<s>
A	O
trackball	B-Device
mouse	I-Device
is	O
a	O
pointing	B-Device
device	I-Device
consisting	O
of	O
a	O
ball	O
held	O
by	O
a	O
socket	O
containing	O
sensors	O
to	O
detect	O
a	O
rotation	O
of	O
the	O
ball	O
about	O
two	O
axes	O
—	O
like	O
an	O
upside-down	O
ball	O
mouse	B-Device
with	O
an	O
exposed	O
protruding	O
ball	O
.	O
</s>
<s>
With	O
most	O
trackballs	B-Device
,	O
operators	O
have	O
to	O
lift	O
their	O
finger	O
,	O
thumb	O
or	O
hand	O
and	O
reposition	O
in	O
on	O
the	O
ball	O
to	O
continue	O
rolling	O
,	O
whereas	O
a	O
mouse	B-Device
would	O
have	O
to	O
be	O
lifted	O
itself	O
and	O
re-positioned	O
.	O
</s>
<s>
Some	O
trackballs	B-Device
have	O
notably	O
low	O
friction	O
,	O
as	O
well	O
as	O
being	O
made	O
of	O
a	O
dense	O
material	O
such	O
as	O
phenolic	O
resin	O
,	O
so	O
they	O
can	O
be	O
spun	O
to	O
make	O
them	O
coast	O
.	O
</s>
<s>
The	O
trackball	B-Device
's	O
buttons	O
may	O
be	O
in	O
similar	O
positions	O
to	O
those	O
of	O
a	O
mouse	B-Device
,	O
or	O
configured	O
to	O
suit	O
the	O
user	O
.	O
</s>
<s>
Large	O
trackballs	B-Device
are	O
common	O
on	O
CAD	B-Application
workstations	I-Application
for	O
easy	O
precision	O
.	O
</s>
<s>
Before	O
the	O
advent	O
of	O
the	O
touchpad	B-Application
,	O
small	O
trackballs	B-Device
were	O
common	O
on	O
portable	B-Device
computers	I-Device
(	O
such	O
as	O
the	O
BlackBerry	B-Operating_System
Tour	O
)	O
where	O
there	O
may	O
be	O
no	O
desk	O
space	O
on	O
which	O
to	O
run	O
a	O
mouse	B-Device
.	O
</s>
<s>
Some	O
small	O
"	O
thumballs	O
"	O
are	O
designed	O
to	O
clip	O
onto	O
the	O
side	O
of	O
the	O
keyboard	B-Device
and	O
have	O
integral	O
buttons	O
with	O
the	O
same	O
function	O
as	O
mouse	B-Device
buttons	O
.	O
</s>
<s>
The	O
trackball	B-Device
was	O
invented	O
as	O
part	O
of	O
a	O
post-World	O
War	O
II-era	O
radar	O
plotting	O
system	O
named	O
Comprehensive	O
Display	O
System	O
(	O
CDS	O
)	O
by	O
Ralph	O
Benjamin	O
when	O
working	O
for	O
the	O
British	O
Royal	O
Navy	O
Scientific	O
Service	O
.	O
</s>
<s>
Benjamin	O
's	O
project	O
used	O
analog	O
computers	O
to	O
calculate	O
the	O
future	O
position	O
of	O
target	O
aircraft	O
based	O
on	O
several	O
initial	O
input	O
points	O
provided	O
by	O
a	O
user	O
with	O
a	O
joystick	B-Device
.	O
</s>
<s>
Benjamin	O
felt	O
that	O
a	O
more	O
elegant	O
input	O
device	O
was	O
needed	O
and	O
invented	O
a	O
ball	B-Device
tracker	I-Device
system	O
called	O
the	O
roller	B-Device
ball	I-Device
for	O
this	O
purpose	O
in	O
1946	O
.	O
</s>
<s>
Production	O
versions	O
of	O
the	O
CDS	O
used	O
joysticks	B-Device
.	O
</s>
<s>
The	O
CDS	O
system	O
had	O
also	O
been	O
viewed	O
by	O
a	O
number	O
of	O
engineers	O
from	O
Ferranti	O
Canada	O
,	O
who	O
returned	O
to	O
