
2 Compilers – Principles and Practice
commands (“add number x to number y and put the result in a store called z”) rather than jobs of even
mild complexity (“solve the quadratic equation ax
2
+ bx + c, given a, b and c”), it was necessary
to supply a complete sequence of elementary commands, specifying how a particular job was to be
done. A sequence of commands is called a program. This necessitated developing and defining the
so-called programming languages.
During the early days of computer evolution, the only language a computing machine could
follow was its binary command language (as most, though not all, machines were built using binary ...