Transcript CLASSIFICATION & CATEGORISATION OF COMPUTERS(1)

 We defined a computer as an electronic device that accepts
inputs, processes these inputs and gives an output, based
on the variable instruction given to it.
 A computer is made up of a number of parts; some
connected to the system unit (peripheral devices) while
others are embedded into the system unit (hardware and
software). It’s the combination of these devices that make
a computer function properly.
CATEGORISATION OF COMPUTER
SYSTEMS
 Broadly speaking, computer categorisation refers to
the distinction made between computers based on
their mode of operation on data or the type of data
they process, as they execute their INPUT, PROCESS
AND OUTPUT mechanisms. Other classifications,
based on size, purpose and function largely fall into
these broad categories.
 Computers are categorised as ANALOGUE, DIGITAL
or HYBRID.
ANALOGUE COMPUTERS
 These are computers that process analogous data.
Analog data can take on any value within a continuous
range.
 They measure continuously at extremely high speeds
and as a result, their results are usually approximations.
 They are special purpose computers commonly used in
manufacturing process control and weather prediction.
 Analogue computers are represented using a
continuous wave form.
 Analog data has 3 main characteristics; FREQUENCY
(Pitch), which refers to the number of times per
second the wave form repeats (measured in Hertz),
AMPLITUDE (Volume) referring to the maximum
height of the wave or strength of the signal (expressed
in volts) and PHASE referring to the rate at which a
signal changes in relation to time (expressed in
degrees).
 The higher the amplitude, the stronger or louder the
signal is.
 Analogue computers have largely been made obsolete
for general purpose mathematical tasks and data
processing by digital computers.
 The Ministry of Information and Telecommunication
Technology (Uganda) has come up with a policy on
digital Migration for television broadcasting in order
to improve signal quality. By the year 2015, Uganda
communication will entirely be digital.
 “The shift in Uganda’s broadcasting sector from analogue
broadcasting to digital broadcasting technologies is set to
revolutionize the broadcasting industry in the same way
when Compact Disc (CDs) and or Digital Video Disc
(DVDs) improved the music and videos industry when
they replaced the old analogue audio and videocassettes.
 This change on the whole is driven by digitization which
has lead to convergence of technologies
DIGITAL COMPUTERS
 A digital computer is a computer that performs
calculations and logical expressions with quantities
expressed as digits or numbers usually in the binary
number system.
 Computer operations work on the basis of electrical
inputs that can attain two states of ON = 1 and OFF =
0.
 Therefore, digital data can take on only a finite set of
discrete values.
 Digital Processing has consumed all aspects of society
today, ranging from computers to home appliances
such as TVs, clocks and microwaves.
HYBRID
 A hybrid – is a thing made by combining two different
elements. In terms of computing, hybrid computers have
features of both analogue and digital computers. This
means that they can process both analogue and digital
data.
 This type of computer is used extensively in process
control, as they provide good precision, that can be
attained by analogue computers and greater control that is
possible with digital computers.
COMPUTER CLASSIFICATION BY
SIZE
 Computers can as well be classified according to their
size; from the smallest (micro computer) to the largest
(super computer)
SUPER COMPUTERS
 They are the fastest, most expensive and powerful
computers. They are employed to execute complex
applications that require immense amounts of memory
and mathematical calculations.
 Application areas of super computers include; weather
forecasting, animated graphics, fluid dynamics,
petroleum exploration, defence and systems design
and analysis and nuclear energy research.
 They produce a lot of heat because of their enormous
size. Special cooling systems should be in place to cool
down the system.
 Typical examples of super computers include; NASA’S
COLUMBIA SUPER COMPUTER, and IBMS’
SEQUOIA super computer found at Lawrence
Livermore National Laboratory.
The Sequoia Super Computer
 Super computers are very expensive, priced from $2
million to about $20
specification.
million
depending
on
the
 They occupy huge spaces, have high processing speeds and
use a lot of electricity.
 All their physical attributes are typical characteristics of
First generation computers.
MAINFRAME COMPUTERS
 Main frame computers are almost similar to super
computers; the main difference being that super
computers are stronger and more expensive.
