In 1951 a major step forward was made in the form of magnetic storage. It uses a magnetisable coating on thin plastic strip, a reader and a writer. The writer is passed over the material or vice versa and its aligns fields of magnetic particles. The polarity of the particles is different for 1ís and 0ís. The reader is used to determine the magnetic polarity of each particle be it a 1 or a 0. The first magnetic medium was tape, whether it is an enclosed setup like modern cassettes or a large mainframe reel to reel system. In this case the tape is moved past the read and write heads using a motor. Magnetic tapes offer a low cost reliable solution to data storage with a large step up in the storage to area ratio. The problem with tape is that itís sequential access, this means if your currently looking at A and want to get to D you have to pass B and C, you cant just jump to D. In reality this meant a large amount of time just getting to the correct position on the tape, known as the seek time.
A large tape reel A cartridge tape drive Modern day tapes
Punch Cards and Valves
The Hard Disk Drive
The Floppy Disk
The Compact Disk