<s>
The	O
DEUCE	O
(	O
Digital	B-Device
Electronic	I-Device
Universal	I-Device
Computing	I-Device
Engine	I-Device
)	O
was	O
one	O
of	O
the	O
earliest	O
British	O
commercially	O
available	O
computers	O
,	O
built	O
by	O
English	O
Electric	O
from	O
1955	O
.	O
</s>
<s>
It	O
was	O
the	O
production	O
version	O
of	O
the	O
Pilot	B-Device
ACE	I-Device
,	O
itself	O
a	O
cut-down	O
version	O
of	O
Alan	O
Turing	O
's	O
ACE	B-Device
.	O
</s>
<s>
It	O
adopted	O
the	O
then	O
high	O
1megahertz	O
clock	O
rate	O
of	O
the	O
Pilot	B-Device
ACE	I-Device
.	O
</s>
<s>
Input/output	O
was	O
via	O
Hollerith	O
80-column	O
punch-card	B-Architecture
equipment	O
.	O
</s>
<s>
The	O
DEUCE	O
also	O
had	O
an	O
8192-word	O
magnetic	B-General_Concept
drum	I-General_Concept
for	O
main	O
storage	O
.	O
</s>
<s>
Compared	O
with	O
contemporaries	O
such	O
as	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
,	O
DEUCE	O
was	O
about	O
ten	O
times	O
faster	O
.	O
</s>
<s>
In	O
the	O
early	O
machines	O
,	O
all	O
instructions	O
involving	O
the	O
magnetic	B-General_Concept
drum	I-General_Concept
were	O
interlocked	O
while	O
an	O
operation	O
was	O
in	O
progress	O
.	O
</s>
<s>
The	O
front	O
panel	O
of	O
the	O
DEUCE	O
featured	O
two	O
CRT	B-Device
displays	I-Device
:	O
one	O
showed	O
the	O
current	O
contents	O
of	O
registers	O
,	O
while	O
the	O
other	O
showed	O
the	O
content	O
of	O
any	O
one	O
of	O
the	O
mercury	O
delay	O
line	O
stores	O
.	O
</s>
<s>
The	O
principal	O
high-level	B-Language
programming	I-Language
languages	I-Language
were	O
GEORGE	B-Language
(	O
General	B-Language
Order	I-Language
Generator	I-Language
)	O
,	O
ALPHACODE	O
,	O
STEVE	O
,	O
TIP	O
,	O
GIP	O
,	O
and	O
ALGOL	B-Language
.	O
</s>
<s>
Assembler	B-Language
language	I-Language
translators	O
included	O
ZP43	O
and	O
STAC	O
.	O
</s>
<s>
Invented	O
by	O
Charles	O
Leonard	O
Hamblin	O
in	O
1957	O
,	O
GEORGE	B-Language
was	O
closest	O
to	O
present-day	O
programming	O
languages	O
.	O
</s>
<s>
It	O
used	O
Reverse	B-Application
Polish	I-Application
Notation	O
.	O
</s>
<s>
GEORGE	B-Language
provided	O
a	O
12-position	O
accumulator	O
as	O
a	O
push-down	O
pop-up	O
stack	B-Application
.	O
</s>
<s>
the	O
value	O
at	O
the	O
top	O
of	O
the	O
stack	B-Application
(	O
accumulator	O
)	O
.	O
</s>
<s>
discard	O
)	O
the	O
value	O
at	O
the	O
top	O
of	O
the	O
stack	B-Application
,	O
the	O
semicolon	O
(	O
;	O
)	O
was	O
used	O
.	O
</s>
<s>
The	O
following	O
GEORGE	B-Language
program	O
reads	O
in	O
ten	O
numbers	O
and	O
prints	O
their	O
squares	O
:	O
</s>
<s>
In	O
the	O
above	O
program	O
,	O
the	O
"	O
dup	O
"	O
command	O
duplicated	O
the	O
top	O
of	O
the	O
stack	B-Application
,	O
</s>
<s>
so	O
that	O
there	O
were	O
then	O
two	O
copies	O
of	O
the	O
value	O
at	O
the	O
top	O
of	O
the	O
stack	B-Application
.	O
</s>
<s>
Its	O
principal	O
service	O
was	O
in	O
the	O
running	O
of	O
programs	O
from	O
the	O
several	O
hundred	O
in	O
the	O
DEUCE	O
linear	B-Language
algebra	I-Language
library	O
.	O
</s>
<s>
Preparation	O
of	O
such	O
a	O
program	O
involved	O
selecting	O
the	O
required	O
bricks	O
(	O
on	O
punch	B-Architecture
cards	I-Architecture
)	O
,	O
copying	O
them	O
and	O
GIP	O
in	O
a	O
reproducing	O
punch	O
,	O
and	O
assembling	O
the	O
copies	O
into	O
a	O
deck	O
of	O
cards	O
.	O
</s>
<s>
STAC	O
was	O
a	O
macro-assembler	O
.	O
</s>
<s>
Delay	O
line11	O
(	O
DL11	O
)	O
served	O
as	O
the	O
buffer	O
between	O
the	O
magnetic	B-General_Concept
drum	I-General_Concept
and	O
the	O
high-speed	O
store	O
.	O
</s>
<s>
By	O
a	O
special	O
link	O
between	O
DL10	O
and	O
one	O
register	O
,	O
namely	O
,	O
register16	O
,	O
DL10	O
could	O
be	O
used	O
as	O
a	O
push-down	O
stack	B-Application
.	O
</s>
