DuckCorp Dico

Found one definition

1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   Packet Assembler/Disassembler
   PAD
      (PAD) Hardware or software device for splitting a data stream
      into discrete packets for transmission over some medium and
      then reforming the stream(s) at the receiver.
      The term is most often used for interfaces to X.25 lines.
      (1995-01-31)