.RE
.
.TP
-.TP
.BR \-D ", " \-\-debug
.RB Use\ \-\-verbose .
.RB The\ \%\-\-debug\ option
.SH NOTES
.
.SS Clocks in a Linux System
-.PP
There are two types of date-time clocks:
.PP
.B The Hardware Clock:
.BR \%settimeofday (2).
.
.SS Hardware Clock Access Methods
-.PP
.B \%hwclock
uses many different ways to get and set Hardware Clock values. The most
normal way is to do I/O to the rtc device special file, which is
only method available on ISA systems which do not have a working rtc
device driver.
.SS The Adjust Function
-.PP
The Hardware Clock is usually not very accurate. However, much of its
inaccuracy is completely predictable - it gains or loses the same amount
of time every day. This is called systematic drift.
.BR \%clock "(8) program with " \%hwclock .
.
.SS Automatic Hardware Clock Synchronization by the Kernel
-.PP
You should be aware of another way that the Hardware Clock is kept
synchronized in some systems. The Linux kernel has a mode wherein it
copies the System Time to the Hardware Clock every 11 minutes. This mode
should not be used with NTP \%'11\ minute\ mode'.
.
.SS ISA Hardware Clock Century value
-.PP
There is some sort of standard that defines CMOS memory Byte 50 on an ISA
machine as an indicator of what century it is.
.B \%hwclock