Translators

• For computers to process any computer language , it first needs to be translated
• In high level languages, (e.g. Python or C++) the source code is easy for humans to write , but computers need to translate it before they can read and run it
• Low-level languages are tricky for humans to read and write but are easier for a computer to run
• Low level languages consist of machine code and assembly languages
• Binary machine code is very tricky for humans to understand

  
• Assembly code is more readable for humans and easier to understand

  
• In assembly code, ADD is the operation code , and the rest of the code tells you what to perform the operation code on

  
• High level languages are popular with programmers
• The advantages of High-Level Languages are:

  • One instruction of high-level code represents many instructions of machine code  
  • The same code will work for many different machines and processors  
  • The programmer can easily store data in lots of different structures (e.g. lists and arrays)  
  • Code is easy to read , understand and modify  
• The disadvantages of High-Level Languages are:

  • Must be translated before a computer is able to understand it  
  • You don’t have much control over what the CPU actually does , so programs will be less memory efficient and slower 
• The advantages of Low-Level Languages are:

  • Commands in machine code can be executed directly without the need for a translator  
  • You control exactly what the CPU does, and how it uses memory , so programs will be more memory efficient and faster 
• The disadvantages of Low-Level Languages are:

  • One instruction of assembly code usually only represents one instruction of machine code  
  • Usually written for one type of machine or processor , and won’t work on any others  
  • The programmer needs to know about the internal structures of the CPU and how it manages energy  
  • Code is very difficult to read , understand and modify 
• Computers only understand instructions given to them as machine code - so high level languages need to be translated before a computer is able to execute instructions
• The 2 types of translator are compilers and interpreters
• Compilers translate high level code directly into machine code , and create an executable file
• Interpreters don't translate directly into machine code
• Interpreters take each instruction in the code and call machine code subroutines within their own code to carry out that instruction
• Characteristics of a Compiler:

  • Translates all of the source code at the same time and creates one executable file  
  • Only needed once to create the executable file  
  • Returns a list of errors for the entire program once compiling is complete  
  • Once compiled, the program runs quickly , but compiling can take a long time 
• Characteristics of an Interpreter:

  • Translates and runs the source code one instruction at a time, but doesn't create an executable file  
  • Needed every time you want to run the program  
  • The interpreter will return the first error it finds, and then stops – this is useful for debugging  
  • Programs will run more slowly because the code is being translated as the program is running 
• The type of translator used will depend on which programming language and IDE you're using
• If the program is stored over multiple source code files then a linker is used to join all of the separate compiled codes into one executable program