Canada	O
and	O
began	O
development	O
of	O
the	O
Royal	O
Canadian	O
Navy	O
's	O
DATAR	B-Device
system	O
in	O
1952	O
.	O
</s>
<s>
Principal	O
designers	O
Tom	O
Cranston	O
,	O
Fred	O
Longstaff	O
and	O
Kenyon	O
Taylor	O
chose	O
the	O
trackball	B-Device
as	O
the	O
primary	O
input	O
,	O
using	O
a	O
standard	O
five-pin	O
bowling	O
ball	O
as	O
the	O
roller	O
.	O
</s>
<s>
DATAR	B-Device
was	O
similar	O
in	O
concept	O
to	O
Benjamin	O
's	O
display	O
,	O
but	O
used	O
a	O
digital	O
computer	O
to	O
calculate	O
tracks	O
,	O
and	O
sent	O
the	O
resulting	O
data	O
to	O
other	O
ships	O
in	O
a	O
task	O
force	O
using	O
pulse-code	B-Algorithm
modulation	I-Algorithm
radio	O
signals	O
.	O
</s>
<s>
DATAR	B-Device
's	O
trackball	B-Device
used	O
four	O
disks	O
to	O
pick	O
up	O
motion	O
,	O
two	O
each	O
for	O
the	O
X	O
and	O
Y	O
directions	O
.	O
</s>
<s>
Since	O
1966	O
,	O
the	O
American	O
company	O
Orbit	O
Instrument	O
Corporation	O
produced	O
a	O
device	O
named	O
X-Y	O
Ball	B-Device
Tracker	I-Device
,	O
a	O
trackball	B-Device
,	O
which	O
was	O
embedded	O
into	O
radar	O
flight	O
control	O
desks	O
.	O
</s>
<s>
A	O
similar	O
trackball	B-Device
device	O
at	O
the	O
German	O
was	O
constructed	O
by	O
a	O
team	O
around	O
of	O
Telefunken	O
as	O
part	O
of	O
the	O
development	O
for	O
the	O
Telefunken	O
computer	O
infrastructure	O
around	O
the	O
main	O
frame	O
,	O
process	O
computer	O
TR	O
86	O
and	O
video	O
terminal	O
SIG	O
100-86	O
,	O
which	O
began	O
in	O
1965	O
.	O
</s>
<s>
This	O
trackball	B-Device
was	O
called	O
(	O
German	O
for	O
"	O
rolling	O
ball	O
"	O
)	O
.	O
</s>
<s>
Somewhat	O
later	O
,	O
the	O
idea	O
of	O
"	O
reversing	O
"	O
this	O
device	O
led	O
to	O
the	O
introduction	O
of	O
the	O
first	O
computer	O
ball	O
mouse	B-Device
(	O
still	O
named	O
,	O
model	O
RKS	O
100-86	O
)	O
,	O
which	O
was	O
offered	O
as	O
an	O
alternative	O
input	O
device	O
to	O
light	O
pens	O
and	O
trackballs	B-Device
for	O
Telefunken	O
's	O
computer	O
systems	O
since	O
1968	O
.	O
</s>
<s>
In	O
later	O
trackball	B-Device
models	O
the	O
electrical	O
contacts	O
were	O
replaced	O
by	O
a	O
"	O
chopper	O
wheel	O
"	O
which	O
had	O
small	O
slots	O
cut	O
into	O
it	O
in	O
the	O
same	O
locations	O
as	O
the	O
contacts	O
.	O
</s>
<s>
Mice	O
used	O
the	O
same	O
basic	O
system	O
for	O
determining	O
motion	O
,	O
but	O
had	O
the	O
problem	O
that	O
the	O
ball	O
was	O
in	O
contact	O
with	O
the	O
desk	O
or	O
mousepad	B-Language
.	O
</s>
<s>
Rolling	O
the	O
mouse	B-Device
tended	O
to	O
pick	O
up	O
any	O
dirt	O
and	O
drag	O
it	O
into	O
the	O
system	O
where	O
it	O
would	O
clog	O
the	O
chopper	O
wheels	O
,	O
demanding	O
cleanup	O
.	O
</s>
<s>
In	O
contrast	O
the	O
trackball	B-Device
is	O
in	O
contact	O
only	O
with	O
