<s>
The	B-Device
analytical	I-Device
engine	I-Device
was	O
a	O
proposed	O
mechanical	O
general-purpose	O
computer	O
designed	O
by	O
English	O
mathematician	O
and	O
computer	O
pioneer	O
Charles	O
Babbage	O
.	O
</s>
<s>
The	B-Device
analytical	I-Device
engine	I-Device
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>
In	O
other	O
words	O
,	O
the	O
structure	O
of	O
the	B-Device
analytical	I-Device
engine	I-Device
was	O
essentially	O
the	O
same	O
as	O
that	O
which	O
has	O
dominated	O
computer	O
design	O
in	O
the	O
electronic	O
era	O
.	O
</s>
<s>
The	B-Device
analytical	I-Device
engine	I-Device
is	O
one	O
of	O
the	O
most	O
successful	O
achievements	O
of	O
Charles	O
Babbage	O
.	O
</s>
<s>
It	O
was	O
not	O
until	O
1941	O
that	O
Konrad	O
Zuse	O
built	O
the	O
first	O
general-purpose	O
computer	O
,	O
Z3	B-Device
,	O
more	O
than	O
a	O
century	O
after	O
Babbage	O
had	O
proposed	O
the	O
pioneering	O
analytical	B-Device
engine	I-Device
in	O
1837	O
.	O
</s>
<s>
Babbage	O
's	O
first	O
attempt	O
at	O
a	O
mechanical	O
computing	O
device	O
,	O
the	O
Difference	O
Engine	O
,	O
was	O
a	O
special-purpose	O
machine	O
designed	O
to	O
tabulate	O
logarithms	O
and	O
trigonometric	O
functions	O
by	O
evaluating	O
finite	B-Algorithm
differences	I-Algorithm
to	O
create	O
approximating	O
polynomials	O
.	O
</s>
<s>
During	O
this	O
project	O
,	O
Babbage	O
realised	O
that	O
a	O
much	O
more	O
general	O
design	O
,	O
the	B-Device
analytical	I-Device
engine	I-Device
,	O
was	O
possible	O
.	O
</s>
<s>
The	O
work	O
on	O
the	O
design	O
of	O
the	B-Device
analytical	I-Device
engine	I-Device
started	O
around	O
1833	O
.	O
</s>
<s>
The	O
input	O
,	O
consisting	O
of	O
programs	O
(	O
"	O
formulae	O
"	O
)	O
and	O
data	B-General_Concept
,	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>
There	O
was	O
to	O
be	O
a	O
store	O
(	O
that	O
is	O
,	O
a	O
memory	B-General_Concept
)	O
capable	O
of	O
holding	O
1,000	O
numbers	O
of	O
50	O
decimal	B-Application
digits	O
each	O
(	O
ca	O
.	O
</s>
<s>
An	O
arithmetic	B-General_Concept
unit	I-General_Concept
(	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
upon	O
its	O
own	B-Device
internal	I-Device
procedures	I-Device
,	O
to	O
be	O
stored	O
in	O
the	O
form	O
of	O
pegs	B-Device
inserted	I-Device
into	I-Device
rotating	I-Device
drums	I-Device
called	O
"	O
barrels	O
"	O
,	O
to	O
carry	O
out	O
some	O
of	O
the	O
more	O
complex	O
instructions	B-General_Concept
the	O
user	O
's	O
program	O
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	O
unit	O
or	O
back	O
.	O
</s>
<s>
Babbage	O
developed	O
some	O
two	O
dozen	O
programs	O
for	O
the	B-Device
analytical	I-Device
engine	I-Device
between	O
1837	O
and	O
1840	O
,	O
and	O
one	O
program	O
later	O
.	O
</s>
<s>
These	O
programs	O
treat	O
polynomials	O
,	O
iterative	O
formulas	O
,	O
Gaussian	B-Algorithm
elimination	I-Algorithm
,	O
and	O
Bernoulli	O
numbers	O
.	O
</s>
<s>
In	O
1843	O
,	O
the	O
description	O
was	O
translated	O
into	O
English	O
and	O
extensively	O
annotated	O
by	O
Ada	B-General_Concept
Lovelace	I-General_Concept
,	O
who	O
had	O
become	O
interested	O
