Kempston Micro Electronics
Kempston Micro Electronics was a British electronics company specializing in the distribution of joysticks and peripherals for home computers in the 1980s ; the company also manufactured some devices itself. The company was headquartered in Kempston , Bedfordshire , England .
In order to open up a market for the joysticks offered by the company, Kempston produced various joystick interfaces for the most popular home computer in Great Britain, the Sinclair ZX Spectrum , which, unlike many other home computers, did not come with sockets for connecting joysticks. With the Kempston interfaces, which were plugged into the universal expansion port on the back of the Spectrum, it became possible to use the Atari 2600 -compatible joysticks with DE-9 connectors on this computer , which were then the de facto standard . With the sale of these joystick interfaces, Kempston also established a standard for reading the joystick position through Spectrum software; a bit pattern of the currently closed contacts appears on the I / O port 31 from the point of view of the Z80 processor and can therefore e.g. B. can be read with the BASIC command "LET j = IN 31". This control logic was later adopted by other companies. Sinclair did not take it over when the company finally offered the "ZX Interface 2", its own joystick interface for the ZX Spectrum. Many later Spectrum games allow the user to choose between several different joystick interfaces or to use the keyboard as a replacement if no interface is available.
Joysticks sold by Kempston that worked with the interface included: a. Competition Pro , Competition Pro Plus, Score Board and Formula 1 and 2.