What Are The Categories Of Computer?

There are five basic categories of computers:

Personal computers: Desktop computers for use at home and by individuals.
Servers: Make programs and make data available for people who are linked to a computer network. They are not used directly.
Minicomputers: Are multi-user systems. They are usually used in small organizations by using remote terminals or personal computers.
Mainframes: Large, multi-user systems used in large organizations. They can handle large data processing jobs.
Supercomputers: Ultra fast computers that are designed to process huge amounts of scientific data.

There are many categories of computer. It might be categorized as



Gateways, Servers, personal computer, super computer, notebooks, workstations, Gaming and Media Centers etc.

The Categories of Computers
Goals and Objectives
By the end of this session, the class should be aware of the four major categories of
computers in the market and for what use they are.
In the hardware, computer category, there are four major groups of computers. They are
the Supercomputer, mainframe, mini and micro-computer. Their definition is largely
historical and an outgrowth of the different requirements that each computer generation
was created for.
Microcomputers
The microcomputer is also known as the "Personal Computer". The monica or naming
the “Personal Computer” is largely related to IBM who introduced and marketed
the first widely available, commercialised microcomputer named
the “IBM PC” where PC stood for Personal Computer. As the most
dominant microcomputer in the introduction of microcomputers the IBM
PC became the standard against which all microcomputers were compared
and the branding that IBM created, the “PC” helped provide a
name for the industry it grew.
The category is termed “micro” because the fundamental component
that allowed the categories development was the CPU created on a
single chip (so this technology was affordable in comparison to
the mini/mainframe) created with the introduction of ‘microprocessors.’
The lower costs in the development and production
of the CPU and various components of the microcomputer allowed microcomputers
to become a broad market general purpose computer.
The general appeal, or focus of microcomputers on the individual’s enjoyment and productivity
has been a key factor in the microcomputer developments and enhancements
over the years. Where other computers were used by a broad group of people within an
organisation, the microcomputer was often used by a single person for single activities.
Where larger systems were focussed on the productivity of the whole department or organisation,
the microcomputer was often only effective for a single individual’s work.
One example of how Microcomputers differ is the use of Games. Many of the microcomputers
contain games because that is what people like to do after working hard.
Microcomputers can be grouped into five smaller groups; the workstations, desktops,
servers, laptops and notebooks. Each referring to the physical usage of the machines
and not necessarily the power.
Workstations generally re- fer to machines used for intensive
calculations on de- signs such as architecture and
buildings. Desktops generally refer to machines used
by business people for word processing, spreadsheeting
etc, and are physically placed onto a desk. The laptop
and the notebook are portable machines. Laptops generally
are bigger and clumsier due to the power supply being encased in
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the box holding the CPU. The notebook is generally smaller. Notebooks and laptops
can work on batteries allowing the user to work with it in aeroplanes, in the car and
places computers are not generally available.
Initially designed as stand-alone machines the PC and the operating systems popular on
the PCs do not integrate as well into networked environments as the other computer systems.
Personal Digital Assistants. PDAs are a very recent enhancement of electronic productivity
tools based on microprocessor technology. Personal Digital Assistants such as
Apple’s Messagepad 2000 provide business people, and technocrats, with common
daily organisation tools (such as a diary, telephone book, notepad) in a small packaging
usually no larger than a stenographer/short-hand notepad.
Minicomputers
Faster than the microcomputer with access to more
storage space and more input and output devices,
the minicomputer is used when large groups need
access to data simultaneously. The minicomputer
can do this because the hardware is designed for
plugging in more devices, and the C.P.U. And
support chips are designed more for this kind of
work than the microcomputer's.
The technology advancement from vacuum
tubes to transistors lead to the ability of manufacturers
and designers being able to create computers
smaller than mainframes and consequently more affordable for a broader
range of buyers. The advancement of technology to microchips and microprocessors
have allowed mincomputers, although more expensive, to maintain a greater processing
power and peripheral devices than the more commonly used microcomputer.
For example, large supermarkets around the world need to have their cash register
send sales information to the same computer (so that the data is collected in one
place). This work requires more input devices (cash registers) and output devices
(screens) than the microcomputer was designed to have access to. Some organisations,
like TCF and Morris Hedstrom, operate the local supermarket using local area
networks and microcomputers, but tie the various (100’s) supermarkets together to
the central office to a minicomputer. The minicomputer is also required to work when
all the sales people key in sales information at the same time, this requires a powerful
machine that can work with all the input devices at
the same time.
