#8. AN/F SQ-7

Manufacturer: IBM

Year: 1958

Another notable milestone in computer history, the AN/F SQ-7 is the largest computer ever built. This huge computer was built over and installed in a 4-storey building, which consisted of two Whirlwind II computers. It’s said that each part supported more than 100 users. The most interesting fact about this machine is that the workers kept one unit operating, with the other unit on hot standby. This role shift was carried at regular intervals, which made workers to perform diagnostics and maintenance in the standby units. It’s said that this monster had several hundreds of tube replacements a day due to certain power failures or overload data. Because of this, workers had to continuously run along floors and racks with cargos of replacements. But whatever be the story, the AN/F SQ-7 provided IBM with monstrous amount of experience in computers which later made them one of the best in personal computer manufacturing.