Nonstandard Time Zones

摘要

Clock signals figure prominently in microprocessor-controlled systems. Regardless of their architecture, digital processing engines generally require a pacing signal to run internal counters that keep track of addresses and data values and drive state machines. To increase the number and types of applications a microcontroller can address, manufacturers have added functionality and sometimes more clocks. For example, the Atmel ATmega 103(L) has a programmable watchdog timer with its own oscillator, a realtime counter with a separate oscillator, and a third oscillator that provides the system clock.