CLASSIFICATION
You know that device, which computers is called computer. For computation, computer takes some input, performs computation on it and gives result.
The type of input that computers accepts, decides its nature and capabilities and the type of computation that it will be able to perform. For example, some of the computers accept input in the form of signals. On the other hand, majority of computers take input in the form of digits. Some computers accept input in both the forms i.e. in the form of digits and signals. On the basis of input type, computers have been classified into following three categories:
Analog computers
Digital computers
Hybrid computers
A brief description is of all these types of computers is given below:
Analog Computer
Let’s first understand what is signal. Signal can be defined as continuous flow of physical identity. Temperature, pressure, water level, speed, voltage, current etc. are few examples of signals.
Those computers, which operate upon signals (by accepting temperature, pressure, speed etc. as input) are called analog computers. Speedometer, thermometer, barometer, voltmeter, ammeter etc. are few example of analog computer.
To understand the concept of analog computers, let’s take the example of speedometer, which is used in scooters and car. It makes use of cable. It make use of cable. One end of the cable remains in contact with the wheel of the vehicle. The other end of cable is inserted in the speedometer. When the wheel rotates, cable also rotates. Cable’s rotation is thus passed to the internal assembly of the speedometer, which in turn rotate the needle on a calibrated scale. Thus when the vehicle moves, its speed gets displayed on the needle on the speedometer’s scale.
The slide rule is hand-operated analog computer for doing arithmetic operations like multiplication, division etc.
Digital Computer
In computer terminology, alphabets, numbers, special characters, etc. are called digits. Those computers, which accept digit (like name, age, e-mail address etc.) as input, are called digital computers. Computers that we see in offices, shops, hotels etc. are digital computers.
Hybrid Computer
The computers, which accept both types of inputs i.e. signals and digital are called hybrid computers. For example, computer placed in ICU (Intensive Care Unit) are examples of hybrid computers. They accept heartbeat of patient (signal) as input. They also accept instructions that need to be carried out in the form of digits. Similarly computers which are placed in atomic reactors (taking radioactivity level and instruction as input) and mines (which take carbon monoxide level and instruction as level and instructions as input) are other examples of hybrid computers.
Note that in this website, we will mainly deal with digital computers. All the aspects, explained now and onwards would mainly apply to digital computers unless stated otherwise.
Types of Computers
Digital computers can be parts into various categories, on the basis of their sizes. When we say, size of the computer, it refers to multiple factors like, size of the hard disk, type of processor used in the computer etc. Digital computers are generally classified into following categories;
1. Microcomputers
2. Mini computers
3. mainframe computers
4. Supercomputers
Micro Computers
Micro computer is the very very small category of computers, in which single microchip is used for two units namely Arithmetic Logic Unit(ALU) and Control Unit(CU). This microchip is often referred to as microprocessor. Microcomputers are further parts into following categories:
1. Personal computers
2. Laptop computers
3. Tablet PC
4. Personal Digital Assistant (PDA)
Personal Computers (PC)
Computers which you commonly see these days are examples of Personal Computers. In short, we can called them PC. They mainly made up of four units i.e. CPU box called chaises, keyboard, VDU and mouse. Only one person can work at a time, so they are called single user computers. Originally single user computers were designed and manufactured by IBM. Later, as they became popular, other manufacturers also started manufacturing similar type of computers which were called as IBM clones.
Tablets PCs
Tablets PC is the largest development in the field of
computers. It
looks like laptop computer with many more enhancements and additional
facilities within same space.
Display system of Tablets PC, vertically rotates, by 1800.
When rotated, it starts accepting input through a special pen which are called
light pen. Whatever is written on Tablet PC’s screen with the light pen or in natural
handwriting, is taken as input. Thus writers need not write their articles on
paper and then give it to typist to get
its formatted copy. They can directly write the text on Tablet PC’s screen using this light pen. Tablet PC will recognize their handwriting and save the
document in predefined format, in desired font, as if typist typed if on
computer. Similarly artists can now draw figures, directly on Tablets PC’s screen
and color them too. Light pens also have the advantage or capability of removing written text or
drawing lines, as if natural eraser was being used for making corrections.
Some of the Tablets PCs also accept voice input, through
microphone. Whatever is spoken in front of them is converted into text file.
Personal Digital Assistant (PDA)
Personal Digital Assistants are very small computers that can be fit within a palm. They are generally of the
size of scientific calculator. This is the reason, why they are also called
Palmtop computers. They are mostly used for storing addresses, telephone
numbers, maintain personal appointments etc. They can also be connected to
higher range computers either through cable or wireless link, for the exchange
of the data information.
Minicomputers
Minicomputers are relatively larger and faster computers.
Apart from single user environment, they also support multi user environment.
They are generally used for automating those applications, which are large in
size, require fast processing capabilities and demand for resource sharing
among multiple users. Main characterstics of minicomputers are described below.
They are built, using high performance and high
capability processors.
Memory size in such type of computers is
generally very large.
They support multiple terminals, which may range
from 2 to 16.
Large capacity disks are used in multiple
numbers so that the data and programs of all the users could be put on-line.
They provide facility to connect multiple printers.
They possess the capability of performing
computer network related major operations.
Mainframes
Mainframes comes under next higher category of computers.
Their internal architecture and circuitry are different from minicomputers.
They use specially designed circuits instead of a single
microprocessor as their CPU. Their circuitry gives higher connectivity,
faster through-puts and large data processing capabilities.
Due to proprietary circuitry, mainframes become quite big in
size and provide facility for connecting minicomputers and microcomputers within.The main characteristics of mainframes are listed below.
They possess the capability of addressing larger
memory sizes than minicomputers.
They also support huge capacity disks like
optical disks etc.
The terminal connectivity can go as high as 256
or beyond.
They possess large number of application that provides great help to developers in developing useful
applications.
Supercomputers
Supercomputers is the largest category of computers. They
use number of CPUs for processing the data and executing the instructions. While
performing a task through Supercomputer, the complete task is divided into
multiple independent tasks. Each CPU takes up individual task and computers it
in parallel processing.
Due to parallel processing, Supercomputers become capable of
processing large volumes of data at very fast speed. They process multi-million commands to few trillion commands per second. Applications like weather forecasting,
nuclear weapon design, projection system modeling etc., which require
huge processing capabilities, can be very well executed on Supercomputers.
No comments:
Post a Comment