Systems Software

What to expect

The history of operating systems, from the first batch loader for the IBM 704 in 1956, through the development of Unix to the launch of Windows and Mac OS.

Discover how the 360 mainframe nearly broke IBM, and how voice user interfaces (VUIs) are all the rage.

At MIT in the mid-1960s, work had stalled on the experimental operating system Multics, which was being designed for the General Electric mainframe. Bell Labs had pulled out of the project, frustrated by Multics complexity. Their researchers Ken Thompson and Dennis Ritchie embarked on a scaled down version on a PDP-7, initially calling it Unics, a pun on Multics. Bell Labs wanted to edit patent documents so Thompson and Ritchie ported the new OS to the much larger PDP-11 and added a word processor. The UNIX Programmer’s Manual was published on 3 November 1971, now considered “Unix’s official birthday”.

As he wrote utilities for the fledgeling OS, Ritchie was frustrated by the limitations of the programming language “B” so he wrote a new high-level language called “C” in 1972, and then rewrote the whole of the Unix operating system in C code in 1973. Unix was presented to the outside world at the 1973 Symposium on Operating Systems Principles, the same conference where six years earlier Larry Roberts had announced the ARPANET (see chapter 9). Unix proved hugely popular in academia, partly because it was so powerful.


Early computers were hard-wired to perform a single program. Running a different program required extensive manual intervention. IBM created a simple operating system for the 704 in 1956 to speed batch processing, but a more ambitious IBM project called STRETCH (1961) and Manchester’s ATLAS computer (1962) provided multiprogramming features for the first time, and abstracted hardware operation from the applications.

In 1964, IBM’s OS/360 delivered indexed data files, program libraries, a job scheduler, interrupt handling and print spooling and the modern operating system was born. Two Bell Labs researchers, Ken Thompson and Dennis Ritchie created Unix in 1971 which became the most popular OS on the planet by 1980.

Apple’s 1984 Macintosh was the world’s first successful home computer with a graphical user interface, based on GUI prototypes seen by Wozniak and Jobs years earlier at Xerox PARC. Mac OS had a user-friendly interface navigated by a mouse, and a year later Bill Gates’s Microsoft released their first GUI called Windows. Each subsequent version of both Mac OS and Windows added more functionality, compatibility with additional hardware and accessibility features, and mobile versions were spun off in the 21st century including iOS and the Windows Phone OS.

Finnish student Linus Torvalds released the first version of Linux in 1991, writing from scratch the features he most liked in Unix. Linux now runs hundreds of millions of devices from home internet routers to Amazon’s data centres servers. Linux is open source, meaning anyone can see, copy, amend and contribute to the source code.

Operating systems come in multitasking, distributed, embedded or real-time versions, each type suited to a different use.

Operating systems are a type of system software. All operating systems exist to manage the hardware and allow applications and users to interact with and control the system. Utilities and drivers are also system software, utilities help keep the computer running smoothly while drivers communicate with the hardware. Anything that is not an application is probably system software.


Refs for this chapter.










[129] Form factor means the size and shape of the computer e.g., desktop, laptop, tablet.