• To Study the different types of computers, ie:
Special Purpose Computers
General Purpose Computers
• To Study Different Generations of Computers.
• To list out advantages and disadvantages of each
type of computer.
• To look into brief history and describe key
features of different types of computers.
A general-purpose computer is one that, given the appropriate
application and required time, should be able to perform most
common computing tasks.
Personal computers, including desktops, notebooks, smartphones and
tablets, are all examples of general-purpose computers. The term is
used to differentiate general-purpose computers from other types, in
particular the specialized embedded computers used in intelligent
ENIAC, designed and built in the 1940s, was the first general-purpose
computer. ENIAC weighed 30 tons and covered an area of about 1,800
square feet. In contrast, a current smartphone weighs a few ounces and
is small enough to slip into a pocket.
A laptop is a portable computer that contains the computer, monitor,
keyboard, and fingerpad all in one unit. When laptops first became
available, they were bulky and very expensive. As demand for laptops
has grown, they have become cheaper to manufacture and purchase.
Advantages of Laptops
• Laptops are compact and light to carry around.
• Wireless networking allows people access to the Internet and
emails whilst travelling.
• The latest batteries last for a lot longer nowadays before
requiring a recharge.
• People who commute or travel to their workplace, can carry their
laptop with them.
Disadvantages of Laptops
• Laptops can be more expensive than desktops with similar
• Some people find the fingerpad very fiddly to use.
• They cannot be customized like desktops, although some options
are available at the time of purchase, e.g. extra RAM
• Documents on screen can be very small if doing detailed work,
due to the limitation of the screen size.
A personal computer (PC) is a general-purpose computer, whose
size, capabilities and original sale price makes it useful for individuals,
and which is intended to be operated directly by an end user with no
intervening computer operator. This contrasted with the batch
processing or time sharing models which allowed larger, more
expensive minicomputers and mainframe systems to be used by many
people, usually at the same time. Large data processing systems
require a full-time staff to operate efficiently.
• They are cheap.
• They can be upgraded, with new components.
• They can be customised to suit a particular need.
The disadvantages of desktops are:
• They are heavy, bulky and not easily portable
• They take up a lot of space
• They get out of date very quickly due to advances in technology.
A tablet is a one-piece mobile computing device with a touchscreen and an on-
screen .virtual keypad The tablet computer and its associated operating system
began with the development .of pen computing
Tablets are equipped with sensors, including cameras, microphone,
accelerometer and ,touchscreen with finger or stylus gestures replacing
.computer mouse and keyboard
Tablets may include physical buttons, e.g., to control basic features such as
speaker volume and power and ports for network communications and to charge
. - , - .the battery An on screen pop up virtual keyboard is usually used for typing
Tablets are typically larger than smart phones or personal digital assistants at 7
( ) , .inches 18 cm or larger measured diagonally
Advantages of tablet PC
• portability (can work from everywhere and small enough to put in handbags)
• can be used as a GPS navigation device
• offer the same functionality as a normal computer
• gesture recognition
• great and handy for note taking
• a multi-touch tablet permits you to interact with all the subject matter material
• comfort and ease of use
• an effective learning and teaching enhancement tool
• you can continue and finish their work while in transit
• serve as an organizer to professional with much less paper on hand.
Disadvantages of tablet PC
• traditional keyboards are much more comfortable.
• the screen size is too small in comparison with a laptop.
• do not come with optical drives for use with CDs or DVDs.
• potential screen damages and repair costs (more chances of screen damage to
tablet PCs than to laptops; tablet computers are prone to problems like cracks,
dead pixels, blown back-light bulbs and bad sensors).
• difficulties to work on the small screen as compared to larger screen size of the
Minicomputers are used by small businesses & firms. Minicomputers are also called as
These are small machines and can be accommodated on a disk with not as processing and
data storage capabilities as super-computers & Mainframes.
These computers are not designed for a single user. Individual departments of a large
company or organizations use Mini-computers for specific purposes. For example, a
production department can use Mini-computers for monitoring certain production
• Texas Instrument TI-990
• IBM Midrange computers
SPECIAL PURPOSE COMPUTERS
As the name states, a Special-Purpose Computer 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 perfom 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 is 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
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
The most powerful computers in terms of performance and data processing are the
These are specialized and task specific computers, used by large organizations.
These computers are used for research and exploration purposes, like NASA uses
supercomputers for launching space shuttles, controlling them and for space exploration
The supercomputers are very expensive and very large in size. It can be accommodated in
large air-conditioned rooms; some super computers can span an entire building.
In 1964, Seymour cray designed the first supercomptuer "CDC 6600".
