FORTRAN

History

FORTRAN - Interesting Facts

FORTRAN is the oldest Language actively in use today.

FORTRAN is still used for new software development in many scientific applications

Many FORTRAN programs written 20-40 years ago are still in active use today!

FORTRAN - Early History

Early 1950’s– Computers very slow– Small memories - 15k typical– Little or no operating system– Programming done in machine/assembly language– Idea of a high level translated language seemed

impractical• code generated would be slower• code generated would be bigger

FORTRAN I

Developed in 1954-1957 IBM team lead by John W. Backus FORTRAN - FORmula TRANslator Designed to ease coding of

mathematical algorithms

FORTRAN I

Programmers skeptical at first Then advantages seen:

– Easier, faster to program– Programs are portable– Programs can be maintained– Program libraries build and shared

Adopted by the scientific and military communities

FORTRAN II

FORTRAN II (1958) was a significant improvement

added the capability for separate compilation of program modules

assembly language modules could also be 'linked loaded' with FORTRAN modules.

FORTRAN III

FORTRAN III (1958) never released to the public

it made it possible to use assembly language code right in the middle of FORTRAN code.

Such "inlined" assembly code can be more efficient, but the advantages of an HLL are lost (e.g. portability, ease of use).

FORTRAN IV

FORTRAN IV (1961) was a 'clean up' of FORTRAN II

improved the implementation of the COMMON and EQUIVALENCE statements

eliminated some machine-dependant language irregularities.

FORTRAN 66 First HLL Standard Card oriented (as were previous

versions)

FORTRAN 77Standard

Added– DO loops with a decreasing control variable

(index). – Block if statements IF ... THEN ... ELSE ...

ENDIF (before F77 there were only IF GOTO). – Pretest of DO loops, before F77 DO loops

were always executed at least once, so you had to add an IF GOTO before the loop.

FORTRAN 77

Added– CHARACTER data type (before characters

were always stored inside INTEGER variables).

– Main program termination without a STOP statement

Fortran 90 standard

Added– Free format source code form (column

independent)– Modern control structures (CASE & DO

WHILE)– Records (structures)– Array notation (array sections, array

operators, etc.)– Dynamic memory allocation

Fortran 90 standard

Added– Dynamic memory allocation– Derived types and operator overloading– Keyword argument passing, INTENT (in,

out, inout)– Numeric precision and range control – Modules– Vector processing

FORTRAN 2000 Standard

Expected about 2002