CBSE Class 6 Computer Science Types of Computers Notes Set 04

Why there are different kinds of computers

Not every job needs the same machine. A weather office has to handle huge amounts of data, while a student only needs to write a project. So computers are built in different sizes, speeds and prices. They are usually compared on three things: processing speed, storage capacity and the area where they are used.

1. Supercomputers

Supercomputers are the fastest and most powerful computers. They have thousands of processors that work on parts of a problem at the same time, which is called parallel processing. They are very costly, so only large institutions own them. Their speed is measured in FLOPS (floating point operations per second). India's first supercomputer, PARAM 8000, was built by C-DAC in 1991, and the country has built many more since. Uses: weather forecasting, space research, studying earthquakes, designing aircraft and running complex simulations.

2. Mainframe computers

A mainframe is a very large and expensive computer that can serve hundreds or thousands of users at once. It stores huge amounts of data and handles many tasks together with great reliability. It needs a clean, cool, air-conditioned room. Uses: banks, insurance companies, railway reservation, government departments and large businesses.

3. Minicomputers

A minicomputer is smaller and cheaper than a mainframe but more powerful than a personal computer. It lets several users work at the same time. Uses: running small and medium companies, controlling factory machines, computer aided design and data processing in engineering firms.

4. Microcomputers

A microcomputer uses a microprocessor chip as its CPU and is meant for one user at a time, which is why it is called a personal computer (PC). It is small, affordable and easy to use. Desktops, laptops and tablets are microcomputers. Uses: homes, schools and offices for writing, drawing, browsing the internet, watching videos and playing games.

Other computing devices

Smartphones are hand-held, wireless devices that can make calls and messages and also browse the web and run apps. Game consoles such as PlayStation and Xbox are made mainly to play games on a screen using a controller. Embedded computers are small computers built into other machines to do one fixed job, such as in a washing machine, microwave oven, ATM or a smart television.

How a computer works: input, process, output

A computer takes in raw data (input), works on it (processing) and gives useful information (output). Keyboards and mice are input devices, and monitors and printers are output devices. Processing takes place in the CPU, the brain of the computer, following a set of instructions called a program.

Parts of the CPU

1. Arithmetic Logic Unit (ALU): does calculations such as addition and subtraction and logical comparisons such as which number is greater.

2. Control Unit (CU): directs and coordinates all the parts of the computer and controls the flow of data and instructions.

3. Memory Unit (MU): holds data, instructions and results while they are being used.

Comparison at a glance

1. Supercomputer: fastest, thousands of processors, scientific work.

2. Mainframe: huge storage, many users together, banks and governments.

3. Minicomputer: mid-sized, several users, small and medium organisations.

4. Microcomputer: single user, low cost, home and office use.

Worked examples

Example 1. Which type of computer would a weather department use to predict a cyclone? A supercomputer, because the forecast needs billions of calculations done quickly.

Example 2. A bank has to keep records of lakhs of customers who access them from many branches at once. Which type of computer suits it? A mainframe, since it supports thousands of users and stores a huge amount of data safely.

Example 3. Name the unit of the CPU that decides whether 45 is greater than 37. The ALU, because it performs logical comparisons.

Key points to remember

1. Computers differ in speed, storage, size and cost.

2. Supercomputer > mainframe > minicomputer > microcomputer in power and cost.

3. The CPU has three parts: ALU, CU and MU.

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