Posts: 18
Threads: 3
Joined: Apr 2010
Hi John,
It takes a CR2016 3 volt watch battery. The instructions say to change it every year and I've always done that without problems. You change the battery while the card is in the calc (With the calc turned on) so that you don't lose the data.
After you insert the card into slot 2, turn the calculator on. It will say "Invalid Card Data". Type 'PINIT' and all is good.
I've read that you should not let the calculator's AAA batteries drop too low while using a GRiD card. I'm not sure why, but you might want to search comp.sys.hp48 usenet archives about it.
Hope that helps,
Ben