Levels of Programming Languages (AQA GCSE Computer Science)

• Since the invention of the computer, people have needed to learn how to communicate with them using programming languages
• Early computers were complex and instructions would have to be in written in binary code, 0s and 1s
• This process was slow, taking days to program simple tasks
• Over time, new generations of programming languages have enabled people to become faster and more efficient at writing programs as they resemble human language
• Generations of programming languages can be split in to two categories:
  • Low-level
    • First generation
    • Second generation
  • High-level
    • Third generation

What is a low-level language?

• A low-level language is a programming language that directly translates to machine code understood by the processor
• Low-level languages allow direct control over hardware components such as memory and registers
• These languages are written for specific processors to ensure they embed the correct machine architecture

First generation

• Machine code is a first-generation language
• Instructions are directly executable by the processor
• Written in binary code

Second generation

• Assembly code is a second-generation language
• The code is written using mnemonics, abbreviated text commands such as LDA (Load), STA(Store) 
• Using this language programmers can write human-readable programs that correspond almost exactly to machine code
• One assembly language instruction translates to one machine code instruction
• Needs to be translated into machine code for the computer to be able to execute it

What is a high-level programming language?

• A high-level programming language uses English-like statements to allow users to program with easy to use code
• Most computer programs are now written in high-level languages
• High-level languages allow for clear debugging and once programs are created they are easier to maintain
• High level languages were needed due to the development of processor speeds and the increase in memory capacity
• One instruction translates into many machine code instructions
• Needs to be translated into machine code for the computer to be able to execute it
• Examples of high-level languages include:
  • Python
  • Java
  • Basic
  • C+