[TriLUG] What did the PS in PS/2 stand for?

[Aaron Joyner]

So here's a trivia question for the old school IBMers who frequent the 
list.  Does anyone know what the PS in the IBM PS/2's name stood for?  
Someone asked me earlier today was asking why the PS2 keyboard port was 
labeled as such (their explanation referred to the playstation 2... :), 
and I knew it was derived from the PS/2, but not what the actual PS in 
that name stood for.

Anyone?  :)
Aaron S. Joyner