in	O
the	O
engine	O
eight	O
years	O
earlier	O
.	O
</s>
<s>
In	O
recognition	O
of	O
her	O
additions	O
to	O
Menabrea	O
's	O
paper	O
,	O
which	O
included	O
a	O
way	O
to	O
calculate	O
Bernoulli	O
numbers	O
using	O
the	O
machine	O
(	O
widely	O
considered	O
to	O
be	O
the	O
first	O
complete	O
computer	B-Application
program	I-Application
)	O
,	O
she	O
has	O
been	O
described	O
as	O
the	O
first	O
computer	B-Application
programmer	I-Application
.	O
</s>
<s>
In	O
1878	O
,	O
a	O
committee	O
of	O
the	O
British	O
Association	O
for	O
the	O
Advancement	O
of	O
Science	O
described	O
the	B-Device
analytical	I-Device
engine	I-Device
as	O
"	O
a	O
marvel	O
of	O
mechanical	O
ingenuity	O
"	O
,	O
but	O
recommended	O
against	O
constructing	O
it	O
.	O
</s>
<s>
This	O
constituted	O
only	O
a	O
small	O
part	O
of	O
the	O
whole	O
engine	O
;	O
it	O
was	O
not	O
programmable	B-Application
and	O
had	O
no	O
storage	O
.	O
</s>
<s>
Henry	O
Babbage	O
's	O
"	O
analytical	B-Device
engine	I-Device
mill	O
"	O
is	O
on	O
display	O
at	O
the	O
Science	O
Museum	O
in	O
London	O
.	O
</s>
<s>
"	O
It	O
is	O
only	O
a	O
question	O
of	O
cards	O
and	O
time	O
"	O
,	O
wrote	O
Henry	O
Babbage	O
in	O
1888	O
,	O
"	O
...	O
and	O
there	O
is	O
no	O
reason	O
why	O
(	O
twenty	O
thousand	O
)	O
cards	O
should	O
not	O
be	O
used	O
if	O
necessary	O
,	O
in	O
an	O
analytical	B-Device
engine	I-Device
for	O
the	O
purposes	O
of	O
the	O
mathematician	O
"	O
.	O
</s>
<s>
2	O
,	O
a	O
design	O
that	O
incorporated	O
refinements	O
Babbage	O
discovered	O
during	O
the	O
development	O
of	O
the	B-Device
analytical	I-Device
engine	I-Device
.	O
</s>
<s>
In	O
October	O
2010	O
,	O
John	O
Graham-Cumming	O
started	O
a	O
"	O
Plan	O
28	O
"	O
campaign	O
to	O
raise	O
funds	O
by	O
"	O
public	O
subscription	O
"	O
to	O
enable	O
serious	O
historical	O
and	O
academic	O
study	O
of	O
Babbage	O
's	O
plans	O
,	O
with	O
a	O
view	O
to	O
then	O
build	O
and	O
test	O
a	O
fully	O
working	O
virtual	O
design	O
which	O
will	O
then	O
in	O
turn	O
enable	O
construction	O
of	O
the	O
physical	O
analytical	B-Device
engine	I-Device
.	O
</s>
<s>
Babbage	O
is	O
not	O
known	O
to	O
have	O
written	O
down	O
an	O
explicit	O
set	O
of	O
instructions	B-General_Concept
for	O
the	O
engine	O
in	O
the	O
manner	O
of	O
a	O
modern	O
processor	O
manual	O
.	O
</s>
<s>
Allan	O
G	O
.	O
Bromley	O
has	O
assumed	O
that	O
the	O
card	B-Architecture
deck	I-Architecture
could	O
be	O
read	O
in	O
forwards	O
and	O
backwards	O
directions	O
as	O
a	O
function	O
of	O
conditional	B-Language
branching	I-Language
after	O
testing	O
for	O
conditions	O
,	O
which	O
would	O
make	O
the	O
engine	O
Turing-complete	B-Algorithm
:	O
</s>
<s>
There	O
would	O
be	O
no	O
mechanical	O
or	O
microprogramming	B-Device
difficulty	O
in	O
placing	O
the	O
direction	O
of	O
motion	O
under	O
the	O
control	O
of	O
the	O
user	O
.	O
</s>
<s>
This	O
emulator	O
does	O
provide	O
a	O
written	O
symbolic	O
instruction	B-General_Concept
set	I-General_Concept
,	O
though	O
this	O
has	O
been	O
constructed	O
by	O
its	O
authors	O
rather	O
than	O
based	O
on	O
Babbage	O
's	O
original	O
works	O
.	O
</s>
