(57) A microprocessor controlled time switch has a liquid crystal display device (13)
with provision for displaying day of the week and time. Below the display a row of
four keys (21 to 24) are used to select programming functions and a key (20) can be
pressed at either end to increment and decrement numerical values. The keys (21 to
24) are multi-function and, above each key, the display device (13) includes a column
of three legends, of which only one is ever displayed at a time. The microprocessor
controls the legends (27) so that, in all phases of operation, the functions performed
by the keys (21 to 24) are apparent.
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