<s>
The	O
game	B-Protocol
port	I-Protocol
is	O
a	O
device	B-Protocol
port	I-Protocol
that	O
was	O
found	O
on	O
IBM	B-Device
PC	I-Device
compatible	O
and	O
other	O
computer	O
systems	O
throughout	O
the	O
1980s	O
and	O
1990s	O
.	O
</s>
<s>
It	O
was	O
the	O
traditional	O
connector	O
for	O
joystick	B-Device
input	O
,	O
and	O
occasionally	O
MIDI	O
devices	O
,	O
until	O
made	O
obsolete	O
by	O
USB	B-Protocol
in	O
the	O
late	O
1990s	O
.	O
</s>
<s>
Originally	O
located	O
on	O
a	O
dedicated	O
Game	B-Protocol
Control	I-Protocol
Adapter	I-Protocol
expansion	B-Device
card	I-Device
,	O
the	O
game	B-Protocol
port	I-Protocol
was	O
later	O
integrated	O
with	O
PC	O
sound	B-Device
cards	I-Device
,	O
and	O
still	O
later	O
on	O
the	O
PC	O
's	O
motherboard	B-Device
.	O
</s>
<s>
During	O
the	O
transition	O
to	O
USB	B-Protocol
,	O
many	O
input	O
devices	O
used	O
the	O
game	B-Protocol
port	I-Protocol
and	O
a	O
USB	B-Protocol
adapter	O
dongle	O
was	O
included	O
for	O
systems	O
without	O
a	O
game	B-Protocol
port	I-Protocol
.	O
</s>
<s>
At	O
the	O
time	O
IBM	O
was	O
developing	O
its	O
game	B-Protocol
port	I-Protocol
,	O
there	O
was	O
no	O
industry	O
standard	O
for	O
controller	O
ports	O
,	O
although	O
the	O
Atari	B-Protocol
joystick	I-Protocol
port	I-Protocol
was	O
close	O
.	O
</s>
<s>
It	O
was	O
introduced	O
in	O
1977	O
with	O
the	O
Atari	B-General_Concept
Video	I-General_Concept
Computer	I-General_Concept
System	I-General_Concept
,	O
and	O
was	O
later	O
used	O
on	O
the	O
VIC-20	B-Device
(	O
1980	O
)	O
,	O
Commodore	O
64	O
(	O
1982	O
)	O
,	O
and	O
Amstrad	O
's	O
PC1512	O
(	O
1986	O
)	O
.	O
</s>
<s>
In	O
contrast	O
with	O
the	O
IBM	O
design	O
,	O
the	O
Atari	O
port	O
was	O
primarily	O
designed	O
for	O
digital	O
inputs	O
(	O
including	O
a	O
pair	O
of	O
two-axis/four	O
-contact	O
digital	O
joysticks	B-Device
,	O
each	O
with	O
a	O
single	O
pushbutton	O
trigger	O
)	O
.	O
</s>
<s>
Its	O
only	O
analog	O
connections	O
were	O
intended	O
for	O
paddles	B-Device
--	O
although	O
,	O
as	O
there	O
were	O
two	O
analog	O
inputs	O
per	O
port	O
,	O
each	O
port	O
could	O
theoretically	O
support	O
a	O
two-axis	O
analog	B-Device
joystick	I-Device
,	O
touchpad	B-Application
,	O
trackball	B-Device
,	O
or	O
mouse	B-Device
(	O
some	O
of	O
these	O
being	O
eventually	O
developed	O
for	O
Atari	O
systems	O
)	O
.	O
</s>
<s>
The	O
Apple	B-Device
II	I-Device
,	O
BBC	B-Device
Micro	I-Device
,	O
Tandy	B-Device
Color	I-Device
Computer	I-Device
,	O
and	O
other	O
popular	O
8-bit	O
machines	O
all	O
used	O
different	O
,	O
incompatible	O
,	O
joysticks	B-Device
and	O
ports	O
.	O
</s>
<s>
The	O
IBM	B-Device
PC	I-Device
game	B-Protocol
port	I-Protocol
first	O
appeared	O
during	O
the	O
initial	O
launch	O
of	O
the	O
original	O
