<s>
The	O
first	O
in	O
the	O
series	O
,	O
the	O
LEO	B-Device
I	I-Device
,	O
was	O
the	O
first	O
computer	O
used	O
for	O
commercial	O
business	O
applications	O
.	O
</s>
<s>
The	O
prototype	O
LEO	B-Device
I	I-Device
was	O
modelled	O
closely	O
on	O
the	O
Cambridge	O
EDSAC	B-Device
.	O
</s>
<s>
Its	O
construction	O
was	O
overseen	O
by	O
Oliver	O
Standingford	O
,	O
Raymond	O
Thompson	O
and	O
David	O
Caminer	O
of	O
J	O
.	O
Lyons	O
and	O
Co	O
.	O
LEO	B-Device
I	I-Device
ran	O
its	O
first	O
business	O
application	O
in	O
1951	O
.	O
</s>
<s>
During	O
the	O
visit	O
,	O
they	O
met	O
Herman	O
Goldstine	O
who	O
was	O
one	O
of	O
the	O
original	O
developers	O
of	O
ENIAC	B-Device
,	O
the	O
first	O
general-purpose	O
electronic	O
computer	O
.	O
</s>
<s>
They	O
also	O
learned	O
from	O
Goldstine	O
that	O
,	O
back	O
in	O
the	O
UK	O
,	O
Douglas	O
Hartree	O
and	O
Maurice	O
Wilkes	O
were	O
actually	O
building	O
another	O
such	O
machine	O
,	O
the	O
pioneering	O
EDSAC	B-Device
computer	O
,	O
at	O
the	O
University	O
of	O
Cambridge	O
.	O
</s>
<s>
Hartree	O
and	O
Wilkes	O
estimated	O
that	O
EDSAC	B-Device
was	O
12	O
–	O
18	O
months	O
from	O
completion	O
,	O
but	O
said	O
that	O
this	O
interval	O
could	O
be	O
shortened	O
by	O
additional	O
funding	O
.	O
</s>
<s>
The	O
board	O
agreed	O
that	O
,	O
as	O
a	O
first	O
step	O
,	O
Lyons	O
would	O
provide	O
Hartree	O
and	O
Wilkes	O
with	O
£	O
2,500	O
for	O
the	O
EDSAC	B-Device
project	O
,	O
and	O
would	O
also	O
provide	O
them	O
with	O
the	O
services	O
of	O
a	O
Lyons	O
electrical	O
engineer	O
,	O
Ernest	O
Lenaerts	O
.	O
</s>
<s>
EDSAC	B-Device
was	O
completed	O
and	O
ran	O
its	O
first	O
program	O
in	O
May	O
1949	O
.	O
</s>
<s>
Following	O
the	O
successful	O
completion	O
of	O
EDSAC	B-Device
,	O
the	O
Lyons	O
board	O
agreed	O
to	O
start	O
the	O
construction	O
of	O
their	O
own	O
machine	O
,	O
expanding	O
on	O
the	O
EDSAC	B-Device
design	O
.	O
</s>
<s>
LEO	B-Device
I	I-Device
's	O
clock	O
speed	O
was	O
500kHz	O
,	O
with	O
most	O
instructions	O
taking	O
about	O
1.5ms	O
to	O
execute	O
.	O
</s>
<s>
Therefore	O
,	O
its	O
chief	O
designer	O
,	O
John	O
Pinkerton	O
,	O
designed	O
the	O
machine	O
to	O
have	O
multiple	O
input/output	O
buffers	B-General_Concept
.	O
</s>
<s>
In	O
the	O
first	O
instance	O
,	O
these	O
were	O
linked	O
to	O
fast	O
paper	O
tape	O
readers	O
and	O
punches	B-Device
,	O
fast	O
punched	B-Device
card	I-Device
readers	I-Device
and	O
punches	B-Device
,	O
and	O
a	O
100	O
line	O
a	O
minute	O
tabulator	O
.	O
</s>
<s>
Its	O
ultrasonic	O
delay-line	O
memory	O
based	O
on	O
tanks	O
of	O
mercury	B-Device
,	O
with	O
2K	O
(	O
2048	O
)	O
