Changes

| accessdate = 2012-03-27}}</ref>

| accessdate = 2012-03-27}}</ref>

Computer users nowadays may not realise the severe technical constraints which applied to programming in the mid 1950's. Modern personal computers have the entire central processing unit on a single chip (integrated circuit), have main memories (RAM) containing many hundred of millions of bytes, and have processing speeds of several million instructions per second. The IBM 704 computer (fairly advanced for its time) had a central processor made up of many thousands of electronic valves (each the size of a light bulb), had a main memory of only four thousand 36-bit words, and had a processing speed of perhaps forty thousand instructions per second.

Computer users nowadays may not realise the severe technical constraints which applied to programming in the mid 1950's. Modern personal computers have the entire central processing unit on a single chip (integrated circuit), have main memories (RAM) containing many hundred of millions of bytes, and have processing speeds of several million instructions per second. The IBM 704 computer (fairly advanced for its time) had a central processor made up of many thousands of electronic valves (each the size of a light bulb), had a main memory of only four thousand 36-bit words, and had a processing speed of perhaps forty thousand instructions per second (modern mobile phones are more powerful than this).

==Outline of the compilation process==

==Outline of the compilation process==