MS-DOS the predecessor of Windows was of course itself surround in controversy. Back in 1980, Clive Sinclair had just released the ZX80 for £99.95 (£383 at 2015 prices). While IBM had turned to a tiny software house called Microsoft for a BASIC run-time for its first micro computer. Bill Gates offered to provide IBM with an O/S (operating system) as well. The only problem was he didn't have one to sell.
So he turned to Tim Paterson's garage based operation Seattle Computer Products (SCP) for a clone of CP/M called 86-DOS. Developed by SCP under the code name QDOS (for "quick and dirty operating system") which Microsoft subsequently turned into the hugely successful MS-DOS franchise and the rest as they say is history.
In fact CP/M was one of three O/S's offered on IBM's first PC, the other being UCSD p-System, but I think its fair to say IBM's distribution and pricing favoured 'their' own OS then known as PC-DOS. CP/M meanwhile reappeared as the O/S for the Amstrad CPC 6128 home computer in 1985.
In an interesting footnote to the battle of O/S's can be found on the Register. Had Digital Research, the owners of CP/M, sued Microsoft and prevailed today's desktop might look very different to Windows 10. They had a very clear road-map for the development of CP/M and their own Graphical User Interface (GUI) GEM.
It's also fair to point out that Windows and Mac OS weren't the only GUI's in town. The 1980's in many ways were the wild west frontier of computing with a slew of home computers coming onto to the market. Some of which were far more successful than others and lead to a generation of bedroom coders, who went on to form the basis of the modern games industry.
The final two heavyweights of the home computer era, before the dominance of the PC swept all aside, where the Commodore Amiga and Atari ST. I'll have to be careful what I say here as I was and still am firmly in the Amiga camp of what was one of the greatest fanboy battle of the 80's, if not all time, about which computer was best. Lets just say the Amiga had the edge graphics wise, being used to generate special effects for TV shows such as Babylon 5, while the ST's built-in MIDI interface made it the musicians choice.
In terms of O/S's the Amiga had Workbench, which introduced a number of new design philosophies to the desktop, subsequently adopted by others. While the Atari ST used Digital Research's GEM. Its a testament to the popularity of both machines that they still have an active fan-base today.
The Amiga O/S lived on to outgrow the custom architecture of the Amiga and become a fully PowerPC compatible O/S with the release of AmigaO/S 4.0 in 2007, 11 years after the Amiga computers themselves were discontinued.
Meanwhile GEM was released under GNU General Public License (GPL) in April 1999 and continues to be developed for PC's as OpenGEM and FreeGEM and ironically perhaps has been ported back to the Atari ST again to be used in the Atari emulator EmuTOS.
I guess what this all proves is that technical excellence alone is not enough to survive in the cut-throat world of big business. Ultimately Apple survived its lean years by withdrawing from the mass consumer market. Carving out a niche with products designed to appeal to a specialist high-end market, such as desktop publishing, where its tightly integrated hardware and software could thrive. While Microsoft went the other way, focusing on licensing its software to a wide of range of generic PC suppliers, utilising economies of scale with off-the-shelf components, that effectively killed off the home computer market. Although the rise of the games console, which was less vulunerable to software piracy, undobutly played a role as well.
Finally I owe an apology to users of Linux, another popular open-source alternative to Windows and MAC OS, with its own loyal userbase, which I've not had time to cover here. Linux is of course a key component of the Raspberry Pi an exciting and so far highly successful initiative to get kids coding again and develop the next generation of bedroom coders who will help build the internet of things.