I gave my very old Macintosh Plus to my mother so she could learn how to use the computer. I failed to give her the system disk and during a move, I apparently lost them. Subsequently she had a Mac "bomb" system error and presed press the pop-up message's restart button. Now the computer can't find the system and is requesting the system disk (which we don't have) to restart the computer. Where can I get one, etc... ?