A Look at Mainframe History as IBM System/360 Turns 50, COBOL Turns 55

by Darryl K. Taft

Before the advent of the mainframe, IBM developed the 350 RAMAC. Built in 1956, it used a stack of fifty 24-inch disks as memory, which held about 4.4MB of data—just enough to store two pictures.

Considered the first modern mainframe, the IBM 360 launched in April 1964. Mainframes like this performed 229,000 calculations per second, helping put man on the moon.

The 1970s brought with them virtualization, which increased mainframe utilization and performance. Bank customers, for example, were able to make cash withdrawals and transfers for the first time, due to mainframe deployment. In fact, IBM 370s proved so popular there was a two-year waiting list.

The IBM personal computer was introduced in 1981 and was the first to wear the “PC” label. Many believed that distributed computing would become a cost-efficient alternative to the mainframe. During this time, mainframes continued to evolve and improve, while maintaining security and compatibility.

IBM introduced the System/390 family, its most comprehensive offering in 25 years. It becomes the first mainframe to smash the 1,000 million instructions per second (MIPS) barrier.

In 1991, Stewart Alsop Jr. predicted that the last mainframe would be unplugged by March 15, 1996. After 1992, mainframe computing capacity increased by more than 30 percent annually. The need for back-office systems and the opening up of the platform to industry standards facilitates its revival.

In May 2003, IBM introduced its most powerful mainframe to date, the zSeries 990, code named T-Rex. This model scales up to 9,000 MIPS on 32 processors—twice the number of processors and almost three times the system capacity of its predecessor.

Ninety-six of the world’s top 100 banks and nine out of 10 of the world’s largest insurance companies use mainframes. It’s a winning system that a risk-averse CIO is unlikely to change.

As Big Blue celebrates the 50th anniversary of the IBM mainframe this April, there seems to be no end in sight for mainframe technology. Enterprises like its reliability, scalability and continuous monitoring, which makes the mainframe an incredibly powerful tool.

Anniversaries are a good time to look forward. And while it’s amusing to see images of old-school mainframes, it’s worth remembering that like the clothes and hairstyles of those operating them, at one time these were all considered cutting-edge. Where will technology take us in 50 years? While the answer is anyone’s guess, we know mainframe technology will help us get there.