the second keyboard part 210 is disposed on the upper surface of the second housing 200 however the second keyboard part 210 may be also located on the sides or on the bottom surface of the first housing 200 as shown in fig1 b the inside of the second housing 200 has a second space 520 and a second outlet 214 of the second space 520 is on the left side part 212 of the second housing 200 as far as the preferred embodiment is concerned the first keyboard part 110 and the second keyboard part 210 respectively have a single layer membrane circuit however in other embodiments the first keyboard part 110 and the second keyboard part 210 may also respectively have a printed circuit or triple layer membrane circuit the structure of the keys on the first keyboard part 110 and the second keyboard part 210 may be elastic rubber structure scissor structure spring leaf structure and any other structure that provides similar functions as shown in fig1 b base 300 has left side part 310 and right side part 330 the left side part 310 movably connects to first housing 100 apropos of embodiments left side part 310 movably connects to the inner wall of the first space 510 through first outlet 114 and right side part 330 movably connects to second housing 200 as far as the embodiment.