<s>
The	O
history	B-Architecture
of	I-Architecture
computing	I-Architecture
hardware	I-Architecture
covers	O
the	O
developments	O
from	O
early	O
simple	O
devices	O
to	O
aid	O
calculation	O
to	O
modern	O
day	O
computers	O
.	O
</s>
<s>
The	O
development	O
of	O
transistor	B-Application
technology	O
and	O
then	O
the	O
integrated	O
circuit	O
chip	O
led	O
to	O
a	O
series	O
of	O
breakthroughs	O
,	O
starting	O
with	O
transistor	B-Device
computers	I-Device
and	O
then	O
integrated	O
circuit	O
computers	O
,	O
causing	O
digital	O
computers	O
to	O
largely	O
replace	O
analog	O
computers	O
.	O
</s>
<s>
Metal-oxide-semiconductor	B-Architecture
(	O
MOS	O
)	O
large-scale	O
integration	O
(	O
LSI	O
)	O
then	O
enabled	O
semiconductor	B-Architecture
memory	I-Architecture
and	O
the	O
microprocessor	B-Architecture
,	O
leading	O
to	O
another	O
key	O
breakthrough	O
,	O
the	O
miniaturized	O
personal	B-Device
computer	I-Device
(	O
PC	O
)	O
,	O
in	O
the	O
1970s	O
.	O
</s>
<s>
The	O
cost	O
of	O
computers	O
gradually	O
became	O
so	O
low	O
that	O
personal	B-Device
computers	I-Device
by	O
the	O
1990s	O
,	O
and	O
then	O
mobile	O
computers	O
(	O
smartphones	B-Application
and	O
tablets	B-Device
)	O
in	O
the	O
2000s	O
,	O
became	O
ubiquitous	O
.	O
</s>
<s>
Devices	O
have	O
been	O
used	O
to	O
aid	O
computation	O
for	O
thousands	O
of	O
years	O
,	O
mostly	O
using	O
one-to-one	B-Algorithm
correspondence	I-Algorithm
with	O
fingers	O
.	O
</s>
<s>
The	O
abacus	B-Application
was	O
early	O
used	O
for	O
arithmetic	O
tasks	O
.	O
</s>
<s>
What	O
we	O
now	O
call	O
the	O
Roman	O
abacus	B-Application
was	O
used	O
in	O
Babylonia	O
as	O
early	O
as	O
c	O
.	O
2700	O
–	O
2300	O
BC	O
.	O
</s>
<s>
In	O
Roman	O
Egypt	O
,	O
Hero	O
of	O
Alexandria	O
(	O
c	O
.	O
10	O
–	O
70	O
AD	O
)	O
made	O
mechanical	O
devices	O
including	O
automata	O
and	O
a	O
programmable	B-General_Concept
cart	O
.	O
</s>
<s>
Other	O
early	O
mechanical	O
devices	O
used	O
to	O
perform	O
one	O
or	O
another	O
type	O
of	O
calculations	O
include	O
the	O
planisphere	O
and	O
other	O
mechanical	O
computing	O
devices	O
invented	O
by	O
Al-Biruni	O
(	O
c	O
.	O
AD	O
1000	O
)	O
;	O
the	O
equatorium	O
and	O
universal	O
latitude-independent	O
astrolabe	O
by	O
Al-Zarqali	O
(	O
c	O
.	O
AD	O
1015	O
)	O
;	O
the	O
astronomical	O
analog	O
computers	O
of	O
other	O
medieval	O
Muslim	O
astronomers	O
and	O
engineers	O
;	O
and	O
the	O
astronomical	O
clock	B-Application
tower	I-Application
of	O
Su	O
Song	O
(	O
1094	O
)	O
during	O
the	O
Song	O
dynasty	O
.	O
</s>
<s>
The	O
castle	O
clock	O
,	O
a	O
hydropowered	O
mechanical	O
astronomical	O
clock	O
invented	O
by	O
Ismail	O
al-Jazari	O
in	O
1206	O
,	O
was	O
the	O
first	O
programmable	B-General_Concept
analog	O
computer	O
.	O
</s>
<s>
It	O
was	O
at	O
this	O
point	O
that	O
he	O
designed	O
his	O
'	O
Napier	O
's	O
bones	O
 '	O
,	O
an	O
abacus-like	O
device	O
that	O
greatly	O
simplified	O
calculations	O
that	O
involved	O
multiplication	O
and	O
division	O
.	O
</s>
<s>
However	O
,	O
up	O
to	O
the	O
1940s	O
,	O
many	O
subsequent	O
designs	O
(	O
including	O
Charles	O
Babbage	O
's	O
machines	O
of	O
the	O
1822	O
and	O
even	O
ENIAC	B-Device
of	O
1945	O
)	O
were	O
based	O
on	O
the	O
decimal	B-Application
system	O
.	O
</s>
<s>
In	O
1804	O
,	O
French	O
weaver	O
Joseph	O
Marie	O
Jacquard	O
developed	O
a	O
loom	B-Language
in	O
which	O
the	O
pattern	O
being	O
woven	O
was	O
controlled	O
by	O
a	O
paper	O
tape	O
constructed	O
from	O
punched	B-Architecture
cards	I-Architecture
.	O
</s>
<s>
The	O
paper	O
tape	O
could	O
be	O
changed	O
without	O
changing	O
the	O
mechanical	O
design	O
of	O
the	O
loom	B-Language
.	O
</s>
<s>
His	O
machine	O
was	O
an	O
improvement	O
over	O
similar	O
weaving	O
looms	B-Language
.	O
</s>
<s>
Punched	B-Architecture
cards	I-Architecture
were	O
preceded	O
by	O
punch	O
bands	O
,	O
as	O
in	O
the	O
machine	O
proposed	O
by	O
Basile	O
Bouchon	O
.	O
</s>
<s>
In	O
the	O
late	O
1880s	O
,	O
the	O
American	O
Herman	O
Hollerith	O
invented	O
data	O
storage	O
on	O
punched	B-Architecture
cards	I-Architecture
that	O
could	O
then	O
be	O
read	O
by	O
a	O
machine	O
.	O
</s>
<s>
To	O
process	O
these	O
punched	B-Architecture
cards	I-Architecture
,	O
he	O
invented	O
the	O
tabulator	O
and	O
the	O
keypunch	B-Device
machine	I-Device
.	O
</s>
<s>
His	O
machines	O
used	O
electromechanical	O
relays	O
and	O
counters	B-Device
.	O
</s>
<s>
When	O
the	O
United	O
States	O
instituted	O
Social	O
Security	O
in	O
1935	O
,	O
IBM	O
punched-card	B-Architecture
systems	I-Architecture
were	O
used	O
to	O
process	O
records	O
of	O
26	O
million	O
workers	O
.	O
</s>
<s>
Punched	B-Architecture
cards	I-Architecture
became	O
ubiquitous	O
in	O
industry	O
and	O
government	O
for	O
accounting	O
and	O
administration	O
.	O
</s>
<s>
Leslie	O
Comrie	O
's	O
articles	O
on	O
punched-card	B-Architecture
methods	O
and	O
W	O
.	O
J	O
.	O
Eckert	O
's	O
publication	O
of	O
Punched	B-Architecture
Card	I-Architecture
Methods	O
in	O
Scientific	O
Computation	O
in	O
1940	O
,	O
described	O
punched-card	B-Architecture
techniques	O
sufficiently	O
advanced	O
to	O
solve	O
some	O
differential	O
equations	O
or	O
perform	O
multiplication	O
and	O
division	O
using	O
floating-point	B-Algorithm
representations	I-Algorithm
,	O
all	O
on	O
punched	B-Architecture
cards	I-Architecture
and	O
unit	O
record	O
machines	O
.	O
</s>
<s>
The	O
word	O
"	O
computer	O
"	O
was	O
a	O
job	B-General_Concept
title	O
assigned	O
to	O
primarily	O
women	O
who	O
used	O
these	O
calculators	O
to	O
perform	O
mathematical	O
calculations	O
.	O
</s>
<s>
By	O
the	O
1920s	O
,	O
British	O
scientist	O
Lewis	O
Fry	O
Richardson	O
's	O
interest	O
in	O
weather	O
prediction	O
led	O
him	O
to	O
propose	O
human	O
computers	O
and	O
numerical	B-General_Concept
analysis	I-General_Concept
to	O
model	O
the	O
weather	O
;	O
to	O
this	O
day	O
,	O
the	O
most	O
powerful	O
computers	O
on	O
Earth	O
are	O
needed	O
to	O
adequately	O
model	O
its	O
weather	O
using	O
the	O
Navier	O
–	O
Stokes	O
equations	O
.	O
</s>
<s>
The	O
world	O
's	O
first	O
all-electronic	O
desktop	O
calculator	O
was	O
the	O
British	O
Bell	O
Punch	O
ANITA	B-Device
,	O
released	O
in	O
1961	O
.	O
</s>
<s>
It	O
used	O
vacuum	O
tubes	O
,	O
cold-cathode	O
tubes	O
and	O
Dekatrons	B-General_Concept
in	O
its	O
circuits	O
,	O
with	O
12	O
cold-cathode	O
"	B-Application
Nixie	I-Application
"	I-Application
tubes	O
for	O
its	O
display	O
.	O
</s>
<s>
The	O
ANITA	B-Device
sold	O
well	O
since	O
it	O
was	O
the	O
only	O
electronic	O
desktop	O
calculator	O
available	O
,	O
and	O
was	O
silent	O
and	O
quick	O
.	O
</s>
<s>
The	O
tube	O
technology	O
was	O
superseded	O
in	O
June	O
1963	O
by	O
the	O
U.S.	O
manufactured	O
Friden	O
EC-130	O
,	O
which	O
had	O
an	O
all-transistor	O
design	O
,	O
a	O
stack	O
of	O
four	O
13-digit	O
numbers	O
displayed	O
on	O
a	O
CRT	B-Device
,	O
and	O
introduced	O
reverse	O
Polish	O
notation	O
(	O
RPN	O
)	O
.	O
</s>
<s>
Charles	O
Babbage	O
,	O
an	O
English	O
mechanical	O
engineer	O
and	O
polymath	O
,	O
originated	O
the	O
concept	O
of	O
a	O
programmable	B-General_Concept
computer	O
.	O
</s>
<s>
Considered	O
the	O
"	O
father	O
of	O
the	O
computer	O
"	O
,	O
he	O
conceptualized	O
and	O
invented	O
the	O
first	O
mechanical	B-Device
computer	I-Device
in	O
the	O
early	O
19th	O
century	O
.	O
</s>
<s>
After	O
working	O
on	O
his	O
revolutionary	O
difference	O
engine	O
,	O
designed	O
to	O
aid	O
in	O
navigational	O
calculations	O
,	O
in	O
1833	O
he	O
realized	O
that	O
a	O
much	O
more	O
general	O
design	O
,	O
an	O
Analytical	B-Device
Engine	I-Device
,	O
was	O
possible	O
.	O
</s>
<s>
The	O
input	O
of	O
programs	O
and	O
data	O
was	O
to	O
be	O
provided	O
to	O
the	O
machine	O
via	O
punched	B-Architecture
cards	I-Architecture
,	O
a	O
method	O
being	O
used	O
at	O
the	O
time	O
to	O
direct	O
mechanical	O
looms	B-Language
such	O
as	O
the	O
Jacquard	O
loom	B-Language
.	O
</s>
<s>
The	O
Engine	O
incorporated	O
an	O
arithmetic	B-General_Concept
logic	I-General_Concept
unit	I-General_Concept
,	O
control	O
flow	O
in	O
the	O
form	O
of	O
conditional	B-Language
branching	I-Language
and	O
loops	O
,	O
and	O
integrated	O
memory	B-General_Concept
,	O
making	O
it	O
the	O
first	O
design	O
for	O
a	O
general-purpose	O
computer	O
that	O
could	O
be	O
described	O
in	O
modern	O
terms	O
as	O
Turing-complete	B-Algorithm
.	O
</s>
<s>
There	O
was	O
to	O
be	O
a	O
store	O
,	O
or	O
memory	B-General_Concept
,	O
capable	O
of	O
holding	O
1,000	O
numbers	O
of	O
40	O
