I worked mostly with large computer systems built by IBM (and a couple of other manufacturers) for most of my career up until the mid ’90’s, when the company I was with went “client-server.” The idea behind client-server was that the workload was spread across multiple computers, with each one having a part in getting the job done. Oddly enough, at least in our interpretation of the task, IBM mainframes were not one of the computers. Never mind that the two companies that had merged in 1989 had made their fortunes writing software that ran on IBM hardware, we were escaping all that.
I think it should have been called client servers, because while the user’s end was a PC with our software loaded onto it, there were usually more than one type of server. One was the database server, which held all the data in SQL databases, another was the processing server, which performed all the work that wasn’t done on the client, and a third was a file server, where all non-database data was kept. Occasionally there were others in there, maybe a maintenance server that could push software changes to the clients, for example. The operating system running on the client machines was Windows, while the server machines would run one of the many flavors of UNIX. Thus, if you were a technical guy like me, you had to know Windows and UNIX. To that end, they sent me to class so I could learn me some UNIX.
One of the first things I learned was that UNIX was a lot like the IBM operating systems I had been working with: they both were multiuser and multitasking. In other words, any number of people could be signed on to a UNIX machine and run any number of jobs, and the stuff that user A was doing didn’t affect user B and vice versa. Next, I learned that UNIX was the brainchild of some engineers at AT&T, who built machines that would use UNIX as their operating system. They did such a good job that they started licensing UNIX to other equipment manufacturers and academic institutions, each of which made its own contributions and customized it to fit their needs, and they in turn rebranded the original UNIX to make it unique: IBM’s was AIX, Microsoft called theirs Xenix, Hewlett-Packard had HP-UX, Sun had Solaris, UC Berkeley created BSD, and so on. Each one was different enough from the others to give you fits.
After a while, AT&T sold UNIX to Novell, who has spun it off and it’s now governed by a group called The Open Group, which developed a Single UNIX Standard to eliminate the annoyances I was just talking about. The current version of UNIX with the largest install base is, believe it or not, Apple’s Mac OS (formerly called Mac OS X), which was based on a version called Darwin.
I started using Macs during the whole Windows Vista debacle. I was in the market for a new computer, and had heard enough bad things about Vista that I knew I didn’t want to have to mess with it. I had been playing with various distros of Linux (an operating system developed by Linus Torvalds at the University of Helsinki that’s virtually the same as UNIX), and when I learned that OS X was based on UNIX, it made my decision much simpler.