<s>
Pegasus	B-Device
was	O
an	O
early	O
British	O
vacuum-tube	O
(	O
valve	O
)	O
computer	O
built	O
by	O
Ferranti	O
,	O
Ltd	O
that	O
pioneered	O
design	O
features	O
to	O
make	O
life	O
easier	O
for	O
both	O
engineers	O
and	O
programmers	O
.	O
</s>
<s>
The	O
first	O
Pegasus	B-Device
was	O
delivered	O
in	O
1956	O
and	O
the	O
last	O
was	O
delivered	O
in	O
1959	O
.	O
</s>
<s>
At	O
least	O
two	O
Pegasus	B-Device
machines	O
survive	O
,	O
one	O
in	O
The	O
Science	O
Museum	O
,	O
London	O
and	O
one	O
which	O
was	O
displayed	O
in	O
the	O
Science	O
and	O
Industry	O
Museum	O
,	O
Manchester	O
but	O
which	O
has	O
now	O
been	O
removed	O
to	O
the	O
storage	O
in	O
the	O
Science	O
Museum	O
archives	O
at	O
Wroughton	O
.	O
</s>
<s>
The	O
Pegasus	B-Device
in	O
The	O
Science	O
Museum	O
,	O
London	O
ran	O
its	O
first	O
program	O
in	O
December	O
1959	O
and	O
was	O
regularly	O
demonstrated	O
until	O
2009	O
when	O
it	O
developed	O
a	O
severe	O
electrical	O
fault	O
.	O
</s>
<s>
The	O
Pegasus	B-Device
officially	O
held	O
the	O
title	O
of	O
the	O
world	O
's	O
oldest	O
computer	O
until	O
2012	O
,	O
when	O
the	O
restoration	O
of	O
the	O
Harwell	B-Device
computer	I-Device
was	O
completed	O
at	O
the	O
National	O
Museum	O
of	O
Computing	O
.	O
</s>
<s>
The	O
needs	O
of	O
the	O
programmer	O
were	O
to	O
be	O
a	O
governing	O
factor	O
in	O
selecting	O
the	O
instruction	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
The	O
rest	O
of	O
the	O
memory	B-General_Concept
was	O
held	O
on	O
a	O
7936-word	O
magnetic	B-General_Concept
drum	I-General_Concept
,	O
which	O
rotated	O
at	O
3750rpm	O
,	O
so	O
it	O
was	O
often	O
necessary	O
to	O
use	O
ingenuity	O
to	O
reduce	O
the	O
number	O
of	O
transfers	O
between	O
the	O
fast	O
store	O
and	O
the	O
drum	O
.	O
</s>
<s>
Pegasus	B-Device
had	O
eight	O
accumulators	B-General_Concept
,	O
seven	O
of	O
which	O
could	O
also	O
be	O
used	O
as	O
index	B-General_Concept
registers	I-General_Concept
,	O
the	O
first	O
computer	O
to	O
allow	O
this	O
dual	O
use	O
.	O
</s>
<s>
In	O
line	O
with	O
Strachey	O
's	O
second	O
objective	O
,	O
it	O
had	O
a	O
relatively	O
generous	O
instruction	B-General_Concept
set	I-General_Concept
for	O
a	O
computer	O
of	O
its	O
time	O
,	O
but	O
there	O
was	O
no	O
explicit	O
hardware	O
provision	O
for	O
handling	O
either	O
characters	O
or	O
floating-point	B-Algorithm
numbers	I-Algorithm
.	O
</s>
<s>
The	O
Pegasus	B-Device
basic	O
instruction	O
cycle	O
time	O
for	O
add/subtract/move	O
and	O
logical	O
instructions	O
was	O
128microseconds	O
.	O
</s>
<s>
To	O
what	O
extent	O
Strachey	O
's	O
third	O
objective	O
was	O
reached	O
,	O
depends	O
on	O
how	O
one	O
views	O
a	O
price	O
of	O
£	O
50,000	O
for	O
Pegasus1	O
,	O
which	O
did	O
not	O
have	O
magnetic	B-Architecture
tape	I-Architecture
drives	I-Architecture
,	O
line	O
printer	O
or	O
punched	B-Architecture
card	I-Architecture
input	O
and	O
output	O
.	O
</s>
<s>
The	O
initial	O
version	O
of	O
Pegasus	B-Device
,	O
Pegasus1	O
was	O
intended	O
for	O
scientific	O
and	O
engineering	O
applications	O
.	O
</s>
<s>
The	O
variant	O
for	O
business	O
data	O
processing	O
was	O
called	O
Pegasus2	O
and	O
could	O
be	O
equipped	O
with	O
punched	B-Architecture
cards	I-Architecture
,	O
magnetic	O
tape	O
and	O
line	O
printer	O
.	O
</s>
<s>
In	O
1956	O
the	O
first	O
Pegasus	B-Device
was	O
used	O
to	O
calculate	O
the	O
stresses	O
and	O
strains	O
in	O
the	O
tail	O
plane	O
of	O
the	O
Saunders-Roe	O
SR.53	O
;	O
the	O
results	O
were	O
used	O
to	O
check	O
the	O
manufacturers	O
figures	O
;	O
the	O
programmer	O
was	O
Anne	O
Robson	O
.	O
</s>
<s>
A	O
Pegasus	B-Device
1	I-Device
was	O
installed	O
at	O
Cyber	O
House	O
,	O
Sheffield	O
by	O
Stafford	O
Beer	O
for	O
the	O
use	O
of	O
United	O
Steel	O
.	O
</s>
<s>
The	O
Pegasus	B-Device
at	O
Southampton	O
University	O
was	O
used	O
for	O
analysis	O
of	O
ground	O
resonance	O
data	O
for	O
the	O
Saro	O
P.531	O
helicopter	O
,	O
which	O
eventually	O
entered	O
production	O
as	O
the	O
Westland	O
Scout	O
and	O
Westland	O
Wasp	O
.	O
</s>
<s>
In	O
1957	O
a	O
Pegasus	B-Device
computer	O
was	O
used	O
to	O
calculate	O
7480	O
digits	O
of	O
,	O
a	O
record	O
at	O
the	O
time	O
.	O
</s>
<s>
The	O
University	O
of	O
Leeds	O
had	O
a	O
Pegasus	B-Device
computer	O
,	O
run	O
by	O
Sandy	O
Douglas	O
.	O
</s>
<s>
Other	O
people	O
who	O
worked	O
on	O
the	O
Pegasus	B-Device
included	O
Hugh	O
McGregor	O
Ross	O
and	O
Donald	O
B	O
.	O
Gillies	O
.	O
</s>
