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The Electronic Computer
A Machine with a Past
G. A. Erskine
It
is
about
130
years
mathematician
Charles
since
and
Babbage,
the
wealthy
amateur
engineer,
conceived
the
idea
of
a completely automatic calculating machine.
Babbage
realized
that
if
his
machine
ming' the Analytical Engine, possibly
clearly
appendices
successive
Bernoulli
results
page
'memory'
the
to
in w h i c h
calculation
sequent
was
use
to
digit
print
an
intermediate
could
by
50
decimal
of
the
be
the
c o n s i s t of
wheels,
machine.
digits.
The
sub-
This
store
of
containing
automatic
control
operations
of
of
in a J a q u a r d
alized
that
machine
a
insight,
truly
lifting
universal
re-
calculating
its
sequence
of o p e r a t i o n s d e p e n d i n g on t h e
unforesee-
a b l e result of i n t e r m e d i a t e c a l c u l a t i o n s .
therefore
provided
for
a
mechanism
w o u l d cause the m a c h i n e to skip
or
backwards
control
over
a specified
He
that
forwards
number
cards when the number
Since
program
shows
of
contained
by the
Babbage's
cost
Babbage
put
and
into
the
Lady Lovelace
practice,
backing
Analytical
horses.
an
devised,
infallible
The
were
occur
if a n y
length,
and
would
result
he
be
exceeded
foresaw
50 digits
the
use
of
in
length arithmetic to deal with s u c h
cases.
anticipated
many
essential features of the m o d e r n
Babbage
prepared
many
parts
of
spent
much
of
experimenting
nism. During
his
detailed
Engine
remainder
pieces
a visit to
the
drawings
Analytical
the
with
of
computer.
of
of
the
Italy, he
of
and
his
described
the p r o p o s e d m a c h i n e to a small g r o u p
people
an
which
army
included
engineer
Menabrea
was
Babbage's
machine
L.F.
and
so
interested
he
published
g e n e r a l d e s c r i p t i o n o f it i n t h e
Universelle
de
Geneve
in
English
of the p o e t
translation
of
by
a
Bibliotheque
1842.
Twentieth
From
Century
the
1871
time
until
the
Lovelace,
Byron, published
Menabrea's
an
article,
invented
could
original
article.
Lady
Lovelace,
tician a n d a friend of B a b b a g e ,
clearly
what
was
involving
in
the
mathemaunderstood
'program-
learnt
of
meeting
should
the
with
the
and
electro-
machinery
Such
subtract,
being
out
entered
was
machines
and
print,
to
sequence
of
an
operations
manual
University
collaboration
Business
construct
Machines
an
automatic
c a l c u l a t o r in w h i c h
operations
was
to
be
t r o l l e d b y a p e r f o r a t e d p a p e r t a p e , in
the
same
which
was
as
Babbage's
Aiken
knew
nothing
be
controlled
to
This
way
machine,
calculator,
In
the
was
Neumann
an
accidental
H.H.
Goldstine.
by
the
thought
of
twenty thousand vacuum tubes being
to
provide
the
such
In a n y
in
inflexible
case, von
ENIAC
team,
set
ENIAC
with
to
the
by
the
Harvard
meantime,
in
work
conrather
(of
time)
Jaquard
completed
the
machine
at
cards.
Mark
1
1944.
had
using
work
school
held
vania
in
published
much
principles
international
were
audience
at t h e
on
and
in a
series
than
hard-
presented
at
were
of
the
compu-
less
University
1946,
and
members
of an electronic
while
used
computing
Neumann
collaboration
principles
as
those
to
a
summer
of
Pennsyl-
subsequently
reports.
but
that
without
into
International
Corporation
a* c o l l e a g u e ,
horrified
The
von
Neumann
The
computer
and
Goldstine
modern
electro-mechanical
in
ter w h i c h w o u l d be far more versatile
In 1939, H o w a r d A i k e n o f t h e
with
ENIAC
construction,
von
to
carried
Harvard
under
John
seems
intervention.
of
still
1930s, t h e r e
card
and
(3 m s ) .
logical
no m e a n s of s p e c i f y i n g
be
addi-
( 2 0 0 \is)
It i s t e m p t i n g t o t h i n k o f v o n N e u m a n n
of
developed.
add,
several
in
improvement
and
to
death
punched
sort,
hours
mircoseconds
was
an
steady
a few
mathematician
ware. These
posal
begun
at
first
Computer
proposed
in
1946
computer.
was
specify
that
the
by von
is
The
Neumann
essentially
form
and
the
held
computer
puter
could
instructions
speed
as
which
to
from
result
a
of
test
the
as
the
was
to
the
store
necessary,
one
the
on
same
another
test
(for
the
jump
in
the
to
the
example,
number
in
This computer, designed by J . W.
i n p u t m e d i u m s u c h a s p a p e r t a p e , it w o u l d
United
States
1946. V a c u u m
provide
Army,
tube
arithmetic
internal
required
circuits
for
10-digit
tubes,
program
were
to
tions,
the
Programming
was
by
used
together
twenty
10-digit
location
whole
puter used approximately twenty
tubes.
possible
in
storage
and
be
completed
capabilities
storage
Each
550
was
com-
thousand
means
of
new
to
load
containing
thus
in a
Using
a
specified
the
location).
and
to
completely electronic computer, the ENIAC.
