Computer Storage Fundamentals
Data are processed and stored in a computer system through the presence or absence of electronic or magnetic signals in the computer’s circuitry or in the media it uses. This is called a “two-state” or binary representation of data, since the computer and the media can exhibit only two possible states or conditions. For example, transistors other semiconductor circuits are either in a conducting or nonconducting state. Media such as magnetic disks and tapes indicate these two states by having magnetized spots whose magnetic fields have one of two different directions, or polarities. This binary characteristic of computer circuitry and media is what makes the binary number system the basis for representing data in computers. Thus, for electronic circuits, the conducting (ON) state represents the number one, while the nonconducting (OFF) state represents the number zero. For magnetic media, the magnetic field of a magnetized sport in one direction represents a one, while magnetism in the other direction represents a zero.
The smallest element of data is called a bit, which can have a value of either zero or one. The capacity of memory chips is usually expressed in terms of bits. A byte is a basic grouping of bits that the computer operates as a single unit. Typically, it consists of eight bits and represents one character of data in most computer coding schemes. Thus, the capacity of a computer’s memory and secondary storage device is usually expressed in terms of bytes. Computer codes such as ASCII (American Standard Code for Information Interchange) use various arrangements of bits to form bytes that represent the numbers zero through nine, the letters of the alphabets, and many other characters.
Storage capacities are frequently measured in kilobytes (KB), megabytes (MB), gigabytes (GB), or terabytes (TB). Although kilo means 1,000 in the metric system, the computer industry uses K to represents 1,024 or (210) storage positions. Therefore, a capacity of 10 megabytes, for example, is really 10,485,760 storage positions, rather than 10 million positions. However, such differences are frequently disregarded in order to simplify descriptions of storage capacity. Thus, a megabyte is roughly 1 million bytes of storage, while a gigabyte is roughly 1 billion bytes and a terabyte represents about 1 trillion bytes.
Data are processed and stored in a computer system through the presence or absence of electronic or magnetic signals in the computer’s circuitry or in the media it uses. This is called a “two-state” or binary representation of data, since the computer and the media can exhibit only two possible states or conditions. For example, transistors other semiconductor circuits are either in a conducting or nonconducting state. Media such as magnetic disks and tapes indicate these two states by having magnetized spots whose magnetic fields have one of two different directions, or polarities. This binary characteristic of computer circuitry and media is what makes the binary number system the basis for representing data in computers. Thus, for electronic circuits, the conducting (ON) state represents the number one, while the nonconducting (OFF) state represents the number zero. For magnetic media, the magnetic field of a magnetized sport in one direction represents a one, while magnetism in the other direction represents a zero.
The smallest element of data is called a bit, which can have a value of either zero or one. The capacity of memory chips is usually expressed in terms of bits. A byte is a basic grouping of bits that the computer operates as a single unit. Typically, it consists of eight bits and represents one character of data in most computer coding schemes. Thus, the capacity of a computer’s memory and secondary storage device is usually expressed in terms of bytes. Computer codes such as ASCII (American Standard Code for Information Interchange) use various arrangements of bits to form bytes that represent the numbers zero through nine, the letters of the alphabets, and many other characters.
Storage capacities are frequently measured in kilobytes (KB), megabytes (MB), gigabytes (GB), or terabytes (TB). Although kilo means 1,000 in the metric system, the computer industry uses K to represents 1,024 or (210) storage positions. Therefore, a capacity of 10 megabytes, for example, is really 10,485,760 storage positions, rather than 10 million positions. However, such differences are frequently disregarded in order to simplify descriptions of storage capacity. Thus, a megabyte is roughly 1 million bytes of storage, while a gigabyte is roughly 1 billion bytes and a terabyte represents about 1 trillion bytes.
