VT300 Mode, 8-Bit Controls

  By default, DECterm emulates a VT300-series terminal with
  7-bit control characters (codes 0-31).  You can change the
  mode to VT300 with 8-bit control characters by clicking
  on the VT300 Mode, 8-Bit Controls option.  This causes

  DECterm to translate 8-bit control characters (codes 128 to
  159) for function keys.