<s>
Designed	O
to	O
be	O
used	O
in	O
smaller	O
offices	O
without	O
a	O
dedicated	O
programming	O
staff	O
,	O
the	O
Sirius	O
used	O
decimal	O
arithmetic	O
instead	O
of	O
binary	O
,	O
supported	O
Autocode	B-Language
to	O
ease	O
programming	O
,	O
was	O
designed	O
to	O
fit	O
behind	O
a	O
standard	O
office	O
desk	O
,	O
and	O
ran	O
on	O
UK	O
standard	O
mains	O
electricity	O
(	O
then	O
240V	O
)	O
with	O
no	O
need	O
for	O
cooling	O
.	O
</s>
<s>
One	O
difference	O
between	O
magnetic	O
logic	O
and	O
conventional	O
tube	O
or	O
transistor	B-Application
systems	O
is	O
that	O
it	O
is	O
the	O
current	O
that	O
defines	O
the	O
logic	O
levels	O
,	O
not	O
voltage	O
.	O
</s>
<s>
For	O
instance	O
,	O
a	O
single	O
core	O
could	O
be	O
used	O
as	O
part	O
of	O
the	O
system	O
that	O
reads	O
instructions	O
from	O
memory	O
,	O
and	O
then	O
again	O
as	O
part	O
of	O
the	O
ALU	B-General_Concept
,	O
as	O
long	O
as	O
both	O
functions	O
do	O
n't	O
operate	O
at	O
the	O
same	O
time	O
(	O
as	O
they	O
would	O
in	O
an	O
instruction	B-General_Concept
pipeline	I-General_Concept
)	O
.	O
</s>
<s>
When	O
they	O
were	O
first	O
being	O
studied	O
,	O
transistors	B-Application
were	O
expensive	O
and	O
unreliable	O
devices	O
,	O
but	O
the	O
introduction	O
of	O
new	O
manufacturing	O
techniques	O
in	O
the	O
late	O
1950s	O
started	O
to	O
address	O
both	O
of	O
these	O
problems	O
.	O
</s>
<s>
In	O
spite	O
of	O
their	O
other	O
advantages	O
,	O
magnetic	O
amplifiers	O
quickly	O
disappeared	O
as	O
transistor	B-Application
based	O
logic	O
became	O
increasingly	O
common	O
,	O
and	O
only	O
a	O
few	O
computers	O
based	O
on	O
these	O
systems	O
were	O
produced	O
.	O
</s>
<s>
This	O
team	O
had	O
a	O
longstanding	O
partnership	O
with	O
Manchester	O
University	O
,	O
after	O
commercializing	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
and	O
several	O
follow-on	O
designs	O
.	O
</s>
<s>
As	O
the	O
prices	O
of	O
transistors	B-Application
dropped	O
,	O
Ken	O
Johnson	O
,	O
an	O
engineer	O
at	O
the	O
lab	O
,	O
proposed	O
a	O
new	O
type	O
of	O
transistor-based	O
logic	O
that	O
followed	O
the	O
same	O
conventions	O
as	O
the	O
magnetic	O
amplifiers	O
,	O
namely	O
that	O
binary	O
logic	O
was	O
based	O
on	O
well	O
known	O
currents	O
instead	O
of	O
voltages	O
.	O
</s>
<s>
Better	O
yet	O
,	O
the	O
system	O
often	O
required	O
only	O
one	O
transistor	B-Application
per	O
logic	O
element	O
,	O
whereas	O
conventional	O
voltage-based	O
logic	O
often	O
required	O
two	O
or	O
more	O
.	O
</s>
<s>
Although	O
transistors	B-Application
were	O
falling	O
in	O
price	O
they	O
were	O
still	O
expensive	O
,	O
so	O
a	O
machine	O
based	O
on	O
Johnson	O
's	O
design	O
might	O
offer	O
similar	O
performance	O
at	O
a	O
much	O
lower	O
price	O
.	O
</s>
<s>
The	O
result	O
was	O
the	O
Sirius	O
,	O
which	O
was	O
much	O
less	O
expensive	O
than	O
similar	O
machines	O
using	O
traditional	O
transistor	B-Application
logic	O
.	O
</s>
<s>
The	O
Sirius	O
was	O
marketed	O
in	O
England	O
for	O
£20	O
,	O
000	O
,	O
a	O
deal	O
compared	O
to	O
its	O
competitors	O
,	O
the	O
Elliott	B-Device
803	I-Device
at	O
£	O
35,000	O
and	O
the	O
ICT	B-Device
1301	I-Device
at	O
£	O
120,000	O
.	O
</s>
<s>
Emerging	O
