IBM's mainframes are the oldest line of computers, dating back to 1964 and
occupy a special place as the world's first instruction set architecture.
This longevity and extreme backwards compatibility are responsible for
perhaps the most lucrative computer franchise. IBM's z196 is the first
mainframe with an out-of-order CMOS microprocessor, and also the first with
an integrated L3 cache. These two innovations are largely responsible for a
30-40% improvement in performance over the previous generation z10 servers.