decimal	B-Application
digits	O
each	O
(	O
ca	O
.	O
</s>
<s>
An	O
arithmetical	B-General_Concept
unit	I-General_Concept
,	O
called	O
the	O
"	O
mill	O
"	O
,	O
would	O
be	O
able	O
to	O
perform	O
all	O
four	O
arithmetic	O
operations	O
,	O
plus	O
comparisons	O
and	O
optionally	O
square	O
roots	O
.	O
</s>
<s>
Like	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
in	O
a	O
modern	O
computer	O
,	O
the	O
mill	O
would	O
rely	O
on	O
its	O
own	O
internal	O
procedures	O
,	O
roughly	O
equivalent	O
to	O
microcode	B-Device
in	O
modern	O
CPUs	O
,	O
to	O
be	O
stored	O
in	O
the	O
form	O
of	O
pegs	O
inserted	O
into	O
rotating	O
drums	O
called	O
"	O
barrels	O
"	O
,	O
to	O
carry	O
out	O
some	O
of	O
the	O
more	O
complex	O
instructions	O
the	O
user	O
's	O
program	B-Application
might	O
specify	O
.	O
</s>
<s>
The	O
programming	B-Application
language	O
to	O
be	O
employed	O
by	O
users	O
was	O
akin	O
to	O
modern	O
day	O
assembly	B-Language
languages	I-Language
.	O
</s>
<s>
Loops	O
and	O
conditional	B-Language
branching	I-Language
were	O
possible	O
,	O
and	O
so	O
the	O
language	O
as	O
conceived	O
would	O
have	O
been	O
Turing-complete	B-Algorithm
as	O
later	O
defined	O
by	O
Alan	O
Turing	O
.	O
</s>
<s>
Three	O
different	O
types	O
of	O
punch	B-Architecture
cards	I-Architecture
were	O
used	O
:	O
one	O
for	O
arithmetical	O
operations	O
,	O
one	O
for	O
numerical	O
constants	O
,	O
and	O
one	O
for	O
load	O
and	O
store	O
operations	O
,	O
transferring	O
numbers	O
from	O
the	O
store	O
to	O
the	O
arithmetical	B-General_Concept
unit	I-General_Concept
or	O
back	O
.	O
</s>
<s>
Babbage	O
's	O
failure	O
to	O
complete	O
the	B-Device
analytical	I-Device
engine	I-Device
can	O
be	O
chiefly	O
attributed	O
to	O
difficulties	O
not	O
only	O
of	O
politics	O
and	O
financing	O
,	O
but	O
also	O
to	O
his	O
desire	O
to	O
develop	O
an	O
increasingly	O
sophisticated	O
computer	O
and	O
to	O
move	O
ahead	O
faster	O
than	O
anyone	O
else	O
could	O
follow	O
.	O
</s>
<s>
Ada	B-General_Concept
Lovelace	I-General_Concept
translated	O
and	O
added	O
notes	O
to	O
the	O
"	O
Sketch	B-Device
of	I-Device
the	I-Device
Analytical	I-Device
Engine	I-Device
"	O
by	O
Luigi	O
Federico	O
Menabrea	O
.	O
</s>
<s>
This	O
appears	O
to	O
be	O
the	O
first	O
published	O
description	O
of	O
programming	B-Application
,	O
so	O
Ada	B-General_Concept
Lovelace	I-General_Concept
is	O
widely	O
regarded	O
as	O
the	O
first	B-Architecture
computer	I-Architecture
programmer	O
.	O
</s>
<s>
He	O
independently	O
designed	O
a	O
programmable	B-General_Concept
mechanical	B-Device
computer	I-Device
,	O
which	O
he	O
described	O
in	O
a	O
work	O
that	O
was	O
published	O
in	O
1909	O
.	O
</s>
<s>
In	O
his	O
Essays	O
on	O
Automatics	O
(	O
1913	O
)	O
Torres	O
y	O
Quevedo	O
designed	O
a	O
Babbage	O
type	O
of	O
calculating	O
machine	O
that	O
used	O
electromechanical	O
parts	O
which	O
included	O
floating-point	B-Algorithm
number	I-Algorithm
representations	O
and	O
built	O
an	O
early	O
prototype	O
in	O
1920	O
.	O
</s>
<s>
Bush	O
's	O
paper	O
Instrumental	O
Analysis	O
(	O
1936	O
)	O
discussed	O
using	O
existing	O
IBM	O
punch	B-Architecture
card	I-Architecture
machines	O
to	O
implement	O
Babbage	O
's	O
design	O
.	O
</s>
<s>
As	O
an	O
analog	O
computer	O
does	O
not	O
use	O
discrete	O
values	O
,	O
but	O
rather	O
continuous	O
values	O
,	O
processes	O
cannot	O
be	O
reliably	O
repeated	O
with	O
exact	O
equivalence	O
,	O
as	O
they	O
can	O
with	O
Turing	B-Architecture
machines	I-Architecture
.	O
</s>
<s>
The	O
differential	B-Device
analyser	I-Device
,	O
a	O
mechanical	O
analog	O
computer	O
designed	O
to	O
solve	O
differential	O
equations	O
by	O
integration	O
using	O
wheel-and-disc	O
mechanisms	O
,	O
was	O
conceptualized	O
in	O
1876	O
by	O
James	O
Thomson	O
,	O
the	O
brother	O
of	O
the	O
more	O
famous	O
Lord	O
Kelvin	O
.	O
</s>
<s>
He	O
explored	O
the	O
possible	O
construction	O
of	O
such	O
calculators	O
,	O
but	O
was	O
stymied	O
by	O
the	O
limited	O
output	O
torque	O
of	O
the	O
ball-and-disk	B-Device
integrators	I-Device
.	O
</s>
<s>
In	O
a	O
differential	B-Device
analyzer	I-Device
,	O
the	O
output	O
of	O
one	O
integrator	O
drove	O
the	O
input	O
of	O
the	O
next	O
integrator	O
,	O
or	O
a	O
graphing	O
output	O
.	O
</s>
<s>
An	O
important	O
advance	O
in	O
analog	O
computing	O
was	O
the	O
development	O
of	O
the	O
first	O
fire-control	B-Application
systems	I-Application
for	O
long	O
range	O
ship	O
gunlaying	O
.	O
</s>
<s>
There	O
the	O
fire	O
direction	O
teams	O
fed	O
in	O
the	O
location	O
,	O
speed	O
and	O
direction	O
of	O
the	O
ship	O
and	O
its	O
target	O
,	O
as	O
well	O
as	O
various	O
adjustments	O
for	O
Coriolis	O
effect	O
,	O
weather	O
effects	O
on	O
the	O
air	O
,	O
and	O
other	O
adjustments	O
;	O
the	O
computer	O
would	O
then	O
output	O
a	O
firing	B-Application
solution	I-Application
,	O
which	O
would	O
be	O
fed	O
to	O
the	O
turrets	O
for	O
laying	O
.	O
</s>
<s>
In	O
1912	O
,	O
British	O
engineer	O
Arthur	B-Application
Pollen	I-Application
developed	O
the	O
first	O
electrically	O
powered	O
mechanical	O
analogue	O
computer	O
(	O
called	O
at	O
the	O
time	O
the	O
Argo	O
Clock	O
)	O
.	O
</s>
<s>
The	O
alternative	O
Dreyer	O
Table	O
fire	B-Application
control	I-Application
system	I-Application
was	O
fitted	O
to	O
British	O
capital	O
ships	O
by	O
mid-1916	O
.	O
</s>
<s>
Mechanical	O
devices	O
were	O
also	O
used	O
to	O
aid	O
the	O
accuracy	B-Application
of	I-Application
aerial	I-Application
bombing	I-Application
.	O
</s>
<s>
Drift	B-Device
Sight	I-Device
was	O
the	O
first	O
such	O
aid	O
,	O
developed	O
by	O
Harry	O
Wimperis	O
in	O
1916	O
for	O
the	O
Royal	O
Naval	O
Air	O
Service	O
;	O
it	O
measured	O
the	O
wind	O
speed	O
from	O
the	O
air	O
,	O
and	O
used	O
that	O
measurement	O
to	O
calculate	O
the	O
wind	O
's	O
effects	O
on	O
the	O
trajectory	O
of	O
the	O
bombs	O
.	O
</s>
<s>
The	O
system	O
was	O
later	O
improved	O
with	O
the	O
Course	B-Device
Setting	I-Device
Bomb	I-Device
Sight	I-Device
,	O
and	O
reached	O
a	O
climax	O
with	O
World	O
War	O
II	O
bomb	B-Application
sights	I-Application
,	O
Mark	B-Device
XIV	I-Device
bomb	I-Device
sight	I-Device
(	O
RAF	O
Bomber	O
Command	O
)	O
and	O
the	O
Norden	B-Device
(	O
United	O
States	O
Army	O
Air	O
Forces	O
)	O
.	O
</s>
<s>
The	O
art	O
of	O
mechanical	O
analog	O
computing	O
reached	O
its	O
zenith	O
with	O
the	O
differential	B-Device
analyzer	I-Device
,	O
built	O
by	O
H	O
.	O
L	O
.	O
Hazen	O
and	O
Vannevar	O
Bush	O
at	O
MIT	O
starting	O
in	O
1927	O
,	O
which	O
built	O
on	O
the	O
mechanical	O
integrators	O
of	O
James	O
Thomson	O
and	O
the	O
torque	O
amplifiers	O
invented	O
by	O
H	O
.	O
W	O
.	O
Nieman	O
.	O
</s>
<s>
A	O
dozen	O
of	O
these	O
devices	O
were	O
built	O
before	O
their	O
obsolescence	O
became	O
obvious	O
;	O
the	O
most	O
powerful	O
was	O
constructed	O
at	O
the	O
University	O
of	O
Pennsylvania	O
's	O
Moore	O
School	O
of	O
Electrical	O
Engineering	O
,	O
where	O
the	O
ENIAC	B-Device
was	O
built	O
.	O
</s>
<s>
By	O
the	O
1950s	O
the	O
success	O
of	O
digital	O
electronic	O
computers	O
had	O
spelled	O
the	O
end	O
for	O
most	O
analog	O
computing	O
machines	O
,	O
but	O
hybrid	B-Device
analog	I-Device
computers	I-Device
,	O
controlled	O
by	O
digital	O
electronics	O
,	O
remained	O
in	O
substantial	O
use	O
into	O
the	O
1950s	O
and	O
1960s	O
,	O
and	O
later	O
in	O
some	O
specialized	O
applications	O
.	O
</s>
<s>
Turing	O
reformulated	O
Kurt	O
Gödel	O
's	O
1931	O
results	O
on	O
the	O
limits	O
of	O
proof	O
and	O
computation	O
,	O
replacing	O
Gödel	O
's	O
universal	O
arithmetic-based	O
formal	O
language	O
with	O
the	O
formal	O
and	O
simple	O
hypothetical	O
devices	O
that	O
became	O
known	O
as	O
Turing	B-Architecture
machines	I-Architecture
.	O
</s>
<s>
He	O
went	O
on	O
to	O
prove	O
that	O
there	O
was	O
no	O
solution	O
to	O
the	O
Entscheidungsproblem	O
by	O
first	O
showing	O
that	O
the	O
halting	O
problem	O
for	O
Turing	B-Architecture
machines	I-Architecture
is	O
undecidable	O
:	O
in	O
general	O
,	O
it	O
is	O
not	O
possible	O
to	O
decide	O
algorithmically	O
whether	O
a	O
given	O
Turing	B-Architecture
machine	I-Architecture
will	O
ever	O
halt	O
.	O
</s>
<s>
He	O
also	O
introduced	O
the	O
notion	O
of	O
a	O
"	O
universal	O
machine	O
"	O
(	O
now	O
known	O
as	O
a	O
universal	O
Turing	B-Architecture
machine	I-Architecture
)	O
,	O
with	O
the	O
idea	O
that	O
such	O
a	O
machine	O
could	O
perform	O
the	O
tasks	O
of	O
any	O
other	O
machine	O
,	O
or	O
in	O
other	O
words	O
,	O
it	O
is	O
