engine required an identical decimal computer operating on numbers of 50 decimal
digits (or words) and having a storage capacity (memory) of 1,000 such digits. The built-in operations
were supposed to include everything that a modern general - purpose computer would need, even the
all important
any order, not just the order in which they were programmed.
The analytical engine was soon to use
which would be read into the machine from several different
supposed to operate automatically, by steam power, and require only one person there.
. The ideas of this design showed a lot of foresight, although this couldn’t beConditional Control Transfer Capability that would allow commands to be executed inpunched cards (similar to those used in a Jacquard loom),Reading Stations. The machine was
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lack of precision machining techniques at the time. Another speculation is that
on a solution of a problem that few people in 1840 really needed to solve. After
temporary loss of interest in automatic digital computers.
Between 1850 and 1900 great advances were made in mathematical physics, and it came to be known
that most events occurring in nature can be measured or described in one equation or another), so
that easy means for their calculation would be helpful.
Moreover, from a practical view, the availability of steam power caused manufacturing (boilers),
transportation (steam engines and boats), and commerce to prosper and led to a period of a lot of
engineering achievements. The designing of railroads, and the making of steamships, textile mills, and
bridges required
's computers were never finished. Various reasons are used for his failure. Most used is theBabbage was workingBabbage, there was amost observable dynamic phenomena can be identified by differential equations (which meantdifferential calculus to determine such things as:
center of gravity
center of buoyancy
moment of inertia
Even the assessment of the power output of a steam engine needed mathematical integration. A
strong need thus developed for a machine that could rapidly perform many repetitive calculations.
stress distributions
Use of Punched Cards by Hollerith
A step towards automated computing was the development of punched cards,
which were first successfully used with computers in 1890 by
Herman Hollerith
devices that could read the information that had been punched into the cards
automatically, without human help. Because of this, reading errors were reduced
dramatically, work flow increased, and, most importantly, stacks of punched cards
could be used as easily accessible memory of almost unlimited size. Furthermore,
different problems could be stored on different stacks of cards and accessed when
These advantages were seen by commercial companies and soon led to the
development of improved punch-card using computers created by
Business Machines
Burroughs, and other corporations. These computers used electromechanical devices in which
electrical power provided mechanical motion -- like turning the wheels of an adding machine. Such
systems included features to:
left) and James Powers, who worked for the US. Census Bureau. They developedInternational(IBM), Remington (yes, the same people that make shavers),
feed in a specified number of cards automatically
add, multiply, and sort
As compared to today’s machines, these computers were slow, usually processing 50 - 220 cards per
minute, each card holding about 80 decimal numbers (characters). At the time, however, punched
cards were a huge step forward. They provided a means of I/O, and memory storage on a huge scale.
For more than 50 years after their first use, punched card machines did most of the world’s first
business computing, and a considerable amount of the computing work in science.
feed out cards with punched results
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Electronic Digital Computers
The start of World War II produced a large need for computer capacity,
especially for the military. New weapons were made for which
W. Mauchly
Engineering of University of Pennsylvania
electronic computer to do the job. This machine became known as
trajectoryand other essential data were needed. In 1942, John P. Eckert, John(left), and their associates at the Moore school of Electricaldecided to build a high - speedENIAC
(Electrical Numerical Integrator And Calculator)
The size of
multiply two of these numbers at a rate of 300 per second, by finding the
value of each product from a multiplication table stored in its memory.
ENIAC’s numerical "word" was 10 decimal digits, and it could
of relay computers.
was therefore about 1,000 times faster then the previous generation
and consumed about 180,000 watts of electrical power. It had punched card I/O, 1 multiplier, 1
divider/square rooter, and 20 adders using decimal ring
quick-access (.0002 seconds) read-write register storage. The executable instructions making up a
program were embodied in the separate "units" of
"route" for the flow of information.
These connections had to be redone after each computation,
together with presetting function tables and switches. This
"wire your own" technique was inconvenient (for obvious
reasons), and with only some latitude could
considered programmable. It was, however, efficient in
handling the particular programs for which it had been
used 18,000 vacuum tubes, about 1,800 square feet of floor space,counters , which served as adders and also asENIAC, which were plugged together to form aENIAC be
electronic digital computer (EDC) and was used from 1946 to
1955. A controversy developed in 1971, however, over the
patentability of
made that another physicist,
already used basically the same ideas in a simpler vacuum -
tube device he had built in the 1930’s while at
the Atanasoff claim.
