The Mac Classic was an early 90's 'budget' Mac running System 6 (check out Low End Mac's history and profile of this model), and I've personally never seem one in action. Since pictures are worth only so many words, I thought I'd post a YouTube video I stumbled across of a Classic starting up. The res/frame rate flicker (funny thing: I had to edit 'flicker' because I originally and instinctively typed 'flickr') and crummy Flash compression certainly don't propel this video to the top of the list in terms of video quality, but I figured this might still be a fun, though brief, look at an old school version of the Mac OS.
If ya'll know of any better videos of older versions of Mac OS booting or running, feel free to link them in the comments. If we can collect enough, I'll round them up in another post.