Chapter 2Input and Processing

Input and ProcessingTechnology

Hardware devices can be grouped according to how and where they are used in the four steps of

the information processing cycle.

Input

Output

Storage Processing

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

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

Data is a collection of raw, unorganized (unprocessed) content in the form of words, numbers, sound, or images.

Data

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.

Command

User Response

A user response tells the program what to do,or the task to perform.

Request

Response

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 ComputersProcess 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 0s and 1s 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 ProcessingUnit (CPU)

In a personal computer the In a personal computer the CPU consists of a CPU consists of a microprocessor, or CPU chip, microprocessor, or CPU chip, that processes the data. The that processes the data. The CPU uses the control unit and CPU uses the control unit and the arithmetic/logic unit to the arithmetic/logic unit to process data. process data.

Control Unit

Controls activity within the computer.

ALU

The Arithmetic/Logic Unit (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 MemoryRAM (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 ROM = Chips on which instructions, information, or data has been prerecorded. Once data has been data has been prerecorded. Once data has been recorded on a ROM chip, it cannot be altered or recorded on a ROM chip, it cannot be altered or removed and can only be read by the computer.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 the system unit for installing additional devices.

On the Horizon

NANOTECHNOLOGYUses individual atoms to build microscopic, massively parallelcomputers 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 CHIPSChips that can change capabilities according to the computing tasks required at any given moment.