Computer System |
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The diagram below shows you the
idea of a computer system in its most basic form.
The computer system has one or
more inputs to provide data. This data is then processed in some way. The
outcome of the processing is sent to an output or it may be stored until some
event happens to cause it to be output.
For processing to take place, there needs to be a set of instructions is
called a program.
This system is called a
stored-program computer. The very first commercial computer in the entire world
of this type was built in Britain in 1949 and was called the Manchester
(Ferranti) Mark 1, see below.
The beauty of this type of
computer system is that it is flexible the machine performs a different task by
simply loading a different program from storage.
Types of Computers by Purpose. |
General Purpose Computers
Most computers in use today are
general-purpose computers-those built for a great variety of processing jobs.
Simply by using a general purpose computer and different software, various
tasks can be accomplished, including writing and edit (word processing),
manipulating facts in a data base, tracing manufacturing inventory, making
scientific calculations, or even controlling organization’s security system,
electricity consumption and building temperature. General purpose computers are
designed to perform a wide variety of functions and operations.
A general purpose computer is able to perform
a wide variety of operations because can store and execute different programs
in its internal storage.
Unfortunately, having this
ability is often achieved at the expense of speed and efficiency. In most
situations, however you will find that having this flexibility makes this
compromise a most acceptable one.
Special Purpose Computers
As the name states, a Special-
Purpose Computers are designed to be task specific and most of the times their
job is to solve one particular problem. They are also known as dedicated
computers, because they are dedicated to perform a single task over and over
again. Such a computer system would be useful in playing graphic intensive
video games; traffic lights control system, navigational system in an aircraft,
weather forecasting satellite launch/ tracking, oil exploration and in automotive industries, keeping time in a digital watch, or Robot helicopter,
While a special purpose computer may have many of the same features found in a
general purpose computer its applicability to a particular problem a function
of its design rather than to a stored program.
The
instructions that control it are built directly into the computer, which makes
for a more efficient and effective operation. They perform only one function
and therefore cut down on the amount of memory needed and also the amount of
information which can be input into them. As these computers have to perform
only one task, therefore, they are fast in processing. A drawback of this
specialization, however, is the computer’s lack of versatility. It cannot be
used to perform other operations.
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There are three basic kinds of
computers. This is based on the hardware structure and the way physical
quantities are represented in a computer. The following are three types.
- Analog Computers
- Digital Computers
- Hybrid Computers
Analog Computers
Analog computers are used to
process analog data. Analog data is of continuous nature and which is not
discrete or separate. Such type of data includes temperature, pressure, speed
weight, voltage, depth etc. These quantities are continuous and having an
infinite variety of values.
It measures
continuous changes in some physical quantity e.g. The Speedometer of a car
measures speed, the change of temperature is measured by a Thermometer, the weight is measured
by Weights machine. These computers are ideal in situations where data can be
accepted directly from measuring instrument without having to convert it into
numbers or codes.
Analog computers are the first computers being
developed and provided the basis for the development of the modern digital
computers. Analog computers are widely used for certain specialized engineering
and scientific applications, for calculation and measurement of analog
quantities. They are frequently used to control process such as those found in
oil refinery where flow and temperature measurements are important. They are
used for example in paper making and in chemical industry. Analog computers do
not require any storage capability because they measure and compare quantities
in a single operation. Output from an analog computer is generally in the form
of readings on a series of dial (Speedometer of a car) or a graph on strip
chart.
Digital Computers
A Digital
Computer, as its name implies, works with digits to represent numerals, letters
or other special symbols. Digital Computers operate on inputs which are ON-OFF
type and its output is also in the form of ON-OFF signal. Normally, an ON is
represented by a 1 and an OFF is represented by a 0. So we can say that digital
computers process information which is based on the presence or the absence of
an electrical charge or we prefer to say a binary 1 or 0.
A digital
computer can be used to process numeric as well as non-numeric data. It can
perform arithmetic operations like addition, subtraction, multiplication and
division and also logical operations. Most of the computers available today are
digital computers. The most common examples of digital computers are accounting
machines and calculators.
The results
of digital computers are more accurate than the results of analog computers.
Analog computers are faster than digital. Analog computers lack memory whereas
digital computers store information.
We can say that digital computers count and analog computers measures.
Hybrid Computers
A hybrid is a combination of digital and analog
computers. It combines the best features of both types of computers, i-e. It
has the speed of analog computer and the memory and accuracy of digital
computer. Hybrid computers are used mainly in specialized applications where
both kinds of data need to be processed. Therefore, they help the user, to
process both continuous and discrete data. For example a petrol pump contains a
processor that converts fuel flow measurements into quantity and price values.
In hospital Intensive Care Unit (ICU), an analog device is used which measures
patient's blood pressure and temperature which are then converted and displayed
in the form of digits. Hybrid computers for example are used for scientific
calculations, in defense and radar systems.
