Extras!
Some keyboards have
weird layouts
Others have extra USB ports
and even others have awkward looking keys,
like a super long spacebar
However, some
have some
truly unique
features, like
a built-in
hardware
mouse!
Well,
not quite a
conventional
mouse, but a
device that is
commonly
called a
trackpoint.
You see, this
device
utilizes
torque in
order to move
the mouse
cursor!
In a modern
optical mouse,
and older
trackball
mice, digital
or analog
values were
adjusted based
on light
reflection and
the number of
revolutions
made by axial
rollers
respectively.
The computer
receives these
values, and
based on them,
the mouse
cursor moves
accordingly on
the screen. In
a somewhat
similar
fashion, when
a tangent
force is
applied to the
trackpoint, a
torque is
applied at the
base of the
trackpoint,
resulting in
more force
downward in a
particular
direction like
so
Now, the base
of the
trackpoint
experiences
torque, it
applies a
force on a
particular
compound at
the bottom of
the stem. When
force is
applied to
this compound,
it results in
the voltage
going across
the compound
changing.
There are
several
sensors which
read the
change in
voltage, then
move the mouse
cursor
according to
the variance
in voltages at
the sensors.
This method
was common on
laptops, such
as on the
original IBM
Thinkpad,
before the
advent of the
trackpad,
which is much
more user
friendly, but
some modern
laptops have
actually
retained this
feature, such
as the
Thinkpad T61
by Lenovo.
Though the
trackpoint is
much smaller,
it uses a
similar
principle.
Most users
prefer
trackpads, but
many fans of
the original
Thinkpad line
of laptops
still prefer
the trackpoint
system over
the trackpad,
claiming it is
more accurate
and responsive
when not using
a proper mouse.