Though it was by no means widely used, IBM launched the first disk drive storage system--the 350--in 1956. It was sold as a component to IBM’s 305 RAMAC computer system. It could store 5 million 6-bit characters on fifty 24-inch diameter disks inside a 60x68x29-inch cabinet, which meant there were 100 recording surfaces, each with 100 tracks. The disks spun at 1200 rotations per minute. A pair of heads moved up and down to select a disk, and in and out to select a data track. Companies that felt an urgency for faster business accounting could lease this fancy system for $3,200 per month. IBM could’ve built larger disks into the 350, but corporate rules dictated that no product could be wider than a standard doorway (29.5-inches). As it was, the unit weighed over a ton and was delivered to companies via forklift cargo airplanes.