"The IBM 305 RAMAC, introduced in 1956, was the first computer to include a hard disk drive. The drive, the IBM 350, stored up to five million characters of data in the magnetic surface coatings of a stack of 52 disks, each 24 inches in diameter, that rotated at 1200 rpm inside a glass cylinder. For “companies [who] long dreamed of an accounting system capable, in a single operation, of recording transactions as they occur,” IBM said in a promotional film, the 305 RAMAC, short for Random Access Method of Accounting and Control, was a “dream come true.”