The front part of the case is occupied by an integrated 40-key membrane keyboard displaying 20 graphic and 54 inverse video characters. Each key has up to five functions, accessed via the SHIFT and FUNCTION keys or depending on context. For example, the P key combines the letter codice_1, the codice_2 character, and the BASIC commands codice_3 and codice_4. The ZX81 uses a standard QWERTY keyboard layout. The keyboard is mechanically very simple, consisting of 40 pressure-pad switches and 8 diodes under a plastic overlay, connected in a matrix of 8 rows and 5 columns.