Kempston joystick

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Kempston joystick interface
Kempston joystick interface

The Kempston joystick interface and its clones were pretty ubiquitous in the Sinclair scene, mainly because of their simplicity. There were other models (Specifically the AMX, Protek, Fuller and Sinclair Joysticks, but Kempston was the most popular and all except the Sinclair died out (And that only because it was built in to the Spectrum +2 and +3)

[edit] Using the joystick in games

The joystick could be accessed using IN 31, either from Basic or Machine code. The bits were active high (Went 1 for action) and were as follows:

  • 0 Right
  • 1 Left
  • 2 Down
  • 3 Up
  • 4 Button 1
  • 5 Button 3
  • 6 Not used
  • 7 Button 2

[edit] The Circuit

Top
Top
Bottom
Bottom

The original is a very simple circuit using two chips, a 74138 and a 74366.

Retrieved from "http://www.salkin.co.uk/~wiki/index.php/Kempston_joystick"
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