Source : Free On-Line Dictionary of Computing

golf ball printer
     
         The IBM 2741, a slow but letter-quality printing
        device and terminal based on the IBM Selectric typewriter.
        The "golf ball" was a little spherical frob bearing reversed
        embossed images of 88 different characters arranged on four
        parallels of latitude; one could change the font by swapping
        in a different golf ball.
     
        This was the technology that enabled {APL} to use a
        non-{EBCDIC}, non-{ASCII}, and in fact completely non-standard
        {character set}.  This put it 10 years ahead of its time -
        where it stayed, firmly rooted, for the next 20, until
        {character displays} gave way to programmable {bit-mapped}
        devices with the flexibility to support other character sets.
     
        (1994-12-15)