Image uploads enabled again, see this topic for next month's plans.

OSI

OSI once upon a time stood for "Origin Systems Incorporated."

This was the name of the company that released the single-player Ultima games upon which UO is based.

They were bought out by EA in September 1992.

For more information, see here:

though of course remember that the Wikipedia, like UO Guide, can be edited by anyone, at any time, for any reason.