ANALOGUE JOYSTICK BOARD
MIDWICH has produced an analogue joystick board which fits both the ZX-81 and the Spectrum. It can take two joysticks by plugging them into two six-way DIN sockets on the side of the bare board. It is input/output-mapped and requires the use of a small section of machine code on the ZX-81.
The board uses a ZN499E A/D converter and a switch to select which direction to measure. The results vary from 0 to 255 for each direction on the joystick - N/S and E/W - and the "FIRE" button operates one bit each of a second port, one giving 0 or 128 and the other 0 or 64; the higher number indicates that the button is pressed. Both pressed gives 128 = 64 (191).
Inserting the power plug is difficult, as not sufficient space has been left between that and the joystick sockets on the Spectrum version.
Midwich sells the board as a kit for £17.20 and assembled for £22.95. The joysticks cost £4.50 uncased with fire button. The kits are well-designed with good instructions. Midwich Computer Co Ltd, Rickinghall House, Richinghall, Suffolk IP22 1HH. Tel: 0379-898571.