Minicomputers are used by medium sized business
and small sites of large organisations. They are also
used in factories to control automated assembly
lines.
Manufacturing, large process control. Where numerous
equipment have to be coordinated and operating
in time-critical sequence, such as a car manufacturing
plant, or chemical plant, minicomputers are
A Hard Disk Unit
used by Mini Computers
for external,
secondary storage
Amainframe
CPU
and control
terminal
Terminals used by
computer operators
to enter and review
data do not have
local hard disks nor
floppy disks.
A typical mini computer
may have 20
to 100 terminals
connected to the
mini allowing as
many people to
review data on
screen, as well as
from printouts.
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found to coordinate the many peripheral devices, collate and assess input from many
other peripheral devices. The microcomputer is inadequate in processing power and peripheral
connections to complete the work and mainframe computers are too expensive
for the job to be cost-effective.
An important measure for minicomputers and mainframes is the reliability of the machine
as it generally has to operate 24 hours where every minute of operation is important
to the company. A minute of downtime, where the computer is not functioning correctly,
is calculated in lost money for organisations. Microcomputers have not been
manufactured nor warranted for critical operations and many microcomputer manufacturers
explicitly state in their promotional material that the microcomputers are not designed
nor intended for critical operations.
Popular makers of minicomputers include DEC - Digital Equipment Corporation who
built the popular VAX minicomputer used in universities, banks and engineering firms.
IBM also creates a very popular mini computer range with a branding of the AS400.
Hewlett Packard has a popular minicomputer range branded the HP9000.
Mainframes
Mainframes have even more access to storage space and to input/output devices. To
work with these extra devices mainframes also have more powerful 'processors'. This
power is useful and required by large corporations who have large amounts of data to
process.
For example, large overseas banks who have millions of customer accounts to update
regular will need very powerful machines to process this data. These large banks
would have a mainframe maintain their customer account records (like their bank
book account balance, how much they withdrew, deposited) so that the customer
can turn-up at any of the branches (local bank building) to withdraw/deposit
money. So Sione who has a bank account in Nuku'alofa can take a trip to Ha'apai,
turn up to the bank in Pangai, Ha'apai to withdraw some money.
Another power of mainframes is that they are designed to connect input/output devices
that span vast distances. Like the above example, to connect devices that can
be as far away from each other as Nuku'alofa and Pangai, Ha'apai.
The powerful hardware and CPU chips that can support the above work can also
be used for making complex calculations, and designs. Mainframes are often used
by corporations who design jets or studying aerodynamics effects etc.
One major inducement for the development of these computers originally was the increasing
volumes of data collected by the US Bureau of Statistics during
the US Census. The volume of data was growing
rapidly such that the data required over
9 years to collate, compile, and publish.
As a consequence the US Census
(which is carried out every 10 years)
would re-occur before the data from
the previous census was available for
the public and the published information
was already significantly inaccurate
on the date of release.
A tape back up unit,
the height of a man,
used by Mainframes
for storing large volumes
of data.
ADisk “Bank” with the
hard disk storage used
by a mainframe
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Due to the limits of existing technologies of the time, the components of the
“Mainframe” were much larger than they are today and required vast spaces to store
them. Hence one of the terms synonymous with mainframe computers is “Big Iron” for
the literrally BIG space the machines took up and the BIG amount of metal it required
to put a machine together.
The most popular maker of mainframes is I.B.M. International Business Machines, a
large Multi-national Corporation headquartered in the U.S.A.
Supercomputers
Supercomputers have been developed from the processing requirements of advanced research
projects by engineers, scientists and more recently by other research fields. The
supercomputer is a title generally given to computers with processing power well exceeding
those of the fastest mainframes and its focus is processing data and manipulation
of tha data. A significant difference between mainframes and supercomputers is
the primary focus of super computers on processing capabilities independent of the
many varied input/output devices expected on mainframes.
The major cause for the development of super-class computers has been the continuing
need in the scientific community for faster and faster calculations. Scientists working
on atomic physics, computer intensive calculations such as natural speech recognition
continue to require more and more computational speed to test their theorems.
An example of the use of supercomputers is the USA National Weather Bureau for
world wide weather analysis. The Bureau collects weather information from around the
world and makes instant analysis of this data. This information is critical for airlines
who cannot afford to be late with their knowledge of what the weather conditions are
over their flight paths. The incredibly large amount of data that needs to be collected,
and the requirement for the answers to become available immediately is why a supercomputer
is used.
Large oil companies use supercomputers to analyse their geological findings and weapons
developers use supercomputers to test out new theories and strategies.