provably	O
capable	O
of	O
computing	O
anything	O
that	O
is	O
computable	O
by	O
executing	O
a	O
program	B-Application
stored	O
on	O
tape	O
,	O
allowing	O
the	O
machine	O
to	O
be	O
programmable	B-General_Concept
.	O
</s>
<s>
Turing	B-Architecture
machines	I-Architecture
are	O
to	O
this	O
day	O
a	O
central	O
object	O
of	O
study	O
in	O
theory	O
of	O
computation	O
.	O
</s>
<s>
Except	O
for	O
the	O
limitations	O
imposed	O
by	O
their	O
finite	O
memory	B-General_Concept
stores	O
,	O
modern	O
computers	O
are	O
said	O
to	O
be	O
Turing-complete	B-Algorithm
,	O
which	O
is	O
to	O
say	O
,	O
they	O
have	O
algorithm	O
execution	O
capability	O
equivalent	O
to	O
a	O
universal	O
Turing	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
The	O
Z2	B-Device
was	O
one	O
of	O
the	O
earliest	O
examples	O
of	O
an	O
electromechanical	O
relay	O
computer	O
,	O
and	O
was	O
created	O
by	O
German	O
engineer	O
Konrad	O
Zuse	O
in	O
1940	O
.	O
</s>
<s>
It	O
was	O
an	O
improvement	O
on	O
his	O
earlier	O
Z1	B-Device
;	O
although	O
it	O
used	O
the	O
same	O
mechanical	O
memory	B-General_Concept
,	O
it	O
replaced	O
the	O
arithmetic	O
and	O
control	O
logic	O
with	O
electrical	O
relay	O
circuits	O
.	O
</s>
<s>
In	O
the	O
same	O
year	O
,	O
electro-mechanical	O
devices	O
called	O
bombes	B-Device
were	O
built	O
by	O
British	O
cryptologists	O
to	O
help	O
decipher	O
German	O
Enigma-machine-encrypted	O
secret	O
messages	O
during	O
World	O
War	O
II	O
.	O
</s>
<s>
The	O
bombe	B-Device
's	O
initial	O
design	O
was	O
created	O
in	O
1939	O
at	O
the	O
UK	O
Government	O
Code	O
and	O
Cypher	O
School	O
(	O
GC&CS	O
)	O
at	O
Bletchley	O
Park	O
by	O
Alan	O
Turing	O
,	O
with	O
an	O
important	O
refinement	O
devised	O
in	O
1940	O
by	O
Gordon	O
Welchman	O
.	O
</s>
<s>
It	O
was	O
a	O
substantial	O
development	O
from	O
a	O
device	O
that	O
had	O
been	O
designed	O
in	O
1938	O
by	O
Polish	O
Cipher	B-Algorithm
Bureau	O
cryptologist	O
Marian	O
Rejewski	O
,	O
and	O
known	O
as	O
the	O
"	O
cryptologic	B-Device
bomb	I-Device
"	O
(	O
Polish	O
:	O
"	O
bomba	B-Device
kryptologiczna	O
"	O
)	O
.	O
</s>
<s>
In	O
1941	O
,	O
Zuse	O
followed	O
his	O
earlier	O
machine	O
up	O
with	O
the	O
Z3	B-Device
,	O
the	O
world	O
's	O
first	O
working	O
electromechanical	O
programmable	B-General_Concept
,	O
fully	O
automatic	O
digital	O
computer	O
.	O
</s>
<s>
The	O
Z3	B-Device
was	O
built	O
with	O
2000	O
relays	O
,	O
implementing	O
a	O
22-bit	O
word	O
length	O
that	O
operated	O
at	O
a	O
clock	O
frequency	O
of	O
about	O
5	O
–	O
10Hz	O
.	O
</s>
<s>
Program	B-Application
code	O
and	O
data	O
were	O
stored	O
on	O
punched	O
film	B-Language
.	O
</s>
<s>
It	O
was	O
quite	O
similar	O
to	O
modern	O
machines	O
in	O
some	O
respects	O
,	O
pioneering	O
numerous	O
advances	O
such	O
as	O
floating-point	B-Algorithm
numbers	I-Algorithm
.	O
</s>
<s>
Replacement	O
of	O
the	O
hard-to-implement	O
decimal	B-Application
system	O
(	O
used	O
in	O
Charles	O
Babbage	O
's	O
earlier	O
design	O
)	O
by	O
the	O
simpler	O
binary	O
system	O
meant	O
that	O
Zuse	O
's	O
machines	O
were	O
easier	O
to	O
build	O
and	O
potentially	O
more	O
reliable	O
,	O
given	O
the	O
technologies	O
available	O
at	O
that	O
time	O
.	O
</s>
<s>
The	O
Z3	B-Device
was	O
proven	O
to	O
have	O
been	O
a	O
Turing-complete	B-Architecture
machine	I-Architecture
in	O
1998	O
by	O
Raúl	O
Rojas	O
.	O
</s>
<s>
In	O
two	O
1936	O
patent	O
applications	O
,	O
Zuse	O
also	O
anticipated	O
that	O
machine	O
instructions	O
could	O
be	O
stored	O
in	O
the	O
same	O
storage	O
used	O
for	O
data	O
—	O
the	O
key	O
insight	O
of	O
what	O
became	O
known	O
as	O
the	O
von	B-Architecture
Neumann	I-Architecture
architecture	I-Architecture
,	O
first	O
implemented	O
in	O
1948	O
in	O
America	O
in	O
the	O
electromechanical	O
IBM	B-Device
SSEC	I-Device
and	O
in	O
Britain	O
in	O
the	O
fully	O
electronic	O
Manchester	B-Device
Baby	I-Device
.	O
</s>
<s>
In	O
1944	O
,	O
the	O
Harvard	B-Device
Mark	I-Device
I	I-Device
was	O
constructed	O
at	O
IBM	O
's	O
Endicott	O
laboratories	O
.	O
</s>
<s>
It	O
was	O
a	O
similar	O
general	O
purpose	O
electro-mechanical	O
computer	O
to	O
the	O
Z3	B-Device
,	O
but	O
was	O
not	O
quite	O
Turing-complete	B-Algorithm
.	O
</s>
<s>
Typically	O
signals	O
have	O
two	O
states	O
–	O
low	O
(	O
usually	O
representing	O
0	O
)	O
and	O
high	O
(	O
usually	O
representing	O
1	O
)	O
,	O
but	O
sometimes	O
three-valued	B-Language
logic	I-Language
is	O
used	O
,	O
especially	O
in	O
high-density	O
memory	B-General_Concept
.	O
</s>
<s>
Modern	O
computers	O
generally	O
use	O
binary	O
logic	O
,	O
but	O
many	O
early	O
machines	O
were	O
decimal	B-Device
computers	I-Device
.	O
</s>
<s>
In	O
these	O
machines	O
,	O
the	O
basic	O
unit	O
of	O
data	O
was	O
the	O
decimal	B-Application
digit	O
,	O
encoded	O
in	O
one	O
of	O
several	O
schemes	O
,	O
including	O
binary-coded	O
decimal	B-Application
or	O
BCD	O
,	O
bi-quinary	B-Algorithm
,	O
excess-3	O
,	O
and	O
two-out-of-five	O
code	O
.	O
</s>
<s>
In	O
the	O
1930s	O
and	O
working	O
independently	O
,	O
American	O
electronic	O
engineer	O
Claude	O
Shannon	O
and	O
Soviet	O
logician	O
Victor	O
Shestakov	O
both	O
showed	O
a	O
one-to-one	B-Algorithm
correspondence	I-Algorithm
between	O
the	O
concepts	O
of	O
Boolean	O
logic	O
and	O
certain	O
electrical	O
circuits	O
,	O
now	O
called	O
logic	O
gates	O
,	O
which	O
are	O
now	O
ubiquitous	O
in	O
digital	O
computers	O
.	O
</s>
<s>
Machines	O
such	O
as	O
the	O
Z3	B-Device
,	O
the	B-Device
Atanasoff	I-Device
–	I-Device
Berry	I-Device
Computer	I-Device
,	O
the	O
Colossus	B-Device
computers	I-Device
,	O
and	O
the	O
ENIAC	B-Device
were	O
built	O
by	O
hand	O
,	O
using	O
circuits	O
containing	O
relays	O
or	O
valves	O
(	O
vacuum	O
tubes	O
)	O
,	O
and	O
often	O
used	O
punched	B-Architecture
cards	I-Architecture
or	O
punched	O
paper	O
tape	O
for	O
input	O
and	O
as	O
the	O
main	O
(	O
non-volatile	B-General_Concept
)	O
storage	O
medium	O
.	O
</s>
<s>
John	O
Vincent	O
Atanasoff	O
and	O
Clifford	O
E	O
.	O
Berry	O
of	O
Iowa	O
State	O
University	O
developed	O
the	B-Device
Atanasoff	I-Device
–	I-Device
Berry	I-Device
Computer	I-Device
(	O
ABC	O
)	O
in	O
1942	O
,	O
the	O
first	O
binary	O
electronic	O
digital	O
calculating	O
device	O
.	O
</s>
<s>
This	O
design	O
was	O
semi-electronic	O
(	O
electro-mechanical	O
control	O
and	O
electronic	O
calculations	O
)	O
,	O
and	O
used	O
about	O
300	O
vacuum	O
tubes	O
,	O
with	O
capacitors	O
fixed	O
in	O
a	O
mechanically	O
rotating	O
drum	O
for	O
memory	B-General_Concept
.	O
</s>
<s>
The	O
machine	O
's	O
special-purpose	O
nature	O
and	O
lack	O
of	O
changeable	O
,	O
stored	O
program	B-Application
distinguish	O
it	O
from	O
modern	O
computers	O
.	O
</s>
<s>
Computers	O
whose	O
logic	O
was	O
primarily	O
built	O
using	O
vacuum	O
tubes	O
are	O
now	O
known	O
as	O
first	B-Device
generation	I-Device
computers	I-Device
.	O
</s>
<s>
The	O
German	O
encryption	O
machine	O
,	O
Enigma	O
,	O
was	O
first	O
attacked	O
with	O
the	O
help	O
of	O
the	O
electro-mechanical	O
bombes	B-Device
.	O
</s>
<s>
Women	O
often	O
operated	O
these	O
bombe	B-Device
machines	O
.	O
</s>
<s>
Tommy	O
Flowers	O
,	O
a	O
senior	O
engineer	O
at	O
the	O
Post	O
Office	O
Research	O
Station	O
was	O
recommended	O
to	O
Max	O
Newman	O
by	O
Alan	O
Turing	O
and	O
spent	O
eleven	O
months	O
from	O
early	O
February	O
1943	O
designing	O
and	O
building	O
the	O
more	O
flexible	O
Colossus	B-Device
computer	I-Device
(	O
which	O
superseded	O
the	O
Heath	O
Robinson	O
)	O
.	O
</s>
<s>
After	O
a	O
functional	O
test	O
in	O
December	O
1943	O
,	O
Colossus	B-Device
was	O
shipped	O
to	O
Bletchley	O
Park	O
,	O
where	O
it	O
was	O
delivered	O
on	O
18	O
January	O
1944	O
and	O
attacked	O
its	O
first	O
message	O
on	O
5	O
February	O
.	O
</s>
<s>
Colossus	B-Device
was	O
the	O
world	O
's	O
first	O
electronic	O
digital	O
programmable	B-General_Concept
computer	O
.	O
</s>
<s>
It	O
had	O
paper-tape	O
input	O
and	O
was	O
capable	O
of	O
being	O
configured	O
to	O
perform	O
a	O
variety	O
of	O
boolean	O
logical	O
operations	O
on	O
its	O
data	O
,	O
but	O
it	O
was	O
not	O
Turing-complete	B-Algorithm
.	O
</s>
<s>
Data	O
input	O
to	O
Colossus	B-Device
was	O
by	O
photoelectric	B-Algorithm
reading	O
of	O
a	O
paper	O
tape	O
transcription	O
of	O
the	O
enciphered	B-Algorithm
intercepted	O
message	O
.	O
</s>
<s>
Colossus	B-Device
Mark	O
1	O
contained	O
1500	O
thermionic	O
valves	O
(	O
tubes	O
)	O
,	O
but	O
Mark	O
2	O
with	O
2400	O
valves	O
and	O
five	O
processors	O
in	O
parallel	O
