A-0 System

The A -0 system (English Arithmetic Language version 0, dt " arithmetic language version 0") is considered the first compiler in computer history. It was developed in 1951 to 1952 by Grace Hopper for the UNIVAC I. A-0 had more the function of a loader or linker than that of a modern compiler. A program for A-0 was specified as a sequence of subroutines and arguments. We identified sub-programs by a numerical code and wrote the arguments of the subroutines directly behind the subroutine code. The A 0 system translated the specification to machine code, which was then input to the computer for execution.

The A -0 system has been further developed in A -1, A -2, A -3 ( ARITH -MATIC ), AT -3 (MATH -MATIC ) and B -0 (FLOW -MATIC ).

A-2

The A- 2 system was developed in 1953 at the UNIVAC Division of Remington Rand and delivered at the end of this year to customers. The customers were given the source code of the system and were invited to return to it improvements to the UNIVAC team. Thus, A -2 can be considered an early example of an open source development process.