The Modern Stored Program EDC
Fascinated by the success of
computation that showed that a computer should have a
simple, fixed physical structure
is commonly accepted as the first successful high - speedENIAC's basic digital concepts, the claim beingJohn V. Atanasoff (left ) hadIowa State. In 1973 the courts found in favor of the company usingENIAC, the mathematician John Von(left) undertook, in 1945, an abstract study ofvery, and yet be able to execute any
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kind of computation by means of a
the unit itself.
proper programmed control without the need for any change in
Von Neumann
and built. These ideas, usually referred to as the stored - program technique, became essential for
future generations of high - speed digital computers and were universally adopted.
The Stored - Program technique involves many features of computer design and function besides the
one that it is named after. In combination, these features make very - high - speed operation
attainable. A glimpse may be provided by considering what 1,000 operations per second means. If
each instruction in a job program were used once in consecutive order, no human programmer could
generate enough instruction to keep the computer busy.
Arrangements must be made, therefore, for parts of the job program (called subroutines) to be used
repeatedly in a manner that depends on the way the computation goes. Also, it would clearly be
helpful if instructions could be changed if needed during a computation to make them behave
called a
started again at any point - and by storing all instruction programs together with data in the same
memory unit, so that, when needed, instructions could be arithmetically changed in the same way as
As a result of these techniques, computing and programming became much faster, more flexible, and
more efficient with work. Regularly used subroutines did not have to be reprogrammed for each new
program, but could be kept in "libraries" and read into memory only when needed. Thus, much of a
given program could be assembled from the subroutine library.
The all - purpose computer memory became the assembly place in which all parts of a long
computation were kept, worked on piece by piece, and put together to form the final results. The
computer control survived only as an "errand runner" for the overall process. As soon as the advantage
of these techniques became clear, they became a standard practice.
The first generation of modern programmed electronic
computers to take advantage of these improvements were
built in 1947. This group included computers using Random
- Access - Memory (RAM), which is a memory designed to
give almost constant access to any particular piece of
contributed a new awareness of how practical, yet fast computers should be organizedVon Neumann met these two needs by making a special type of machine instruction,Conditional control transfer - which allowed the program sequence to be stopped and
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information. . These machines had punched - card or punched tape I/O devices and RAM’s of 1,000 -
word capacity and access times of .5 Greek MU seconds (.5*10-6 seconds). Some of them could
perform multiplications in 2 to 4 MU seconds. Physically, they were much smaller than
were about the size of a grand piano and used
the earlier
reached probably about 70 to 80% reliability of operation (ROO) and were used for 8 to 12 years. They
were usually programmed in ML, although by the mid 1950’s progress had been made in several
aspects of advanced programming. This group of computers included
ENIAC. Someonly 2,500 electron tubes, a lot less then required byENIAC. The first - generation stored - program computers needed a lot of maintenance,EDVAC (above) and UNIVAC
(right) the first commercially available computers.
Advances in the 1950’s
Early in the 50’s two important engineering discoveries changed the image of the electronic -
computer field, from one of fast but unreliable hardware to an image of relatively high reliability and
even more capability. These discoveries were the
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.
One such mode is batch processing, in which problems are prepared and then held ready for
computation on a relatively cheap storage medium. Magnetic drums, magnetic - disk packs, or
magnetic tapes were usually used. When the computer finishes with a problem, it "dumps" the whole
problem (program and results) on one of these peripheral storage units and starts on a new problem.
Another mode for fast, powerful machines is called time-sharing. In time-sharing, the computer
processes many jobs in such rapid succession that each job runs as if the other jobs did not exist, thus
keeping each "customer" satisfied. Such operating modes need elaborate
attend to the administration of the various tasks.
magnetic core memory and the Transistor - Circuit. These technical discoveries quickly found their way into new models of digital computers.executable programs to
Advances in the 1960’s
In the 1960’s, efforts to design and develop the fastest possible computer with the greatest capacity
reached a turning point with the LARC machine, built for the
University of California by the Sperry - Rand Corporation, and the
had a base memory of 98,000 words and multiplied in 10 Greek MU seconds. Stretch was made with
several degrees of memory having slower access for the ranks of greater capacity, the fastest access
time being less then 1 Greek MU Second and the total capacity in the vicinity of 100,000,000 words.
