The IBM Model 350 was the world's very first hard drive ever made, and was exclusively made to be used by the IBM 305 RAMAC computer that IBM started delivering to businesses back in 1956. The hard drive and the computer were mainly used by financial institutions for business accounting. The hard drive was built using 50 discs that were 24-inches in diameter and all together they stored about 4.4MB of data. The discs of the hard-drive spun at a maximum of 1,200RPM and the drives were able to be read at up to 8,800 bits per second, but that excludes the access time of approximately one second.