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5.3.1 Software: Programming Languages


You are not expected to have a detailed understanding of programming languages at GCSE level. However, the exam paper is likely to have a question on using or interpreting Logo commands and you should have a basic understanding of how control languages are used.

All computer programs are written using a programming language. The program is a set of instructions that the computer follows when it runs the program. Programs can be stored in a computer's RAM or ROM memory or on some form of storage media.

Programming languages can be divided into 2 groups:

  • Low level languages - such as machine code and assembly language. These languages are simple for the computer to understand so are fast to run but they are difficult for programmers to understand and debug. Machine code programs written for a particular type of computer may not work on other types.
  • High level languages - such as BBC Basic, Visual Basic, Fortran, C++, COBOL, JAVA, HTML and LOGO. These languages are often developed for a specific programming purpose. They are written in a form which resembles English so they are much easier for humans to write and debug. Another advantage of high level languages is that they can be used on different types of computer with little alteration.

All programming languages actually run as machine code. Assembly language is converted before the program is run. High level languages are either translated into machine code while they are running (slower but easier to make changes) or compiler software converts the whole program into machine code before it is run.

Logo:

This is simple computer language that is usually used to draw shapes on a computer screen but it can be used to move a motorised buggy or "turtle" around the floor.

Example Logo instructions:

  • REPEAT 4 [FORWARD 20 RIGHT 90 ]

These instructions would make the 'turtle' draw a square. It would repeat 4 times the commands to move forward 20 and then turn right 90 degrees.

HyperText Markup Language (HTML):

This language is used to write web pages. An Internet browser translates the HTML and then display the text and images on your screen. To see the HLML that produces a web page, select  view => source and it should be displayed in notepad. You do not need to learn HTML for the GCSE exam.

Example HTML code:

  • <i>This is some text</i>
  • <br>
  • <img src="picture.jpg">

This HTML code would make the browser:

  1. Display This is some text in italics
  2. Start a new line
  3. Display the image picture.jpg

Application software   Software index   Programming languages Control Software  System software   Expert systems   Database structure/data types