the	O
user	O
's	O
hand	O
,	O
which	O
tends	O
to	O
be	O
cleaner	O
.	O
</s>
<s>
In	O
the	O
late	O
1990s	O
both	O
mice	O
and	O
trackballs	B-Device
began	O
using	O
direct	O
optical	O
tracking	O
which	O
follows	O
dots	O
on	O
the	O
ball	O
,	O
avoiding	O
the	O
need	O
for	O
anti-slip	O
surface	O
treatment	O
.	O
</s>
<s>
As	O
with	O
modern	O
mice	O
,	O
most	O
trackballs	B-Device
now	O
have	O
an	O
auxiliary	O
device	O
primarily	O
intended	O
for	O
scrolling	O
.	O
</s>
<s>
Kensington	O
's	O
SlimBlade	O
Trackball	B-Device
similarly	O
tracks	O
the	O
ball	O
itself	O
in	O
three	O
dimensions	O
for	O
scrolling	O
.	O
</s>
<s>
and	O
into	O
the	O
2020s	O
,	O
two	O
major	O
companies	O
produce	O
consumer	O
trackballs	B-Device
,	O
Logitech	O
and	O
Kensington	O
,	O
although	O
Logitech	O
has	O
narrowed	O
its	O
product	O
line	O
to	O
two	O
models	O
.	O
</s>
<s>
Other	O
smaller	O
companies	O
occasionally	O
offer	O
a	O
trackball	B-Device
in	O
their	O
product	O
line	O
.	O
</s>
<s>
Microsoft	O
produced	O
popular	O
models	O
including	O
The	O
Microsoft	O
Trackball	B-Device
Explorer	O
,	O
but	O
has	O
since	O
discontinued	O
all	O
of	O
its	O
products	O
.	O
</s>
<s>
In	O
September	O
2017	O
Logitech	O
announced	O
release	O
of	O
MX-Ergo	O
Mouse	B-Device
,	O
which	O
was	O
released	O
after	O
6	O
years	O
of	O
its	O
last	O
trackball	B-Device
mouse	I-Device
.	O
</s>
<s>
Large	O
trackballs	B-Device
are	O
sometimes	O
seen	O
on	O
computerized	O
special-purpose	O
workstations	O
,	O
such	O
as	O
the	O
radar	O
consoles	O
in	O
an	O
air-traffic	B-Application
control	I-Application
room	O
or	O
sonar	B-Application
equipment	O
on	O
a	O
ship	O
or	O
submarine	O
.	O
</s>
<s>
However	O
,	O
military	O
mobile	O
anti-aircraft	O
radars	O
,	O
commercial	O
airliners	O
(	O
such	O
as	O
Airbus	O
A380	O
and	O
Airbus	O
A350	O
)	O
and	O
submarine	O
sonars	B-Application
tend	O
to	O
continue	O
using	O
trackballs	B-Device
,	O
since	O
they	O
can	O
be	O
made	O
more	O
durable	O
and	O
more	O
fit	O
for	O
fast	O
emergency	O
use	O
.	O
</s>
<s>
Large	O
and	O
well	O
made	O
ones	O
allow	O
easier	O
high	O
precision	O
work	O
,	O
for	O
which	O
reason	O
they	O
may	O
still	O
be	O
used	O
in	O
these	O
applications	O
(	O
where	O
they	O
are	O
often	O
called	O
"	O
tracker	O
balls	O
"	O
)	O
and	O
in	O
computer-aided	B-Application
design	I-Application
.	O
</s>
<s>
Trackballs	B-Device
have	O
appeared	O
in	O
video	O
games	O
,	O
particularly	O
early	O
arcade	O
games	O
(	O
see	O
a	O
List	B-Application
of	I-Application
trackball	I-Application
arcade	I-Application
games	I-Application
)	O
.	O
</s>
<s>
In	O
March	O
1978	O
,	O
Sega	O
released	O
World	O
Cup	O
,	O
an	O
association	B-Application
football	I-Application
game	I-Application
with	O
