RTC(3) RTC(3)
NAME
rtc - real-time clock and non-volatile memory
SYNOPSIS
bind -b '#r' /dev
/dev/rtc
/dev/rtcid
/dev/nvram
DESCRIPTION
The rtc device provides access to the real-time clock and
any associated non-volatile memory. Physical devices sup-
ported include the Mostek MK48T12-15 Zeropower/Timekeeper,
the Dallas Semiconductor DS1687 real-time clock, and the IBM
PC real-time clock on various platforms.
The rtc file when read returns the time as a decimal number,
expressed as the number of seconds since the epoch, 1 Jan-
uary 1970 00:00 GMT. The clock is set by writing the
desired number of seconds since the epoch to the file. Set-
ting the time in this device has no effect on system time
returned by /dev/time (see cons(3)), which must be set sepa-
rately if desired. For example, when rtc is available
osinit (see init(8)) uses it to set /dev/time.
The nvram file provides access to the non-volatile memory
commonly implemented by these clock chips. There are no
cross-platform standards for the range of addresses that can
be safely used by Inferno, or for the content and format of
the data.
The rtcid file holds a decimal number giving the serial num-
ber of the device, set during manufacturing. The file
exists only if a particular device provides such a number.
SOURCE
/os/*/devrtc.c
SEE ALSO
cons(3)
BUGS
The rtc file returns seconds but /dev/time returns microsec-
onds: it's history.
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