DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   silo
    n.
       The FIFO input-character buffer in an RS-232 line card. So called from DEC
     terminology used on DH and DZ line cards for the VAX and PDP-11,
       presumably because it was a storage space for fungible stuff that went in
       at the top and came out at the bottom.