<s>
The	O
Harwell	B-Device
computer	I-Device
,	O
or	O
Harwell	B-Device
Dekatron	I-Device
computer	I-Device
,	O
later	O
known	O
as	O
the	O
Wolverhampton	B-Device
Instrument	I-Device
for	I-Device
Teaching	I-Device
Computing	I-Device
from	I-Device
Harwell	I-Device
(	O
WITCH	B-Device
)	O
,	O
is	O
an	O
early	O
British	O
computer	O
of	O
the	O
1950s	O
based	O
on	O
valves	O
and	O
relays	O
.	O
</s>
<s>
The	O
museum	O
uses	O
the	O
computer	O
's	O
visual	O
,	O
dekatron-based	O
memory	O
to	O
teach	O
schoolchildren	O
about	O
computers	O
.	O
</s>
<s>
It	O
used	O
dekatrons	B-General_Concept
for	O
volatile	B-General_Concept
memory	I-General_Concept
,	O
similar	O
to	O
RAM	B-Architecture
in	O
a	O
modern	O
computer	O
,	O
and	O
paper	O
tape	O
for	O
input	O
and	O
program	O
storage	O
.	O
</s>
<s>
The	O
machine	O
was	O
decimal	O
and	O
initially	O
had	O
twenty	O
eight-digit	O
dekatron	B-General_Concept
registers	O
for	O
internal	O
storage	O
,	O
which	O
was	O
increased	O
to	O
40	O
which	O
appeared	O
to	O
be	O
enough	O
for	O
nearly	O
all	O
calculations	O
.	O
</s>
<s>
The	O
computer	O
was	O
renamed	O
as	O
the	O
WITCH	B-Device
,	O
the	O
Wolverhampton	B-Device
Instrument	I-Device
for	I-Device
Teaching	I-Device
Computing	I-Device
from	I-Device
Harwell	I-Device
.	O
</s>
<s>
The	O
WITCH	B-Device
was	O
donated	O
to	O
the	O
Museum	O
of	O
Science	O
and	O
Industry	O
,	O
Birmingham	O
in	O
1973	O
.	O
</s>
<s>
The	O
museum	O
,	O
a	O
registered	O
charity	O
,	O
invited	O
members	O
of	O
the	O
public	O
and	O
industry	O
to	O
sponsor	O
the	O
restoration	O
of	O
the	O
Harwell	B-Device
computer	I-Device
by	O
purchasing	O
one	O
of	O
25	O
shares	O
at	O
£	O
4,500	O
each	O
.	O
</s>
<s>
A	O
painting	O
of	O
the	O
machine	O
,	O
Portrait	O
of	O
a	O
Dead	O
Witch	B-Device
was	O
made	O
by	O
the	O
artist	O
John	O
Yeadon	O
in	O
1983	O
.	O
</s>
