<s>
A	O
vacuum-tube	B-Device
computer	I-Device
,	O
now	O
termed	O
a	O
first-generation	B-Device
computer	I-Device
,	O
is	O
a	O
computer	O
that	O
uses	O
vacuum	O
tubes	O
for	O
logic	O
circuitry	O
.	O
</s>
<s>
Although	O
superseded	O
by	O
second-generation	O
transistorized	B-Device
computers	I-Device
,	O
vacuum-tube	B-Device
computers	I-Device
continued	O
to	O
be	O
built	O
into	O
the	O
1960s	O
.	O
</s>
<s>
This	O
circuit	O
became	O
the	O
basis	O
of	O
the	O
flip-flop	B-General_Concept
,	O
a	O
circuit	O
with	O
two	O
states	O
that	O
became	O
the	O
fundamental	O
element	O
of	O
electronic	O
binary	O
digital	O
computers	O
.	O
</s>
<s>
The	B-Device
Atanasoff	I-Device
–	I-Device
Berry	I-Device
computer	I-Device
,	O
a	O
prototype	O
of	O
which	O
was	O
first	O
demonstrated	O
in	O
1939	O
,	O
is	O
now	O
credited	O
as	O
the	O
first	O
vacuum-tube	B-Device
computer	I-Device
.	O
</s>
<s>
The	O
German	O
military	O
establishment	O
during	O
the	O
war	O
did	O
not	O
prioritize	O
computer	B-Architecture
development	I-Architecture
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
work	O
started	O
on	O
the	O
ENIAC	B-Device
computer	I-Device
late	O
in	O
the	O
Second	O
World	O
War	O
.	O
</s>
<s>
Although	O
one	O
application	O
which	O
motivated	O
its	O
development	O
was	O
the	O
production	O
of	O
firing	O
tables	O
for	O
artillery	O
,	O
one	O
of	O
the	O
first	O
uses	O
of	O
ENIAC	B-Device
was	O
to	O
carry	O
out	O
calculations	O
related	O
to	O
the	O
development	O
of	O
a	O
hydrogen	O
bomb	O
.	O
</s>
<s>
ENIAC	B-Device
was	O
initially	O
programmed	O
with	O
plugboards	O
and	O
switches	O
instead	O
of	O
an	O
electronically	O
stored	O
program	O
.	O
</s>
<s>
A	O
post-war	O
series	O
of	O
lectures	O
disclosing	O
the	O
design	O
of	O
ENIAC	B-Device
,	O
and	O
a	O
report	O
by	O
John	O
von	O
Neumann	O
on	O
a	O
foreseeable	O
successor	O
to	O
ENIAC	B-Device
,	O
First	O
Draft	O
of	O
a	O
Report	O
on	O
the	O
EDVAC	B-Device
,	O
were	O
widely	O
distributed	O
and	O
were	O
influential	O
in	O
the	O
design	O
of	O
post-war	O
vacuum-tube	B-Device
computers	I-Device
.	O
</s>
<s>
The	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
(	O
1951	O
)	O
is	O
considered	O
the	O
first	O
commercial	O
vacuum	B-Device
tube	I-Device
computer	I-Device
.	O
</s>
<s>
The	O
ENIAC	B-Device
computer	I-Device
(	O
1946	O
)	O
had	O
over	O
17,000	O
tubes	O
and	O
suffered	O
a	O
tube	O
failure	O
(	O
which	O
would	O
take	O
15minutes	O
to	O
locate	O
)	O
on	O
average	O
every	O
two	O
days	O
.	O
</s>
<s>
In	O
operation	O
the	O
ENIAC	B-Device
consumed	O
150kilowatts	O
of	O
power	O
,	O
of	O
which	O
80kilowatts	O
were	O
used	O
for	O
heating	O
tubes	O
,	O
45kilowatts	O
for	O
DC	O
power	O
supplies	O
,	O
20kilowatts	O
for	O
ventilation	O
blowers	O
,	O
and	O
5kilowatts	O
for	O
punched-card	O
auxiliary	O
equipment	O
.	O
</s>
<s>
Marginal	O
testing	O
was	O
built	O
into	O
sub-systems	O
of	O
a	O
vacuum-tube	B-Device
computer	I-Device
;	O
by	O
lowering	O
plate	O
or	O
heater	O
voltages	O
and	O
testing	O
for	O
proper	O
operation	O
,	O
components	O
at	O
risk	O
of	O
early	O
failure	O
could	O
be	O
detected	O
.	O
</s>
<s>
Two	O
broad	O
types	O
of	O
logic	O
circuits	O
were	O
used	O
in	O
construction	O
of	O
vacuum-tube	B-Device
computers	I-Device
.	O
</s>
<s>
An	O
example	O
of	O
a	O
"	O
pulse	O
"	O
(	O
synchronous	O
)	O
compute	O
was	O
the	O
MIT	B-Device
Whirlwind	I-Device
.	O
</s>
<s>
The	O
IAS	O
computers	O
(	O
ILLIAC	B-Device
