Number Systems

Octal number system

A base eight numbering system that uses numbers 0-7, 10-17, 20-27, and so on. There are no 8s or 9s in the octal number system.

Gray code

A binary coding scheme that allows only 1 bit in the data word to change state at each increment of the code sequence.

Significant digit

A digit that contributes to the precision of a number. The number of significant digits is counted beginning with the digit contributing the most value, called the most significant digit (left most), and ending with the digit contributing the least value, called the least significant digit (rightmost).

Byte

A group of adjacent bits usually operated on as a unit, such as when moving data to and from memory. There are 8 bits per byte.

Hexadecimal

A number system having base of 16. This numbering system requires 16 elements for representation, and thus uses the decimal digits zero (0) through nine (9) and the first six letters of the alphabet, A through F

Binary

A number system using 2 as a base. The binary number system requires only two digits, zero (0) and one (1), to express any alphanumeric quantity desired by the user.

Binary word

A related group of 1's and 0's that has meaning assigned by position or by numerical value in the binary system of numbers

Binary-coded decimal (BCD)

A system of numbering that expresses each individual decimal digit (0 through 9) of a number as a series of 4-bit binary notations. The binary-coded decimal system is often referred to as 8421 code.

American National Standard Code for Information Interchange (ASCII)

An 8-bit (7 bits plus parity) code that represents all characters of a standard typewriter keyboard, both uppercase and lowercase, as well as a group of special characters used for control purposes

Bit

An abbreviated term for the words binary digit. The bit is the smallest unit of information in the binary numbering system. It represents a decision between one of two possible and equally likely values or states. It is often used to represent an off or on state as well as a true or false condition

Parity

The use of a self-checking code that employs binary digits in which the total number of 1s is always even or odd.

Sign bit

An extra digit used to represent a binary number as either positive or negative

Most significant digit (MSD)

The digit representing the greatest value of a byte or word.

Least significant digit (LSD)

The digit that represents the smallest value in a byte or word.