<s>
where	O
the	O
CB	O
is	O
the	O
conditional	B-Language
branch	O
instruction	O
or	O
"	O
combination	O
card	O
"	O
used	O
to	O
make	O
the	O
control	O
flow	O
jump	O
,	O
in	O
this	O
case	O
backward	O
by	O
11	O
cards	O
.	O
</s>
<s>
Babbage	O
understood	O
that	O
the	O
existence	O
of	O
an	O
automatic	O
computer	O
would	O
kindle	O
interest	O
in	O
the	O
field	O
now	O
known	O
as	O
algorithmic	B-General_Concept
efficiency	I-General_Concept
,	O
writing	O
in	O
his	O
Passages	O
from	O
the	O
Life	O
of	O
a	O
Philosopher	O
,	O
"	O
As	O
soon	O
as	O
an	O
analytical	B-Device
engine	I-Device
exists	O
,	O
it	O
will	O
necessarily	O
guide	O
the	O
future	O
course	O
of	O
the	O
science	O
.	O
</s>
<s>
Percy	O
Ludgate	O
wrote	O
about	O
the	O
engine	O
in	O
1914	O
and	O
published	O
his	O
own	O
design	O
for	O
an	O
analytical	B-Device
engine	I-Device
in	O
1909	O
.	O
</s>
<s>
Ludgate	O
's	O
engine	O
would	O
be	O
much	O
smaller	O
(	O
about	O
,	O
which	O
corresponds	O
to	O
cube	B-Application
of	O
side	O
length	O
)	O
than	O
Babbage	O
's	O
,	O
and	O
hypothetically	O
would	O
be	O
capable	O
of	O
multiplying	O
two	O
20-decimal-digit	O
numbers	O
in	O
about	O
six	O
seconds	O
.	O
</s>
<s>
The	O
paper	O
also	O
contains	O
the	O
idea	O
of	O
floating-point	B-Algorithm
arithmetic	I-Algorithm
.	O
</s>
<s>
In	O
the	O
same	O
year	O
he	O
started	O
the	O
Rapid	O
Arithmetical	O
Machine	O
project	O
to	O
investigate	O
the	O
problems	O
of	O
constructing	O
an	O
electronic	O
digital	B-General_Concept
computer	O
.	O
</s>
<s>
Despite	O
this	O
groundwork	O
,	O
Babbage	O
's	O
work	O
fell	O
into	O
historical	O
obscurity	O
,	O
and	O
the	B-Device
analytical	I-Device
engine	I-Device
was	O
unknown	O
to	O
builders	O
of	O
electromechanical	O
and	O
electronic	O
computing	O
machines	O
in	O
the	O
1930s	O
and	O
1940s	O
when	O
they	O
began	O
their	O
work	O
,	O
resulting	O
in	O
the	O
need	O
to	O
re-invent	O
many	O
of	O
the	O
architectural	O
innovations	O
Babbage	O
had	O
proposed	O
.	O
</s>
<s>
Howard	O
Aiken	O
,	O
who	O
built	O
the	O
quickly-obsoleted	O
electromechanical	O
calculator	O
,	O
the	O
Harvard	B-Device
Mark	I-Device
I	I-Device
,	O
between	O
1937	O
and	O
1945	O
,	O
praised	O
Babbage	O
's	O
work	O
likely	O
as	O
a	O
way	O
of	O
enhancing	O
his	O
own	O
stature	O
,	O
but	O
knew	O
nothing	O
of	O
the	B-Device
analytical	I-Device
engine	I-Device
's	O
architecture	O
during	O
the	O
construction	O
of	O
the	O
Mark	O
I	O
,	O
and	O
considered	O
his	O
visit	O
to	O
the	O
constructed	O
portion	O
of	O
the	B-Device
analytical	I-Device
engine	I-Device
"	O
the	O
greatest	O
disappointment	O
of	O
my	O
life	O
"	O
.	O
</s>
<s>
The	O
Mark	O
I	O
showed	O
no	O
influence	O
from	O
the	B-Device
analytical	I-Device
engine	I-Device
and	O
lacked	O
the	B-Device
analytical	I-Device
engine	I-Device
's	O
most	O
prescient	O
architectural	O
feature	O
,	O
conditional	B-Language
branching	I-Language
.	O
</s>
<s>
J	O
.	O
Presper	O
Eckert	O
and	O
John	O
W	O
.	O
Mauchly	O
similarly	O
were	O
not	O
aware	O
of	O
the	O
details	O
of	O
Babbage	O
's	O
analytical	B-Device
engine	I-Device
work	O
prior	O
to	O
the	O
