JargonFile/entries/heartbeat.txt
2014-04-26 16:54:15 +01:00

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heartbeat
n. 1. The signal emitted by a Level 2 Ethernet transceiver at the end of
every packet to show that the collision-detection circuit is still
connected. 2. A periodic synchronization signal used by software or
hardware, such as a bus clock or a periodic interrupt. 3. The natural
oscillation frequency of a computer's clock crystal, before frequency
division down to the machine's clock rate. 4. A signal emitted at regular
intervals by software to demonstrate that it is still alive. Sometimes
hardware is designed to reboot the machine if it stops hearing a heartbeat.
See also breath-of-life packet.