Mac OS 7.6.1
This is not much of an upgrade, just a matnience upgrade for free. However, this should eliminate much of the system crash type 11 that was in 7.6. But this version of Mac OS is a part of history. This is the last chance before the Mac OS 8.0. Some people probably say, "Whhaa, it's about time!" Yeah, it is, but this is the last chance before going to that secret PC OS. Well, call it what you like. Last chance.
Price-Free from Apple