Half-century milestone for IBM mainframes

The first System 360 mainframe was unveiled on 7 April 1964 and its arrival marked a break with all general purpose computers that came before.

The machines made it possible to upgrade the processors but still keep using the same code and peripherals from earlier models.

Later this year the British rival to IBM's machine, the ICL 1900, also celebrates its 50th anniversary.

Despite their age, mainframes are still in wide use now, said Barry Heptonstall, a spokesman for IBM.

"I don't think people realise how often during the day they interact with a mainframe," he said.

Mr Heptonstall said mainframes were behind many of the big information systems that keep the modern world humming and handled such things as airline reservations, cash machine withdrawals and credit card payments.