Hugh Pickens DOT Com writes: Those of us of a certain age remember well the breakthrough that the IBM 360 series mainframes represented when it was unveiled fifty years ago on 7 April 1964. Now Mark Ward reports at BBC that the first System 360 mainframe marked a break with all general purpose computers that came before because it was possible to upgrade the processors but still keep using the same code and peripherals from earlier models. "Before System 360 arrived, businesses bought a computer, wrote programs for it and then when it got too old or slow they threw it away and started again from scratch," says Barry Heptonstall. IBM bet the company when they developed the 360 series. At the time IBM had a huge array of conflicting and incompatible lines of computers, and this was the case with the computer industry in general at the time, it was largely a custom or small scale design and production industry, but IBM was such a large company and the problems of this was getting obvious: When upgrading from one of the smaller series of IBM computers to a larger one, the effort in doing that transition was so big so you might as well go for a competing product from the "BUNCH" (Burroughs, Univac, NCR, CDC and Honeywell). Fred Brooks managed the development of IBM's System/360 family of computers and the OS/360 software support package and based his software classic "The Mythical Man-Month" on his observation that "adding manpower to a late software project makes it later." The S/360 was also the first computer to use microcode to implement many of its machine instructions, as opposed to having all of its machine instructions hard-wired into its circuitry. Despite their age, mainframes are still in wide use today and are behind many of the big information systems that keep the modern world humming handling such things as airline reservations, cash machine withdrawals and credit card payments. "We don't see mainframes as legacy technology," says Charlie Ewen. "They are resilient, robust and are very cost-effective for some of the work we do."