trackball	B-Device
controls	O
.	O
</s>
<s>
In	O
October	O
1978	O
,	O
Atari	O
released	O
Atari	B-Application
Football	I-Application
,	O
which	O
popularized	O
the	O
use	O
of	O
a	O
trackball	B-Device
,	O
with	O
the	O
game	O
's	O
developers	O
mentioning	O
it	O
was	O
inspired	O
by	O
an	O
earlier	O
Japanese	O
association	B-Application
football	I-Application
game	I-Application
.	O
</s>
<s>
Other	O
notable	O
trackball	B-Device
games	O
include	O
Atari	O
's	O
Centipede	B-Application
and	O
Missile	B-Application
Command	I-Application
–	O
though	O
Atari	O
spelled	O
it	O
"	O
trak-ball	O
"	O
.	O
</s>
<s>
Console	B-Device
trackballs	B-Device
,	O
now	O
fairly	O
rare	O
,	O
were	O
common	O
in	O
the	O
early	O
1980s	O
:	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
and	O
5200	B-General_Concept
consoles	O
,	O
as	O
well	O
as	O
the	O
competing	O
ColecoVision	B-Device
console	B-Device
,	O
though	O
using	O
a	O
joystick	B-Device
as	O
their	O
standard	O
controller	O
,	O
each	O
had	O
one	O
as	O
an	O
optional	O
peripheral	O
.	O
</s>
<s>
The	O
Apple	B-Device
Pippin	I-Device
,	O
a	O
console	B-Device
introduced	O
in	O
1996	O
,	O
had	O
a	O
trackball	B-Device
built	O
into	O
its	O
gamepad	B-Device
as	O
standard	O
.	O
</s>
<s>
Trackballs	B-Device
were	O
occasionally	O
used	O
in	O
e-sports	O
prior	O
to	O
the	O
mainstreaming	O
of	O
optical	O
mice	O
in	O
the	O
early	O
2000s	O
because	O
they	O
were	O
more	O
reliable	O
than	O
ball	O
mice	O
,	O
but	O
now	O
they	O
are	O
extremely	O
rare	O
because	O
optical	O
mice	O
offer	O
superior	O
speed	O
and	O
precision	O
.	O
</s>
<s>
Trackballs	B-Device
remain	O
in	O
use	O
in	O
pub	O
golf	O
machines	O
(	O
such	O
as	O
Golden	B-Application
Tee	I-Application
)	O
to	O
simulate	O
swinging	O
the	O
club	O
.	O
</s>
<s>
Trackballs	B-Device
have	O
also	O
been	O
regarded	O
as	O
excellent	O
complements	O
to	O
analog	B-Device
joysticks	I-Device
,	O
as	O
pioneered	O
by	O
the	O
Assassin	O
3D	O
,	O
a	O
trackball	B-Device
released	O
in	O
1996	O
with	O
joystick	B-Device
pass-through	O
capability	O
.	O
</s>
<s>
Later	O
in	O
1996	O
,	O
Mad	O
Catz	O
released	O
the	O
Panther	B-Device
XL	I-Device
,	O
which	O
was	O
based	O
on	O
the	O
Assassin	O
3D	O
.	O
</s>
<s>
This	O
combination	O
provides	O
for	O
two-hand	O
aiming	O
and	O
a	O
high	O
accuracy	O
and	O
consistency	O
replacement	O
for	O
the	O
traditional	O
mouse	B-Device
and	O
keyboard	B-Device
combo	O
generally	O
used	O
on	O
first-person	O
shooter	O
games	O
.	O
</s>
<s>
Many	O
such	O
games	O
natively	O
support	O
joysticks	B-Device
and	O
analog	O
player	O
movement	O
,	O
like	O
Valve	O
's	O
Half-Life	B-Application
and	O
id	O
Software	O
's	O
Quake	O
series	O
.	O
</s>
<s>
,	O
one	O
professional	O
eSport	O
