Many did -- e.g. the original G4 Towers: http://en.wikipedia.org/wiki/Power_Mac_G4 http://en.wikipedia.org/wiki/Power_Mac_G4 The gray oval in the center of the

Many did -- e.g. the original G4 Towers: http://en.wikipedia.org/wiki/Power_Mac_G4 http://en.wikipedia.org/wiki/Power_Mac_G4 The gray oval in the center of the drive door cover is the load of a class 3 lever that pushes the eject button on a relatively commodity optical drive. It was eliminated once the Quicksilver generation came out. Those early G4s could also be purchased with a ZIP drive, the coverplate to which infuriatingly had a thin section of plastic covering the ZIP eject button, such that you could see the LED in it but not push it. Now that's just mean.