Date and time
One of the basic functions of the BIOS is to manage the on-board hardware clock. This clock is initially set in the BIOS configuration by entering the date and time in the appropriate fields. Once set, the internal clock keeps track of time and makes the time available to the operating system. The operating system can also set the hardware clock, which is often useful if an accurate external time reference, such as an NTPD server (see Chapter 16), is available on the network while the system is running.