,	O
was	O
both	O
5	O
times	O
faster	O
and	O
simpler	O
to	O
operate	O
than	O
Mark	O
1	O
,	O
greatly	O
speeding	O
the	O
decoding	O
process	O
.	O
</s>
<s>
Allen	O
Coombs	O
took	O
over	O
leadership	O
of	O
the	O
Colossus	B-Device
Mark	O
2	O
project	O
when	O
Tommy	O
Flowers	O
moved	O
on	O
to	O
other	O
projects	O
.	O
</s>
<s>
The	O
first	O
Mark	O
2	O
Colossus	B-Device
became	O
operational	O
on	O
1	O
June	O
1944	O
,	O
just	O
in	O
time	O
for	O
the	O
Allied	O
Invasion	O
of	O
Normandy	O
on	O
D-Day	O
.	O
</s>
<s>
Most	O
of	O
the	O
use	O
of	O
Colossus	B-Device
was	O
in	O
determining	O
the	O
start	O
positions	O
of	O
the	O
Tunny	O
rotors	O
for	O
a	O
message	O
,	O
which	O
was	O
called	O
"	O
wheel	O
setting	O
"	O
.	O
</s>
<s>
Colossus	B-Device
included	O
the	O
first-ever	O
use	O
of	O
shift	B-General_Concept
registers	I-General_Concept
and	O
systolic	B-Architecture
arrays	I-Architecture
,	O
enabling	O
five	O
simultaneous	O
tests	O
,	O
each	O
involving	O
up	O
to	O
100	O
Boolean	O
calculations	O
.	O
</s>
<s>
Both	O
models	O
were	O
programmable	B-General_Concept
using	O
switches	O
and	O
plug	O
panels	O
in	O
a	O
way	O
their	O
predecessors	O
had	O
not	O
been	O
.	O
</s>
<s>
Without	O
the	O
use	O
of	O
these	O
machines	O
,	O
the	O
Allies	O
would	O
have	O
been	O
deprived	O
of	O
the	O
very	O
valuable	O
intelligence	O
that	O
was	O
obtained	O
from	O
reading	O
the	O
vast	O
quantity	O
of	O
enciphered	B-Algorithm
high-level	O
telegraphic	O
messages	O
between	O
the	O
German	O
High	O
Command	O
(	O
OKW	O
)	O
and	O
their	O
army	O
commands	O
throughout	O
occupied	O
Europe	O
.	O
</s>
<s>
Winston	O
Churchill	O
personally	O
issued	O
an	O
order	O
for	O
their	O
destruction	O
into	O
pieces	O
no	O
larger	O
than	O
a	O
man	O
's	O
hand	O
,	O
to	O
keep	O
secret	O
that	O
the	O
British	O
were	O
capable	O
of	O
cracking	O
Lorenz	O
SZ	O
cyphers	O
(	O
from	O
German	O
rotor	O
stream	O
cipher	B-Algorithm
machines	I-Algorithm
)	O
during	O
the	O
oncoming	O
Cold	O
War	O
.	O
</s>
<s>
A	O
reconstructed	O
working	O
copy	O
of	O
one	O
of	O
the	O
Colossus	B-Device
machines	O
is	O
now	O
on	O
display	O
at	O
Bletchley	O
Park	O
.	O
</s>
<s>
The	O
US-built	O
ENIAC	B-Device
(	O
Electronic	B-Device
Numerical	I-Device
Integrator	I-Device
and	I-Device
Computer	I-Device
)	O
was	O
the	O
first	O
electronic	O
programmable	B-General_Concept
computer	O
built	O
in	O
the	O
US	O
.	O
</s>
<s>
Although	O
the	O
ENIAC	B-Device
was	O
similar	O
to	O
the	O
Colossus	B-Device
it	O
was	O
much	O
faster	O
and	O
more	O
flexible	O
.	O
</s>
<s>
It	O
was	O
unambiguously	O
a	O
Turing-complete	B-Algorithm
device	O
and	O
could	O
compute	O
any	O
problem	O
that	O
would	O
fit	O
into	O
its	O
memory	B-General_Concept
.	O
</s>
<s>
Like	O
the	O
Colossus	B-Device
,	O
a	O
"	B-Application
program	I-Application
"	I-Application
on	O
the	O
ENIAC	B-Device
was	O
defined	O
by	O
the	O
states	O
of	O
its	O
patch	O
cables	O
and	O
switches	O
,	O
a	O
far	O
cry	O
from	O
the	O
stored	O
program	B-Application
electronic	O
machines	O
that	O
came	O
later	O
.	O
</s>
<s>
Once	O
a	O
program	B-Application
was	O
written	O
,	O
it	O
had	O
to	O
be	O
mechanically	O
set	O
into	O
the	O
machine	O
with	O
manual	O
resetting	O
of	O
plugs	O
and	O
switches	O
.	O
</s>
<s>
The	O
programmers	O
of	O
the	O
ENIAC	B-Device
were	O
women	O
who	O
had	O
been	O
trained	O
as	O
mathematicians	O
.	O
</s>
<s>
High-speed	O
memory	B-General_Concept
was	O
limited	O
to	O
20	O
words	O
(	O
equivalent	O
to	O
about	O
80	O
bytes	O
)	O
.	O
</s>
<s>
Built	O
under	O
the	O
direction	O
of	O
John	O
Mauchly	O
and	O
J	O
.	O
Presper	O
Eckert	O
at	O
the	O
University	O
of	O
Pennsylvania	O
,	O
ENIAC	B-Device
's	O
development	O
and	O
construction	O
lasted	O
from	O
1943	O
to	O
full	O
operation	O
at	O
the	O
end	O
of	O
1945	O
.	O
</s>
<s>
Early	O
computing	O
machines	O
executed	O
the	O
set	O
sequence	O
of	O
steps	O
,	O
known	O
as	O
a	O
"	B-Application
program	I-Application
"	I-Application
,	O
that	O
could	O
be	O
altered	O
by	O
changing	O
electrical	O
connections	O
using	O
switches	O
or	O
a	O
patch	B-Protocol
panel	I-Protocol
(	O
or	O
plugboard	O
)	O
.	O
</s>
<s>
Stored-program	B-Architecture
computers	O
,	O
by	O
contrast	O
,	O
were	O
designed	O
to	O
store	O
a	O
set	O
of	O
instructions	O
(	O
a	O
program	B-Application
)	O
,	O
in	O
memory	B-General_Concept
–	O
typically	O
the	O
same	O
memory	B-General_Concept
as	O
stored	O
data	O
.	O
</s>
<s>
The	O
theoretical	O
basis	O
for	O
the	O
stored-program	B-Architecture
computer	O
had	O
been	O
proposed	O
by	O
Alan	O
Turing	O
in	O
his	O
1936	O
paper	O
.	O
</s>
<s>
In	O
1945	O
Turing	O
joined	O
the	O
National	O
Physical	O
Laboratory	O
and	O
began	O
his	O
work	O
on	O
developing	O
an	O
electronic	O
stored-program	B-Architecture
digital	O
computer	O
.	O
</s>
<s>
Meanwhile	O
,	O
John	O
von	O
Neumann	O
at	O
the	O
Moore	O
School	O
of	O
Electrical	O
Engineering	O
,	O
University	O
of	O
Pennsylvania	O
,	O
circulated	O
his	O
First	O
Draft	O
of	O
a	O
Report	O
on	O
the	O
EDVAC	B-Device
in	O
1945	O
.	O
</s>
<s>
Although	O
substantially	O
similar	O
to	O
Turing	O
's	O
design	O
and	O
containing	O
comparatively	O
little	O
engineering	O
detail	O
,	O
the	O
computer	O
architecture	O
it	O
outlined	O
became	O
known	O
as	O
the	O
"	O
von	B-Architecture
Neumann	I-Architecture
architecture	I-Architecture
"	O
.	O
</s>
<s>
Turing	O
presented	O
a	O
more	O
detailed	O
paper	O
to	O
the	O
National	O
Physical	O
Laboratory	O
(	O
NPL	O
)	O
Executive	O
Committee	O
in	O
1946	O
,	O
giving	O
the	O
first	O
reasonably	O
complete	O
design	O
of	O
a	O
stored-program	B-Architecture
computer	O
,	O
a	O
device	O
he	O
called	O
the	O
Automatic	B-Device
Computing	I-Device
Engine	I-Device
(	O
ACE	B-Device
)	O
.	O
</s>
<s>
However	O
,	O
the	O
better-known	O
EDVAC	B-Device
design	O
of	O
John	O
von	O
Neumann	O
,	O
who	O
knew	O
of	O
Turing	O
's	O
theoretical	O
work	O
,	O
received	O
more	O
publicity	O
,	O
despite	O
its	O
incomplete	O
nature	O
and	O
questionable	O
lack	O
of	O
attribution	O
of	O
the	O
sources	O
of	O
some	O
of	O
the	O
ideas	O
.	O
</s>
<s>
Turing	O
thought	O
that	O
the	O
speed	O
and	O
the	O
size	O
of	O
computer	B-General_Concept
memory	I-General_Concept
were	O
crucial	O
elements	O
,	O
so	O
he	O
proposed	O
a	O
high-speed	O
memory	B-General_Concept
of	O
what	O
would	O
today	O
be	O
called	O
25	O
KB	O
,	O
accessed	O
at	O
a	O
speed	O
of	O
1	O
MHz	O
.	O
</s>
<s>
The	O
ACE	B-Device
implemented	O
subroutine	O
calls	O
,	O
whereas	O
the	O
EDVAC	B-Device
did	O
not	O
,	O
and	O
the	O
ACE	B-Device
also	O
used	O
Abbreviated	O
Computer	O
Instructions	O
,	O
an	O
early	O
form	O
of	O
programming	B-Application
language	O
.	O
</s>
<s>
The	O
Manchester	B-Device
Baby	I-Device
(	O
Small	B-Device
Scale	I-Device
Experimental	I-Device
Machine	I-Device
,	O
SSEM	O
)	O
was	O
the	O
world	O
's	O
first	O
electronic	O
stored-program	B-Architecture
computer	O
.	O
</s>
<s>
It	O
was	O
built	O
at	O
the	O
Victoria	O
University	O
of	O
Manchester	O
by	O
Frederic	O
C	O
.	O
Williams	O
,	O
Tom	O
Kilburn	O
and	O
Geoff	O
Tootill	O
,	O
and	O
ran	O
its	O
first	O
program	B-Application
on	O
21June	O
1948	O
.	O
</s>
<s>
The	O
machine	O
was	O
not	O
intended	O
to	O
be	O
a	O
practical	O
computer	O
but	O
was	O
instead	O
designed	O
as	O
a	O
testbed	O
for	O
the	O
Williams	B-General_Concept
tube	I-General_Concept
,	O
the	O
first	O
random-access	B-Architecture
digital	O
storage	O
device	O
.	O
</s>
<s>
Invented	O
by	O
Freddie	O
Williams	O
and	O
Tom	O
Kilburn	O
at	O
the	O
University	O
of	O
Manchester	O
in	O
1946	O
and	O
1947	O
,	O
it	O
was	O
a	O
cathode-ray	B-Device
tube	I-Device
that	O
used	O
an	O
effect	O
called	O
secondary	O
emission	O
to	O
temporarily	O
store	O
electronic	O
binary	O
data	O
,	O
and	O
was	O
used	O
successfully	O
in	O
several	O
early	O
computers	O
.	O
</s>
<s>
As	O
soon	O
as	O
it	O
had	O
demonstrated	O
the	O
feasibility	O
of	O
its	O
design	O
,	O
a	O
project	O
was	O
initiated	O
at	O
the	O
university	O
to	O
develop	O
the	O
design	O
into	O
a	O
more	O
usable	O
computer	O
,	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
.	O
</s>
<s>
The	O
Mark	O
1	O
in	O
turn	O
quickly	O
became	O
the	O
prototype	O
for	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
,	O
the	O
world	O
's	O
first	O
commercially	O
available	O
general-purpose	O
computer	O
.	O
</s>
<s>
The	O
Baby	O
had	O
a	O
32-bit	O
word	O
length	O
and	O
a	O
memory	B-General_Concept
of	O
32words	O
.	O
</s>
<s>
As	O
it	O
was	O
designed	O
to	O
be	O
the	O
