All of these programs originated in the mainframe era, originally running on Control Data machines. The code was written in FORTRAN and designed to take input from punch card stacks in column-delimited format and then print the results on a line printer. These early versions were widely ported to a number of other big-iron platforms. AMP added support for disk-based files by emulating the original system, writing out the data from a single punch card to 80-column line in a text file, with the file as a whole representing a deck of cards. With the move from punch card input to the use of text files, a profusion of slightly different file formats appeared, which was later described as "close to free format".