The A-0 system (Arithmetic Language version 0) was an early[1] compiler related tool developed for electronic computers, written by Grace Murray Hopper[2] in 1951 and 1952 originally for the UNIVAC I.
The A-0 system converted the specification into machine code that could be fed into the computer a second time to execute the said program.
The A-2 system was developed at the UNIVAC division of Remington Rand in 1953 and released to customers by the end of that year.
[8] Customers were provided the source code for A-2 and invited to send their improvements back to UNIVAC.
Thus, A-2 could be considered an example of the result of an early philosophy similar to free and open-source software.