Setup problems

[Grizzlybear]

I have a old Tandy 4860 HD laptop given to us.
In the past it worked fine. Then after getting newer one, it sat in closet for quite awhile. Now when I tried to get it to work it does this:
Turned on. Needed to set time/date in setup. Set and clicked F4 to save and exit setup, and reboot.
But after it shows:
Real time clock failure.
Invalid configuration info. please run setup program.
It keeps showing up even after tried again.
I have been told that I need to get the setup disk. Is this true? If so, does anyone have one I can get a copy or know where I can get one?

[hypnotizeminds]

Unplug the power from the motherboard and remove the little battery attached to the board to reset the CMOS settings. Leave it out for about 20min, then put it back in, plug the power back into the motherboard and turn it on.