Java Reference
In-Depth Information
The
Insert
,
Delete
,
Page Up
, and
Page Down keys
are used in word processing and other
programs for inserting text and objects, deleting text and objects, and moving up or down
through a document one screen at a time.
Insert key
Delete key
Page Up key
Page Down key
The Mouse
A
mouse
is a pointing device. It is used to move a graphical pointer (usually in the shape of
an arrow) called a
cursor
around the screen or to click on-screen objects (such as a button) to
trigger them to perform an action.
The Monitor
The
monitor
displays information (text and graphics). The screen resolution and dot pitch
determine the quality of the display.
The
screen resolution
specifies the number of pixels in horizontal and vertical dimensions
of the display device.
Pixels
(short for “picture elements”) are tiny dots that form an image on
the screen. A common resolution for a 17-inch screen, for example, is 1,024 pixels wide and
768 pixels high. The resolution can be set manually. The higher the resolution, the sharper
and clearer the image is.
The
dot pitch
is the amount of space between pixels, measured in millimeters. The smaller
the dot pitch, the sharper the display.
screen resolution
pixels
dot pitch
1.2.6 Communication Devices
Computers can be networked through communication devices, such as a dial-up modem
(
mo
dulator/
dem
odulator), a DSL or cable modem, a wired network interface card, or a wire-
less adapter.
A
dial-up modem
uses a phone line and can transfer data at a speed up to 56,000 bps
(bits per second).
dial-up modem
■
A
digital subscriber line (DSL)
connection also uses a standard phone line, but it can
transfer data 20 times faster than a standard dial-up modem.
digital subscriber line (DSL)
■
A
cable modem
uses the cable TV line maintained by the cable company and is gen-
erally faster than DSL.
cable modem
■
A
network interface card (NIC)
is a device that connects a computer to a
local area
network (LAN)
. LANs are commonly used in universities, businesses, and government
agencies. A high-speed NIC called
1000BaseT
can transfer data at 1,000 million bits
per second (mbps).
network interface card (NIC)
local area network (LAN)
million bits per second
(mbps)
■
Wireless networking is now extremely popular in homes, businesses, and schools.
Every laptop computer sold today is equipped with a wireless adapter that enables
the computer to connect to a local area network and the Internet.
■
Note
Answers to checkpoint questions are on the Companion Website.
1.1
✓
✓
What are hardware and software?
Check
1.2
Point
List five major hardware components of a computer.
1.3
What does the acronym “CPU” stand for?
1.4
What unit is used to measure CPU speed?
1.5
What is a bit? What is a byte?
1.6
What is memory for? What does RAM stand for? Why is memory called RAM?
1.7
What unit is used to measure memory size?
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