completion	O
of	O
their	O
design	O
for	O
the	O
first	O
electronic	O
general-purpose	O
computer	O
,	O
the	O
ENIAC	B-Device
.	O
</s>
<s>
If	O
the	B-Device
analytical	I-Device
engine	I-Device
had	O
been	O
built	O
,	O
it	O
would	O
have	O
been	O
digital	B-General_Concept
,	O
programmable	B-Application
and	O
Turing-complete	B-Algorithm
.	O
</s>
<s>
Luigi	O
Federico	O
Menabrea	O
reported	O
in	O
Sketch	B-Device
of	I-Device
the	I-Device
Analytical	I-Device
Engine	I-Device
:	O
"	O
Mr.	O
Babbage	O
believes	O
he	O
can	O
,	O
by	O
his	O
engine	O
,	O
form	O
the	O
product	O
of	O
two	O
numbers	O
,	O
each	O
containing	O
twenty	O
figures	O
,	O
in	O
three	O
minutes	O
"	O
.	O
</s>
<s>
By	O
comparison	O
the	O
Harvard	B-Device
Mark	I-Device
I	I-Device
could	O
perform	O
the	O
same	O
task	O
in	O
just	O
six	O
seconds	O
.	O
</s>
<s>
Name	O
First	O
operational	O
Numeral	O
system	O
Computing	O
mechanism	O
Programming	B-Application
Turing	B-Algorithm
complete	I-Algorithm
Memory	B-General_Concept
Difference	O
Engine	O
Not	O
built	O
until	O
the	O
1990s	O
(	O
design	O
1820s	O
)	O
Decimal	B-Application
Mechanical	O
Not	O
programmable	B-Application
;	O
initial	O
numerical	O
constants	O
of	O
polynomial	O
differences	O
set	O
physically	O
Physical	O
state	O
of	O
wheels	O
in	O
axes	O
Analytical	B-Device
Engine	I-Device
Not	O
built	O
(	O
design	O
1830s	O
)	O
Decimal	B-Application
Mechanical	O
Program-controlled	O
by	O
punched	B-Architecture
cards	I-Architecture
Physical	O
state	O
of	O
wheels	O
in	O
axesLudgate	O
's	O
Analytical	O
EngineNot	O
built	O
(	O
design	O
1909	O
)	O
DecimalMechanicalProgram-controlled	O
by	O
punched	B-Architecture
cards	I-Architecture
Physical	O
state	O
of	O
rods	O
Torres	O
y	O
Quevedo	O
's	O
Analytical	O
machine	O
1920DecimalElectromechanicalNot	O
programmable	B-Application
;	O
input	O
and	O
output	O
settings	O
specified	O
by	O
patch	O
cables	O
Mechanical	O
relaysZuse	O
Z1	B-Device
1939Binary	O
floating	O
pointMechanicalNot	O
programmable	B-Application
;	O
cipher	O
input	O
settings	O
specified	O
by	O
patch	O
cables	O
Physical	O
state	O
of	O
rods	O
Bombe	B-Device
1939	O
(	O
Polish	B-Device
)	O
,	O
March	O
1940	O
(	O
British	O
)	O
,	O
May	O
1943	O
(	O
US	O
)	O
Character	O
computations	O
Electro-mechanical	O
Not	O
programmable	B-Application
;	O
cipher	O
input	O
settings	O
specified	O
by	O
patch	O
cables	O
Physical	O
state	O
of	O
rotorsZuse	O
Z2	B-Device
1940Binary	O
floating	O
pointElectro-mechanical	O
(	O
Mechanical	O
memory	B-General_Concept
)	O
Program-controlled	O
by	O
punched	O
35	O
mm	O
film	O
stock	O
Physical	O
state	O
of	O
rods	O
Zuse	B-Device
Z3	I-Device
May	O
1941	O
Binary	B-Algorithm
floating	I-Algorithm
point	I-Algorithm
Electro-mechanical	O
Program-controlled	O
by	O
punched	O
35	O
mm	O
film	O
stock	O
In	O
principle	O
Mechanical	O
relays	O
Atanasoff	B-Device
–	I-Device
Berry	I-Device
Computer	I-Device
1942	O
Binary	O
Electronic	O
Not	O
programmable	B-Application
;	O
linear	O
system	O
coefficients	O
input	O
using	O
punched	B-Architecture
cards	I-Architecture
Regenerative	O
capacitor	O
memory	B-General_Concept
