IBM computer 4 Megabyte hard drive, 1984.
© Science Museum / Science & Society Picture Library
Hard disks are rigid non-removable magnetic disks used for storing information in a computer. The first computer to incorporate a hard disk drive was the IBM XT introduced in 1983, which had a hard drive capable of storing 10 megabytes of information. Improvements in technology mean that modern hard disks not only have greater memory capacity, but are also very much smaller than earlier ones such as this example.