player	O
was	O
known	O
for	O
using	O
a	O
trackball	B-Device
.	O
</s>
<s>
Trackballs	B-Device
are	O
provided	O
as	O
the	O
pointing	B-Device
device	I-Device
in	O
some	O
public	O
internet	O
access	O
terminals	O
.	O
</s>
<s>
Unlike	O
a	O
mouse	B-Device
,	O
a	O
trackball	B-Device
can	O
easily	O
be	O
built	O
into	O
a	O
console	B-Device
,	O
and	O
cannot	O
be	O
ripped	O
away	O
or	O
easily	O
vandalized	O
.	O
</s>
<s>
Because	O
trackballs	B-Device
for	O
personal	O
computers	O
are	O
stationary	O
,	O
they	O
may	O
require	O
less	O
space	O
for	O
operation	O
than	O
a	O
mouse	B-Device
,	O
simplifying	O
use	O
in	O
confined	O
or	O
cluttered	O
areas	O
such	O
as	O
a	O
small	O
desk	O
or	O
a	O
rack-mounted	B-Application
terminal	O
.	O
</s>
<s>
Trackballs	B-Device
were	O
often	O
included	O
in	O
laptop	B-Device
computers	I-Device
,	O
but	O
since	O
the	O
late	O
1990s	O
these	O
have	O
been	O
replaced	O
by	O
touchpads	B-Application
and	O
pointing	B-Device
sticks	I-Device
.	O
</s>
<s>
Trackballs	B-Device
are	O
still	O
used	O
as	O
separate	O
input	O
devices	O
with	O
standard	O
desktop	O
computers	O
,	O
but	O
this	O
application	O
is	O
also	O
moving	O
to	O
touchpads	B-Application
due	O
to	O
the	O
prevalence	O
of	O
multi	B-Application
touch	I-Application
gesture	O
control	O
in	O
new	O
desktop	O
operating	O
systems	O
.	O
</s>
<s>
People	O
with	O
a	O
mobility	O
impairment	O
use	O
trackballs	B-Device
as	O
an	O
assistive	O
technology	O
input	O
device	O
.	O
</s>
<s>
Access	O
to	O
an	O
alternative	O
pointing	B-Device
device	I-Device
has	O
become	O
even	O
more	O
important	O
for	O
them	O
with	O
the	O
dominance	O
of	O
graphically-oriented	O
operating	O
systems	O
.	O
</s>
<s>
The	O
control	O
surface	O
of	O
a	O
trackball	B-Device
is	O
easier	O
to	O
manipulate	O
and	O
the	O
buttons	O
can	O
be	O
activated	O
without	O
affecting	O
the	O
pointer	O
position	O
.	O
</s>
<s>
Trackball	B-Device
users	O
also	O
often	O
state	O
that	O
they	O
are	O
not	O
limited	O
to	O
using	O
the	O
device	O
on	O
a	O
flat	O
desk	O
surface	O
.	O
</s>
<s>
Trackballs	B-Device
can	O
be	O
used	O
whilst	O
browsing	O
a	O
laptop	B-Device
in	O
bed	O
,	O
or	O
wirelessly	O
from	O
an	O
armchair	O
to	O
a	O
PC	O
playing	O
a	O
movie	O
.	O
</s>
<s>
Trackballs	B-Device
are	O
generally	O
either	O
thumb-operated	O
,	O
with	O
a	O
ball	O
about	O
an	O
inch	O
in	O
diameter	O
or	O
smaller	O
moved	O
by	O
one	O
digit	O
(	O
almost	O
always	O
the	O
thumb	O
)	O
and	O
the	O
buttons	O
clicked	O
by	O
others	O
,	O
or	O
finger-operated	O
,	O
with	O
a	O
ball	O
over	O
two	O
inches	O
in	O
diameter	O
operated	O
by	O
the	O
middle	O
fingers	O
and	O
the	O
buttons	O
by	O
the	O
thumb	O
and	O
little	O
finger	O
.	O
</s>
<s>
Thumb-operated	O
trackballs	B-Device
