Well the IBM,Burroughs, UNIVAC, NCR, Control data,honeywell,general electric and RCA were the manufacturers. The examples of mainframe computers are IBM zSeries, System z9 and System z10 servers.
Absolutely, the Facebook Chat History Manager is a very good firefox extension. Using the addon you can view your chat history any time either you are online or offline. You can view, delete or if you wish you can export the chat history.