I remember it roughly like this: Before the PC era computers were mostly integrated in the keyboard (many 8-bit home computers), the monitor (Apple Lisa) or bo

I remember it roughly like this: Before the PC era computers were mostly integrated in the keyboard (many 8-bit home computers), the monitor (Apple Lisa) or both (Commodore PET). Then they became more or less flat boxes on the desktop. Early PC's were like that (the bulky version) but also early workstations like Sun's SPARCstation (the more elegant version). They were meant to put a monitor atop. Over time the boxes got bigger and louder and the monitors got bigger which made this design impractical. Some people flipped the boxes, put them under their table and the tower was born. Not long and professionally made tower cases appeared. Over time the bulky towers got smaller and we had Midi- and Mini-Towers on the PC side and things like the Sun Ultra 24 or the SGI O2 on the workstation side. These could be put on the table again but this time next to the monitor and not below it.