[manual index][section index]


rtc - real-time clock and non-volatile memory


bind -b '#r' /dev



The rtc device provides access to the real-time clock and any associated non-volatile memory. Physical devices supported 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 January 1970 00:00 GMT. The clock is set by writing the desired number of seconds since the epoch to the file. Setting the time in this device has no effect on system time returned by /dev/time (see cons(3)), which must be set separately 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 number of the device, set during manufacturing. The file exists only if a particular device provides such a number.






The rtc file returns seconds but /dev/time returns microseconds: it's history.

RTC(3 ) Rev:  Thu Feb 15 14:43:36 GMT 2007