IBM	B-Device
PC	I-Device
in	O
1981	O
,	O
in	O
the	O
form	O
of	O
an	O
optional	O
US$55	O
expansion	B-Device
card	I-Device
known	O
as	O
the	O
Game	B-Protocol
Control	I-Protocol
Adapter	I-Protocol
.	O
</s>
<s>
The	O
design	O
allowed	O
for	O
four	O
analog	O
axes	O
and	O
four	O
buttons	O
on	O
one	O
port	O
,	O
allowing	O
two	O
joysticks	B-Device
or	O
four	O
paddles	B-Device
to	O
be	O
connected	O
via	O
a	O
special	O
"	O
Y-splitter	O
"	O
cable	O
.	O
</s>
<s>
Originally	O
available	O
only	O
as	O
add-on	O
that	O
took	O
up	O
an	O
entire	O
slot	O
,	O
game	B-Protocol
ports	I-Protocol
remained	O
relatively	O
rare	O
in	O
the	O
early	O
days	O
of	O
the	O
IBM	B-Device
PC	I-Device
,	O
and	O
most	O
games	O
used	O
the	O
keyboard	O
as	O
an	O
input	O
.	O
</s>
<s>
IBM	O
did	O
not	O
release	O
a	O
joystick	B-Device
of	O
its	O
own	O
for	O
the	O
PC	O
,	O
which	O
did	O
not	O
help	O
.	O
</s>
<s>
The	O
most	O
common	O
device	O
available	O
was	O
the	O
Kraft	O
joystick	B-Device
,	O
originally	O
developed	O
for	O
the	O
Apple	B-Device
II	I-Device
but	O
easily	O
adapted	O
to	O
the	O
IBM	O
with	O
the	O
addition	O
of	O
another	O
button	O
on	O
the	O
back	O
of	O
the	O
case	O
.	O
</s>
<s>
When	O
IBM	O
finally	O
did	O
release	O
a	O
joystick	B-Device
,	O
for	O
the	O
IBM	B-Device
PCjr	I-Device
,	O
it	O
was	O
a	O
version	O
of	O
the	O
Kraft	O
stick	O
.	O
</s>
<s>
The	O
game	B-Protocol
port	I-Protocol
became	O
somewhat	O
more	O
common	O
in	O
the	O
mid-1980s	O
,	O
as	O
improving	O
electronic	O
density	O
began	O
to	O
produce	O
expansion	B-Device
cards	I-Device
with	O
ever-increasing	O
functionality	O
.	O
</s>
<s>
By	O
1983	O
,	O
it	O
was	O
common	O
to	O
see	O
cards	O
combining	O
memory	O
,	O
game	B-Protocol
ports	I-Protocol
,	O
serial	O
and	O
parallel	O
ports	O
and	O
a	O
realtime	O
clock	O
on	O
a	O
single	O
expansion	B-Device
card	I-Device
.	O
</s>
<s>
The	O
era	O
of	O
combo	O
expansion	B-Device
cards	I-Device
largely	O
came	O
to	O
an	O
end	O
by	O
the	O
late	O
1980s	O
,	O
as	O
many	O
of	O
the	O
separate	O
functions	O
normally	O
provided	O
on	O
plug-in	O
boards	O
became	O
common	O
features	O
of	O
the	O
motherboard	B-Device
itself	O
.	O
</s>
<s>
Game	B-Protocol
ports	I-Protocol
were	O
not	O
always	O
part	O
of	O
this	O
supported	O
set	O
of	O
ports	O
.	O
</s>
<s>
However	O
,	O
the	O
game	B-Protocol
port	I-Protocol
was	O
given	O
a	O
major	O
boost	O
in	O
usage	O
in	O
1989	O
,	O
with	O
the	O
introduction	O
of	O
the	O
first	O
Sound	B-Application
Blaster	I-Application
.	O
</s>
<s>
As	O
sound	B-Device
cards	I-Device
were	O
primarily	O
used	O
with	O
computer	O
games	O
,	O
Creative	O
Labs	O
took	O
the	O
opportunity	O
to	O
include	O
a	O
game	B-Protocol
port	I-Protocol
on	O
the	O
card	O
,	O
producing	O
an	O
all-in-one	O
gaming	O
