Development of Low-Level Languages
All computers operate by following machine language programs, a long sequence of instructions called machine code that is addressed to the hardware of the computer and is written in binary notation (see numeration), which uses only the digits 1 and 0. First-generation languages, called machine languages, required the writing of long strings of binary numbers to represent such operations as
and compare. Later improvements allowed octal, decimal, or hexadecimal representation of the binary strings.
Because writing programs in machine language is impractical (it is tedious and error prone), symbolic, or assembly, languages—second-generation languages—were introduced in the early 1950s. They use simple mnemonics such as A for
add or M for
multiply, which are translated into machine language by a computer program called an assembler. The assembler then turns that program into a machine language program. An extension of such a language is the macro instruction, a mnemonic (such as
READ) for which the assembler substitutes a series of simpler mnemonics. The resulting machine language programs, however, are specific to one type of computer and will usually not run on a computer with a different type of central processing unit (CPU).
Sections in this article:
- Development of Low-Level Languages
- Evolution of High-Level Languages
- Compilers and Interpreters
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