VARIOUS TYPES OF COMPUTER SYSTEMS

 1. Analog Computers

Analog is the Greek word, which means similar. So, in analog computers, the similarities
between any two quantities are measure by electrical voltages or current. The analog computers
operate by measuring instead of counting.
The analog computer works on the supply of continuous electrical signals. The display is
also continuous. Its output is in the form of graphs.
Analog Signal: An analog signal is a continuous variable electromagnetic wave. It can
consume an infinite number of voltage or current values.

Characteristics of analog computer

The analog computer has the following important characteristics:
a) It operates by measuring.
b) It requires physical analog.
c) It functions on continuously varying quantities.
d) The output is usually represented in the form of graph.
e) In analog, the calculations are first converted in equation and later converted into electrical
signals.
f) The accuracy of the output is poor.
g) It has limited memory space.
h) It is not versatile. i.e., it has limited application.
i) The speed of analog computer is low.
j) Not suitable for business and industry.

2. Digital Computers

These computers work with quantities represented as digits. They operate on discrete
quantities. In digital computer, both numeric and non-numeric information are represented as
strings of digits. These computers use binary codes, 0’s and 1’s, to represent the information.
The information is given to the computer in the form of discrete electrical signals.
The basic operation performed by a digital computer is addition. Hence, the other
operations such as multiplication, division, subtraction and exponentiation are first converted
into “addition” and then computed.

Characteristics of digital computer

The digital computer has the following characteristics:
a) It operates by counting.
b) It functions on discrete numbers.
c) The calculations are converted into binary numbers i.e., 1s and 0s.
d) The output is represented in the form of discrete values.
e) Its accuracy is good.

 f) It has large memory space
g) It is versatile in nature and is suitable for a number of applications
h) In digital computers , the numbers, words and symbols can be used.
i) Its processing speed is high.
j) It is highly suitable for business application.

 3. Hybrid computers:

The computer which possess the features of both analog and digital computers are called
hybrid computers. That is, the hybrid computers have the good qualities of both analog and
digital computer.
With the hybrid computer the user can process both continuous and discrete data. This
computer accepts either digital or analog or both types of input and gives the results as per
requirements through special devices. In the hybrid computers a converter is fixed to convert the
analog data into digital data and vice versa. These are special purpose devices and are not
widely used.

 4. General Purpose Computer

These are designed and constructed to cater almost all the needs of the society. They can
perform various operations. In fields of engineering, science, commerce and industry. They are
able to perform according to the programs created to meet different needs. The general – purpose
computer can be used to prepare stores reports, sales reports, payroll, etc. a general purpose
computer can solve a much broader class problems specifically a general purpose digital
computer is remarkably versatile.

5. Special Purpose Computers

These computers are designed to solve a particular problem or task, the computers are
provided with limited memory and speed necessary for a particular job. The instructions needed
to perform the particular task are incorporated into the internal memory of the computer. It does
not posses unnecessary options, hence it is economical. E.g. Business purpose computers and
scientific purpose computers.

6. Micro Computers

Because of its small size and the use of micro-processor, this computer is called micro
computer. All the computers have three units namely input, output and central processing unit,
(CPU). The entire CPU is contained in a single or a few microchips. When equipped with
memory and input/output control circuitry, it is called micro computer. Its storage capacity is
low when compared to mini and main frame computers. It is able to accept most of the high
level languages. However, it uses an interpreter or complier for running high level languages.
Microchips contain micro electronic circuitries which are very tiny. Large numbers of
these can be packed tightly on to a single tiny piece of silicon. Silicon is a material found in
sand. The microchip is made by building up a series of very thin layers of silicon and of the tiny
components which are held in it.

 The Micro computers are small and portable. They are relatively inexpensive, the micro
computers have excellent graphic capabilities. The maximum word length varies according to
the configuration of the microcomputers.

Kinds of Microchips

The microchips can be classified as follows:
a) Micro Processors: These are the most powerful kind. They are almost tiny computers in
themselves. Each one ahs a processing Unit, a memory and a special area to handle input
and output. Microprocessors are the most important part of the CPU of a modern computer
b) Memory Chips: These are the common form of computer memory. They are used to hold
information either temporarily or permanently.
c) Input and Output Chips: In these chip circuits the flow of information is the both
directions.

