<s>
The	O
Pilot	B-Device
ACE	I-Device
(	O
Automatic	B-Device
Computing	I-Device
Engine	I-Device
)	O
was	O
one	O
of	O
the	O
first	O
computers	O
built	O
in	O
the	O
United	O
Kingdom	O
.	O
</s>
<s>
Built	O
at	O
the	O
National	O
Physical	O
Laboratory	O
(	O
NPL	O
)	O
in	O
the	O
early	O
1950s	O
,	O
it	O
was	O
also	O
one	O
of	O
the	O
earliest	O
general-purpose	O
,	O
stored-program	O
computers	O
–	O
joining	O
other	O
UK	O
designs	O
like	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
and	O
EDSAC	B-Device
of	O
the	O
same	O
era	O
.	O
</s>
<s>
It	O
was	O
a	O
preliminary	O
version	O
of	O
the	O
full	O
ACE	B-Device
,	O
which	O
was	O
designed	O
by	O
Alan	O
Turing	O
,	O
who	O
left	O
NPL	O
before	O
the	O
construction	O
was	O
completed	O
.	O
</s>
<s>
Pilot	B-Device
ACE	I-Device
was	O
built	O
to	O
a	O
cut	O
down	O
version	O
of	O
Turing	O
's	O
full	O
ACE	B-Device
design	O
.	O
</s>
<s>
After	O
Turing	O
left	O
NPL	O
(	O
in	O
part	O
because	O
he	O
was	O
disillusioned	O
by	O
the	O
lack	O
of	O
progress	O
on	O
building	O
the	O
ACE	B-Device
)	O
,	O
James	O
H	O
.	O
Wilkinson	O
took	O
over	O
the	O
project	O
.	O
</s>
<s>
The	O
Pilot	B-Device
ACE	I-Device
ran	O
its	O
first	O
program	O
on	O
10	O
May	O
1950	O
,	O
and	O
was	O
demonstrated	O
to	O
the	O
press	O
in	O
November	O
1950	O
.	O
</s>
<s>
One	O
reason	O
Pilot	B-Device
ACE	I-Device
was	O
useful	O
is	O
that	O
it	O
was	O
able	O
to	O
perform	O
floating-point	B-Algorithm
arithmetic	I-Algorithm
necessary	O
for	O
scientific	O
calculations	O
.	O
</s>
<s>
When	O
first	O
built	O
,	O
Pilot	B-Device
ACE	I-Device
did	O
not	O
have	O
hardware	O
for	O
either	O
multiplication	O
or	O
division	O
,	O
in	O
contrast	O
to	O
other	O
computers	O
at	O
that	O
time	O
.	O
</s>
<s>
Pilot	B-Device
ACE	I-Device
started	O
out	O
using	O
fixed-point	O
multiplication	O
and	O
division	O
implemented	O
as	O
software	O
.	O
</s>
<s>
It	O
only	O
took	O
a	O
short	O
time	O
to	O
write	O
new	O
software	O
so	O
that	O
Pilot	B-Device
ACE	I-Device
could	O
do	O
floating-point	B-Algorithm
arithmetic	I-Algorithm
.	O
</s>
<s>
After	O
that	O
,	O
James	O
Wilkinson	O
became	O
an	O
expert	O
and	O
wrote	O
a	O
book	O
on	O
rounding	B-Algorithm
errors	I-Algorithm
in	O
floating-point	B-Algorithm
calculations	O
,	O
which	O
eventually	O
sold	O
well	O
.	O
</s>
<s>
Pilot	B-Device
ACE	I-Device
used	O
approximately	O
800	O
vacuum	O
tubes	O
.	O
</s>
<s>
A	O
4096-word	O
drum	B-General_Concept
memory	I-General_Concept
was	O
added	O
in	O
1954	O
.	O
</s>
<s>
The	O
machine	O
was	O
so	O
successful	O
that	O
a	O
commercial	O
version	O
of	O
it	O
,	O
named	O
the	O
DEUCE	B-Device
,	O
was	O
constructed	O
and	O
sold	O
by	O
the	O
English	O
Electric	O
Company	O
.	O
</s>
<s>
Pilot	B-Device
ACE	I-Device
was	O
shut	O
down	O
in	O
May	O
1955	O
,	O
and	O
was	O
given	O
to	O
the	O
Science	O
Museum	O
,	O
where	O
it	O
remains	O
today	O
.	O
</s>
<s>
Installing	O
the	O
magnetic	B-General_Concept
drum	I-General_Concept
in	O
1954	O
opened	O
the	O
way	O
to	O
develop	O
a	O
control	O
program	O
for	O
running	O
programs	O
dealing	O
with	O
matrices	O
.	O
</s>
<s>
GIP	O
was	O
running	O
in	O
1954	O
,	O
and	O
was	O
re-written	O
for	O
DEUCE	B-Device
,	O
the	O
successor	O
to	O
Pilot	B-Device
ACE	I-Device
.	O
</s>
<s>
To	O
use	O
regular	O
floating-point	B-Algorithm
would	O
have	O
required	O
two	O
words	O
for	O
each	O
element	O
.	O
</s>