 They contain one to 16 CPU’s or even more. Its
processing speeds range from 80 to 550 MIPS
 Super computers and mainframes are almost similar in
shape and sometimes speed; the main difference being
that super computers channel all its power into executing
a few programs as fast as possible, whereas mainframes
uses its power to execute multiple programs
simultaneously.
 MARK I and IBM 704 Mainframe are examples of
mainframe computers
MINI COMPUTERS
 Mini computers are significantly smaller than mainframe
computers.
 According to Ronald E Anderson (1972), mini computers
have smaller memory modules, restricted instruction
sets and don’t necessarily come with peripheral
devices.
 Webopedia (2012) says that mini computers lie between
workstations and Mainframe computers.
 It is a cheaper version of the mainframe. They are also used
in scientific laboratories, engineering plants and in
manufacturing process control.
 They can as well be used for office work such as word
processing, spreadsheets and database management.
MICRO COMPUTERS
 Microcomputers are computers that use a microprocessor
for its central processing unit
 As earlier noted, micro computers are categorised as 4th
generation computers as compared to 1st generation (that
used vacuum tubes for internal circuitry), 2nd generation
(that used transistors) and third generation (that
employed Integrated circuits for internal circuitry).
THE PROCESSOR
 Due to advanced microprocessor technology, we have seen
cheaper and smaller computers, and therefore more
accessible technology.
 Because Micro computers are small and affordable, they
are the most common form of computer used in small
businesses, offices, training institutions, military, and in
the construction sector to name a few.
 Examples
of
micro computers include; Desktop
computers, Notebooks or Laptops and Personal
Digital Assistants (PDAs)
MICRO COMPUTERS
CLASSIFCATION BY FUNCTION
 This classification is based on how computers are
used; they can be Stand-alone, Networked, ReaTime or Integrated systems.
STAND-ALONE
COMPUTERS
 Stand-Alone computers can be a desktop or a laptop
computer that is used on its own, without requiring a
connection to a local area network (LAN) or a wide area
network (WAN).
NETWORKED COMPUTERS
 These are two or more computers that are connected
together to form a computer network with the aim of
sharing resources (hardware and software resources).
Networked computers are usually interconnected
through a communication medium (physical or
wireless communication medium).
NETWORKED COMPUTERS
REAL-TIME SYSTEMS
 REAL TIME systems are computers that execute tasks
under a time constraint. The correctness of the system
isn’t entirely dependant on the logical results of the
computation, but also on the time at which the results
are produced.
 Such computer systems employ a number of sensors (for
detecting slight changes in parameters), conditioning
circuits (for converting sensor output to the desired state)
and real time software.
 Examples of Real time systems include; Air traffic control
Systems, Automobile Braking Systems, Networked
Multimedia Systems, and Command Control Systems.
INTERGRATED
SYSTEMS
 Integrated Systems is a computer network that links
together different computing systems and software
applications physically or functionally to act as a
whole.
 It can also be defined as a collection of distinct
elements or components that have been built into a
single unit.
 This interconnection allows for common access to sensor
information and command and control.
 For better efficiency especially in terms of security,
Integrated Systems are designed in such a way as to
enforce independence, rather than inter-dependence.
 This means that failure of one system unit doesn’t affect
the other systems.
CLASSIFICATION ACCORDING TO
PURPOSE
 Computers can also be classified according to the tasks
they perform. Computers can be General Purpose or
Special Purpose.
GENERAL PURPOSE COMPUTERS
 These computers are designed to be able to deal with a
number of different tasks or problems, and should be able
to respond to a number of programs written for different
tasks.
 They are also able to store a number of software programs
and respond appropriately, for example, such computers
can do word processing, spreadsheets, accounting, data
and information management depending on the users
needs.
SPECIAL PURPOSE COMPUTERS
 As the name implies, such computers are designed to
perform one specific task. A specific set of limited
instructions is embedded into the computer system at
the manufacturing stage.
 Therefore, these highly specialised computers and are
very efficient at doing a specific task.
 They are usually referred to as ‘Dedicated Computers’,
because they are tied to a specific task.
 Examples of special purpose computers include Robots
used in specific manufacturing tasks, and electronic
calculators that do arithmetic only.