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Introduction to computers: Class 9 Computer Science
What a computer is, its characteristics, the input process output cycle, data and information, generations of computers, types by size and the uses of computers.
Key points
A computer is an electronic device that accepts data, processes it according to instructions and produces information as output. It can also store data for later use.
Characteristics of a computer:
- Speed: it can do millions of operations in a second.
- Accuracy: it gives correct results if the data and instructions are correct.
- Diligence: it can work for long periods without getting tired.
- Versatility: it can be used for many different tasks.
- Storage: it can store large amounts of data.
- Automation: it follows a stored program with little human help.
A computer works in four steps:
- Input: data is entered with devices such as the keyboard and mouse.
- Processing: the central processing unit works on the data.
- Output: results are shown on devices such as the monitor and printer.
- Storage: data and results are saved in memory or on storage devices.
Data is a collection of raw facts and figures, such as numbers and names. Information is data that has been processed so that it is meaningful and useful. The marks of students are data. The list of students arranged by position is information.
Generations of computers:
- First generation (about 1940 to 1956): vacuum tubes. They were very large and used much electricity.
- Second generation (about 1956 to 1963): transistors, which were smaller and faster.
- Third generation (about 1964 to 1971): integrated circuits.
- Fourth generation (about 1971 onwards): microprocessors, which led to personal computers.
- Fifth generation: artificial intelligence and advanced technologies.
By size and power, computers are grouped as supercomputers, mainframe computers, minicomputers and microcomputers. Supercomputers are the fastest and are used for weather forecasting and scientific research. Mainframes serve many users in banks and large organisations. Microcomputers such as desktops, laptops and tablets are used by individuals.
Computers are used in education, business, banks, hospitals, industry, communication, entertainment and government offices. Information and communication technology (ICT) is the use of computers and communication devices to collect, store, process and share information.
Study tip: Make a small table of the five generations with the technology of each. It is a common short question.
Definitions and flashcards
Say the meaning first, then open the card to check.
Computer
An electronic device that accepts data, processes it and gives information.
Data
Raw facts and figures that have not been processed.
Information
Data that has been processed into a meaningful form.
Input
Data or instructions entered into a computer.
Output
The result that a computer gives after processing.
Hardware
The physical parts of a computer that can be touched.
Software
The programs and instructions that tell the hardware what to do.
Microprocessor
A single chip that contains the central processing unit.
Supercomputer
The fastest and most powerful type of computer.
ICT
Information and communication technology.
Short questions with model answers
These are the kind of questions asked for 2, 3 and 5 marks. Try each one before opening the answer.
Define a computer. (2 marks)
A computer is an electronic device that accepts data, processes it according to a set of instructions and produces information. It can also store data.
Differentiate between data and information. (2 marks)
Data is raw facts and figures. Information is data that has been processed so that it is useful. A list of marks is data, and the position list made from the marks is information.
Write any three characteristics of a computer. (3 marks)
Speed, accuracy and storage. A computer can perform millions of operations in a second, gives correct results if the input and instructions are correct, and can store large amounts of data.
Name the four steps of the computer working cycle. (2 marks)
Input, processing, output and storage.
Which technology was used in each of the first three generations of computers? (3 marks)
The first generation used vacuum tubes, the second used transistors and the third used integrated circuits.
Describe the types of computers by size. (5 marks)
Supercomputers are the fastest and are used for tasks such as weather forecasting. Mainframe computers are large machines that serve many users at once, for example in banks. Minicomputers are smaller than mainframes and are used by small organisations. Microcomputers, which include desktops, laptops and tablets, are used by one person at a time.
What is ICT? Give two uses of computers in daily life. (3 marks)
ICT is information and communication technology, the use of computers and communication devices to collect, store, process and share information. Computers are used in banks for accounts and in schools for teaching and learning.
Common mistakes
- Using data and information as if they mean the same thing.
- Mixing up the order of the generations and their technologies.
- Saying that a computer thinks by itself. A computer follows instructions given by a program.