solution	O
.	O
</s>
<s>
Previous	O
MIDI	O
systems	O
like	O
the	O
MPU-401	O
used	O
their	O
own	O
separate	O
expansion	B-Device
cards	I-Device
and	O
a	O
complex	O
external	O
adapter	O
,	O
whereas	O
the	O
Sound	B-Application
Blaster	I-Application
only	O
required	O
an	O
inexpensive	O
adapter	O
to	O
produce	O
the	O
same	O
result	O
.	O
</s>
<s>
By	O
the	O
end	O
of	O
the	O
year	O
the	O
Sound	B-Application
Blaster	I-Application
was	O
the	O
best	O
selling	O
expansion	B-Device
card	I-Device
on	O
the	O
PC	O
,	O
and	O
the	O
game	B-Protocol
port	I-Protocol
was	O
receiving	O
widespread	O
software	O
support	O
.	O
</s>
<s>
With	O
the	O
exception	O
of	O
laptops	O
—	O
for	O
which	O
companies	O
released	O
joystick	B-Device
adapters	O
for	O
parallel	O
or	O
serial	O
ports	O
,	O
which	O
needed	O
custom	O
software	O
drivers	O
—	O
through	O
the	O
early	O
1990s	O
,	O
the	O
game	B-Protocol
port	I-Protocol
was	O
universally	O
supported	O
on	O
sound	B-Device
cards	I-Device
,	O
and	O
increasingly	O
became	O
built-in	O
features	O
as	O
motherboards	B-Device
added	O
sound	O
support	O
of	O
their	O
own	O
.	O
</s>
<s>
This	O
remained	O
true	O
through	O
the	O
second	O
half	O
of	O
the	O
1990s	O
,	O
by	O
which	O
time	O
integrated	O
sound	O
support	O
had	O
displaced	O
the	O
third-party	O
sound	B-Device
card	I-Device
to	O
a	O
large	O
degree	O
.	O
</s>
<s>
By	O
the	O
early	O
2000s	O
,	O
such	O
support	O
was	O
so	O
widespread	O
that	O
newer	O
sound	B-Device
cards	I-Device
began	O
to	O
dispense	O
with	O
the	O
game	B-Protocol
port	I-Protocol
as	O
it	O
was	O
certain	O
the	O
machine	O
they	O
would	O
be	O
used	O
in	O
already	O
had	O
such	O
support	O
,	O
including	O
MIDI	O
.	O
</s>
<s>
Every	O
Sound	B-Application
Blaster	I-Application
card	I-Application
from	O
the	O
first	O
model	O
up	O
to	O
August	O
2001	O
included	O
a	O
game	B-Protocol
port	I-Protocol
.	O
</s>
<s>
In	O
2001	O
the	O
Sound	B-Device
Blaster	I-Device
Audigy	I-Device
moved	O
the	O
game	B-Protocol
port	I-Protocol
to	O
a	O
second	O
expansion	B-Device
slot	I-Device
,	O
which	O
connected	O
to	O
a	O
header	O
on	O
the	O
card	O
.	O
</s>
<s>
The	O
introduction	O
of	O
the	O
first	O
USB	B-Protocol
standard	O
in	O
1996	O
,	O
was	O
aimed	O
squarely	O
at	O
the	O
sort	O
of	O
roles	O
provided	O
by	O
the	O
game	B-Protocol
port	I-Protocol
,	O
but	O
initially	O
had	O
little	O
market	O
impact	O
.	O
</s>
<s>
The	O
introduction	O
of	O
the	O
iMac	B-Device
,	O
which	O
was	O
based	O
almost	O
entirely	O
on	O
USB	B-Protocol
expansion	O
,	O
began	O
a	O
rapid	O
expansion	O
of	O
USB	B-Protocol
in	O
the	O
market	O
.	O
</s>
<s>
This	O
led	O
both	O
to	O
new	O
gaming	O
devices	O
using	O
USB	B-Protocol
,	O
as	O
well	O
as	O
the	O
profusion	O
of	O
adapters	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