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Super Computers
A supercomputer is a computer with a
high-level computational capacity compared to a general-purpose computer.
Performance of a supercomputer is measured in floating point operations per
second (FLOPS) instead of million instructions per second (MIPS). As of 2015,
there are supercomputers which can perform up to quadrillions of FLOPS.
Supercomputers were introduced in
the 1960s, made initially, and for decades primarily, by Seymour Cray at
Control Data Corporation (CDC), Cray Research and subsequent companies bearing
his name or monogram. While the supercomputers of the 1970s used only a few
processors, in the 1990s machines with thousands of processors began to appear
and, by the end of the 20th century, massively parallel supercomputers with
tens of thousands of "off-the-shelf" processors were the norm.[3][4]
Since its introduction in June 2013, China's Tianhe-2 supercomputer is
currently the fastest in the world at 33.86 petaFLOPS (PF-LOPS), or 33.86
quadrillions of FLOPS.
Supercomputers play an important
role in the field of computational science, and are used for a wide range of
computationally intensive tasks in various fields, including quantum mechanics,
weather forecasting, climate research, oil and gas exploration, molecular
modeling (computing the structures and properties of chemical compounds,
biological macromolecules, polymers, and crystals), and physical simulations
(such as simulations of the early moments of the universe, airplane and
spacecraft aerodynamics, the detonation of nuclear weapons, and nuclear
fusion). Throughout their history, they have been essential in the field of
cryptanalysis.
Systems with massive numbers of
processors generally take one of two paths: In one approach (e.g., in
distributed computing), a large number of discrete computers (e.g., laptops)
distributed across a network (e.g., the Internet) devote some or all of their
time to solving a common problem; each individual computer (client) receives
and completes many small tasks, reporting the results to a central server which
integrates the task results from all the clients into the overall solution. In
another approach, a large number of dedicated processors are placed in close
proximity to each other (e.g. in a computer cluster); this saves considerable
time moving data around and makes it possible for the processors to work
together (rather than on separate tasks), for example in mesh and hypercube
architectures.
The
use of multi-core processors combined with centralization is an emerging trend;
one can think of this as a small cluster (the multi-core processor in a
smartphone, tablet, laptop, etc.) that both depends upon and contributes to the
cloud.
Mainframe Computers
A mainframe computer is a big
computer. IBM builds mainframe computers. Today, a mainframe refers to IBM's
System Z servers. Many large corporations like banks, insurance companies,
travel and retail sector, telecom companies process data on a mainframe. Today,
thousands of people around the globe book flights do wire transfers make
credit-card purchases. These transactions are processed in a snap by a
mainframe.
Well, not quite. Mainframes are not
good at number-crunching or don't do scientific calculations. A Mainframe is
not a Super-computer. You wouldn’t use a Mainframe computer to calculate the
value of Pi, up to 1000-decimal Places. Mainframe-Computers are not meant for
speed. They aren’t fast, rather they can process humungous data reliably. You
can't play games like Counter-Strike or Half-Life on a Mainframe.
Mainframe computers don’t have a
beautiful user-interface like the PC at your home. You wouldn’t find desktop
wallpaper or icons on a mainframe computer.
Mini Computers
Mini
computers have been very popular in business. Minis are frequently used to add
computer power with mainframes. Sometimes an organization decides to
decentralize or distribute its computer power to various stations or locations
within user’s departments. Mini computers are ideal for processing data in a
decentralized mode since they are small. More over mini have also made it
possible for many smaller organizations to afford a computer for the first
time. The input/output devices are lesser as compared to mainframe. The speed
is usually from 10 MIPS to onward. RAM is from 2 MB to onward.
Minicomputer
is smaller, less expensive, and less powerful than a mainframe or
supercomputer, but more expensive and more powerful than a personal computer.
Minicomputers are used for scientific and engineering computations,
business-transaction processing, file handling, and database management, and
are often now referred to as small or midsize servers.
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Micro Computers
Microcomputer
is an electronic device with a microprocessor as its central processing unit
(CPU). Microcomputer was formerly a commonly used term for personal computers,
particularly any of a class of small digital computers whose CPU is contained
on a single integrated semiconductor chip. Thus, a microcomputer uses a single
microprocessor for its CPU, which performs all logic and arithmetic operations.
The system also contains a number of associated semiconductor chips that serve
as the main memory for storing program instructions and data and as interfaces
for exchanging data of this sort with peripheral equipment—namely, input/output
devices (e.g., keyboard, video display, and printer) Moreover micros are
frequently used to provide additional computer power for companies that already
have mainframes or minis. These are rare input/output devices with
microcomputers. It is mostly used as a single user. Its speed is usually
counted in MHz rather than MIPS. The speed is generally from 8 MHz to onward.
The RAM is from 640 KB to onward.
