Abstract LISP1.9 provides new input/output facilities, the conceptual channel and the current channel, which make program writing easier and execution faster. The channel attributes‐column‐setting, line number option, prompt‐string, user‐buffer, eol‐handler, eof‐handler and access rights‐are useful for program writing; the channel interaction attributes‐input‐memo, output‐memo and file I/O verification‐are useful for system development. Random file I/O, array I/O, record handling, array‐string conversion and Japanese character output are also provided.