cram(7) INTERACTIVE UNIX System cram(7)
NAME
cram - CMOS RAM interface
DESCRIPTION
The cram driver provides an interface to the 64 bytes of
battery backed-up RAM. This memory contains information
such as diagnostics and configuration information. For
details see the appropriate hardware technical reference
manual for your computer.
Ioctl Calls
CMOSREAD This call is used to read the contents of one of
the CMOS RAM locations. The argument to the ioctl
is the address of a buffer of two unsigned charac-
ters, the first of which is the address to be
read. The ioctl will fill in the second byte with
the data. An address less than 0xe or greater
than 0x3f will result in an error, with errno set
to ENXIO.
CMOSWRITE This call is used to write a value into one of the
CMOS RAM locations. The argument to the ioctl is
the address of a buffer of two unsigned charac-
ters, the first of which is the address and the
second of which is the value to write at that
address. An address less than 0xe or greater than
0x3f will result in an error, with errno set to
ENXIO. Note that only the superuser may open the
CMOS RAM device for writing, and that the
CMOSWRITE ioctl will fail for any user other than
the superuser.
FILES
/dev/cram
ADDED VALUE
This entry, supplied by INTERACTIVE Systems Corporation,
contains enhancements to UNIX System V.
Rev. 1.3 Page 1