Hardware Reference
In-Depth Information
Touch Screen and Stylus Input
A
touch screen
is a pressure-sensitive video display. Touch screens are found at bank
ATMs, airport check-in counters, mall kiosks, and many other locations where consumers
need to interact with a video display without a keyboard or mouse.
Tablet computers
are notebook computers that include touch-screen technology, either
as a primary or secondary form of user input. Some tablet computers, like the Apple iPad,
use the touch-screen capability for all input, including keyboarding. (A keyboard appears
on the video display, and you touch the screen to type.) Others either have a built-in
keyboard or can accept an attached keyboard and/or mouse via USB port.
Most touch screens made today are fi nger-touch activated, but earlier models, especially
those made for Windows-based tablet PCs, used a technology called
pen computing
. With
pen computing, the touch screen is activated only when touched by a special pen stylus
that comes with the device. The stylus transmits a signal to sensors in the display's surface
to make the connection; a plain fi nger-touch does nothing. Some gaming devices, like the
Nintendo 3DS, also use this technology.
Game Controllers
Gaming consoles have input controllers specifi cally designed for game playing, which is
one reason why the consoles are so popular with gaming enthusiasts. Similar controllers
are also available for personal computers to make playing certain games easier and more
enjoyable. For example, game controllers that are identical to those that come with popular
gaming consoles are available for PCs, as are joysticks that make it easier to play fl ight
simulator games.
Internal and External Storage Devices
After data enters the computer via an input device—then what? The incoming data is
temporarily stored in RAM, but eventually it has to be saved to a storage device in order to
preserve it. A variety of storage devices are available for personal computers, each with its
own unique set of pros and cons in terms of speed, cost, portability, and convenience. In
this section, you'll learn about some of the most popular storage devices available.
Storage space is measured in kilobytes (KB, thousands of bytes), megabytes (MB,
millions of bytes), and gigabytes (GB, billions of bytes). The original storage device for
a personal computer, the fl oppy disk, held between 360 KB and 1.44 MB, which seems
laughably small nowadays. But at the time, entire applications could be stored on a single
disk. Table 2.1 summarizes the various measurements of storage capacity and provides
notes and examples. Notice that the multipliers aren't exact thousands, but multiples of
1,024. That's because of the binary nature of number storage in computers. For example,
a kilobyte is 1,024 bytes, not exactly 1,000. The decimal value 1,024 is 10000000000
when converted to binary.
