Gone but not forgotten: 10 operating systems the world left behind

A DOS by any other name

DOS was dealt a death blow when Windows 95 came out in 1995, but many of us old keyboard jockeys still drop out to the command line from Windows to flex our old DOS muscles occasionally. It just feels more efficient to type a quick command than to monkey around with the mouse and menus. We may be fooling ourselves -- like the people who wait in line for self-checkout at the supermarket when the Express checkout clerk is twiddling her thumbs -- but it's all about perception, right?

Of course, DOS wasn't a single homogeneous operating system. It came in many flavors from several different vendors. Even the iconic PC-DOS, introduced to the world in 1981 along with the IBM PC, didn't come from one vendor: It was branded by IBM and developed by Microsoft from its MS-DOS, which was in turn licensed from Seattle Computer, where it was called QDOS -- which was by some accounts ripped off from Digital Research's CP/M.

Most old propeller-heads cite 1987's MS-DOS 3.3 as their favorite. It introduced support for more than one logical drive per hard disk and could handle those high-capacity 3.5-inch floppy disks. (You remember, the double-density HD ones with a massive 1.44MB capacity?) No matter how many bug fixes Microsoft came up with for DOS 4.0, it was shunned; 3.3 was the MS-DOS of choice until DOS 5.0 came around in 1991.

And then there were the people who used DR-DOS instead. When Digital Research's DOS 5 debuted in 1990, it left so much more memory free than any version of Microsoft DOS that it made many instant converts. Purists were quick to point out it was a Digital Research product, the firstborn son of CP/M, not like the Microsoft's versions of DOS, the clones of CP/M's clone.

And besides, DR-DOS pioneered the MOVE command, a vast improvement over MS-DOS's convoluted two-step COPY and DEL. What's not to love about that?

Some of us favored the Tandy/Radio Shack brand of DOS, TRS-DOS (called triss-DOS by its friends and trash-DOS by its detractors). Now this was a DOS with some pedigree -- and no relationship to MS-DOS at all. It appeared in 1977, and its popularity may have had something to do with the fact it came on cheap retail machines four years before IBM entered the PC arena. Or perhaps people just liked TRS-DOS's dramatically named KILL command, which beat MS-DOS's more prosaic DEL hands-down.

But by any of its names, the DOS family was never for dummies. So if you miss it as badly as we do, pretend it's still around on your Windows machine: Hold down the Window key, press R, and type in CMD for old time's sake. Or go all the way and try out FreeDOS, an open-source project that's bringing DOS back to life on modern PCs.

Not just any system... THE System

Ah, we remember Mac OS fondly.

Yes, we know there's still a Mac OS, but we're talking about the classic Mac OS. It ran on Motorola chips. It wasn't built on BSD Unix; it was built on itself. And it was so self-evident, we just called it the System.

Now don't get us wrong ... we love the Tigers and Leopards and the other jungle cats of the OS world, but we still have a soft spot for the versions before Mac OS X. After all, it first inspired technolust in 1984, it lasted till the end of the millennium, and it spawned a rash of imitators -- and look-and-feel lawsuits.