2. How does a computer work?
3. What parts does a typical computer consist of? Describe the role of each of them. Speak about different types of computers.
4. What do you know about the history of computers? Speak briefly about the five generations of computers.
5. What is software? What types of programs do you know? What is each of them used for?
6. How is a computer program written?
7. Speak about programming languages and the communication with the computer.
What are computers?
Computers are electronic devices which accept data, process the data and give results of the processing.
Computers help us do many jobs quickly and easily.
We can use the computer to
• write and edit documents
• make calculations
• collect, organize, store and retrieve large amounts of data
• send and receive e-mails
• listen to music and watch films
• look for information and publish information on the Internet
• order goods and pay bills over the Internet
• communicate with other people in chat rooms
• write music, make photos and films
• publish books
• design buildings, cars or clothes and draw pictures
• control other machines and equipment
• learn
• play games
What does a computer consist of?
All the mechanical and electronic parts of a computer are called hardware. The instructions (programs) and data are called software.
http://www.webopedia.com/TERM/c/computer.html
How does a computer work?
The user communicates with the computer over input and output devices. He uses programs, gives instructions (commands) and inputs data. The input goes to the Central Processing Unit. The CPU executes programs and processes data. It is called the “brain“ of the computer. The computer gives results (output) on the screen, in printed form or as sounds.
The programs that are running and the documents that are being worked on are stored in the computer memory (RAM). Programs and data are permanently stored on storage devices, e.g. on a hard disk, a floppy disk or a CD ROM.
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http://www.webopedia.com/DidYouKnow/Hardware_Software/2002/FiveGenerations.asp
Software
All programs and data are called software. Programs are sets of instructions that make the computer execute operations and tasks. Without programs, computers were useless.
There are two main types of software:
1. system software
2. applications software.
The system software controls the basic functions of a computer, e.g.
• operating systems
• utilities (antivirus, backup programs, disk defragmenters,disk compression software)
The applications software is used for specific purposes. There are many types of applications software:
• word processors
• spreadsheets / spreadsheet programs
• graphics programs
• database management systems
• web browsers, …
http://www.webopedia.com/TERM/s/software.html
http://mcis.jsu.edu/faculty/malam/CS201-Lecture7.htm
How to write a program
1. Come up with an idea for a program and define the problem.
2. Think of a typical user of the program and of the computer it will be run on.
3. Choose the programming language you will use.
4. Design the program: make a step-by-step plan how to solve the problem
(= design an algorithm).
5. Draw a flowchart – use special symbols to do that.
6. Translate the steps in the flowchart into instructions written in a computer language.
7. Use a compiler to translate these instructions into machine code.
8. Test the program with sample data.
9. Debug the program (=clear it of errors / bugs).
10. Test again and fix the problems until the program is perfect.
11. Write instructions explaining how to use the program.
12. Release the program to the public.
Programming languages
http://www.webopedia.com/TERM/P/programming_language.html
Computers cannot understand any natural language. The only language they can understand is called machine language (machine code). It consists of a series of binary digits (1s and 0s). Each CPU has its own machine language. It is difficult to write instructions in machine language.
Programmers use an assembly language (=low-level language) or high-level languages instead. They are easier to use.
Assembly language programs are translated into machine language by a program called an assembler.
Programs written in high-level languages are translated into machine language by a special program called a compiler. Another way is to use an interpreter. It is a program that translates high-level instructions into a simpler form which is then executed.
Lying above high-level languages are languages called fourth-generation languages (4GL) – they are closest to human languages and are used to access databases.
High-level languages: BASIC, C++, COBOL, FORTRAN, Ada, Pascal, Delphi, Python – each of them has its specific keywords and special syntax for organizing program instructions.
The development of programming languages went hand in hand with the development of computers:
• First generation + machine language
• Second generation + assembly language
• Third generation + high-level programming languages (C, C++, Java)
• Fourth generation + 4GL
• Fifth generation + languages used for artificial intelligence and neural networks
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