Languages and Translators

Languages and Translators

1. High level languages

   • Source code is easy for humans to write but computers need to translate it into machine code before they can read and run it
   • 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 (such as lists or arrays) without knowing about the memory structure
   • Code is easy to understand, read, and modify
   • Must be translated into machine code before a computer is able to understand it
   • Programmer does not have much control over what the CPU does so programs will be less memory efficient and slower
   • Examples include Python and C++
   • Independent of hardware (portable)

2. Low level languages

   • Tricky for humans to read and write but easy for a computer to run.
   • Consist of machine code and assembly languages
     • Binary machine code - 01001100
       • Produced by compiler, interpreter or assembler
     • Assembly code, the first bit is the operation code and the rest tells you what to perform the operation on - ADD r4, r2. r3
       • Processor specific
   • 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
   • Programmer needs to know about the internal structure of the CPU and how it manages the memory
   • Code is very difficult to read, understand, and modify
   • 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
   • Gives programmer complete control over the system components so it can be used to control and manipulate specific hardware components
   • Very efficient code can be written for a particular type of processor, so it will occupy less memory and execute faster than a compiled high level language

3. Compiler

   • Translates all of the source code at the same time and creates one executable file
   • Only needed to be compiled 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
     • Executes faster as it is already in machine code
   • Doesn't need to be present when the object code (code produced by compiler or interpreter) is run
   • Source code can't be seen when program is distributed
   • Used for software that will be run frequently or copyright software sold to a third party

4. Interpreter

   • Translates and runs the source code one instruction at a time, but doesn't create an executable file
   • Interpreter must be installed every time you want to run the program
   • The interpreter will run the first error it finds and then stops, meaning it is useful for debugging
   • Programs will run more slowly because the code is being translated as the program is running
   • Source code can be seen and copied
   • Used for program development

5. Computers can only understand instructions given to them in machine code so high level languages get translated. Compilers and interpreters both turn high level code into machine code.

6. The type of translator depends on the programming language

7. Assembler

   • Converts assembly language into machine code. This is a simple conversion as in general, every assembly language instruction is translated into a single machine code instruction.