simplest	O
possible	O
stored-program	B-Architecture
computer	O
,	O
the	O
only	O
arithmetic	O
operations	O
implemented	O
in	O
hardware	B-Architecture
were	O
subtraction	O
and	O
negation	O
;	O
other	O
arithmetic	O
operations	O
were	O
implemented	O
in	O
software	O
.	O
</s>
<s>
The	O
program	B-Application
consisted	O
of	O
17instructions	O
and	O
ran	O
for	O
52minutes	O
before	O
reaching	O
the	O
correct	O
answer	O
of	O
131	O
,	O
072	O
,	O
after	O
the	O
Baby	O
had	O
performed	O
3.5million	O
operations	O
(	O
for	O
an	O
effective	O
CPU	O
speed	O
of	O
1.1	O
kIPS	O
)	O
.	O
</s>
<s>
The	O
successive	O
approximations	O
to	O
the	O
answer	O
were	O
displayed	O
as	O
a	O
pattern	O
of	O
dots	O
on	O
the	O
output	O
CRT	B-Device
which	O
mirrored	O
the	O
pattern	O
held	O
on	O
the	O
Williams	B-General_Concept
tube	I-General_Concept
used	O
for	O
storage	O
.	O
</s>
<s>
The	O
SSEM	O
led	O
to	O
the	O
development	O
of	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
at	O
the	O
University	O
of	O
Manchester	O
.	O
</s>
<s>
Work	O
began	O
in	O
August	O
1948	O
,	O
and	O
the	O
first	O
version	O
was	O
operational	O
by	O
April	O
1949	O
;	O
a	O
program	B-Application
written	O
to	O
search	O
for	O
Mersenne	O
primes	O
ran	O
error-free	O
for	O
nine	O
hours	O
on	O
the	O
night	O
of	O
16/17	O
June	O
1949	O
.	O
</s>
<s>
The	O
computer	O
is	O
especially	O
historically	O
significant	O
because	O
of	O
its	O
pioneering	O
inclusion	O
of	O
index	B-General_Concept
registers	I-General_Concept
,	O
an	O
innovation	O
which	O
made	O
it	O
easier	O
for	O
a	O
program	B-Application
to	O
read	O
sequentially	O
through	O
an	O
array	O
of	O
words	O
in	O
memory	B-General_Concept
.	O
</s>
<s>
Thirty-four	O
patents	O
resulted	O
from	O
the	O
machine	O
's	O
development	O
,	O
and	O
many	O
of	O
the	O
ideas	O
behind	O
its	O
design	O
were	O
incorporated	O
in	O
subsequent	O
commercial	O
products	O
such	O
as	O
the	O
and	O
702	B-Device
as	O
well	O
as	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
.	O
</s>
<s>
In	O
1951	O
they	O
started	O
development	O
work	O
on	O
Meg	O
,	O
the	O
Mark1	O
's	O
successor	O
,	O
which	O
would	O
include	O
a	O
floating-point	B-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
The	O
other	O
contender	O
for	O
being	O
the	O
first	O
recognizably	O
modern	O
digital	O
stored-program	B-Architecture
computer	O
was	O
the	O
EDSAC	B-Device
,	O
designed	O
and	O
constructed	O
by	O
Maurice	O
Wilkes	O
and	O
his	O
team	O
at	O
the	O
University	O
of	O
Cambridge	O
Mathematical	O
Laboratory	O
in	O
England	O
at	O
the	O
University	O
of	O
Cambridge	O
in	O
1949	O
.	O
</s>
<s>
The	O
machine	O
was	O
inspired	O
by	O
John	O
von	O
Neumann	O
's	O
seminal	O
First	O
Draft	O
of	O
a	O
Report	O
on	O
the	O
EDVAC	B-Device
and	O
was	O
one	O
of	O
the	O
first	O
usefully	O
operational	O
electronic	O
digital	O
stored-program	B-Architecture
computer	O
.	O
</s>
<s>
EDSAC	B-Device
ran	O
its	O
first	O
programs	O
on	O
6May	O
1949	O
,	O
when	O
it	O
calculated	O
a	O
table	O
of	O
squares	O
and	O
a	O
list	O
of	O
prime	O
numbers.The	O
EDSAC	B-Device
also	O
served	O
as	O
the	O
basis	O
for	O
the	O
first	O
commercially	O
applied	O
computer	O
,	O
the	O
LEO	B-Device
I	I-Device
,	O
used	O
by	O
food	O
manufacturing	O
company	O
J	O
.	O
Lyons	O
&	O
Co	O
.	O
Ltd	O
.	O
EDSAC	B-Device
1	I-Device
was	O
finally	O
shut	O
down	O
on	O
11	O
July	O
1958	O
,	O
having	O
been	O
superseded	O
by	O
EDSAC	B-Device
2	I-Device
which	O
stayed	O
in	O
use	O
until	O
1965	O
.	O
</s>
<s>
ENIAC	B-Device
inventors	O
John	O
Mauchly	O
and	O
J	O
.	O
Presper	O
Eckert	O
proposed	O
the	O
EDVAC	B-Device
's	O
construction	O
in	O
August	O
1944	O
,	O
and	O
design	O
work	O
for	O
the	O
EDVAC	B-Device
commenced	O
at	O
the	O
University	O
of	O
Pennsylvania	O
's	O
Moore	O
School	O
of	O
Electrical	O
Engineering	O
,	O
before	O
the	O
ENIAC	B-Device
was	O
fully	O
operational	O
.	O
</s>
<s>
The	O
design	O
implemented	O
a	O
number	O
of	O
important	O
architectural	O
and	O
logical	O
improvements	O
conceived	O
during	O
the	O
ENIAC	B-Device
's	O
construction	O
,	O
and	O
a	O
high-speed	O
serial-access	B-General_Concept
memory	B-General_Concept
.	O
</s>
<s>
The	O
first	O
commercial	O
computer	O
was	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
,	O
built	O
by	O
Ferranti	O
and	O
delivered	O
to	O
the	O
University	O
of	O
Manchester	O
in	O
February	O
1951	O
.	O
</s>
<s>
It	O
was	O
based	O
on	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
.	O
</s>
<s>
The	O
main	O
improvements	O
over	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
were	O
in	O
the	O
size	O
of	O
the	O
primary	O
storage	O
(	O
using	O
random	B-Architecture
access	I-Architecture
Williams	B-General_Concept
tubes	I-General_Concept
)	O
,	O
secondary	O
storage	O
(	O
using	O
a	O
magnetic	B-General_Concept
drum	I-General_Concept
)	O
,	O
a	O
faster	O
multiplier	O
,	O
and	O
additional	O
instructions	O
.	O
</s>
<s>
The	O
LEO	B-Device
I	I-Device
computer	O
(	O
Lyons	B-Device
Electronic	I-Device
Office	I-Device
)	O
became	O
operational	O
in	O
April	O
1951	O
and	O
ran	O
the	O
world	O
's	O
first	O
regular	O
routine	O
office	O
computer	O
job	B-General_Concept
.	O
</s>
<s>
On	O
17	O
November	O
1951	O
,	O
the	O
J	O
.	O
Lyons	O
company	O
began	O
weekly	O
operation	O
of	O
a	O
bakery	O
valuations	O
job	B-General_Concept
on	O
the	O
LEO	B-Device
–	O
the	O
first	O
business	O
application	O
to	O
go	O
live	O
on	O
a	O
stored	O
program	B-Application
computer	O
.	O
</s>
<s>
In	O
June	O
1951	O
,	O
the	B-Operating_System
UNIVAC	I-Operating_System
I	O
(	O
Universal	B-Operating_System
Automatic	I-Operating_System
Computer	I-Operating_System
)	O
was	O
delivered	O
to	O
the	O
U.S.	O
Census	O
Bureau	O
.	O
</s>
<s>
Remington	O
Rand	B-Application
eventually	O
sold	O
46	O
machines	O
at	O
more	O
than	O
each	O
( $	O
as	O
of	O
)	O
.	O
</s>
<s>
Its	O
primary	O
storage	O
was	O
serial-access	B-General_Concept
mercury	O
delay	O
lines	O
capable	O
of	O
storing	O
1,000	O
words	O
of	O
11	O
decimal	B-Application
digits	O
plus	O
sign	O
(	O
72-bit	O
words	O
)	O
.	O
</s>
<s>
The	O
IBM	B-Device
650	I-Device
weighed	O
over	O
,	O
the	O
attached	O
power	O
supply	O
weighed	O
around	O
and	O
both	O
were	O
held	O
in	O
separate	O
cabinets	O
of	O
roughly	O
1.50.9	O
.	O
</s>
<s>
Its	O
drum	B-General_Concept
memory	I-General_Concept
was	O
originally	O
2,000	O
ten-digit	O
words	O
,	O
later	O
expanded	O
to	O
4,000	O
words	O
.	O
</s>
<s>
Memory	B-General_Concept
limitations	O
such	O
as	O
this	O
were	O
to	O
dominate	O
programming	B-Application
for	O
decades	O
afterward	O
.	O
</s>
<s>
The	O
program	B-Application
instructions	O
were	O
fetched	O
from	O
the	O
spinning	O
drum	O
as	O
the	O
code	O
ran	O
.	O
</s>
<s>
Efficient	O
execution	O
using	O
drum	B-General_Concept
memory	I-General_Concept
was	O
provided	O
by	O
a	O
combination	O
of	O
hardware	B-Architecture
architecture	O
–	O
the	O
instruction	O
format	O
included	O
the	O
address	O
of	O
the	O
next	O
instruction	O
–	O
and	O
software	O
:	O
the	O
Symbolic	B-Application
Optimal	I-Application
Assembly	I-Application
Program	I-Application
,	O
SOAP	O
,	O
assigned	O
instructions	O
to	O
the	O
optimal	O
addresses	O
(	O
to	O
the	O
extent	O
possible	O
by	O
static	O
analysis	O
of	O
the	O
source	O
program	B-Application
)	O
.	O
</s>
<s>
In	O
1951	O
,	O
British	O
scientist	O
Maurice	O
Wilkes	O
developed	O
the	O
concept	O
of	O
microprogramming	B-Device
from	O
the	O
realisation	O
that	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
of	O
a	O
computer	O
could	O
be	O
controlled	O
by	O
a	O
miniature	O
,	O
highly	O
specialized	O
computer	B-Application
program	I-Application
in	O
high-speed	O
ROM	B-Device
.	O
</s>
<s>
Microprogramming	B-Device
allows	O
the	O
base	O
instruction	O
set	O
to	O
be	O
defined	O
or	O
extended	O
by	O
built-in	O
programs	O
(	O
now	O
called	O
firmware	B-Application
or	O
microcode	B-Device
)	O
.	O
</s>
<s>
It	O
was	O
widely	O
used	O
in	O
the	O
CPUs	O
and	O
floating-point	B-General_Concept
units	I-General_Concept
of	O
mainframe	B-Architecture
and	O
other	O
computers	O
;	O
it	O
was	O
implemented	O
for	O
the	O
first	O
time	O
in	O
EDSAC	B-Device
2	I-Device
,	O
which	O
also	O
used	O
multiple	O
identical	O
"	O
bit	O
slices	O
"	O
to	O
simplify	O
design	O
.	O
</s>
<s>
Magnetic	B-General_Concept
drum	I-General_Concept
memories	I-General_Concept
were	O
developed	O
for	O
the	O
US	O
Navy	O
during	O
WW	O
II	O
with	O
the	O
work	O
continuing	O
at	O
Engineering	O
Research	O
Associates	O
(	O
