Lecture notes
Computer science Chapter 7 Notes
- Module
- Computer Science
- Institution
- Cambridge University (CAM)
This is a comprehensive and detailed note on Chapter 7; High and low level language for computer science. Essential!!
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CIE IGCSE COMPUTER SCIENCETheory of computer science
Chapter 7 – High- and low-level languages
7.1 Introduction
People use many different languages to communicate with each other. In order for two people to understand
each other they need to speak the same language or another person, an interpreter, is needed to translate
from one language to the other language. Programmers use many different programming languages to
communicate with computers. Computers only ‘understand’ their own machine code. A program needs to be
translated into machine code before it can be ‘understood’ by a computer.
7.2 Programming languages
7.2.1 What is a program?
Programs are people’s way of telling computers what to do, how to do it and when to do it. This enables a
single computer to perform many different types of tasks. A computer can be used to stream videos, write
reports, provide weather forecasts and many, many other jobs.
An example of a simple task that can be performed by a computer is the provision of a multiplication tables
test. The figure below shows a simple program to set this up and the image that follows shows an example of
the test in use.
The program above was written in Scratch.
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, The program in use is shown above.
A compute program is a list of instructions that enable a computer to perform a specific task. Computer
programs can be written in high-level languages or low-level languages, depending on the task to be
performed and the computer to be used. Most programmers write programs in high-level languages.
7.2.2 High-level languages
High-level languages enable a programmer to focus on the problem to be solved and require no knowledge of
the hardware and instruction set of the computer that will use the program. Many high-level programming
languages are portable and can be used on different types of computer.
High-level languages are designed with programmes in mind; programming statements are easier to
understand than those written in a low-level language. This means that programs written in a high-level
language are easier to:
read and understand as the language used is closer to human language
write in a shorter time
debug at the development stage
maintain once in use.
The following snippet of program to add two numbers is a simple program statement written in s typical high-
level language. It shows how easy it is to understand what is happening in a high-level language program:
There are many different high-level programming languages in use today including C++, Delphi, Java, Pascal,
Python, Visual Basic and many more. Once a programmer has learnt the techniques of programming in any
high-level language, these can be transferred to working in other high-level languages.
Activity 7.1
High-level programming languages are said to be problem oriented. What type of problems are the languages
names above used for?
C++ is a powerful general-purpose programming language used to develop operating systems,
browsers, games and so on.
Delphi is a high-level programming language used to build applications for Windows systems but can
be used to build applications for variety of operating systems.
Java is a widely used programming language expressly designed for use in the distributed environment
of the internet. It is the most popular programming language for Android smartphone applications and is
also among the most favoured for the development of edge devices and the internet of things.
Pascal is a general-purpose, high-level language developed for teaching programming as a systematic
discipline and to develop reliable and efficient programs.
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