1997	O
Microsoft	O
Precision	O
Pro	O
joystick	B-Device
was	O
re-introduced	O
in	O
a	O
version	O
that	O
used	O
a	O
game	B-Protocol
port	I-Protocol
connector	O
,	O
but	O
also	O
included	O
a	O
USB	B-Protocol
adapter	O
in	O
the	O
box	O
.	O
</s>
<s>
The	O
rapid	O
takeover	O
of	O
USB	B-Protocol
meant	O
that	O
this	O
was	O
superfluous	O
when	O
the	O
Precision	O
Pro	O
2	O
was	O
released	O
the	O
next	O
year	O
in	O
1998	O
.	O
</s>
<s>
By	O
2000	O
,	O
game	B-Protocol
ports	I-Protocol
were	O
purely	O
for	O
backward	O
compatibility	O
with	O
now	O
outdated	O
devices	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
discontinued	O
support	O
for	O
the	O
game	B-Protocol
port	I-Protocol
with	O
Windows	B-Application
Vista	I-Application
,	O
though	O
USB	B-Protocol
converters	O
can	O
serve	O
as	O
a	O
workaround	O
.	O
</s>
<s>
The	O
game	B-Protocol
port	I-Protocol
's	O
DA-15	B-Protocol
connector	O
includes	O
inputs	O
for	O
a	O
total	O
of	O
four	O
analog	O
channels	O
and	O
four	O
buttons	O
.	O
</s>
<s>
These	O
were	O
almost	O
always	O
implemented	O
as	O
two	O
joysticks	B-Device
with	O
two	O
buttons	O
each	O
,	O
but	O
it	O
is	O
also	O
possible	O
to	O
support	O
four	O
paddle	B-Device
controllers	I-Device
each	O
with	O
one	O
button	O
,	O
or	O
a	O
single	O
gamepad	O
with	O
two	O
analog	O
sticks	O
and	O
four	O
buttons	O
using	O
the	O
same	O
inputs	O
.	O
</s>
<s>
In	O
most	O
similar	O
game	B-Protocol
ports	I-Protocol
,	O
like	O
those	O
on	O
the	O
Atari	O
,	O
a	O
single	O
+5V	O
and	O
ground	O
is	O
used	O
for	O
all	O
the	O
channels	O
.	O
</s>
<s>
The	O
game	B-Protocol
port	I-Protocol
was	O
originally	O
mounted	O
on	O
a	O
dedicated	O
ISA	B-Architecture
card	I-Architecture
.	O
</s>
<s>
Since	O
the	O
early	O
1990s	O
,	O
when	O
the	O
game	B-Protocol
port	I-Protocol
moved	O
from	O
dedicated	O
expansion	B-Device
cards	I-Device
to	O
PC	O
I/O	B-General_Concept
or	O
sound	B-Device
cards	I-Device
,	O
these	O
connectors	O
have	O
usually	O
doubled	O
as	O
connectors	O
for	O
MIDI	O
instruments	O
;	O
two	O
of	O
the	O
redundant	O
+5V	O
and	O
GND	O
pins	O
of	O
the	O
original	O
standard	O
were	O
rededicated	O
to	O
MIDI	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
to	O
make	O
this	O
possible	O
.	O
</s>
<s>
To	O
use	O
a	O
game	B-Protocol
port	I-Protocol
with	O
MIDI	O
instruments	O
,	O
a	O
break-out	O
cable	O
with	O
the	O
necessary	O
opto-isolation	O
hardware	O
and	O
compatible	O
connectors	O
is	O
required	O
-	O
typically	O
these	O
consisted	O
of	O
a	O
male	O
and	O
a	O
female	O
DA-15	B-Protocol
and	O
two	O
male	O
5-pin	O
DIN	B-Architecture
connectors	I-Architecture
.	O
</s>
<s>
For	O
many	O
sound	B-Device
cards	I-Device
,	O
the	O
game	B-Protocol
port	I-Protocol
midi	O