are	O
not	O
generally	O
available	O
in	O
left-handed	O
configurations	O
,	O
due	O
to	O
small	O
demand	O
.	O
</s>
<s>
Some	O
computer	O
users	O
prefer	O
a	O
trackball	B-Device
over	O
the	O
more	O
common	O
mouse	B-Device
for	O
ergonomic	O
reasons	O
.	O
</s>
<s>
There	O
seems	O
to	O
be	O
no	O
conclusive	O
evidence	O
from	O
studies	O
performed	O
to	O
determine	O
which	O
type	O
of	O
pointing	B-Device
device	I-Device
works	O
best	O
for	O
most	O
applications	O
.	O
</s>
<s>
Some	O
disabled	O
users	O
find	O
trackballs	B-Device
easier	O
since	O
they	O
only	O
have	O
to	O
move	O
their	O
thumb	O
relative	O
to	O
their	O
hand	O
,	O
instead	O
of	O
moving	O
the	O
whole	O
hand	O
,	O
while	O
others	O
incur	O
unacceptable	O
fatigue	O
of	O
the	O
thumb	O
.	O
</s>
<s>
Elderly	O
people	O
sometimes	O
have	O
difficulty	O
holding	O
a	O
mouse	B-Device
still	O
while	O
double-clicking	O
;	O
the	O
trackball	B-Device
allows	O
them	O
to	O
let	O
go	O
of	O
the	O
ball	O
while	O
using	O
the	O
button	O
.	O
</s>
<s>
At	O
times	O
when	O
a	O
user	O
is	O
browsing	O
menus	O
or	O
websites	O
rather	O
than	O
typing	O
,	O
it	O
is	O
also	O
possible	O
to	O
hold	O
a	O
trackball	B-Device
in	O
the	O
right	O
hand	O
like	O
a	O
television	O
remote	O
control	O
,	O
operating	O
the	O
ball	O
with	O
the	O
right	O
thumb	O
and	O
pressing	O
the	O
buttons	O
with	O
the	O
left	O
thumb	O
,	O
thus	O
giving	O
the	O
fingers	O
a	O
rest	O
.	O
</s>
<s>
Some	O
mobile	O
devices	O
have	O
trackballs	B-Device
,	O
including	O
those	O
in	O
the	O
BlackBerry	B-Operating_System
range	O
,	O
the	O
T-Mobile	O
Sidekick	O
3	O
,	O
and	O
many	O
early	O
HTC	O
smartphones	B-Application
.	O
</s>
<s>
These	O
miniature	O
trackballs	B-Device
are	O
made	O
to	O
fit	O
within	O
the	O
thickness	O
of	O
a	O
mobile	O
device	O
,	O
and	O
are	O
controlled	O
by	O
the	O
tip	O
of	O
a	O
finger	O
or	O
thumb	O
.	O
</s>
<s>
These	O
have	O
mostly	O
been	O
replaced	O
on	O
smartphones	B-Application
by	O
touch	O
screens	O
,	O
although	O
on	O
the	O
blackberry	B-Operating_System
range	O
they	O
were	O
replaced	O
by	O
an	O
"	O
optical	O
trackball	B-Device
"	O
or	O
"	O
optical	B-Device
trackpad	I-Device
"	O
before	O
later	O
being	O
replaced	O
with	O
touch	O
screens	O
.	O
</s>
<s>
In	O
lieu	O
of	O
a	O
scroll	O
wheel	O
,	O
some	O
mice	O
include	O
a	O
tiny	O
trackball	B-Device
sometimes	O
called	O
a	O
scroll	O
ball	O
.	O
</s>
<s>
A	O
popular	O
example	O
is	O
Apple	O
's	O
Mighty	B-Device
Mouse	I-Device
.	O
</s>
<s>
Mice	O
with	O
a	O
larger	O
trackball	B-Device
on	O
a	O
side	O
may	O
be	O
designed	O
to	O
stay	O
stationary	O
,	O
using	O
the	O
trackball	B-Device
to	O
move	O
the	O
mouse	B-Device
cursor	O
instead	O
of	O
moving	O
the	O
mouse	B-Device
.	O
</s>
