Chapter 18: Keyboards, Mice, and Pointing Devices^447
Cursor Control Keys
The 101-key design of the keyboard included a separate group of cursor control keys.
Prior to this design, the number pad had to serve double-duty as cursor control keys. The
NUM LOCKkey was used to toggle and lock the number pad between these two functions.
On the 101-key design and those that followed, a set of four dedicated cursor control
(arrow) keys and a six-key set of cursor action (a.k.a. navigation) keys were added between
the alphabetic keys and the number pad, as illustrated in Figure 18-5.
This group of keys includes:
Cursor control (arrow) keys This group of four directional keys is used to
move the cursor left, up, down, and right. Virtually all software supports the
use of these keys. Game software relies on these keys to move characters
through scenes using points of the compass represented by these four keys
where up is north, down is south, left is east, and right is west. Some keyboards
add four diagonal direction keys that move the cursor (or the action) in
directions between the standard four keys.
Cursor command/navigation keys A grou pof six keys located to the right
of the alphabetic keys and above the cursor control keys, these keys, shown in
Figure 18-6, duplicate the six control functions originally included in the number
pad’s cursor control keys. The keys included areINSERT,DELETE,HOME,END,
andPAGE UPandPAGE DOWN. The function of each of these keys is as follows:
INSERT This is a locking key that toggles software between insert and replace
modes. Insert mode, which is the default mode for most word processing
systems, inserts characters at the point indicated by the cursor. Replace mode,
which is also called typeover mode, replaces any existing characters with the
characters being entered.Figure 18-5. The cursor control keys on a standard keyboard