ERA	O
)	O
in	O
1946	O
and	O
1947	O
.	O
</s>
<s>
ERA	O
,	O
then	O
a	O
part	O
of	O
Univac	O
included	O
a	O
drum	B-General_Concept
memory	I-General_Concept
in	O
its	O
1103	B-Device
,	O
announced	O
in	O
February	O
1953	O
.	O
</s>
<s>
The	O
first	O
mass-produced	O
computer	O
,	O
the	O
IBM	B-Device
650	I-Device
,	O
also	O
announced	O
in	O
1953	O
had	O
about	O
8.5	O
kilobytes	O
of	O
drum	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
Magnetic	O
core	O
memory	B-General_Concept
patented	O
in	O
1949	O
with	O
its	O
first	O
usage	O
demonstrated	O
for	O
the	O
Whirlwind	O
computer	O
in	O
August	O
1953	O
.	O
</s>
<s>
Magnetic	O
core	O
was	O
used	O
in	O
peripherals	O
of	O
the	O
IBM	B-Device
702	I-Device
delivered	O
in	O
July	O
1955	O
,	O
and	O
later	O
in	O
the	O
702	B-Device
itself	O
.	O
</s>
<s>
The	O
IBM	B-Device
704	I-Device
(	O
1955	O
)	O
and	O
the	O
Ferranti	O
Mercury	O
(	O
1957	O
)	O
used	O
magnetic-core	O
memory	B-General_Concept
.	O
</s>
<s>
It	O
went	O
on	O
to	O
dominate	O
the	O
field	O
into	O
the	O
1970s	O
,	O
when	O
it	O
was	O
replaced	O
with	O
semiconductor	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
As	O
late	O
as	O
1980	O
,	O
PDP-11/45	O
machines	O
using	O
magnetic-core	O
main	O
memory	B-General_Concept
and	O
drums	O
for	O
swapping	O
were	O
still	O
in	O
use	O
at	O
many	O
of	O
the	O
original	O
UNIX	O
sites	O
.	O
</s>
<s>
The	O
bipolar	O
transistor	B-Application
was	O
invented	O
in	O
1947	O
.	O
</s>
<s>
From	O
1955	O
onward	O
transistors	B-Application
replaced	O
vacuum	O
tubes	O
in	O
computer	O
designs	O
,	O
giving	O
rise	O
to	O
the	O
"	O
second	O
generation	O
"	O
of	O
computers	O
.	O
</s>
<s>
Compared	O
to	O
vacuum	O
tubes	O
,	O
transistors	B-Application
have	O
many	O
advantages	O
:	O
they	O
are	O
smaller	O
,	O
and	O
require	O
less	O
power	O
than	O
vacuum	O
tubes	O
,	O
so	O
give	O
off	O
less	O
heat	O
.	O
</s>
<s>
Silicon	O
junction	O
transistors	B-Application
were	O
much	O
more	O
reliable	O
than	O
vacuum	O
tubes	O
and	O
had	O
longer	O
service	O
life	O
.	O
</s>
<s>
Transistorized	B-Device
computers	I-Device
could	O
contain	O
tens	O
of	O
thousands	O
of	O
binary	O
logic	O
circuits	O
in	O
a	O
relatively	O
compact	O
space	O
.	O
</s>
<s>
Transistors	B-Application
greatly	O
reduced	O
computers	O
 '	O
size	O
,	O
initial	O
cost	O
,	O
and	O
operating	O
cost	O
.	O
</s>
<s>
Typically	O
,	O
second-generation	O
computers	O
were	O
composed	O
of	O
large	O
numbers	O
of	O
printed	O
circuit	O
boards	O
such	O
as	O
the	O
IBM	B-Device
Standard	I-Device
Modular	I-Device
System	I-Device
,	O
each	O
carrying	O
one	O
to	O
four	O
logic	O
gates	O
or	O
flip-flops	B-General_Concept
.	O
</s>
<s>
At	O
the	O
University	O
of	O
Manchester	O
,	O
a	O
team	O
under	O
the	O
leadership	O
of	O
Tom	O
Kilburn	O
designed	O
and	O
built	O
a	O
machine	O
using	O
the	O
newly	O
developed	O
transistors	B-Application
instead	O
of	O
valves	O
.	O
</s>
<s>
Initially	O
the	O
only	O
devices	O
available	O
were	O
germanium	O
point-contact	O
transistors	B-Application
,	O
less	O
reliable	O
than	O
the	O
valves	O
they	O
replaced	O
but	O
which	O
consumed	O
far	O
less	O
power	O
.	O
</s>
<s>
Their	O
first	O
transistorized	B-Device
computer	I-Device
,	O
and	O
the	O
first	O
in	O
the	O
world	O
,	O
was	O
operational	O
by	O
1953	O
,	O
and	O
a	O
second	O
version	O
was	O
completed	O
there	O
in	O
April	O
1955	O
.	O
</s>
<s>
The	O
1955	O
version	O
used	O
200	O
transistors	B-Application
,	O
1,300	O
solid-state	O
diodes	O
,	O
and	O
had	O
a	O
power	O
consumption	O
of	O
150	O
watts	O
.	O
</s>
<s>
However	O
,	O
the	O
machine	O
did	O
make	O
use	O
of	O
valves	O
to	O
generate	O
its	O
125kHz	O
clock	O
waveforms	O
and	O
in	O
the	O
circuitry	O
to	O
read	O
and	O
write	O
on	O
its	O
magnetic	B-General_Concept
drum	I-General_Concept
memory	I-General_Concept
,	O
so	O
it	O
was	O
not	O
the	O
first	O
completely	O
transistorized	B-Device
computer	I-Device
.	O
</s>
<s>
That	O
distinction	O
goes	O
to	O
the	O
Harwell	B-Device
CADET	I-Device
of	O
1955	O
,	O
built	O
by	O
the	O
electronics	O
division	O
of	O
the	O
Atomic	O
Energy	O
Research	O
Establishment	O
at	O
Harwell	O
.	O
</s>
<s>
The	O
design	O
featured	O
a	O
64-kilobyte	O
magnetic	B-General_Concept
drum	I-General_Concept
memory	I-General_Concept
store	O
with	O
multiple	O
moving	O
heads	O
that	O
had	O
been	O
designed	O
at	O
the	O
National	O
Physical	O
Laboratory	O
,	O
UK	O
.	O
</s>
<s>
By	O
1953	O
this	O
team	O
had	O
transistor	B-Application
circuits	O
operating	O
to	O
read	O
and	O
write	O
on	O
a	O
smaller	O
magnetic	B-General_Concept
drum	I-General_Concept
from	O
the	O
Royal	O
Radar	O
Establishment	O
.	O
</s>
<s>
CADET	B-Device
used	O
324-point-contact	O
transistors	B-Application
provided	O
by	O
the	O
UK	O
company	O
Standard	O
Telephones	O
and	O
Cables	O
;	O
76	O
junction	O
transistors	B-Application
were	O
used	O
for	O
the	O
first	O
stage	O
amplifiers	O
for	O
data	O
read	O
from	O
the	O
drum	O
,	O
since	O
point-contact	O
transistors	B-Application
were	O
too	O
noisy	O
.	O
</s>
<s>
From	O
August	O
1956	O
CADET	B-Device
was	O
offering	O
a	O
regular	O
computing	O
service	O
,	O
during	O
which	O
it	O
often	O
executed	O
continuous	O
computing	O
runs	O
of	O
80	O
hours	O
or	O
more	O
.	O
</s>
<s>
Problems	O
with	O
the	O
reliability	O
of	O
early	O
batches	O
of	O
point	O
contact	O
and	O
alloyed	O
junction	O
transistors	B-Application
meant	O
that	O
the	O
machine	O
's	O
mean	O
time	O
between	O
failures	O
was	O
about	O
90minutes	O
,	O
but	O
this	O
improved	O
once	O
the	O
more	O
reliable	O
bipolar	O
junction	O
transistors	B-Application
became	O
available	O
.	O
</s>
<s>
The	O
Manchester	O
University	O
Transistor	B-Device
Computer	I-Device
's	O
design	O
was	O
adopted	O
by	O
the	O
local	O
engineering	O
firm	O
of	O
Metropolitan-Vickers	O
in	O
their	O
Metrovick	B-Device
950	I-Device
,	O
the	O
first	O
commercial	O
transistor	B-Device
computer	I-Device
anywhere	O
.	O
</s>
<s>
Six	O
Metrovick	B-Device
950s	I-Device
were	O
built	O
,	O
the	O
first	O
completed	O
in	O
1956	O
.	O
</s>
<s>
A	O
second	B-Device
generation	I-Device
computer	I-Device
,	O
the	O
IBM	B-Device
1401	I-Device
,	O
captured	O
about	O
one	O
third	O
of	O
the	O
world	O
market	O
.	O
</s>
<s>
Transistorized	O
electronics	O
improved	O
not	O
only	O
the	O
CPU	O
(	O
Central	B-General_Concept
Processing	I-General_Concept
Unit	I-General_Concept
)	O
,	O
but	O
also	O
the	O
peripheral	O
devices	O
.	O
</s>
<s>
The	O
second	O
generation	O
disk	B-Device
data	I-Device
storage	I-Device
units	I-Device
were	O
able	O
to	O
store	O
tens	O
of	O
millions	O
of	O
letters	O
and	O
digits	O
.	O
</s>
<s>
Next	O
to	O
the	O
fixed	B-Device
disk	I-Device
storage	O
units	O
,	O
connected	O
to	O
the	O
CPU	O
via	O
high-speed	O
data	O
transmission	O
,	O
were	O
removable	O
disk	B-Device
data	I-Device
storage	I-Device
units	I-Device
.	O
</s>
<s>
A	O
removable	O
disk	B-Operating_System
pack	I-Operating_System
can	O
be	O
easily	O
exchanged	O
with	O
another	O
pack	O
in	O
a	O
few	O
seconds	O
.	O
</s>
<s>
Even	O
if	O
the	O
removable	O
disks	B-Device
 '	O
capacity	O
is	O
smaller	O
than	O
fixed	B-Device
disks	I-Device
,	O
their	O
interchangeability	O
guarantees	O
a	O
nearly	O
unlimited	O
quantity	O
of	O
data	O
close	O
at	O
hand	O
.	O
</s>
<s>
Magnetic	B-Architecture
tape	I-Architecture
provided	O
archival	O
capability	O
for	O
this	O
data	O
,	O
at	O
a	O
lower	O
cost	O
than	O
disk	B-Device
.	O
</s>
<s>
For	O
example	O
,	O
while	O
the	O
communication	O
processor	O
controlled	O
card	O
reading	O
and	O
punching	O
,	O
the	O
main	O
CPU	O
executed	O
calculations	O
and	O
binary	O
branch	B-General_Concept
instructions	I-General_Concept
.	O
</s>
<s>
One	O
databus	B-General_Concept
would	O
bear	O
data	O
between	O
the	O
main	O
CPU	O
and	O
core	O
memory	B-General_Concept
at	O
the	O
CPU	O
's	O
fetch-execute	B-General_Concept
cycle	I-General_Concept
rate	O
,	O
and	O
other	O
databusses	O
would	O
typically	O
serve	O
the	O
peripheral	O
devices	O
.	O
</s>
<s>
On	O
the	O
PDP-1	B-Device
,	O
the	O
core	O
memory	B-General_Concept
's	O
cycle	O
time	O
was	O
5	O
microseconds	O
;	O
consequently	O
most	O
arithmetic	O
instructions	O
took	O
10	O
microseconds	O
(	O
100,000	O
operations	O
per	O
second	O
)	O
because	O
most	O
operations	O
took	O
at	O
least	O
two	O
memory	B-General_Concept
cycles	O
;	O
one	O
for	O
the	O
instruction	O
,	O
one	O
for	O
the	O
operand	O
data	O
fetch	O
.	O
</s>
<s>
During	O
the	O
second	O
generation	O
remote	B-Application
