Binary System (page 3)
Computers are often classified by the number of bits they can process at one time, as well as by the number of bits used to represent addresses in their main memory (RAM). Computer graphics are described by the number of bits used to represent pixels (short for picture elements), the smallest identifiable parts of an image. In monochrome images, each pixel is made up of one bit. In 256-color and gray-scale images, each pixel is made up of one byte (eight bits). In true color images, each pixel is made up of at least 24 bits. The particular sequence of bits in a byte encodes a unit of information such as a keyboard character. One byte typically represents a single character such as a number, letter, or symbol. Software designers use computers and software to combine bytes in complex ways and create meaningful data in the form of text files or binary files (files that contain data to be processed and interpreted by a computer). Bits and bytes are the basis for representing all meaningful information and programs on computers.
Bytes are the major unit for measuring quantities of data or data capacity. Data quantity is commonly measured in kilobytes (1024 bytes), megabytes (1,048,576 bytes), or gigabytes (about 1 billion bytes). A regular, floppy disk normally holds 1.44 megabytes of data, which equates to approximately 1,400,000 keyboard characters. At this storage capacity, a single disk can hold a document approximately 700 pages long, with 2000 characters per page. The number of bits used by a computer's Central Processing Unit (CPU) for addressing information represents one measure of a computer's speed and power. Computers today often use 16, 32, or 64 bits in groups of 2, 4, and 8 bytes in their addressing.
In computing, digital is synonymous with binary because the computers familiar to most people process information coded as combinations of binary digits (bits). One bit can represent at most two values; 2 bits, four values; 8 bits, 256 values; and so on. Values that fall between two numbers are represented as either the lower or the higher of the two. Because digital representation represents a value as a coded number, the range of values represented can be very wide, although the number of possible values is limited by the number of bits used.
Digitizing means to convert any analog (or continuously varying signal), such as the lines in a drawing or a sound signal, into a series of discrete units represented by the digits 0 and 1. A drawing or photograph, for example, can be digitized by a scanner that converts lines and shading into combinations of 0's and 1's by sensing different intensities of light and dark.
Analog-to-digital converters are commonly used to perform this translation. Analog-To-Digital Converter or ADC, is an electronic device for converting data from analog (continuous) to digital (discrete) form for use in electronic equipment such as digital computers, digital audio and video recorders, and data storage devices. Analog or continuously varying electrical waveforms are applied to the device and are sampled at a fixed rate. Sample values are then expressed as a digital number, using a binary numbering system consisting only of 0's and 1's. The resulting digital codes can be used in various types of communications systems.
