Wavetek 9100 calibrator NVRAM backup/restore. How?

[Finderbinder]

Device works ok by now. But having his age in mind, internal (Dallas?) battery dies one day. As I understand at least CAL data would be lost, or maybe some other problems would arise?
Bearing this in mind I would do NVRAM backup. The questions are:
1) how to backup it the simple way? Or any way if simple way do not exist?
2) how to restore it from backup?...

Any other suggestion to do to ease self life in case of device failing?

[Testtech]

I think cal constants are in Flash, not the Dallas chip. I have replaced a few NVRAM chips in these and not had a problem.

[ManateeMafia]

I just replaced the DS12887 in mine with a DS12887+

I would remove the old one and install a socket. They have an estimated 10yr life so it might be a good investment now.
The old one caused mine to be locked up and threw 2 errors that I could not access from the front panel. GPIB was also not functioning.
The date/time is obviously lost.

The installed options might also be stored there but I don't have any on mine so I didn't notice anything. 

Cal constants are in flash memory like Testtech stated.

[Finderbinder]

...
The installed options might also be stored there but I don't have any on mine so I didn't notice anything. 

Cal constants are in flash memory like Testtech stated.

Ok. Then written above is valid for options backing up.
Or it is not critical and options may be restored after the fact?
Accordingly maybe new options could be added the same way?

[ap]

If you are concerned, you can remove the Dallas RAMs, copy them, and install new ones on sockets.