Again, the incredible amounts of data that geologists collect, and
the complexity of matching data with what can be potentially oil or
minerals requires very powerful computing facilities.
Car manufacturers simulate in three dimensions a car design and the
number of probable accidents that can occur to manage the design
safety requirements of vehicles without having to solder any metal
or build an engine. Supercomputers have been required for this
simulation process due to the complex calculations evaluating a
simulated accident and the display in three dimensions.
Most people do not currently need the ability to chart their
own world weather map so the supercomputer is not
for everyone. Supercomputers usually require specially
built facilities and a large staff of computer technicians
and computer engineers to maintain the hardware
and software.
The Cray XMP
Super Computer
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The most commonly known Supercomputer brand is the "Cray", from Cray Research
the first company to develop a "Super" computer. The distinctive, good looks of the
Cray Super Computer housed elaborate electronics in a look good box that was poured
through with liquid coolant to keep the system cool while it works.
History in the Making
Prior to electronic computers, mechanical devices used for calculations tabulations used
mechanical gearing to tabulate occurrences of events and were problematic due to the
wear (malfunctions) that occur with moving pieces of machinery and the problems of
creating accurate finishes on the mechanical devices to fit the designs.
The First Electric Calculating Machines – Herman Hollerith
To solve the problem, Herman Hollerith invented a calculating, tabulating machine that
used electricity rather than mechanical gears. Holes representing information to be
tabulated were punched in cards with the location of each hole representing a specific
piece of information (male, female, age, etc.) The cards were then inserted into the machine
and metal pins used to open and close electrical circuits.
Hollerith’s machine was immensely successful and based on its success and together
with some friends they formed a company that eventually became known as International
Business Machines (IBM).
The first computer-like machine is generally thought to be the Mark I, which was built
by a team from IBM and Harvard University. The Mark I used mechanical telephone
relay switches to store information and accepted data on punched cards, processed it and
then output the new data. Because it could not make decisions about the data it processed,
the Mark I was not, however, a real computer but was instead a highly sophisticated
calculator. It was, nevertheless, impressive and has now been dismantled (decommissioned)
with parts of it on display at the Undergraduate Science building at Harvard
University.
The First Electronic Computer – Eniac.
In 1943 work began on the Electronic Numerical Integration and Calculator, or
ENIAC. It was originally a secret military project which was to be used to calculate the
trajectory of artillery shells. In one of its first demonstrations it was given a problem
that would have taken a team of mathematicians three days to solve. It solved the problem
in twenty seconds.
ENIAC was different from the Mark I in several important ways. First, it occupied
1500 square feet, which is the same area taken up by the average two bedroom house
and it weighed 30 tons. Second, it used 17,000 vacuum tubes instead of relay switches.
Most importantly, because it was able to make decisions, it is considered to be the first
true computer.
ENIAC had two major shortcomings. First, it was difficult to change its instructions to
allow the computer to solve different problems. It had originally been designed only to
compute artillery trajectory tables, but when it needed to work on another problem it
could take up to three days of wire pulling, re-plugging and switch flipping to change
instructions. Second, because the tubes it contained were constantly burning out, the
ENIAC was unreliable.
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The mainframe grew out of vacuum tubes and as technology improved the mainframe
became smaller and less expensive. Correspondingly, the organisations who could afford
the original expensive machines had more money to spend on more features, capabilities
so although the mainframe decreased significantly in size, it still remained a
large creature using up a lot of electricity and space.
The Stored Program Computer – John von Neumann
In the late 1940’s, John von Neumann considered the idea of storing computer instructions
and data in memory, which was accessed by a central processing unit, or CPU.
The CPU would control all the functions of the computer electronically so that it would
not be necessary to flip switches or pull wires to change the instructions. Now it would
be possible to solve many different problems by simply typing in new instructions at the
keyboard. Together with other computer scientists, von Neumann designed and built
the EDVAC (Electronic Discrete Variable Automatic Computer) and the EDSAC
(Electronic Discrete Storage Automatic Computer).
With the development of the concept of stored instructions or “programs”, the modern
computer age was ready to begin. Since then the development of new computers has
progressed rapidly, but von Newmann’s concept has remained, for most part, unchanged.
The next computer to employ von Neumann’s concepts was the UNIVersal
Automatic Computer, called UNIVAC, developed in 1951.
Computers at this time continued to use many vacuum tubes which made them large and
expensive. UNIVAC weighed 35 tons. These computers were so expensive to purchase
and run that only the largest corporations and the US government could afford them.
