What is a Mainframe Operating System?

A mainframe operating system is networking software infrastructure that allows a mainframe computer to run programs, connect linked machines, and process complex numerical and data-driven tasks. All computers use some sort of basic operating system (OS), which is what enables them to organize files and execute commands. The biggest difference between a simple, one-computer OS and a mainframe operating system is where each is located. Simply put, a mainframe system works on a mainframe computer, which is usually thought of as sort of the “headquarters” or server for a computer network. Most major networks and infrastructures have a mainframe, which is where data is backed up and systems are broadly organized. Back in the early days of computing, all computers were mainframes, and most were very cumbersome to use and operate. Things have come a long way, but there is still an important role for these larger operating systems when it comes to supporting all of the machinations of the modern technological landscape.

Just like the keyboard and mouse are the interface between the computer and the user, the operating system is the interface between the computer and the software it’s running. The operating system acts like a traffic cop pushing and pulling data to and from memory, registers, input and output devices, and the processor. The easiest way to think about a mainframe operating system simply is as an operating system on a mainframe computer, a powerful device used mainly by governments and businesses to process large amounts of information and support a great number of users.

In the 1950s, before desktop computers and long before laptops, all computing was done on mainframe computers. These computers could take up a whole room and most weren’t powerful, at least not by modern standards. They typically did less work than one of today’s laptop computers. As a matter of fact, the earliest computers were designed to only do one job or run a single program.

As computer programs got more complicated and computer hardware accordingly became less expensive, it became more effective to build computers that could run more than one type of program at once. To enable this, computer engineers had to develop a way that the computer could adapt itself to a new and different program. The mainframe OS developed accordingly.

One of the earliest functions of the system was reading punch cards, which were basically very early versions of floppy disks and readable CDs. On those first computers, not only was there no mouse, there was also no keyboard. All input into the computer came from cards with holes punched in them in specific patterns. The position of the holes determined the data that was being transmitted and transferred. The OS read each cards and translated it into the binary data that the computer understood and could use to execute certain specific functions.

This old computer input method is a good example of what an operating system does. If a computer program is looking for a series of numbers, for example, it doesn’t really matter where those numbers are coming from. Binary data can come from punch cards, a keyboard, an Internet script, or voice recognition software. The operating system takes the number from the input device and hands it off to the program, which then uses it as needed.

It was through these early days of operating system functionality that aspects of modern computing were first pioneered. Concepts such as batch processing, multitasking, buffering, and spooling — all key elements of how computers work today — were first introduced in the mainframe operating systems of the 1950s, though obviously in much simpler forms. Technicians have built on these early ideas to enable everything from remote data transfer to smartphone Internet connectivity.