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Chapter 2 Input and Processing

Chapter 2Input and Processing

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Presentation Overview

• Input Technology• Data Processing by Computers• The System Unit• Power Supply• Storage Bays• The Motherboard

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Input Technology

Hardware devices are grouped by how and where they are used in the four steps of the information processing cycle.

– Input– Processing– Output– Storage

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Input Technology

What is an input device?– An input device is a hardware device that

allows users to enter programs, data, and commands into a computer system.

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Input Technology

What are some examples of input devices?– Keyboards and touch screens– Mice and other point-and-click devices– Pens and tablets– Optical scanners– Bar code and optical readers– Graphic and video input devices– Audio input devices

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Input Technology

A computer keyboard is organized into groups of related keys.

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Input Technology

A touch screen allows a user to make selections from a group of options displayed on a screen by pressing a finger against the chosen option.

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Input Technology

Moving a mouse moves a pointer on the screen which allows users to make selections from a menu and activate program icons displayed on screen.

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Input Technology

Every movement of the mouse corresponds to the movement of the mouse pointer on the display screen.

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Input Technology

• With a touch pad, the user traces a finger on the pad, moving the pointer on the screen.

• Below the touch pad there are buttons for clicking commands.

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Input Technology

What are some other input devices?– Optical scanner– Bar code and optical reader– Digital camera– Webcam– Video camera– Microphone

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Input Technology

A scanner captures text and/or images and converts them into a format the computer can understand for display and storage.

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Input Technology

• A digital camera captures images by converting them from analog to digital format and storing them on a storage medium.

• The pictures can then be printed or inserted into a document.

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Input Technology

A digital video camera can be plugged directly into a computer to display the recorded video.

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Data Processing by Computers

What is a program?– A program is a series of instructions that use a

binary system to switch registers on and off.– A program tells a computer how to perform

tasks, including• How to process data• How to deliver desired information

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Data Processing by Computers

• The binary number system uses a condition similar to what happens when an electrical switch is turned on, causing current to flow.

• In the binary system, a 1 represents “on” and a 0 represents “off.”

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Data Processing by Computers

• ASCII is a coding scheme many computers, including personal computers, use.

• The EBCDIC coding scheme is used mainly on IBM servers and mainframe computers.

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Data Processing by Computers

• Pressing a key generates an electronic signal that is converted into binary form (a byte) and stored in memory.

• The computer processes the digital signal and displays the character on the screen.

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The System Unit

• The system unit is the main part of a desktop computer system.

• It contains the components necessary for processing information.

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Power Supply

Like other electronic devices, a computer requires a power supply to supply energy to the computer.

– Many personal computers use a power cord that connects the computer to AC current.

– The power supply unit in the system must then convert the current from AC to DC.

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Storage Bays

• A storage bay is a site where a storage device is installed.

• The desktop computer shown contains a CD/DVD drive bay and a hard drive bay.

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The Motherboard

• A motherboard is a thin sheet of fiberglass or other material with electrical pathways.

• It holds the major processing and memory components, including– The central processing unit, to manipulate

data– The system clock, to synchronize activities– Slots for RAM chips to contain temporary

memory

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The Motherboard

• A motherboard is a thin sheet of fiberglass or other material with electrical pathways.

• It holds the major processing and memory components, including– ROM chips to contain permanent memory– Expansion slots to attach expansion cards– Ports to connect input and output devices– Buses that allow communication between

computer components

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The Motherboard

The motherboard holds the major processing and memory components, including the CPU, RAM, and ROM chips.

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The Motherboard

The motherboard contains the central processing unit (CPU).

– The CPU interprets and executes the instructions for most computer operations.

– In a personal computer, the CPU is a single chip called a microprocessor, and all processing functions are contained on it.

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The Motherboard

The central processing unit performs a machine cycle, which

– Fetches an instruction– Decodes the instruction– Executes the instruction– Stores the result

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The Motherboard

The machine cycle includes the four steps for reading and carrying out an instruction.

– Fetching– Decoding– Executing– Storing

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The Motherboard

The CPU contains a control unit, an arithmetic/logic unit (ALU), and registers.

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The Motherboard

The control unit on the CPU– Directs and coordinates the overall operation of

the computer– Performs the first two machine cycle functions

• Fetching an instruction• Decoding an instruction

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The Motherboard

• The arithmetic/logic unit (ALU) on the CPU– Performs the executing step of the machine

cycle• The ALU can

– Add/subtract– Multiply/divide – Perform logical operations, such as comparing

data items

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The Motherboard

• The registers on the CPU– Are a temporary storage location (the storing

step of the machine cycle)– Record results to memory

• Types of registers include– Instruction registers– Data registers– Storage registers

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The Motherboard

The power and speed of microprocessor (CPU) chips are determined primarily by

– The number of transistors– The clock speed– The number of bits that can be handled as a

single unit

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The Motherboard

A Comparison of Desktop Personal Computer Processors

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The Motherboard

A Comparison of Notebook Computer and Mobile Device Processors

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The Motherboard

Processing speed is improved with pipelining.– With pipelining, the computer begins executing a new

instruction as soon as the previous instruction reaches the next phase of the machine cycle.

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The Motherboard

Without pipelining, the computer executes an instruction after the previous instruction completes the machine cycle. This is less efficient.

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The Motherboard

• A dual-core processor is a CPU that includes two complete cores per physical processor.

• This means that a single integrated circuit (silicon chip) contains two processors and their cache memories.

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The Motherboard

The system clock controls timing of all computer operations.

– Its speed is measured by number of clock pulses per second, or hertz.– One clock cycle is equal to two ticks of the clock.

– A CPU uses a fixed number of clock cycles to execute each instruction.

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The Motherboard

Random access memory (RAM) is temporary memory in which programs and data are stored.

– RAM performs three functions:• It accepts and holds program instructions and data.• It acts as the CPU’s source for data and instructions

and as a destination for operation results.• It holds the final processed information until it can

be sent to the desired output or storage devices.

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The Motherboard

• RAM chips temporarily store programs and data during the processing stage.

• On some computers, ROM chips contain permanent storage of the operating system and instructions for managing peripheral devices.

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The Motherboard

Measures of Data Storage

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The Motherboard

Computer Memory Comparisons

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The Motherboard

Cache Memory – A holding area in which the data and

instructions most recently called by the processor from RAM are stored.

– Helps to shorten processing time.

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The Motherboard

Memory Access Times

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The Motherboard

• Flash memory can be erased and reused, or reprogrammed.

• This type of memory is used for storing programs and data on handheld devices such as digital cameras and cellular phones.

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The Motherboard

Expansion– An expansion slot is an opening in the

motherboard for an expansion card.– An expansion card is a component that adds a

new function. Examples include• Sound cards• Video cards• Network cards• Modem card

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The Motherboard

Expansion Cards

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The Motherboard

Ports – Are external plug-in slots that connect devices

such as monitors, keyboards, and printers to the system unit.

– Are visible on the back of the system unit.

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The Motherboard

Types of Ports– USB ports, which connect high-speed devices

such as scanners and modems– Serial ports, which connect devices such as

keyboards and modems– Video ports, which connect monitors– Network ports, which connect computer

systems to local area networks

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The Motherboard

• Data, as bits, travel along a bus from one computer system location to another.

• Bits travel along a bus from memory to CPU, input devices to memory, CPU to memory, and memory to storage devices.

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On the Horizon

Based on the information presented in this chapter and your own experience, what do you think is on the horizon?