<s>
Regenerative	B-General_Concept
capacitor	I-General_Concept
memory	I-General_Concept
is	O
a	O
type	O
of	O
computer	B-General_Concept
memory	I-General_Concept
that	O
uses	O
the	O
electrical	O
property	O
of	O
capacitance	O
to	O
store	O
the	O
bits	O
of	O
data	O
.	O
</s>
<s>
Other	O
types	O
of	O
computer	B-General_Concept
memory	I-General_Concept
exist	O
that	O
use	O
the	O
electrical	O
property	O
of	O
capacitance	O
to	O
store	O
the	O
data	O
,	O
but	O
do	O
not	O
require	O
regeneration	O
.	O
</s>
<s>
Traditionally	O
these	O
have	O
either	O
been	O
somewhat	O
impractical	O
(	O
e.g.	O
,	O
the	O
Selectron	O
tube	O
)	O
or	O
are	O
considered	O
to	O
be	O
suitable	O
only	O
as	O
read-only	B-Device
memory	I-Device
(	O
e.g.	O
,	O
EPROM	B-General_Concept
,	O
EEPROM/Flash	O
memory	O
)	O
since	O
writing	O
data	O
takes	O
significantly	O
longer	O
than	O
reading	O
.	O
</s>
<s>
The	O
first	O
regenerative	B-General_Concept
capacitor	I-General_Concept
memory	I-General_Concept
built	O
was	O
the	O
rotating	O
capacitor	O
drum	O
memory	O
of	O
the	B-Device
Atanasoff	I-Device
–	I-Device
Berry	I-Device
Computer	I-Device
(	O
1942	O
)	O
.	O
</s>
<s>
Each	O
of	O
its	O
two	O
drums	O
stored	O
thirty	O
50-bit	O
binary	O
numbers	O
(	O
1500	O
bits	O
each	O
)	O
,	O
rotated	O
at	O
60	O
rpm	O
and	O
was	O
regenerated	O
every	O
rotation	O
(	O
1Hz	O
refresh	B-General_Concept
rate	O
)	O
.	O
</s>
<s>
The	O
first	O
random	B-General_Concept
access	I-General_Concept
regenerative	B-General_Concept
capacitor	I-General_Concept
memory	I-General_Concept
was	O
the	O
Williams	B-General_Concept
tube	I-General_Concept
(	O
1947	O
)	O
.	O
</s>
<s>
As	O
fitted	O
to	O
the	O
first	B-Device
practical	I-Device
programmable	I-Device
digital	I-Device
computer	I-Device
,	O
a	O
single	O
Williams	B-General_Concept
tube	I-General_Concept
held	O
a	O
total	O
of	O
2560	O
bits	O
,	O
arranged	O
in	O
two	O
'	O
pages	O
 '	O
.	O
</s>
<s>
One	O
page	O
was	O
an	O
array	O
of	O
thirty	O
two	O
40-bit	O
binary	O
numbers	O
,	O
the	O
capacity	O
of	O
a	O
basic	O
Williams-Kilburn	B-General_Concept
Tube	I-General_Concept
.	O
</s>
<s>
The	O
refresh	B-General_Concept
rate	O
required	O
varied	O
depending	O
on	O
the	O
type	O
of	O
CRT	B-Device
used	O
.	O
</s>
<s>
The	O
modern	O
DRAM	O
(	O
1966	O
)	O
is	O
a	O
regenerative	B-General_Concept
capacitor	I-General_Concept
memory	I-General_Concept
.	O
</s>