Colossus	B-Device
Mark	O
1	O
December	O
1943	O
Binary	O
Electronic	O
Program-controlled	O
by	O
patch	O
cables	O
and	O
switches	O
Thermionic	O
valves	O
(	O
vacuum	O
tubes	O
)	O
and	O
thyratrons	O
Harvard	B-Device
Mark	I-Device
I	I-Device
–	O
IBM	B-Device
ASCC	I-Device
May	O
1944	O
Decimal	B-Application
Electro-mechanical	O
Program-controlled	O
by	O
24-channel	O
punched	O
paper	O
tape	O
(	O
but	O
no	O
conditional	B-Language
branch	O
)	O
Mechanical	O
relays	O
Zuse	B-Device
Z4	I-Device
March	O
1945	O
(	O
or	O
1948	O
)	O
Binary	B-Algorithm
floating	I-Algorithm
point	I-Algorithm
Electro-mechanical	O
Program-controlled	O
by	O
punched	O
35	O
mm	O
film	O
stock	O
In	O
1950	O
Mechanical	O
relays	O
ENIAC	B-Device
July	O
1946	O
Decimal	B-Application
Electronic	O
Program-controlled	O
by	O
patch	O
cables	O
and	O
switches	O
Vacuum	O
tube	O
triode	O
flip-flops	B-General_Concept
Manchester	B-Device
Baby	I-Device
1948	O
Binary	O
Electronic	O
Binary	O
program	O
entered	O
into	O
memory	B-General_Concept
by	O
keyboard	O
(	O
first	O
electronic	O
stored-program	O
digital	B-General_Concept
computer	O
)	O
Williams	B-General_Concept
cathode	I-General_Concept
ray	I-General_Concept
tube	I-General_Concept
EDSAC	B-Device
1949	O
Binary	O
Electronic	O
Five-bit	O
opcode	O
and	O
variable-length	O
operand	O
(	O
first	O
stored-program	O
computer	O
offering	O
computing	O
services	O
to	O
a	O
wide	O
community	O
)	O
.	O
</s>
<s>
The	O
cyberpunk	O
novelists	O
William	O
Gibson	O
and	O
Bruce	O
Sterling	O
co-authored	O
a	O
steampunk	O
novel	O
of	O
alternative	O
history	O
titled	O
The	O
Difference	O
Engine	O
in	O
which	O
Babbage	O
's	O
difference	O
and	O
analytical	B-Device
engines	I-Device
became	O
available	O
to	O
Victorian	O
society	O
.	O
</s>
<s>
Moriarty	O
by	O
Modem	O
,	O
a	O
short	O
story	O
by	O
Jack	O
Nimersheim	O
,	O
describes	O
an	O
alternative	O
history	O
where	O
Babbage	O
's	O
analytical	B-Device
engine	I-Device
was	O
indeed	O
completed	O
and	O
had	O
been	O
deemed	O
highly	O
classified	O
by	O
the	O
British	O
government	O
.	O
</s>
<s>
The	O
characters	O
of	O
Sherlock	B-Application
Holmes	I-Application
and	O
Moriarty	O
had	O
in	O
reality	O
been	O
a	O
set	O
of	O
prototype	O
programs	O
written	O
for	O
the	B-Device
analytical	I-Device
engine	I-Device
.	O
</s>
<s>
This	O
short	O
story	O
follows	O
Holmes	O
as	O
his	O
program	O
is	O
implemented	O
on	O
modern	O
computers	O
and	O
he	O
is	O
forced	O
to	O
compete	O
against	O
his	O
nemesis	O
yet	O
again	O
in	O
the	O
modern	O
counterparts	O
of	O
Babbage	O
's	O
analytical	B-Device
engine	I-Device
.	O
</s>
<s>
It	O
features	O
an	O
alternative	O
history	O
where	O
Ada	B-General_Concept
Lovelace	I-General_Concept
and	O
Babbage	O
have	O
built	O
the	B-Device
analytical	I-Device
engine	I-Device
and	O
use	O
it	O
to	O
fight	O
crime	O
at	O
Queen	O
Victoria	O
's	O
request	O
.	O
</s>
<s>
Each	O
is	O
the	O
size	O
of	O
a	O
large	O
asteroid	O
,	O
only	O
capable	O
of	O
surviving	O
in	O
microgravity	O
conditions	O
,	O
and	O
processes	O
data	B-General_Concept
at	O
0.5	O
%	O
the	O
speed	O
of	O
a	O
human	O
brain	O
.	O
</s>