Uses of Super Computers
Supercomputers are used to study the origin of the universe, the dark-matters. For these
studies scientist use IBM’s powerful supercomputer “Roadrunner” at National Laboratory
Supercomputers are used to study the Earthquakes phenomenon. Besides that
supercomputers are used for natural resources exploration, like natural gas, petroleum,
Supercomputers are used for weather forecasting, and to study the nature and extent of
Hurricanes, Rainfalls, windstorms, etc.
Nuclear weapons testing
Supercomputers are used to run weapon simulation that can test the Range, accuracy &
impact of Nuclear weapons.
Mainframe computers are used by large companies to do complex
tasks, such as manage and control all aspects of a large production
line, or process millions of financial transactions.
Mainframes can carry out many different tasks at the same time. They
also complete these tasks very quickly and reliably.
A mainframe may work continuously for many years, without failing.
The vast majority of mainframes are made by IBM, and cost between
£30,000 and £500,000. The electricity costs for a mainframe could be
as high as £10,000 a year.
Originally mainframes were the size of a large room (this is where the
name comes from), however modern mainframes are about the size of
a large wardrobe.
An embedded computer is frequently a computer that is implemented for a particular
purpose. In contrast, an average PC computer usually serves a number of purposes:
checking email, surfing the internet, listening to music, word processing, etc... However,
embedded systems usually only have a single task, or a very small number of related
tasks that they are programmed to perform.
Every home has several examples of embedded computers. Any appliance that has a
digital clock, for instance, has a small embedded micro-controller that performs no other
task than to display the clock. Modern cars have embedded computers onboard that
control such things as ignition timing and anti-lock brakes using input from a number of
In general, an Embedded System: It is a combination of hardware and software to
performs a specific task.
• Is a system built to perform its duty, completely or partially independent of human
• Is specially designed to perform a few tasks in the most efficient way.
• Interacts with physical elements in our environment, viz. controlling and driving a
motor, sensing temperature, etc.
Most embedded systems are time critical applications meaning that the embedded system
is working in an environment where timing is very important: the results of an operation
are only relevant if they take place in a specific time frame.
Embedded systems are considered when the cost of implementing a product designed in
software on a microprocessor and some small amount of hardware, is cheaper, more
reliable, or better for some other reason than a discrete hardware design.
Embedded computers may be economical, but they are often prone to some very specific
Another problem with embedded computers is that they are often installed in systems for
which unreliability is not an option. For instance, the computer controlling the brakes in
your car cannot be allowed to fail under any condition.
An embedded system will have very few resources when compared to full blown
computing systems like a desktop computer, the memory capacity and processing power
in an embedded system is limited. It is more challenging to develop an embedded system
when compared to developing an application for a desktop system as we are developing a
program for a very constricted environment.
SYSTEM EXAMPLES: WATCH
It is a time display SYSTEM
Parts: Hardware, Needles, Battery, Dial, Chassis and Strap
• All needles move clockwise.
• Only a thin needle rotates every second.
• A long needle rotates every minute.
• A short needle rotates every hour.
• All needles return to the original position after 12 hours.
SYSTEM EXAMPLES: WASHING MACHINE
It is an automatic clothes washing SYSTEM
Parts: Status display panel, Switches & Dials, Motor, Power supply & control unit, Inner
water level sensor and solenoid valve.
• Wash by spinning
• Wash over by blinking
• Each step display the process stage
• In case interruption, execute only the remaining.
Five Generation Of Computers
• First Generation Of Computers
• Second Generation Of Computers
• Third Generation Of Computers
• Fourth Generation Of Computers
• Fifth Generation Of Computers
First Generation Of Computers
The computers of this generation use electronic devices known as Vacum
Tubes and punched cards to record data.
• Period : 1940-1956
• Size : Very Huge( Size of 3 rooms)
• Devices Used : Vacum Tubes
• Examples : Mark1, UNIVAC 1, EDVAC, EDSAC
Second Generation Of Computers
These computers use transistors in place of Vacum Tubes.
• Period : 1957-1963
• Size : Much Smaller Than First Generation Computers
• Devices Used : Transistors
Third Generation Of
Integerated Circuits are made by many transistors.
• Period : 1964-1971
• Size : Much smaller than second generation of computers
• Devices Used : Integerated Circuits
Fourth Generation Of
A large number of integerated circuits were put together in a material
called silicon chips. Silicon chips were reliable and cheap.
• Period : After 1972 to present
• Size : Very Small in Size
• Devices Used : Silicon Chips
Fifth Generation Of
These computers are based on artificial intelligence. Parallel
processing and superconductors are used.
• Period : Present and Beyond
• Size : Very Small
• Devices Used : Superconductors
• Examples : Robots