Bits, Bytes, & Words

1. Bits, Bytes, & Words By PresenterMedia.com

2. Bits • A bit is a binary digit, 0 or 1. • The name (probably) comes from the b from binary and the t from digit and one of the i's. • A bit can represent anything that has two states: true/false, yes/no, on/off,... • In computers, bits are represented by switches: 0 is off and 1 is on.

3. Bytes Since bits can only represent types of data that consist of only two values a scheme is necessary to represent classes of data consisting of more than two values, such as keystrokes. Bytes are used for this representation. Bytes consist of sequences of bits. These sequences have been 8 bits long for over forty years.

4. Bytes (continued) • Since bytes are 8 bits long they can represent more than two values. Each of the bits can represent two values and therefore 8 bits can represent 28 = 256 values. • 00000000 up to 11111111, with two options for each position. • So any classification consisting of 256 or fewer different values can be represented by a byte. • Keystrokes are represented by bytes.

5. Byte Standards • Two standards for byte representations are ASCII (ass-key) and EBCDIC (ib-suh-dik). • A standard is necessary so that what your computer stores when you press 'a' is the same as what is stored when I press 'a' on my keyboard.

6. Double Bytes • There is a third standard, unicode, which takes two bytes to store values but can represent 216 = 65536 different values. • It is therefore useful for classifications that contain more than 256 values, such as Chinese, Arabic, and other languages. • Unicode will probably be the standard for most data representation within a few years if it is not already.

7. Words A word is the amount of data that the CPU manipulates at one time. Most current (personal) computers have a word size of 64 bits. Thirty-two bits was the standard size until a few years ago. Thirty years ago the standard was 16 bits.