<s>
The	O
Mercury	B-Language
was	O
an	O
early	O
commercial	O
computer	O
from	O
the	O
mid-1950s	O
built	O
by	O
Ferranti	O
.	O
</s>
<s>
It	O
was	O
the	O
successor	O
to	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
,	O
adding	O
a	O
floating	B-General_Concept
point	I-General_Concept
unit	I-General_Concept
for	O
improved	O
performance	O
,	O
and	O
increased	O
reliability	O
by	O
replacing	O
the	O
Williams	B-General_Concept
tube	I-General_Concept
memory	O
with	O
core	B-General_Concept
memory	I-General_Concept
and	O
using	O
more	O
solid-state	O
components	O
.	O
</s>
<s>
Nineteen	O
Mercuries	B-Language
were	O
sold	O
before	O
Ferranti	O
moved	O
on	O
to	O
newer	O
designs	O
.	O
</s>
<s>
The	O
primary	O
concern	O
was	O
the	O
drum	B-General_Concept
memory	I-General_Concept
system	O
,	O
which	O
broke	O
down	O
all	O
the	O
time	O
.	O
</s>
<s>
The	O
Williams	B-General_Concept
tubes	I-General_Concept
,	O
used	O
as	O
random-access	B-Architecture
memory	I-Architecture
and	O
registers	O
,	O
were	O
reliable	O
but	O
required	O
constant	O
maintenance	O
.	O
</s>
<s>
One	O
team	O
decided	O
to	O
produce	O
a	O
much	O
smaller	O
and	O
more	O
cost-effective	O
system	O
built	O
entirely	O
with	O
transistors	B-Application
.	O
</s>
<s>
It	O
first	O
ran	O
in	O
November	O
1953	O
and	O
is	O
believed	O
to	O
be	O
the	O
first	O
entirely	O
transistor-based	O
computer	O
.	O
</s>
<s>
Metropolitan-Vickers	O
later	O
built	O
this	O
commercially	O
as	O
the	O
Metrovick	B-Device
950	I-Device
,	O
delivering	O
seven	O
.	O
</s>
<s>
At	O
the	O
time	O
,	O
transistors	B-Application
were	O
very	O
expensive	O
,	O
compared	O
to	O
tubes	O
.	O
</s>
<s>
These	O
were	O
much	O
less	O
expensive	O
than	O
transistors	B-Application
,	O
yet	O
enough	O
of	O
them	O
were	O
used	O
in	O
the	O
design	O
that	O
replacing	O
just	O
the	O
diodes	O
would	O
still	O
result	O
in	O
a	O
significant	O
simplification	O
and	O
improvement	O
in	O
reliability	O
.	O
</s>
<s>
At	O
that	O
time	O
computers	O
were	O
used	O
almost	O
always	O
in	O
the	O
sciences	O
,	O
and	O
they	O
decided	O
to	O
add	O
a	O
floating-point	B-General_Concept
unit	I-General_Concept
to	O
greatly	O
improve	O
performance	O
in	O
this	O
role	O
.	O
</s>
<s>
This	O
was	O
a	O
result	O
of	O
the	O
physical	O
properties	O
of	O
the	O
Williams	B-General_Concept
tubes	I-General_Concept
,	O
which	O
were	O
used	O
to	O
make	O
eight	O
B-lines	O
,	O
or	O
in	O
modern	O
terminology	O
,	O
accumulator/index	O
registers	O
.	O
</s>
<s>
The	O
floating-point	B-General_Concept
unit	I-General_Concept
used	O
three	O
words	O
for	O
a	O
30-bit	O
mantissa	O
,	O
and	O
another	O
as	O
a	O
10-bit	O
exponent	O
.	O
</s>
<s>
It	O
could	O
add	O
two	O
floating-point	B-Algorithm
numbers	I-Algorithm
in	O
about	O
180microseconds	O
,	O
and	O
multiply	O
them	O
in	O
about	O
360microseconds	O
.	O
</s>
<s>
Ferranti	O
,	O
which	O
had	O
built	O
the	O
Mark	O
I	O
for	O
the	O
university	O
,	O
continued	O
development	O
of	O
the	O
prototype	O
Meg	O
to	O
produce	O
the	O
Mercury	B-Language
.	O
</s>
<s>
The	O
main	O
change	O
was	O
to	O
replace	O
the	O
Williams	B-General_Concept
tubes	I-General_Concept
with	O
core	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
The	O
first	O
of	O
an	O
eventual	O
19	O
Mercury	B-Language
computers	O
was	O
delivered	O
in	O
August	O
1957	O
.	O
</s>
<s>
A	O
Mercury	B-Language
bought	O
in	O
1959	O
was	O
the	O
UK	O
Met	O
Office	O
's	O
first	O
computer	O
.	O
</s>
<s>
The	O
machine	O
could	O
run	O
Mercury	B-Language
Autocode	I-Language
,	O
a	O
simplified	O
coding	O
system	O
of	O
the	O
type	O
later	O
described	O
as	O
a	O
high-level	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Detailed	O
information	O
both	O
about	O
the	O
Mercury	B-Language
hardware	O
and	O
the	O
Autocode	B-Language
coding	O
system	O
is	O
included	O
in	O
a	O
downloadable	O
Spanish-language	O
Autocode	B-Language
manual	O
.	O
</s>
<s>
Mercury	B-Language
weighed	O
.	O
</s>
