ECMA-23

ECMA-23 is a standard for a bit-paired keyboard layout adopted in 1969 and revised in 1975.

As a bit-paired layout, shifted keys correspond to toggling bits in the ASCII keycode.

This is most visible in the digits on the top row, where shifting 6789 give &'(), and ;+, :* and -= are paired.

In the UK, ECMA-23 layout keyboards were used on most 8-bit computers such as the Acorn BBC computers and the earlier Atom and Systems, the Amstrad CPC series, and (to an extent) the ZX Spectrum.

While bit-paired layouts have generally given way to typewriter layouts, the Japanese keyboard layout still uses one.