terminal	I-Application
units	O
(	O
often	O
in	O
the	O
form	O
of	O
Teleprinters	O
like	O
a	O
Friden	B-Application
Flexowriter	I-Application
)	O
saw	O
greatly	O
increased	O
use	O
.	O
</s>
<s>
The	O
early	O
1960s	O
saw	O
the	O
advent	O
of	O
supercomputing	B-Architecture
.	O
</s>
<s>
The	O
Atlas	B-Device
was	O
a	O
joint	O
development	O
between	O
the	O
University	O
of	O
Manchester	O
,	O
Ferranti	O
,	O
and	O
Plessey	O
,	O
and	O
was	O
first	O
installed	O
at	O
Manchester	O
University	O
and	O
officially	O
commissioned	O
in	O
1962	O
as	O
one	O
of	O
the	O
world	O
's	O
first	O
supercomputers	B-Architecture
–	O
considered	O
to	O
be	O
the	O
most	O
powerful	O
computer	O
in	O
the	O
world	O
at	O
that	O
time	O
.	O
</s>
<s>
It	O
was	O
said	O
that	O
whenever	O
Atlas	B-Device
went	O
offline	O
half	O
of	O
the	O
United	O
Kingdom	O
's	O
computer	O
capacity	O
was	O
lost	O
.	O
</s>
<s>
It	O
was	O
a	O
second-generation	O
machine	O
,	O
using	O
discrete	O
germanium	O
transistors	B-Application
.	O
</s>
<s>
Atlas	B-Device
also	O
pioneered	O
the	O
Atlas	B-Application
Supervisor	I-Application
,	O
"	O
considered	O
by	O
many	O
to	O
be	O
the	O
first	O
recognisable	O
modern	O
operating	B-General_Concept
system	I-General_Concept
"	O
.	O
</s>
<s>
The	O
CDC	B-Device
6600	I-Device
,	O
released	O
in	O
1964	O
,	O
is	O
generally	O
considered	O
the	O
first	O
supercomputer	B-Architecture
.	O
</s>
<s>
The	O
CDC	B-Device
6600	I-Device
outperformed	O
its	O
predecessor	O
,	O
the	O
IBM	B-Device
7030	I-Device
Stretch	I-Device
,	O
by	O
about	O
a	O
factor	O
of	O
3	O
.	O
</s>
<s>
With	O
performance	O
of	O
about	O
1megaFLOPS	O
,	O
the	O
CDC	B-Device
6600	I-Device
was	O
the	O
world	O
's	O
fastest	B-Operating_System
computer	I-Operating_System
from	O
1964	O
to	O
1969	O
,	O
when	O
it	O
relinquished	O
that	O
status	O
to	O
its	O
successor	O
,	O
the	O
CDC	B-Device
7600	I-Device
.	O
</s>
<s>
The	O
basis	O
for	O
Noyce	O
's	O
monolithic	O
IC	O
was	O
Fairchild	O
's	O
planar	B-Algorithm
process	I-Algorithm
,	O
which	O
allowed	O
integrated	O
circuits	O
to	O
be	O
laid	O
out	O
using	O
the	O
same	O
principles	O
as	O
those	O
of	O
printed	O
circuits	O
.	O
</s>
<s>
The	O
planar	B-Algorithm
process	I-Algorithm
was	O
developed	O
by	O
Noyce	O
's	O
colleague	O
Jean	B-Application
Hoerni	O
in	O
early	O
1959	O
,	O
based	O
on	O
Mohamed	O
M	O
.	O
Atalla	O
's	O
work	O
on	O
semiconductor	O
surface	O
passivation	O
by	O
silicon	O
dioxide	O
at	O
Bell	O
Labs	O
in	O
the	O
late	O
1950s	O
.	O
</s>
<s>
The	O
first	O
silicon	O
IC	O
computer	O
was	O
the	O
Apollo	B-Application
Guidance	I-Application
Computer	I-Application
or	O
AGC	O
.	O
</s>
<s>
The	O
MOSFET	B-Architecture
(	O
metal	B-Architecture
–	I-Architecture
oxide	I-Architecture
–	I-Architecture
semiconductor	I-Architecture
field-effect	I-Architecture
transistor	I-Architecture
,	O
or	O
MOS	B-Architecture
transistor	I-Architecture
)	O
was	O
invented	O
by	O
Mohamed	O
M	O
.	O
Atalla	O
and	O
Dawon	O
Kahng	O
at	O
Bell	O
Labs	O
in	O
1959	O
.	O
</s>
<s>
In	O
addition	O
to	O
data	O
processing	O
,	O
the	O
MOSFET	B-Architecture
enabled	O
the	O
practical	O
use	O
of	O
MOS	B-Architecture
transistors	I-Architecture
as	O
memory	B-Algorithm
cell	I-Algorithm
storage	O
elements	O
,	O
a	O
function	O
previously	O
served	O
by	O
magnetic	O
cores	O
.	O
</s>
<s>
Semiconductor	B-Architecture
memory	I-Architecture
,	O
also	O
known	O
as	O
MOS	B-Architecture
memory	I-Architecture
,	O
was	O
cheaper	O
and	O
consumed	O
less	O
power	O
than	O
magnetic-core	O
memory	B-General_Concept
.	O
</s>
<s>
MOS	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
,	O
in	O
the	O
form	O
of	O
static	B-Architecture
RAM	I-Architecture
(	O
SRAM	O
)	O
,	O
was	O
developed	O
by	O
John	O
Schmidt	O
at	O
Fairchild	O
Semiconductor	O
in	O
1964	O
.	O
</s>
<s>
In	O
1966	O
,	O
Robert	O
Dennard	O
at	O
the	O
IBM	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
developed	O
MOS	O
dynamic	O
RAM	B-Architecture
(	O
DRAM	O
)	O
.	O
</s>
<s>
In	O
1967	O
,	O
Dawon	O
Kahng	O
and	O
Simon	O
Sze	O
at	O
Bell	O
Labs	O
developed	O
the	O
floating-gate	B-Algorithm
MOSFET	I-Algorithm
,	O
the	O
basis	O
for	O
MOS	O
non-volatile	B-General_Concept
memory	I-General_Concept
such	O
as	O
EPROM	B-General_Concept
,	O
EEPROM	B-General_Concept
and	O
flash	B-Device
memory	I-Device
.	O
</s>
<s>
The	O
"	O
fourth-generation	O
"	O
of	O
digital	O
electronic	O
computers	O
used	O
microprocessors	B-Architecture
as	O
the	O
basis	O
of	O
their	O
logic	O
.	O
</s>
<s>
The	O
microprocessor	B-Architecture
has	O
origins	O
in	O
the	O
MOS	O
integrated	O
circuit	O
(	O
MOS	O
IC	O
)	O
chip	O
.	O
</s>
<s>
Due	O
to	O
rapid	O
MOSFET	B-Architecture
scaling	O
,	O
MOS	O
IC	O
chips	O
rapidly	O
increased	O
in	O
complexity	O
at	O
a	O
rate	O
predicted	O
by	O
Moore	O
's	O
law	O
,	O
leading	O
to	O
large-scale	O
integration	O
(	O
LSI	O
)	O
with	O
hundreds	O
of	O
transistors	B-Application
on	O
a	O
single	O
MOS	O
chip	O
by	O
the	O
late	O
1960s	O
.	O
</s>
<s>
The	O
application	O
of	O
MOS	O
LSI	O
chips	O
to	O
computing	O
was	O
the	O
basis	O
for	O
the	O
first	O
microprocessors	B-Architecture
,	O
as	O
engineers	O
began	O
recognizing	O
that	O
a	O
complete	O
computer	O
processor	O
could	O
be	O
contained	O
on	O
a	O
single	O
MOS	O
LSI	O
chip	O
.	O
</s>
<s>
The	O
subject	O
of	O
exactly	O
which	O
device	O
was	O
the	O
first	O
microprocessor	B-Architecture
is	O
contentious	O
,	O
partly	O
due	O
to	O
lack	O
of	O
agreement	O
on	O
the	O
exact	O
definition	O
of	O
the	O
term	O
"	O
microprocessor	B-Architecture
"	O
.	O
</s>
<s>
The	O
earliest	O
multi-chip	O
microprocessors	B-Architecture
were	O
the	O
Four-Phase	O
Systems	O
AL-1	O
in	O
1969	O
and	O
Garrett	O
AiResearch	O
MP944	B-Device
in	O
1970	O
,	O
developed	O
with	O
multiple	O
MOS	O
LSI	O
chips	O
.	O
</s>
<s>
The	O
first	O
single-chip	O
microprocessor	B-Architecture
was	O
the	O
Intel	B-General_Concept
4004	I-General_Concept
,	O
developed	O
on	O
a	O
single	O
PMOS	B-Algorithm
LSI	O
chip	O
.	O
</s>
<s>
While	O
the	O
earliest	O
microprocessor	B-Architecture
ICs	O
literally	O
contained	O
only	O
the	O
processor	O
,	O
i.e.	O
</s>
<s>
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
,	O
of	O
a	O
computer	O
,	O
their	O
progressive	O
development	O
naturally	O
led	O
to	O
chips	O
containing	O
most	O
or	O
all	O
of	O
the	O
internal	O
electronic	O
parts	O
of	O
a	O
computer	O
.	O
</s>
<s>
The	O
integrated	O
circuit	O
in	O
the	O
image	O
on	O
the	O
right	O
,	O
for	O
example	O
,	O
an	O
Intel	O
8742	B-Device
,	O
is	O
an	O
8-bit	O
microcontroller	B-Architecture
that	O
includes	O
a	O
CPU	O
running	O
at	O
12MHz	O
,	O
128	O
bytes	O
of	O
RAM	B-Architecture
,	O
2048	O
bytes	O
of	O
EPROM	B-General_Concept
,	O
and	O
I/O	B-General_Concept
in	O
the	O
same	O
chip	O
.	O
</s>
<s>
IBM	O
implemented	O
its	O
IBM	B-Algorithm
Solid	I-Algorithm
Logic	I-Algorithm
Technology	I-Algorithm
modules	O
in	O
hybrid	O
circuits	O
for	O
the	O
IBM	O
System/360	O
in	O
1964	O
.	O
</s>
<s>
As	O
late	O
as	O
1975	O
,	O
Sperry	O
Univac	O
continued	O
the	O
manufacture	O
of	O
second-generation	O
machines	O
such	O
as	O
the	B-Operating_System
UNIVAC	I-Operating_System
494	O
.	O
</s>
<s>
The	O
Burroughs	B-Device
large	I-Device
systems	I-Device
such	O
as	O
the	O
B5000	O
were	O
stack	B-Application
machines	I-Application
,	O
which	O
allowed	O
for	O
simpler	O
programming	B-Application
.	O
</s>
<s>
These	O
pushdown	B-Application
automatons	I-Application
were	O
also	O
implemented	O
in	O
minicomputers	O
and	O
microprocessors	B-Architecture
later	O
,	O
which	O
influenced	O
programming	B-Application
language	O
design	O
.	O
</s>
<s>
It	O
became	O
possible	O
to	O
simulate	O
analog	O
circuits	O
with	O
the	O
simulation	O
program	B-Application
with	O
integrated	O
circuit	O
emphasis	O
,	O
or	O
SPICE	B-Protocol
(	O
1971	O
)	O
on	O
minicomputers	O
,	O
one	O
of	O
the	O
programs	O
for	O
electronic	O
design	O
automation	O
(	O
EDA	O
)	O
.	O
</s>
<s>
The	O
microprocessor	B-Architecture
led	O
to	O
the	O
development	O
of	O
microcomputers	B-Architecture
,	O
small	O
,	O
low-cost	O
computers	O
that	O
could	O
be	O
owned	O
by	O
individuals	O
and	O
small	O
businesses	O
.	O
</s>
<s>
Microcomputers	B-Architecture
,	O
the	O
first	O
of	O
which	O
appeared	O
in	O
the	O
1970s	O
,	O
became	O
ubiquitous	O
in	O
the	O
1980s	O
and	O
beyond	O
.	O
</s>
<s>
While	O
which	O
specific	O
product	O
is	O
considered	O
the	O
first	O
microcomputer	B-Architecture
system	O
is	O
a	O
matter	O
of	O
debate	O
,	O
one	O
