The Kempston Interface is a
joystick interface used on the
ZX Spectrum series of computers that allows controllers complying with the
de facto Atari joystick port standard (using the
DE-9 connector) to be used with the machine. The interface itself would be attached to the computer's rear expansion port with a single joystick port on the front or top of the system. Apart from implementing existing joystick interfacing modes they produced their own standard which delivered the joystick state on the Z80 bus at port 31 (read in BASIC using IN 31). This meant that the joystick did not produce key-presses like the other standards, such as
Cursor, and the method was soon borrowed by other interface manufacturers and became quite popular. It was one of the most widely supported standards on the machine, coming out as the clear winner against other standards such as Protek and AGF's cursor-based solution and the Fuller standard during the days of the 48K Spectrum. When
Amstrad released the
ZX Spectrum +2, the computer featured a built-in joystick interface that was software-compatible with Sinclair's
ZX Interface 2 standard. However, the bundled
SJS-1 joystick was electrically incompatible with the Atari standard. The Interface 2 standard simulated keypresses on the numerical keys ( to and to being left, right, down, up, fire for the 'left' and 'right' joysticks respectively) and hence were ideal for games with no official joystick support but in which the keys could be redefined. Inserting or removing the joystick interface when the computer was turned on was inadvisable as it would almost certainly damage the computer hardware. == Mouse ==