The pcfclock(4) driver for GNU/Linux supports the parallel port radio
clock sold by Conrad Electronic under order number 967602. The radio
clock, which is put between your parallel port and your printer,
receives the legal German time, i.e. CET or CEST, from the DCF77
transmitter and uses it to set its internal quartz clock. The DCF77
transmitter is located near to Frankfurt/Main and covers a radius of
more than 1500 kilometers.