Data and Storage

In computer format, data has a basic format. A bit can take one of two values - zero or one. This pattern of numbers is binary digit in computer. It can be stored in primary storage like RAM (Random Access Memory) or ROM (Read Only Memory) and secondary storage like diskettes, hard disks, tape storage (magnetic), recordable CDs or CD ROM (optical).

In the early days of the computer industry, tapes were one of the main storage media. The technology, like that of tapes in the music industry, is stable and mature, and they are relatively inexpensive and high capacity. However, as computer applications became more and more on-line and interactive, tapes became inadequate as they could not respond quickly enough to the new applications. Data can only be stored or retrieved from tapes sequentially. Therefore, magnetic tape has become obsolete for online computing system.

One common advantage of using CD-ROM, CD-R and CD-RW is one metal disk can contain a vast amount of information. Also, it combines elements of print, visual images (both still and moving) and capabilities for sound (narration, music, sound effects) under the control of an overarching computer program that provides flexible access to these bits of information. However, using CD-ROM has a limitation. The memory in   CD-ROM is read only memory. This is installed with a particular program at manufacturing stage and its contents can not be erased.

The Open University of Hong Kong (1994) 'Working systems' in CE150 Foundations in Microcomputing, Hong Kong: OUHK.

The Open University of Hong Kong (1998) 'Data communication' in CE150 Foundations in Microcomputing, Hong Kong: OUHK.