Definition: timing signals
Electrical pulses generated in the processor or in external devices in order to synchronize computer operations. The main timing signal comes from the computer's clock, which provides a frequency that can be divided into many slower cycles. Other timing signals may come from a timesharing or real-time clock.
In disk drives, timing signals for reading and writing are generated by holes or marks on one of the platters, or by the way the digital data are actually recorded.