Chapter 2
Input and Processing
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Presentation Overview
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Input Technology
Data Processing by Computers
The System Unit
The 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 4 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?
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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Input Technology
What are some examples of input devices?
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Keyboards
Touch screens
Mice and other 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
Input Device: Touch Screen
allows a user to make
selections from a group
of options displayed on a
screen by pressing a
finger on a chosen object
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Input Technology
Input Device: Mouse
– second most common input device
– moving the mouse moves a pointer on 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 that
haven’t been mentioned?
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Optical scanner
Bar code and optical readers
Digital camera
Webcams
Video cameras
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
be printed or
inserted into a
document.
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Input Technology
A digital video camera can plug directly into a computer to
display the recorded video.
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Data Processing by Computers
What is a program?
– A series of instructions, using a binary system
to switch registers on and off
– Tells a computer how to perform tasks
• 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 number system,
a one (1) represents an “on”
state in which there is an
electrical charge, and a zero
(0) represents an “off” state in
which there is no electrical
charge.
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Data Processing
by Computers
ASCII is a coding scheme
many computers, including
personal computers, use.
The EBDIC coding scheme is
used mainly on large
computers such as IBM
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 main part
of a personal
computer
system,
containing
components
necessary for
processing
information
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The Power Supply
connects the computer to AC current and
converts the AC current to DC current
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Storage
Bays
The desktop
computer shown
contains a
CD/DVD drive bay
and a hard drive
bay.
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The Motherboard
holds major processing and memory
components, including:
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Central processing unit to manipulate data
System clock to synchronize activities
Slots for RAM chips to contain temporary memory
ROM chips to contain permanent memory
Expansion slots to attach expansion cards
Ports to connect input and output devices
Buses to communicate 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 Central Processing Unit
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interprets and executes the instructions for
most computer operations
– on a personal computer, it is a single chip
called a microprocessor, and all
processing functions are contained on it
– called a CPU or microprocessor
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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 central processing unit (CPU) contains a control unit,
arithmetic/logic unit (ALU), and registers.
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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 Control Unit
– directs and coordinates the overall operation of
the computer
– performs machine cycle functions
• fetching an instruction
• decoding an instruction
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The Motherboard
The Arithmetic/Logic Unit (ALU)
executes (carries out) instructions and performs
arithmetic and logical operations on data. It can
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add
subtract
multiply
divide
perform logical operations, such as comparing data items
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The Motherboard
Registers
– temporary storage location
– records result to memory
– types
• instruction registers
• data registers
• storage registers
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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
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
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
System Clock
– controls timing of all computer operations
– 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
A multi-core
processor
is a CPU that
includes more than
complete core
per physical
processor, so a
single integrated
circuit (silicon chip)
contains several
processors and
their cache
memories.
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The Motherboard
Random Access Memory (RAM)
– temporary memory in which programs and
data are stored
– performs these functions:
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accepts and holds program instructions and data
acts as CPU’s source for data and instructions and as a
destination for operation results
holds final processed information until it can be sent to
desired output or storage 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 secondary type of processing storage
• a holding area where data and instructions most
recently called by the processor from RAM are
stored
• shortens processing time
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The Motherboard
Memory access times
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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
Flash Memory
– can be erased and reused or
reprogrammed
– used for storing programs
and data on handheld
computers and devices
such as digital cameras,
cellular phones, and printers
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The Motherboard
Expansion
– Expansion slots – openings in
motherboard for expansion card
– Expansion card – component that adds
new functions
• sound card
• video card
• network card
• 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. Ports are visible on the back of the
system unit.
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The Motherboard
Ports
an external plug-in slot on a computer used to connect
to a peripheral device
• USB ports connect high-speed
devices such as scanners and modems
• serial ports connect devices
such as keyboards and modems
• parallel ports connect printers
• video ports connect monitors
• SCSI ports have faster transmission
rates than parallel or serial ports
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The Motherboard
Data, as bits, travel along a bus from one computer system location to
another, like cars travel along a highway. 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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