DEFINITION MODULE BIOSKeyboard;
  EXPORT QUALIFIED Status, Read, Check, GetStatus;
  TYPE
    Status = SET OF (RightShift, LeftShift, CtlShift, AltShift, ScrollState,
                     NumState, CapsState, InsState);
  PROCEDURE Read(VAR ch, scan: CHAR);
  PROCEDURE Check(VAR ch, scan: CHAR; VAR avail: BOOLEAN);
  PROCEDURE GetStatus(VAR stat: Status);
  END BIOSKeyboard.
