From embeddedTS Manuals

The RTC includes 128 bytes of NVRAM which can be used for custom applications. The utility 'nvramctl' can be used to read/write the NVRAM. The source for this utility is available from our ts4900-utils github.

The utility reads/writes a byte at a time, and returns the value in hex.

nvramctl --addr 10 --set 0x40
nvramctl --addr 10 --get
# Returns "nvram10=0x40".
# This can also be used with eval
eval $(nvramctl --addr 10 --get)
echo $nvram10
# Returns "0x40"

The NVRAM code can be included in your application by using these two files: