Compatibility of restart discs?

I have an eMac that was given to me. sadly, I have neither the password or the restart disc. I can borrow a restart disc from a 1999 iMac. Are they likely to be compatible?
Thanks!

If it's a restore disc, it has to be from an identical model.

Thanks Mike.

What are the specs of the emac?

Either Leopard OS X.5 for the 1/1.25/1.42GHz models, or Tiger OS X.4 for the 700/800MHz models. Make sure you look for a full retail install DVD, which is black. If it is an older eMac with only a CD drive, you will find trouble locating operating system discs in CD version.

Auction sites such as eBay might well be the go.

thanks

What Model ? It doesn't want to tell me.
S/N ?
Memory ? 256MB DDR SDRAM
OS ? OS X Version 10.3.5