During this period, the major computer manufacturers began to offer a range of capabilities and
prices, as well as accessories such as:
Livermore Radiation Laboratories of theStretch computer by IBM. The LARC
Card Feeders
Page Printers
Cathode - ray - tube displays
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These were widely used in businesses for such things as:
Graphing devices
Inventory control
Ordering Supplies
CPU’s for these uses did not have to be very fast arithmetically and were usually used to access large
amounts of records on file, keeping these up to date. By far, the most number of computer systems
were sold for the more simple uses, such as hospitals (keeping track of patient records, medications,
and treatments given). They were also used in libraries, such as the
system, and in the
known chemical compounds.
BillingNational Medical Library retrievalChemical Abstracts System, where computer records on file now cover nearly all
More Recent Advances
The trend during the 1970's was, to some extent, moving away from very powerful, single - purpose
computers and toward a larger range of applications for cheaper computer systems. Most
used computers of smaller capability for controlling and regulating their jobs.
In the 1960’s, the problems in programming applications were an obstacle to the independence of
medium sized on-site computers, but gains in applications programming language technologies
removed these obstacles. Applications languages were now available for controlling a great range of
manufacturing processes, for using machine tools with computers, and for many other things.
Moreover, a new revolution in computer hardware was under way, involving shrinking of computerlogic
circuitry and of components by what are called
1950s it was realized that "scaling down" the size of electronic digital computer circuits and parts
would increase speed and efficiency and by that, improve performance, if they could only find a way
to do this. About 1960
developed. Then it became possible to build resistors and capacitors into the circuitry by the same
process. In the 1970’s,
with adders, shifting registers, and counters, became available on tiny "chips."
In the 1980’s,
placed on a single chip, became more and more common. Many companies, some new to the computer
field, introduced in the 1970s programmable
"shrinking" trend continued with the introduction of personal computers (PC’s), which are
programmable machines small enough and inexpensive enough to be purchased and used by
Many companies, such as
1970s, encouraged in part by a fad in computer (video) games. In the 1980s some friction occurred in
the crowded PC field, with
chips, the
firms were making strong economic advances, especially in the area of memory chips. By the late
1980s, some personal computers were run by microprocessors that, handling 32 bits of data at a time,
could process about 4,000,000 instructions per second.
continuousprocess, such as petroleum refining and electrical-power distribution systems, nowlarge-scale integration (LSI) techniques. In thephoto printing of conductive circuit boards to eliminate wiring became morevacuum deposition of transistors became the norm, and entire assemblies,very large scale integration (VLSI), in which hundreds of thousands of transistors wereminicomputers supplied with software packages. TheApple Computer and Radio Shack, introduced very successful PC’s in theApple and IBM keeping strong. In the manufacturing of semiconductorIntel and Motorola Corporations were very competitive into the 1980s, although Japanese
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Microprocessors equipped with read-only memory (ROM), which stores constantly used, unchanging
programs, now performed an increased number of process-control, testing, monitoring, and diagnosing
functions, like automobile ignition systems, automobile-engine diagnosis, and production-line
inspection duties.
computer systems, through the 1970s and 1980s. In the early 1980s, however, the Japanese
government announced a gigantic plan to design and build a new generation of supercomputers. This
new generation, the so-called "fifth" generation, is using new technologies in very large integration,
along with new programming languages, and will be capable of amazing feats in the area of artificial
intelligence, such as voice recognition.
Progress in the area of software has not matched the great advances in hardware. Software has
become the major cost of many systems because programming productivity has not increased very
quickly. New programming techniques, such as object-oriented programming, have been developed to
help relieve this problem. Despite difficulties with software, however, the
computers is rapidly lessening, and their convenience and efficiency are expected to increase in the
early future.
The computer field continues to experience huge growth. Computer networking, computer mail, and
electronic publishing are just a few of the applications that have grown in recent years. Advances in
technologies continue to produce cheaper and more powerful computers offering the promise that in
the near future, computers or terminals will reside in most, if not all homes, offices, and schools.
Research and Control Data Inc. dominated the field of supercomputers, or the most powerfulcost per calculation of
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