of	O
the	O
earliest	O
is	O
R2E	O
's	O
Micral	O
N	O
(	O
François	O
Gernelle	O
,	O
André	O
Truong	O
)	O
launched	O
"	O
early	O
1973	O
"	O
using	O
the	O
Intel	O
8008	O
.	O
</s>
<s>
The	O
first	O
commercially	O
available	O
microcomputer	B-Architecture
kit	O
was	O
the	O
Intel	O
8080-based	O
Altair	B-Architecture
8800	I-Architecture
,	O
which	O
was	O
announced	O
in	O
the	O
January	O
1975	O
cover	O
article	O
of	O
Popular	O
Electronics	O
.	O
</s>
<s>
However	O
,	O
the	O
Altair	B-Architecture
8800	I-Architecture
was	O
an	O
extremely	O
limited	O
system	O
in	O
its	O
initial	O
stages	O
,	O
having	O
only	O
256	O
bytes	O
of	O
DRAM	O
in	O
its	O
initial	O
package	O
and	O
no	O
input-output	B-General_Concept
except	O
its	O
toggle	O
switches	O
and	O
LED	O
register	O
display	O
.	O
</s>
<s>
Several	O
early	O
third-party	O
vendors	O
such	O
as	O
Cromemco	O
and	O
Processor	O
Technology	O
soon	O
began	O
supplying	O
additional	O
S-100	B-Architecture
bus	I-Architecture
hardware	B-Architecture
for	O
the	O
Altair	B-Architecture
8800	I-Architecture
.	O
</s>
<s>
In	O
April	O
1975	O
at	O
the	O
Hannover	O
Fair	O
,	O
Olivetti	O
presented	O
the	O
P6060	B-Device
,	O
the	O
world	O
's	O
first	O
complete	O
,	O
pre-assembled	O
personal	B-Device
computer	I-Device
system	O
.	O
</s>
<s>
The	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
consisted	O
of	O
two	O
cards	O
,	O
code	O
named	O
PUCE1	O
and	O
PUCE2	O
,	O
and	O
unlike	O
most	O
other	O
personal	B-Device
computers	I-Device
was	O
built	O
with	O
TTL	B-General_Concept
components	O
rather	O
than	O
a	O
microprocessor	B-Architecture
.	O
</s>
<s>
It	O
had	O
one	O
or	O
two	O
8	B-Device
"	I-Device
floppy	B-Device
disk	I-Device
drives	I-Device
,	O
a	O
32-character	O
plasma	O
display	O
,	O
80-column	O
graphical	O
thermal	O
printer	O
,	O
48	O
Kbytes	O
of	O
RAM	B-Architecture
,	O
and	O
BASIC	O
language	O
.	O
</s>
<s>
It	O
was	O
in	O
competition	O
with	O
a	O
similar	O
product	O
by	O
IBM	O
that	O
had	O
an	O
external	O
floppy	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
From	O
1975	O
to	O
1977	O
,	O
most	O
microcomputers	B-Architecture
,	O
such	O
as	O
the	O
MOS	B-Device
Technology	I-Device
KIM-1	I-Device
,	O
the	O
Altair	B-Architecture
8800	I-Architecture
,	O
and	O
some	O
versions	O
of	O
the	O
Apple	B-Device
I	I-Device
,	O
were	O
sold	O
as	O
kits	O
for	O
do-it-yourselfers	O
.	O
</s>
<s>
Pre-assembled	O
systems	O
did	O
not	O
gain	O
much	O
ground	O
until	O
1977	O
,	O
with	O
the	O
introduction	O
of	O
the	O
Apple	B-Device
II	I-Device
,	O
the	O
Tandy	B-Device
TRS-80	I-Device
,	O
the	O
first	O
SWTPC	O
computers	O
,	O
and	O
the	O
Commodore	B-Device
PET	I-Device
.	O
</s>
<s>
Computing	O
has	O
evolved	O
with	O
microcomputer	B-Architecture
architectures	O
,	O
with	O
features	O
added	O
from	O
their	O
larger	O
brethren	O
,	O
now	O
dominant	O
in	O
most	O
market	O
segments	O
.	O
</s>
<s>
A	O
NeXT	O
Computer	O
and	O
its	O
object-oriented	B-Language
development	O
tools	O
and	O
libraries	O
were	O
used	O
by	O
Tim	O
Berners-Lee	O
and	O
Robert	O
Cailliau	O
at	O
CERN	O
to	O
develop	O
the	O
world	O
's	O
first	O
web	B-Application
server	I-Application
software	O
,	O
CERN	B-Application
httpd	I-Application
,	O
and	O
also	O
used	O
to	O
write	O
the	O
first	O
web	B-Application
browser	I-Application
,	O
WorldWideWeb	B-Language
.	O
</s>
<s>
ENIAC	B-Device
remained	O
on	O
,	O
in	O
continuous	O
operation	O
from	O
1947	O
to	O
1955	O
,	O
for	O
eight	O
years	O
before	O
being	O
shut	O
down	O
.	O
</s>
<s>
By	O
the	O
simple	O
strategy	O
of	O
never	O
shutting	O
down	O
ENIAC	B-Device
,	O
the	O
failures	O
were	O
dramatically	O
reduced	O
.	O
</s>
<s>
The	O
vacuum-tube	O
SAGE	B-Device
air-defense	O
computers	O
became	O
remarkably	O
reliable	O
–	O
installed	O
in	O
pairs	O
,	O
one	O
off-line	O
,	O
tubes	O
likely	O
to	O
fail	O
did	O
so	O
when	O
the	O
computer	O
was	O
intentionally	O
run	O
at	O
reduced	O
power	O
to	O
find	O
them	O
.	O
</s>
<s>
Hot-pluggable	B-Device
hard	B-Device
disks	I-Device
,	O
like	O
the	O
hot-pluggable	B-Device
vacuum	O
tubes	O
of	O
yesteryear	O
,	O
continue	O
the	O
tradition	O
of	O
repair	O
during	O
continuous	O
operation	O
.	O
</s>
<s>
Semiconductor	B-Architecture
memories	I-Architecture
routinely	O
have	O
no	O
errors	O
when	O
they	O
operate	O
,	O
although	O
operating	B-General_Concept
systems	I-General_Concept
like	O
Unix	O
have	O
employed	O
memory	B-General_Concept
tests	O
on	O
start-up	O
to	O
detect	O
failing	O
hardware	B-Architecture
.	O
</s>
<s>
Today	O
,	O
the	O
requirement	O
of	O
reliable	O
performance	O
is	O
made	O
even	O
more	O
stringent	O
when	O
server	B-Operating_System
farms	I-Operating_System
are	O
the	O
delivery	O
platform	O
.	O
</s>
<s>
Google	O
has	O
managed	O
this	O
by	O
using	O
fault-tolerant	O
software	O
to	O
recover	O
from	O
hardware	B-Architecture
failures	O
,	O
and	O
is	O
even	O
working	O
on	O
the	O
concept	O
of	O
replacing	O
entire	O
server	B-Operating_System
farms	I-Operating_System
on-the-fly	O
,	O
during	O
a	O
service	O
event	O
.	O
</s>
<s>
In	O
the	O
21st	O
century	O
,	O
multi-core	B-Architecture
CPUs	I-Architecture
became	O
commercially	O
available	O
.	O
</s>
<s>
Content-addressable	B-Data_Structure
memory	I-Data_Structure
(	O
CAM	B-Data_Structure
)	O
has	O
become	O
inexpensive	O
enough	O
to	O
be	O
used	O
in	O
networking	O
,	O
and	O
is	O
frequently	O
used	O
for	O
on-chip	O
cache	B-General_Concept
memory	I-General_Concept
in	O
modern	O
microprocessors	B-Architecture
,	O
although	O
no	O
computer	O
system	O
has	O
yet	O
implemented	O
hardware	B-Architecture
CAMs	B-Data_Structure
for	O
use	O
in	O
programming	B-Application
languages	O
.	O
</s>
<s>
Currently	O
,	O
CAMs	B-Data_Structure
(	O
or	O
associative	O
arrays	O
)	O
in	O
software	O
are	O
programming-language-specific	O
.	O
</s>
<s>
Semiconductor	B-Architecture
memory	I-Architecture
cell	O
arrays	O
are	O
very	O
regular	O
structures	O
,	O
and	O
manufacturers	O
prove	O
their	O
processes	O
on	O
them	O
;	O
this	O
allows	O
price	O
reductions	O
on	O
memory	B-General_Concept
products	O
.	O
</s>
<s>
During	O
the	O
1980s	O
,	O
CMOS	B-Device
logic	O
gates	O
developed	O
into	O
devices	O
that	O
could	O
be	O
made	O
as	O
fast	O
as	O
other	O
circuit	O
types	O
;	O
computer	O
power	O
consumption	O
could	O
therefore	O
be	O
decreased	O
dramatically	O
.	O
</s>
<s>
Unlike	O
the	O
continuous	O
current	O
draw	O
of	O
a	O
gate	O
based	O
on	O
other	O
logic	O
types	O
,	O
a	O
CMOS	B-Device
gate	O
only	O
draws	O
significant	O
current	O
during	O
the	O
'	O
transition	O
 '	O
between	O
logic	O
states	O
,	O
except	O
for	O
leakage	O
.	O
</s>
<s>
CMOS	B-Device
circuits	O
have	O
allowed	O
computing	O
to	O
become	O
a	O
commodity	O
which	O
is	O
now	O
ubiquitous	O
,	O
embedded	O
in	O
many	B-Architecture
forms	I-Architecture
,	O
from	O
greeting	O
cards	O
and	O
telephones	O
to	O
satellites	O
.	O
</s>
<s>
The	O
thermal	B-General_Concept
design	I-General_Concept
power	I-General_Concept
which	O
is	O
dissipated	O
during	O
operation	O
has	O
become	O
as	O
essential	O
as	O
computing	O
speed	O
of	O
operation	O
.	O
</s>
<s>
The	O
SoC	B-Architecture
(	O
system	B-Architecture
on	I-Architecture
a	I-Architecture
chip	I-Architecture
)	O
has	O
compressed	O
even	O
more	O
of	O
the	O
integrated	O
circuitry	O
into	O
a	O
single	O
chip	O
;	O
SoCs	O
are	O
enabling	O
phones	O
and	O
PCs	B-Device
to	O
converge	O
into	O
single	O
hand-held	O
wireless	O
mobile	O
devices	O
.	O
</s>
<s>
Quantum	B-Architecture
computing	I-Architecture
is	O
an	O
emerging	O
technology	O
in	O
the	O
field	O
of	O
computing	O
.	O
</s>
<s>
Google	O
researchers	O
have	O
been	O
able	O
to	O
extend	O
the	O
50	O
microsecond	O
time	O
limit	O
,	O
as	O
reported	O
14	O
July	O
2021	O
in	O
Nature	O
;	O
stability	O
has	O
been	O
extended	O
100-fold	O
by	O
spreading	O
a	O
single	O
logical	O
qubit	O
over	O
chains	O
of	O
data	O
qubits	O
for	O
quantum	B-Device
error	I-Device
correction	I-Device
.	O
</s>
<s>
See	O
:	O
Quantum	B-Device
supremacy	I-Device
Silicon	O
qubit	O
systems	O
have	O
demonstrated	O
entanglement	O
at	O
non-local	O
distances	O
.	O
</s>
<s>
Computing	B-Architecture
hardware	I-Architecture
and	O
its	O
software	O
have	O
even	O
become	O
a	O
metaphor	O
for	O
the	O
operation	O
of	O
the	O
universe	O
.	O
</s>
<s>
After	O
1945	O
,	O
others	O
read	O
John	O
von	O
Neumann	O
's	O
First	O
Draft	O
of	O
a	O
Report	O
on	O
the	O
EDVAC	B-Device
,	O
and	O
immediately	O
started	O
implementing	O
their	O
own	O
systems	O
.	O
</s>