capabilities	O
were	O
based	O
around	O
the	O
Roland	O
MPU-401	O
MIDI	O
interface	O
(	O
in	O
UART	O
mode	O
only	O
)	O
,	O
however	O
some	O
older	O
sound	B-Device
cards	I-Device
(	O
notably	O
the	O
original	O
Sound	B-Application
Blaster	I-Application
and	O
Sound	B-Application
Blaster	I-Application
Pro	I-Application
)	O
used	O
a	O
proprietary	O
interface	O
that	O
was	O
not	O
compatible	O
with	O
the	O
MPU-401	O
.	O
</s>
<s>
The	O
analog	O
channels	O
are	O
read	O
by	O
sending	O
voltage	O
into	O
the	O
line	O
,	O
through	O
a	O
potentiometer	B-Device
in	O
the	O
controller	O
,	O
in	O
this	O
case	O
100,000	O
ohm	O
,	O
and	O
then	O
into	O
a	O
capacitor	O
.	O
</s>
<s>
The	O
rate	O
varied	O
depending	O
on	O
the	O
resistance	O
,	O
and	O
thus	O
physical	O
position	O
,	O
of	O
the	O
potentiometer	B-Device
.	O
</s>
<s>
In	O
the	O
PC	O
there	O
is	O
no	O
similar	O
clock	O
because	O
video	O
functionality	O
is	O
normally	O
provided	O
on	O
an	O
expansion	B-Device
card	I-Device
.	O
</s>
<s>
Instead	O
,	O
a	O
software	O
routine	O
needs	O
to	O
first	O
trigger	O
capacitor	O
discharge	O
by	O
issuing	O
an	O
IO	O
write	O
to	O
the	O
Gameport	B-Protocol
,	O
and	O
then	O
measure	O
the	O
time	O
it	O
takes	O
to	O
charge	O
them	O
again	O
by	O
constantly	O
polling	O
Gameport	B-Protocol
.	O
</s>
<s>
Using	O
original	O
IBM	O
formula	O
,	O
Time	O
=	O
24.2	O
μs	O
+	O
0.011	O
(	O
r	O
)	O
μs	O
and	O
assuming	O
100Kohm	O
potentiometers	B-Device
this	O
process	O
can	O
take	O
up	O
to	O
1.1ms	O
per	O
readout	O
,	O
or	O
over	O
60ms	O
if	O
we	O
decide	O
to	O
read	O
joystick	B-Device
position	O
60	O
times	O
a	O
second	O
.	O
</s>
<s>
This	O
significant	O
overhead	O
was	O
the	O
reason	O
why	O
using	O
original	O
Gameport	B-Protocol
on	O
the	O
PC	O
could	O
consume	O
up	O
to	O
10%	O
of	O
CPU	O
time	O
independent	O
of	O
CPU	O
speed	O
.	O
</s>
<s>
Initially	O
there	O
was	O
no	O
standardized	O
software	O
for	O
running	O
the	O
joysticks	B-Device
;	O
applications	O
would	O
poll	O
the	O
known	O
ports	O
associated	O
with	O
the	O
sticks	O
as	O
part	O
of	O
their	O
game	O
loop	O
.	O
</s>
<s>
This	O
changed	O
in	O
Windows	B-Application
95	I-Application
,	O
which	O
introduced	O
standardized	O
Windows	B-Protocol
registry	I-Protocol
entries	O
to	O
hold	O
these	O
values	O
and	O
make	O
it	O
easier	O
for	O
applications	O
to	O
find	O
these	O
devices	O
.	O
</s>
<s>
DirectX	B-Application
further	O
expanded	O
the	O
options	O
through	O
DirectInput	O
with	O
the	O
"	O
joystick	B-Device
mini-driver	O
"	O
with	O
a	O
number	O
of	O
new	O
capabilities	O
.	O
</s>
<s>
It	O
also	O
supported	O
up	O
to	O
16	O
such	O
devices	O
,	O
which	O
could	O
be	O
connected	O
using	O
any	O
interface	O
,	O
not	O
just	O
the	O
game	B-Protocol
port	I-Protocol
.	O
</s>
