Source : Free On-Line Dictionary of Computing

fas
     
        1. Frankenstein Cross Assemblers.  A reconfigurable assembler
        package, especially suited for 8-bit processors, consisting of
        a base assembler module and a {yacc} parser, for each
        {microprocessor}, to handle {mnemonics} and addressing.
        Second party parser modules available from many sites.
     
        Base assembler and yacc parser modules by Mark Zenier.  FTP:
        ftp.njit.edu/pub/msdos/frankasm/frankasm.zoo.
     
        2. FAS.  A general purpose language sponsored by the Finnish
        government in the 70's and 80's.