Most types of semiconductor memory have the property of random access,which means that it takes the same amount of time to access any memory location. This means that data can efficiently be accessed in any random order.This contrasts with data storage media such as hard disks and CDs which read and write data consecutively therefore, explains why the data can only be accessed in the same sequence it was written.
Semiconductor memory also has much faster access times than other types of data storage; a byte of data can be written to or read from semiconductor memory within a few nanoseconds, while access time for rotating storage such as hard disks is in the range of milliseconds. For these reasons it is used for main computer memory (primary storage), to hold data the computer is currently working on, among other uses.
Storage costs are a big factor in choosing the type of storage media, especially for larger projects and firms. Tasks that require large backups tend to move to magnetic (tape) memory because of the relatively low cost and high overall storage capacity. However, when working with projects that require faster memory and access that is instantaneous, chip memory, even at a higher cost, is more preferable since it is always accessible.