as	O
the	O
Ferranti	B-Device
Orion	I-Device
in	O
1961	O
,	O
the	O
system	O
proved	O
to	O
be	O
a	O
disaster	O
.	O
</s>
<s>
A	O
ground-up	O
redesign	O
using	O
traditional	O
transistor	B-Application
logic	O
followed	O
and	O
emerged	O
in	O
1964	O
as	O
the	O
Orion	O
2	O
.	O
</s>
<s>
Numbers	O
were	O
stored	O
as	O
a	O
string	O
of	O
ten	O
decimal	O
digits	O
in	O
one	O
of	O
eight	O
accumulators	B-General_Concept
,	O
along	O
with	O
a	O
parity	O
bit	O
.	O
</s>
<s>
The	O
accumulators	B-General_Concept
were	O
backed	O
by	O
what	O
Ferranti	O
called	O
a	O
"	O
single-level	O
store	O
"	O
,	O
a	O
main	O
memory	O
formed	O
out	O
of	O
a	O
series	O
of	O
torsional	O
delay-line	O
memory	O
elements	O
storing	O
50	O
words	O
each	O
.	O
</s>
<s>
The	O
instruction	B-General_Concept
set	I-General_Concept
was	O
a	O
single-address	O
format	O
stored	O
in	O
single	O
decimal	O
digits	O
of	O
a	O
word	O
,	O
containing	O
a	O
6-digit	O
address	O
,	O
a	O
2-digit	O
instruction	O
code	O
,	O
and	O
1-digit	O
specifying	O
the	O
"	O
A	O
"	O
and	O
"	O
B	O
"	O
accumulators	B-General_Concept
.	O
</s>
<s>
As	O
the	O
Sirius	O
used	O
decimals	O
for	O
storage	O
,	O
the	O
system	O
offered	O
a	O
number	O
of	O
instructions	O
that	O
quickly	O
multiplied	O
the	O
input	O
or	O
output	O
by	O
10	O
,	O
by	O
shifting	O
the	O
numbers	O
in	O
the	O
accumulators	B-General_Concept
.	O
</s>
<s>
The	O
Sirius	O
was	O
also	O
supplied	O
with	O
a	O
version	O
of	O
Autocode	B-Language
adapted	O
from	O
the	O
Ferranti	B-Device
Pegasus	I-Device
,	O
and	O
Autocode	B-Language
programs	O
from	O
the	O
Pegasus	B-Device
could	O
be	O
run	O
on	O
the	O
Sirius	O
"	O
with	O
very	O
little	O
alteration.	O
"	O
</s>
<s>
The	O
ALU	B-General_Concept
was	O
serial	O
,	O
so	O
addition	O
or	O
subtraction	O
took	O
240microseconds	O
,	O
and	O
overall	O
processing	O
speed	O
was	O
about	O
4,000	O
operations	O
a	O
second	O
.	O
</s>
<s>
Although	O
this	O
is	O
relatively	O
slow	O
,	O
even	O
for	O
the	O
era	O
,	O
Ferranti	O
boasted	O
that	O
"	O
The	O
Sirius	O
computer	O
is	O
nearly	O
twice	O
as	O
fast	O
as	O
any	O
other	O
existing	O
computer	O
at	O
its	O
price	O
,	O
both	O
as	O
regards	O
speeds	O
of	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
and	O
speeds	O
of	O
computation.	O
"	O
</s>
<s>
A	O
single	O
column	O
on	O
the	O
left	O
was	O
used	O
to	O
select	O
an	O
accumulator	B-General_Concept
,	O
and	O
the	O
other	O
than	O
to	O
input	O
the	O
ten	O
digit	O
value	O
.	O
</s>
<s>
Output	O
consisted	O
of	O
two	O
ten-digit	O
displays	O
using	O
nixie	B-Application
tubes	I-Application
on	O
the	O
front	O
of	O
the	O
machine	O
,	O
which	O
also	O
featured	O
a	O
large	O
electric	O
clock	O
.	O
</s>
<s>
Further	O
input/output	B-General_Concept
was	O
offered	O
through	O
two	O
input	O
and	O
two	O
output	O
channels	O
,	O
normally	O
connected	O
to	O
a	O
five-way	O
switch	O
box	O
that	O
allowed	O
the	O
operator	O
to	O
select	O
which	O
devices	O
were	O
fed	O
to	O
which	O
channels	O
.	O
</s>
<s>
Magnetic	O
tape	O
,	O
punched	B-Architecture
card	I-Architecture
,	O
printers	O
and	O
other	O
common	O
I/O	B-General_Concept
devices	I-General_Concept
were	O
supported	O
through	O
these	O
channels	O
.	O
</s>