and	O
others	O
)	O
used	O
asynchronous	O
,	O
direct-coupled	O
logic	O
stages	O
.	O
</s>
<s>
Thyratrons	O
were	O
sometimes	O
used	O
,	O
such	O
as	O
for	O
driving	O
I/O	O
devices	O
or	O
to	O
simplify	O
design	O
of	O
latches	B-General_Concept
and	O
holding	O
registers	O
.	O
</s>
<s>
Often	O
vacuum-tube	B-Device
computers	I-Device
made	O
extensive	O
use	O
of	O
solid-state	O
(	O
"	O
crystal	O
"	O
)	O
diodes	O
to	O
perform	O
AND	O
and	O
OR	O
logic	O
functions	O
,	O
and	O
only	O
used	O
vacuum	O
tubes	O
to	O
amplify	O
signals	O
between	O
stages	O
or	O
to	O
construct	O
elements	O
such	O
as	O
flip-flops	B-General_Concept
,	O
counters	O
,	O
and	O
registers	O
.	O
</s>
<s>
The	B-Device
Atanasoff	I-Device
–	I-Device
Berry	I-Device
computer	I-Device
of	O
1942	O
stored	O
numerical	O
values	O
as	O
binary	O
numbers	O
in	O
a	O
revolving	O
mechanical	O
drum	O
,	O
with	O
a	O
special	O
circuit	O
to	O
refresh	O
this	O
"	O
dynamic	O
"	O
memory	O
on	O
every	O
revolution	O
.	O
</s>
<s>
The	O
war-time	O
ENIAC	B-Device
could	O
store	O
20	O
numbers	O
,	O
but	O
the	O
vacuum-tube	O
registers	O
used	O
were	O
too	O
expensive	O
to	O
build	O
to	O
store	O
more	O
than	O
a	O
few	O
numbers	O
.	O
</s>
<s>
Maurice	O
Wilkes	O
built	O
EDSAC	B-Device
in	O
1947	O
,	O
which	O
had	O
a	O
mercury	O
delay-line	O
memory	O
that	O
could	O
store	O
32words	O
of	O
17bits	O
each	O
.	O
</s>
<s>
Mercury	O
delay-line	O
memory	O
was	O
used	O
by	O
J	O
.	O
Presper	O
Eckert	O
in	O
the	O
EDVAC	B-Device
and	O
UNIVAC	O
I	O
.	O
Eckert	O
and	O
John	O
Mauchly	O
received	O
a	O
patent	O
for	O
delay-line	O
memory	O
in	O
1953	O
.	O
</s>
<s>
Williams	B-General_Concept
tubes	I-General_Concept
were	O
the	O
first	O
true	O
random-access	B-Architecture
memory	I-Architecture
device	O
.	O
</s>
<s>
The	O
Williams	B-General_Concept
tube	I-General_Concept
displays	O
a	O
grid	O
of	O
dots	O
on	O
a	O
cathode-ray	O
tube	O
(	O
CRT	O
)	O
,	O
creating	O
a	O
small	O
charge	O
of	O
static	O
electricity	O
over	O
each	O
dot	O
.	O
</s>
<s>
Frederic	O
Calland	O
Williams	O
and	O
Tom	O
Kilburn	O
applied	O
for	O
patents	O
for	O
the	O
Williams	B-General_Concept
tube	I-General_Concept
in	O
1946	O
.	O
</s>
<s>
The	O
Williams	B-General_Concept
tube	I-General_Concept
was	O
much	O
faster	O
than	O
the	O
delay	O
line	O
,	O
but	O
suffered	O
from	O
reliability	O
problems	O
.	O
</s>
<s>
The	O
UNIVAC	O
1103	O
used	O
36	O
Williams	B-General_Concept
tubes	I-General_Concept
with	O
a	O
capacity	O
of	O
1,024	O
bits	O
each	O
,	O
giving	O
a	O
total	O
random	B-Architecture
access	I-Architecture
memory	I-Architecture
of	O
1,024	O
words	O
of	O
36bits	O
each	O
.	O
</s>
<s>
Magnetic	B-General_Concept
drum	I-General_Concept
memory	I-General_Concept
was	O
invented	O
in	O
1932	O
by	O
Gustav	O
Tauschek	O
in	O
Austria	O
.	O
</s>
<s>
The	O
IBM650	O
had	O
a	O
drum	B-General_Concept
memory	I-General_Concept
of	O
1,000	O
to	O
4,000	O
10-digit	O
words	O
with	O
an	O
average	O
access	O
time	O
of	O
2.5milliseconds	O
.	O
</s>
<s>
It	O
was	O
quickly	O
put	O
to	O
use	O
in	O
computers	O
such	O
as	O
the	O
MIT/IBM	O
Whirlwind	B-Device
,	O
where	O
an	O
initial	O
1,024	O
16-bit	O
words	O
of	O
memory	O
were	O
installed	O
replacing	O
Williams	B-General_Concept
tubes	I-General_Concept
.	O
</s>
<s>
Likewise	O
the	O
UNIVAC	O
1103	O
was	O
upgraded	O
to	O
the	O
1103A	O
in	O
1956	O
,	O
with	O
core	O
memory	O
replacing	O
Williams	B-General_Concept
tubes	I-General_Concept
.	O
</s>
