<s>
Kempston	B-Device
Micro	I-Device
Electronics	I-Device
was	O
an	O
electronics	O
company	O
based	O
in	O
Kempston	O
,	O
Bedfordshire	O
,	O
England	O
specialising	O
in	O
computer	B-Device
joysticks	I-Device
and	O
related	O
home	O
computer	O
peripherals	O
during	O
the	O
1980s	O
.	O
</s>
<s>
The	O
Kempston	O
Interface	O
,	O
a	O
peripheral	O
which	O
allowed	O
a	O
joystick	B-Device
using	O
the	O
de	O
facto	O
Atari	B-Protocol
joystick	I-Protocol
port	I-Protocol
standard	O
to	O
be	O
connected	O
to	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
,	O
was	O
one	O
of	O
the	O
most	O
widely	O
used	O
add-ons	O
to	O
the	O
machine	O
.	O
</s>
<s>
The	O
Kempston	O
Interface	O
is	O
a	O
joystick	B-Device
interface	O
used	O
on	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
series	O
of	O
computers	O
that	O
allows	O
controllers	O
complying	O
with	O
the	O
de	O
facto	O
Atari	B-Protocol
joystick	I-Protocol
port	I-Protocol
standard	O
(	O
using	O
the	O
DE-9	B-Protocol
connector	I-Protocol
)	O
to	O
be	O
used	O
with	O
the	O
machine	O
.	O
</s>
<s>
The	O
interface	O
itself	O
would	O
be	O
attached	O
to	O
the	O
computer	O
's	O
rear	O
expansion	O
port	O
with	O
a	O
single	O
joystick	B-Device
port	O
on	O
the	O
front	O
or	O
top	O
of	O
the	O
system	O
.	O
</s>
<s>
Apart	O
from	O
implementing	O
existing	O
joystick	B-Device
interfacing	O
modes	O
they	O
produced	O
their	O
own	O
standard	O
which	O
delivered	O
the	O
joystick	B-Device
state	O
on	O
the	O
Z80	O
bus	O
at	O
port	O
31	O
(	O
read	O
in	O
BASIC	O
using	O
IN	O
31	O
)	O
.	O
</s>
<s>
This	O
meant	O
that	O
the	O
joystick	B-Device
did	O
not	O
produce	O
key-presses	O
like	O
the	O
other	O
standards	O
,	O
such	O
as	O
Cursor	O
,	O
and	O
the	O
method	O
was	O
soon	O
borrowed	O
by	O
other	O
interface	O
manufacturers	O
and	O
became	O
quite	O
popular	O
.	O
</s>
<s>
When	O
Amstrad	O
released	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
+2	O
,	O
the	O
computer	O
featured	O
a	O
built-in	O
joystick	B-Device
interface	O
that	O
was	O
software-compatible	O
with	O
Sinclair	O
's	O
ZX	B-Device
Interface	I-Device
2	I-Device
standard	O
.	O
</s>
<s>
However	O
,	O
the	O
bundled	O
SJS-1	O
joystick	B-Device
was	O
electrically	O
incompatible	O
with	O
the	O
Atari	O
standard	O
.	O
</s>
<s>
The	O
Interface	O
2	O
standard	O
simulated	O
keypresses	O
on	O
the	O
numerical	O
keys	O
(	O
to	O
and	O
to	O
being	O
left	O
,	O
right	O
,	O
down	O
,	O
up	O
,	O
fire	O
for	O
the	O
'	O
left	O
 '	O
and	O
'	O
right	O
 '	O
joysticks	B-Device
respectively	O
)	O
and	O
hence	O
were	O
ideal	O
for	O
games	O
with	O
no	O
official	O
joystick	B-Device
support	O
but	O
in	O
which	O
the	O
keys	O
could	O
be	O
redefined	O
.	O
</s>
<s>
Inserting	O
or	O
removing	O
the	O
joystick	B-Device
interface	O
when	O
the	O
computer	O
was	O
turned	O
on	O
was	O
inadvisable	O
as	O
it	O
would	O
almost	O
certainly	O
damage	O
the	O
computer	O
hardware	O
.	O
</s>
<s>
It	O
uses	O
the	O
Atari	B-General_Concept
2600	I-General_Concept
standard	O
DE-9	B-Protocol
connector	I-Protocol
and	O
was	O
primarily	O
designed	O
to	O
work	O
with	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
Kempston	O
joystick	B-Device
interface	O
;	O
it	O
also	O
works	O
with	O
the	O
compatible	O
ports	O
of	O
other	O
home	O
computers	O
such	O
as	O
the	O
Amstrad	B-Device
CPC	I-Device
,	O
Commodore	O
64	O
,	O
VIC-20	B-Device
,	O
and	O
later	O
Amiga	B-Device
and	O
Atari	B-Device
ST	I-Device
.	O
An	O
Atari	B-General_Concept
5200	I-General_Concept
model	O
uses	O
the	O
existing	O
CX52	O
controller	O
for	O
the	O
keypad	O
functionality	O
.	O
</s>