35-bit	O
words	O
(	O
i.e.	O
,	O
8	O
kilobytes	O
)	O
,	O
was	O
four	O
times	O
as	O
large	O
as	O
that	O
of	O
EDSAC	B-Device
.	O
</s>
<s>
Lyons	O
used	O
LEO	B-Device
I	I-Device
initially	O
for	O
valuation	O
jobs	O
,	O
but	O
its	O
role	O
was	O
extended	O
to	O
include	O
payroll	O
,	O
inventory	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
The	O
LEO	O
project	O
was	O
also	O
a	O
pioneer	O
in	O
outsourcing	B-Architecture
:	O
in	O
1956	O
,	O
Lyons	O
started	O
doing	O
the	O
payroll	O
calculations	O
for	O
Ford	O
UK	O
and	O
others	O
on	O
the	O
LEO	B-Device
I	I-Device
machine	O
.	O
</s>
<s>
Met	O
Office	O
staff	O
used	O
a	O
LEO	B-Device
I	I-Device
before	O
the	O
Met	O
Office	O
bought	O
its	O
own	O
computer	O
,	O
a	O
Ferranti	B-Device
Mercury	I-Device
,	O
in	O
1959	O
.	O
</s>
<s>
It	O
was	O
microprogrammed	B-Device
and	O
was	O
controlled	O
by	O
a	O
multitasking	B-Operating_System
"	O
Master	O
program	O
"	O
operating	O
system	O
,	O
which	O
allowed	O
concurrent	O
running	O
of	O
as	O
many	O
as	O
12	O
application	O
programs	O
.	O
</s>
<s>
Users	O
of	O
LEO	O
computers	O
programmed	O
in	O
two	O
coding	O
languages	O
:	O
Intercode	O
,	O
a	O
low-level	O
assembler	B-Language
type	O
language	O
;	O
and	O
CLEO	O
(	O
acronym	O
:	O
Clear	O
Language	O
for	O
Expressing	O
Orders	O
)	O
,	O
the	O
COBOL	B-Application
equivalent	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
there	O
were	O
still	O
ICL	B-Device
2900	I-Device
mainframes	O
running	O
LEO	O
programs	O
,	O
using	O
an	O
emulator	O
written	O
in	O
ICL2960	O
microcode	B-Device
at	O
the	O
Dalkeith	O
development	O
centre	O
.	O
</s>
<s>
Nick	O
Pelling	O
notes	O
that	O
before	O
LEO	B-Device
I	I-Device
the	O
company	O
already	O
had	O
a	O
proven	O
,	O
industry-leading	O
system	O
using	O
clerks	O
that	O
gave	O
it	O
"	O
near-real-time	O
management	O
information	O
on	O
more	O
or	O
less	O
all	O
aspects	O
of	O
its	O
business	O
"	O
,	O
and	O
that	O
no	O
jobs	O
were	O
lost	O
when	O
the	O
system	O
was	O
computerized	O
.	O
</s>
<s>
The	O
Centre	O
's	O
museum	O
gallery	O
has	O
an	O
area	O
dedicated	O
to	O
LEO	O
,	O
and	O
they	O
are	O
also	O
working	O
on	O
a	O
LEO	O
virtual	B-Application
reality	I-Application
project	O
.	O
</s>
<s>
In	O
November	O
2021	O
,	O
to	O
coincide	O
with	O
the	O
70th	O
anniversary	O
of	O
the	O
first	O
successful	O
full	O
program	O
run	O
on	O
LEO	B-Device
I	I-Device
,	O
the	O
project	O
released	O
a	O
film	O
about	O
the	O
history	O
of	O
LEO	O
,	O
which	O
went	O
on	O
to	O
win	O
Video	O
of	O
the	O
Year	O
in	O
the	O
Association	O
of	O
British	O
Science	O
Writers	O
Awards	O
in	O
July	O
2022	O
.	O
</s>
