The death knells of the mainframe have been sounded for years now, yet despite all these calls, the mainframe lives on. It has not died, and it is showing no signs of dying. Despite competition for workloads from high-end Unix and Intel-based servers, as well as the rise of cloud computing, mainframes - or 'big iron' as they're colloquially referred to - persist. However, the terminals or 'green screens' that were traditionally used to communicate with mainframes have not persisted, instead being replaced with terminal emulation software ( 3270 emulation, for example), which mimics the role terminal hardware once played.

Why Has the Mainframe Persisted?

The mainframe remains strong in the face of predictions of its demise because, quite simply, it still retains many benefits that other servers cannot offer. One of its biggest benefits is its ability to host multiple operating systems and run major software packages. IBM's z990, for example, is able to virtualize hundreds of software applications at once and can handle 13 billion transactions on a daily basis. In fact, IBM's mainframes were the first to ever offer this sort of flexibility and performance, and they continue to do so today. It's one of the reasons the majority of the world's largest corporations and banks continue to rely on them.

Additionally, mainframes boast security capabilities that distributed architecture simply cannot offer. In a world where online security is a major issue and intruders are breaking into and stealing information from large corporations and even major governments on a regular basis, the value of such peace of mind cannot be underestimated. The IBM z9, for example, stores its master encryption keys in anti-tamper packages that zero out data and prevent intruders from capturing them. Additionally, on a mainframe, different partitions, or virtual servers, can be segregated from each other far more effectively. This allows background functions such as backing up data to take place without the performance of other applications being affected. Once again, peace of mind is the key.

Of course, there are also many challenges that the mainframe faces in its quest to remain at the forefront of server systems. One of the biggest is that, quite simply, mainframe techniques aren't taught in college any more. Of roughly 100,000 employees in the mainframe workforce, almost half are approaching retirement. IBM is combating this with a major investment in training young zSeries technical staff, but they've had to take this task upon themselves. Additionally, mainframes are still very expensive compared with other server solutions, and many predict that IBM will have to lower costs in order to keep their market share from Unix and Intel-based servers.

What Happened to Terminals?

When mainframes first surged to popularity, computer terminals were utilized by end users to interact with the mainframe. They were character-based, unlike today's graphics-based interfaces such as Microsoft Windows or Apple's Snow Leopard. Additionally, they had no intelligence (it's why they're often referred to as 'dumb terminals'… as well as 'green screens', after the usual color of their characters) and were really only capable of sending the end user's keystrokes to the mainframe and displaying the return output sent back from the host.

Because graphics-based interfaces have become the norm in modern computing thanks to the personal computer, the terminal has become obsolete, but terminals are still necessary to access mainframes. Because of this, terminal emulation software has become essential in harnessing the power of the mainframe. End users can access Windows terminal emulators, Apple terminal emulators, smartphone terminal emulators (such as the iPhone and Android phones) and more. Wherever access to a mainframe is required, terminal emulation software has been created for the job.