Their ability to perform up to 1000 calculations per second, however, made them popular.
The Transistor – BELL Laboratories.
It was BELL Laboratories’ invention of the transistor that made smaller and less expensive
computers possible, with increased calculating speeds of up to 10,000 calculations
per second. Although the size of the computers shrank, they were still large and expensive.
In 1963, IBM, using ideas it had learned while working on projects for the military,
introduced the first medium-sized computer named the “model 650.” It was still
expensive, but it was capable of handling the flood of paperwork produced by the many
government agencies and businesses.
These new computers also saw a change in the way data was stored. Punched cards
were replaced by magnetic tape and high speed reel-to-reel tape machines. Using magnetic
tape gave computers the ability to read (access) and write (store) data quickly and
more reliably.
Another important advance occurring at the time was the development of programming
languages. Previously, computers had to be programmed by setting different switches
to their On or Off positions. The first programming languages were very similar, being
strings of 1’s and 0’s representing the status of the switches (1 for On, and 0 for Off).
These were called “low-level” languages. Languages such as FORTRAN (FORmula
TRANslator), which was the first popular “high-level” language, allowed programmers
to use English-like instructions such as READ and WRITE. With them, it was possible
to type instructions directly into the computer or on punched cards, eliminating the
time consuming task of re-writing.
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A number of high-level languages have been developed since that time including COBOL
(Common Business Oriented Language), BASIC (Beginner’s All-purpose Symbolic
Instruction Code), Ada, C, and Pascal.
Cobol was commissioned by the US Department of Defence in 1959 to provide a common
language for use on all computers and the development committee was chaired by
Commodore Grace Murray Hopper of the US Navy.
The Integrated Circuits and the Microprocessor
The next major technological advancement was the replacement of the transistor by tiny
integrated circuits or “chips.” Chips are blocks of silicon with logic circuits etched onto
their surface. They are smaller and cheaper than transistors and can contain thousands
of circuits on a single chip. Integrated circuits also give computers tremendous speed
allowing them to process information at a rate of 1,000,000 calculations per second.
One of the most important benefits of using integrated circuits is to decrease the cost
and size of computers. The IBM System 360 was one of the first computers to use integrated
circuits and was so popular with businesses that IBM had difficulty keeping up
with the demand. Computers had come down in size and price to such a point that
smaller organisations such as universities and hospitals could now afford them.
A very important advance to occur in the early 70’s was the invention of the microprocessor,
an entire CPU on a single chip. In 1970, Marcian Hoff, an engineer at Intel Corporation,
designed the first of these chips. As a result, in 1975 the ALTAIR microcomputer
was born which led to the creation of small software companies such as Microsoft
and in 1977 Stephen Wozniak and Steven Jobs designed and built the first mass market
microcomputer, the Apple. Microcomputers were inexpensive and engineers, hobbyists
were able to take their computers home.
The computer revolution had finally come home for many.
Homework Review Questions - Video Assignments
Over the next week, watch at least one of these videos, and be prepared to discuss in
class what type of computer was used, and what was it used for.
1. War Games 7. Jurassic park
2. Patriot Games (Harrison Ford) 8. Air Force One
3. Star Trek 9. Face-Off
4. Star Wars 10. Men-In-Black
5. Tron 11.
6. Rambo Part II 12.
Questions.
What was the movie about?
For what purpose was the computer used?
How did it help the hero/heroine solve his/her problem?
Review Questions
1. A mainframe is the name of one of the 4 types of computers give the names of the
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other two:
2. For the above 3 types, give 4 features that one can use to differentiate between them
3. Give one application of mainframe computers
4. Computers are sometimes referred to as “digital computers”. Define what is meant
by this term.
5. What was so important about Von Neumann’s contribution.
Sources and References
Presley, Bruce and William Freitas, A guide to structured programming in Basic for the
IBM PC and Comptabiles 3rd Edition, (Pennington, Lawrenceville Press, 1992)
Corel CD Office Companion
Long, Larry, Introduction to Computers and Information Systems, 4th Ed. (Englewood
Cliffs, Prentice Hall, 1994)
Beekman, George, Computer Currents, Navigating Tomorrow’s Technology, (Redwood
City, The Benjamin/Cummings Publishing Co, Inc, 1994)
Siliva, Tonga. Liahona High School 1997 Term 4 Final Exam, Computer Studies Form
5 (TSC)
www.tongatapu.net.to - Computer Studies Course Notes
www.tongatapu.net.to - Tonga on the 'NET
Tonga on the 'NET is available on all networked computers at Queen Salote College
and participating schools.