1. Low level language concepts

A low level language is one whose programming statements are geared towards a particular CPU family, such as the x86 family of processors. Low level languages are almost (but not quite) machine code.

'Assembly language' is an example of a low level programming language.

Chip makers such as Intel and ARM provide programmers with an Assembly Language with which to code their particular CPU.

Some features of Low Level languages include

  • They are CPU specific, making direct use of internal registers
  • 'Mnemonics' are used as programming code such as MOV or ADD
  • Many different memory modes can be used
  • Labels are used as reference points to allow the code to jump from one part to another.

Pros.

  • Low level languages are excellent for close control of the CPU, for example many device drivers are coded in assembly language.
  • They can be very efficient. Well-optimised code written in a low level language can be made to run very quickly compared to other programming paradigms.

Cons

  • They are difficult to use as the programming commands can be quite obscure
  • A good assembly language programmer needs to know a lot of detail about the internal structure of the CPU - e.g.its registers and memory management methods
  • Low level languages produce the least portable source code.

Assembly language looks like this:

.MODEL SMALL;
.STACK;
.CODE;
mov ah,1h; moves the value 1h to register ah
mov cx,07h;moves the value 07h to register cx
int 10h;

 

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