The
increasing use of micros in home, school, business and professional offices has
been even more revolutionary. Although these computers have limited memory and
speed, their cost makes them very attractive for applications that would
otherwise not be feasible.
Mobile Computers
Mobile
computing is human–computer interaction by which a computer is expected to be
transported during normal usage. Mobile computing involves mobile
communication, mobile hardware, and mobile software. Communication issues
include ad hoc and infrastructure networks as well as communication properties,
protocols, data formats and concrete technologies. Hardware includes mobile
devices or device components. Mobile software deals with the characteristics
and requirements of mobile applications.
Some
of the most common forms of mobile computing devices are as follows.
- Portable computers, compacted lightweight units including a full character set keyboard and primarily intended as hosts for software that may be parametrized, as laptops, notebooks, notepads, etc.
- Mobile phones including a restricted key set primarily intended but not restricted to for vocal communications, as cell phones, smart phones, phone pads, etc.
- Smart cards that can run multiple applications but typically payment, travel and secure area access
- Wearable computers mostly limited to functional keys and primarily intended as incorporation of software agents, as watches, wristbands, necklaces, key less implants, etc.
- The existence of these classes is expected to be long lasting, and complementary in personal usage, none replacing one the other in all features of convenience.
Other
types of mobile computers have been introduced since the 1990s including the:
- Portable computer (discontinued)
- Personal digital assistant/Enterprise digital assistant (discontinued)
- Ultra-Mobile PC (discontinued)
- Laptop
- Smartphone
- Robots
- Tablet computer
- Wearable computer
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Types of Computers by Generations
First Generation (1940-1956) – Vacuum Tubes
The first
computers used vacuum tubes for circuitry and magnetic drums for memory, and
were often enormous, taking up entire rooms. They were very expensive to
operate and in addition to using a great deal of electricity, generated a lot
of heat, which was often the cause of malfunctions.
First
generation computers relied on machine language, the lowest-level programming
language understood by computers, to perform operations, and they could only
solve one problem at a time. Input was based on punched cards and paper tape,
and output was displayed on printouts.
The UNIVAC
and ENIAC computers are examples of first-generation computing devices. The
UNIVAC was the first commercial computer delivered to a business client, the
U.S. Census Bureau in 1951.
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Second Generation (1956-1963) - Transistors
Transistors
replaced vacuum tubes and ushered in the second generation of computers. The
transistor was invented in 1947 but did not see widespread use in computers
until the late 1950s. The transistor was far superior to the vacuum tube,
allowing computers to become smaller, faster, cheaper, more energy-efficient
and more reliable than their first-generation predecessors. Though the
transistor still generated a great deal of heat that subjected the computer to
damage, it was a vast improvement over the vacuum tube. Second-generation
computers still relied on punched cards for input and printouts for output.
Second-generation
computers moved from cryptic binary machine language to symbolic, or assembly,
languages, which allowed programmers to specify instructions in words.
High-level programming languages were also being developed at this time, such
as early versions of COBOL and FORTRAN. These were also the first computers
that stored their instructions in their memory, which moved from a magnetic
drum to magnetic core technology.
The first
computers of this generation were developed for the atomic energy industry.
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Third Generation (1964-1971)- Integrated Circuits
The development
of the integrated circuit was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on silicon chips, called
semiconductors, which drastically increased the speed and efficiency of
computers.
Instead of punched
cards and printouts, users interacted with third generation computers through
keyboards and monitors and interfaced with an operating system, which allowed
the device to run many different applications at one time with a central
program that monitored the memory. Computers for the first time became
accessible to a mass audience because they were smaller and cheaper than their
predecessors.
Fourth Generation (1971-Present) Microprocessors
The
microprocessor brought the fourth generation of computers, as thousands of
integrated circuits were built onto a single silicon chip. What in the first
generation filled an entire room could now fit in the palm of the hand. The
Intel 4004 chip, developed in 1971, located all the components of the computer—from
the central processing unit and memory to input/output controls—on a single
chip.
In 1981 IBM
introduced its first computer for the home user, and in 1984 Apple introduced
the Macintosh. Microprocessors also moved out of the realm of desktop computers
and into many areas of life as more and more everyday products began to use
microprocessors.
As these
small computers became more powerful, they could be linked together to form
networks, which eventually led to the development of the Internet. Fourth generation
computers also saw the development of GUI s, the mouse and handheld devices.
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Fifth Generation (Present and Beyond) Artificial Intelligence
Fifth generation computing devices, based on
artificial intelligence, are still in development, though there are some
applications, such as voice recognition, that are being used today. The use of
parallel processing and superconductors is helping to make artificial
intelligence a reality. Quantum computation and molecular and nanotechnology
will radically change the face of computers in years to come. The goal of
fifth-generation computing is to develop devices that respond to natural
language input and are capable of learning and self-organization.
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