Here is a relatively old paper about RT/Quick-response.
http://news.cnet.com/Novell-to-launc...&tag=nefd.lede
Since then, in the financial world where money is (... err) lost by black-box trading (r-quanted algorythms) the response time now is in th order of nano-seconds.
In order to keep transmission delays as short as possible, the brokers and the main traders now have their trading boxes at the premises of the exchanges themselves.
Question: what is real-time? Be specific, milli-, micro-, nano- ?