Assembly Language (Cambridge (CIE) O Level Computer Science) : Revision Note

Assembly Language

What is assembly language?

• Assembly language is a second generation, low-level language designed to simplify the writing of machine code instructions for programmers

• Programmers use assembly language for the following reasons:

  • Need to make use of specific hardware or parts of the hardware

  • To complete specific machine dependent instructions

  • To ensure that too much space is not taken up in RAM

  • To ensure code can completed much faster

• Assembly languages allow programmers to program with mnemonics. e.g.

  • LDA Load - this will ensure a value is added to the accumulator

  • ADD Addition - this will add the value input or loaded from memory to the value in the accumulator

  • STO, Store - stores the value in the accumulator in RAM

• Assembly language allowed continuation of working directly with the hardware but removed an element of complexity

• A mnemonic is received by the computer and it is looked up within a specific table

• An assembler is needed to check the word so that it can be converted into machine code

• If a match from the word is found e.g. STO the word is replaced with the relevant binary code to match that sequence