Hardware Reference
In-Depth Information
Different keyboards have different key layouts. QWERTY is the most common type.
The QWERTY arrangement of the keys on a typewriter (whose name comes from the fi rst
six keys on the top row) was conceived to slow down typing enough to prevent jamming
the metal arms of the typewriter, which struck a ribbon and transferred print characters
to a piece of paper. Even though metal arms are long gone, this key layout is still used on
computers today. Other layouts have been developed, such as the Dvorak layout, which
enable faster typing once the user memorizes the key locations, but the QWERTY layout is
so entrenched in our culture that other layouts have never caught on.
Most desktop keyboards today use a USB connection to attach to the computer as shown
in Figure 2.2. As with other USB devices, a USB keyboard is hot pluggable, meaning that you
can connect it to and disconnect it from the computer without shutting down the computer.
FIGURE 2.2
A USB connector
Photo credit: Andreas Frank
Older keyboards may use a PS/2 connector, which is a small round plug. Figure 2-3 shows a
PS/2 connector. PS/2 connectors aren't hot pluggable, so you must shut down the computer
before you connect or disconnect a PS/2 keyboard.
FIGURE 2.3
A PS/2 connector