Features of Micro Computers

a) Its storage capacity is low.
b) Its rate of acceptance and transfer of data is limited i.e., a maximum of 5 lack bytes / second.
c) It is able to accept most high level languages. However it uses an interpreter when running
high level language because most micros do not have sufficiently large memory to support
compliers.
d) The maximum word length it holds is 16-bits.
Advantages
a) They are small and portable.
b) They are relatively inexpensive.
c) They work as soon as they are switched on.
d) They have excellent graphic capabilities,
e) They do not occupy much space.
f) They do not consume much power.
Disadvantages
a) Micros have a limited storage capacity.
b) They are relatively slow.

7. Workstation

Workstation is a type of computer used for engineering applications (CAD/ CAM), desk
top publishing, software development, and other types of applications that required a moderate
amount of computing power and relatively high quality graphics capabilities. Workstations
generally come with a large, high-resolution graphics screen, at least 64MB (Mega bytes) of
RAM, built – in network support, and a graphical user interface. Most workstations also have a
mass storage device such as a dish drive, but a special type of workstation, called a diskless
workstation, comes without a disk drive. The most common operating systems for workstations
are UNIX and Windows NT. In terms of computing power, workstations lie between personal
computers and mini-computers, although the line is fuzzy on both ends high-end personal
computers are equivalent to low-end workstations. And high-end workstations are equivalent to
minicomputers. Like personal computers, most workstations are single-user computers.
However, workstations are typically liked together to form a local-area network, although they
can also be used as stand-alone systems.

8. Mini Computers

The size of the mini-computer is in between the size of micro and main frame computers.
It is more powerful than a micro computer. Mini computers are usually designed to serve
multiple users. Today, mini-computers are the popular data processing systems in the field of
business and industry. These computers accept all high level languages.

Characteristics

1. It is a general purpose machine with a smaller CPU than a main frame
2. Its storage capacity is about 2 mega words
3. Its word lengths are usually 12, 16, 24, 32 bits.
4. Its rate of acceptance and transfer of data is a maximum of 4 million bytes/seconds
5. It can support all high level languages.
6. It can support many terminals i.e., more than 20 terminals.
Advantages
a) It performs almost all the tasks that a mainframe computer does.
b) It is relatively inexpensive and is within the purchasing power of the small and medium sized
business firms.
Disadvantages
a) They are very expensive
b) They required large room space.
c) Their consumption of electricity is very high.
d) Maintenance coast is also very high.

9. Super Computers

The super computers are very costly. Hence it is rarely used. Its capacity is abnormally
high, it cannot be compared with any other computers in capacity, function, speed, accuracy,
language etc., they have operations done in parallel, rather than sequential. They are employed
for specialized applications that require immense amounts of mathematical calculations. The
chief difference between a super computer and a main frame computer is that a super computer
channels all its power into executing a few programs as fast as possible. But main frame uses its
power to execute many programs concurrently. CRAY – 3, Cyber 205, and PARAM are some
well known super computers.

Characteristics

a) They use several processors working simultaneously.
b) They process at a rapid speed.
c) The main memory ranges form 8 to 64 megabytes.
d) They have operations done in parallel, rather than sequentially. They are used in weather
forecasting, supersonic aircrafts design and other works that require billions of calculations
per second.
e) They can be used for animated graphics-fluid dynamic calculations etc.,

10. Laptop computer:

Laptop computer, simply laptop (notebook computer or notebook), is a small mobile computer,
which usually weighs 2-18 pounds (1-6 kilograms), depending on size, materials, and other
factors.
Laptops usually run on a single main battery or from an external AC/DC adapter which
can charge the battery while also supplying power to the computer itself. Many computers also
have a 3 volt cell to run the clock and other processes in the event of a power failure.
As personal computers, laptops are capable of the same tasks as a desktop computer,
although they are typically less powerful for the same price. They contain components that are
similar to their desktop counterparts and perform the same functions, but are miniaturized and
optimized for mobile use and efficient power consumption. Laptops usually have liquid crystal
displays and most of them use different memory modules for their random access memory
(RAM), for instance, SO-DIMM in lieu of the larger DIMMs. In addition to a built-in keyboard,
they may utilize a touchpad (also known as a trackpad) or a pointing stick for input, though an
external keyboard or mouse can usually be attached.