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Chapter 2 Input and
Processing
Chapter 2
Input and Processing
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Presentation Overview
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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.
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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?
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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?
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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
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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
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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.
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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
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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?
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