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Hardware: Input and Processing
Input and Processing Technology Input Storage Processing Output Hardware devices can be grouped according to how and where they are used in the four steps of the information processing cycle.
Input The term input refers to data and instructions entered into a computer enabling the computer to perform the task desired by the user.
Input Devices An input device allows programs, data, commands, and responses to be entered into a computer system. Include keyboards, mice (plural for mouse), trackballs, touch pads and touch screens, joysticks, pens and tablets, graphics tablets, optical scanners, bar code readers, audio input devices, video input devices, and digital cameras.
Mouse A mouse uses either a ball or a light sensor to track movement.
Trackball: Plastic sphere resting on rollers, inset in a small, external case
Joy Stick Small box containing a vertical lever that moves the graphics cursor
Other Input Devices • • • Pens and tablets Optical Scanners Microphone Video camera Digital camera
Information Processing: Programs and Data A program is a series of instructions telling a computer how to perform the tasks necessary to process the data and deliver the desired information.
Stored Program Concept A program can be entered a single time and used again and again.
Data is a collection of raw, unorganized (unprocessed) content in the form of words, numbers, sound, or images.
Data is coded in coding schemes such as ASCII, EBCDIC, and Unicode.
A Command A command is an instruction to a program issued by a user.
User Response Request Response A user response tells the program what to do, or the task to perform.
Information Processing Also called data processing or simply processing, the term information processing refers to the manipulation of data according to instructions in a computer program.
How Computers Process Data All computers are digital devices that use the binary number system. They are capable of recognizing only “off” and “on” (“ 0” and “ 1”) states. Each of these “ 0” and “ 1” digits is called a bit.
Bit A bit Represents the smallest unit of data in the binary system. A group of eight bits is called a byte. Combinations of 0 s and 1 s are used to represent letters, numbers, and special characters.
System Unit Includes microprocessor (CPU), memory boards and chips, ports, expansion slots, and expansion boards Allows peripheral devices such as monitors, keyboards, mice, and disk drives to function properly. Buses allow data to move about inside the system unit.
The Central Processing Unit (CPU) In a personal computer the CPU consists of a microprocessor, or CPU chip, that processes the data. The CPU uses the control unit and the arithmetic/logic unit to process data.
Control Unit Controls activity within the computer.
The Arithmetic/Logic Unit (ALU) ALU Performs processing operations on the data.
Registers Stores instructions and data until they are needed for processing. The system clock synchronizes or controls the timing of all computer operations.
Internal Memory RAM (random-access memory) Chips inside the system unit are used to store programs while they are being executed, and data while it is being processed. The amount of RAM is measured in bytes.
Cache Memory Provides for faster access to instructions and data, speeding up computer applications.
ROM (Read-Only Memory) ROM = Chips on which instructions, information, or data has been prerecorded. Once data has been recorded on a ROM chip, it cannot be altered or removed and can only be read by the computer.
Flash Memory can be erased and reprogrammed.
Computer Expansion: Ports A port is a plug-in slot on a computer for connecting a peripheral device.
Expansion Slot An expansion slot is an opening in a computer where a circuit board, called an expansion board, can be inserted to add new capabilities to the computer.
PC card A PC card is a small expansion board that plugs into the side of a notebook or portable computer.
Bays A bay is an area within system unit for installing additional devices.
On the Horizon NANOTECHNOLOGY Uses individual atoms to build microscopic, massively parallel computers that are more powerful than today’s supercomputers CELLULAR COMPUTERS Tiny processors that are integrated directly with memory and communications circuits. NEW AND IMPROVED INPUT DEVICES • Keypad with functions such as Print built in • V-Pen • Head mounted mouse RECONFIGURABLE CHIPS Chips that can change capabilities according to the computing tasks required at any given moment.