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TOPIC 1
INTRODUCTION
Programs
A computer program is a series of organised instructions that directs a computer to perform tasks. Without programs, computers are useless.
A program is like a recipe. It contains a list of variables (called ingredients) and a list of statements (called directions) that tell the computer what to do with the variables.
Programming
Programming is a creation of a set of commands or instructions which directs a computer in carrying out a task.
Programming languages
A programming language is a set of words, symbols and codes that enables humans to communicate with computers.
Examples of programming languages are:
BASIC (Beginner’s All Purpose Symbolic Instruction Code)
Pascal
C
Smalltalk.
Types of programing languages
There are three main kinds of programming language:
Machine language
Assembly language
High-level language
We just went over what machine language is – it’s the language of machines, consisting of bits (1s and 0s) put together into chunks like bytes, a group of 8 bits, and lots of other larger sizes.
It’s highly unlikely you will ever have to write in machine language, but in the old days, we used to plot 1s and 0s on graph paper and then type them in, to make pictures appear on the computer screen. Very tedious!
Assembly language is a little easier than machine language, but not much! It uses more convenient numbers, symbols, and abbreviations to describe the huge strings of 1s and 0s, to
make it both easier and more memorable to type in instructions. The computer knows that certain strings of numbers are commands, so assembly language lets you use English-like strings instead of numbers to refer to those. Plus, with assembly language you have access to all kinds of resources to organize your programming code. Then you tell a program called an assembler to assemble your instructions, which just means they get turned into 1s and 0s for you.
The third type of language are the high-level languages. These languages use English like statements and symbols, and are independent of the type of computer you are using. You can even put in lots of English labels and comments to help remember what the instructions are doing. This makes your programs much easier to read and modify. There are far more high-level languages than any other type of computer language, each one tailored for a certain kind of use.