Mauchly
storage
the
numbers,
to
of
com-
successive
according
simple
sign
which
The
be m a d e
place
some
high-speed
at
extract
sequence
on
same
numbers
extract
could
be
numerical
operate.
then
from
it
could, when
easily
in
device
pro-
of o p e r a t i o n s
p e r f o r m e d , s h o u l d be c o d e d into
storage
the
fundamental
'instructions',
the sequence
instruction
t h e U n i v e r s i t y of P e n n s y l v a n i a o n t h e
numbers.
of
ENIAC
calcu-
a
time
might
S o m e t i m e in t h e s u m m e r of 1944, w h i l e
under-
with
length
200
general-purpose
which
the
from
lator. M a n u a l l y o p e r a t e d calculators
mechanical
the
ENIAC was certainly fast:
took
the
pletely
went
and
multiplication 3 milliseconds
the
to w h i c h she added explanatory appendices
were three times
tion
have b e e n no a t t e m p t to c o n s t r u c t a c o m automatic
wires,
Babbage's
of
late
plug-in
anything
facilities.
a n d J . P. E c k e r t u n d e r a c o n t r a c t w i t h
In t h e s a m e y e a r , L a d y A u g u s t a
daughter
of
Menabrea,
mathematician.
much
that
life
mecha-
be
days. The
Goldstine,
what
multi-
Babbage
called
would
programmed
Thus
now
automatic
which
for
disas-
trous.
arbitrary s e q u e n c e of arithmetic
overflow
and
system
results
its s i g n . H e a l s o p r o v i d e d f o r t h e
the
Engine,
and
required to set up a n e w calculation
the
there was
of
to
t u n e w a s not sufficient to p a y for t h e
constructing
switches
the
was
machine.
on some specified storage column changed
detection
how
for-
of
even
(see
substantial
The
loom.
Babbage
w o u l d need to vary
The
relation
be exploited
kind used for controlling the
remarkable
recurrence
of
w a s to be p r o v i d e d by perforated c a r d s
With
165).
a
results
the
the warp threads
of
repetitive n a t u r e of t h e c a l c u l a t i o n
columns
arithmetic
means
and
calcu-
numbers
or
for
column
of
and
the
her
—
for
store
placed
a thousand
each
sequence
its
internal
complete
lating
it
have
a
more
O n e of
program
by
require
gives
himself.
modern —
intervention,
would
Babbage
completely
w a s to operate w i t h o u t h u m a n
would
than
few
seconds
hundreds
preparing
the
of
a
instruc-
computer
for
a
calculation.
The von Neumann and Goldstine
also
an
describe
the
programs
(already
and
means
the
(sequences
of
use
of
a
foreseen
by
by
which
instructions
for
reports
library
of
Babbage)
sub-routines
performing
163
The first programmer,
Ada Augusta, the
Countess of Lovelace, and (opposite) the first
programm,
prepared by Lady Lovelace in 1842
for calculating
the Bernoulli numbers on
Babbage's Analytical
Engine.
(Reproduced
from Lord Bowden's
book
'Faster Than Thought' with
acknowledgement
to Lady
Wentworth).
frequently occurring operations),
in a f o r m w h i c h
final
position
'relocated'
was
in
the
before
prepared
i n d e p e n d e n t of
store,
the
their
could
beginning
be
of
a
calculation.
One
was
effect
to
This
the
a
race
headed
of
of
start
was
by
M.V.
into
shortly
won
Wilkes
Cambridge,
came
1946 s u m m e r
school
computer-building
the
University
EDSAC
operation
behind
a
of
whose
in
came
race.
by
computer
May
the
team
1949.
Only
University
M a n c h e s t e r w i t h its c o m p u t e r
of
incorporating
the first index registers.
a b o v e c a n b e w r i t t e n in F o r t r a n as f o l l o w s :
The
Vanishing
Programmer
SUM
=
0.0
D O 10 J =
The
designers
assumed
of
that
the
early
programming
computers
would
t h e h a n d s of a s m a l l g r o u p of
probably
in
specialists,
that
it
w o u l d be undesirable to m a k e the task
too
easy.
mathematicians,
be
For
example,
and
von
Neumann
and
10 S U M
where
the
In t h i s
=
SUM
asterisk
way,
it-yourself
1,16
+
A(J)*B(J)
denotes
activity,
to
those
job
whose
and
multiplication.
became
the
remain
in
it w a s
have
been
successfully
programmed
to
algebra
and
calculus.
programming
programmers
computers
only
a
'do-
(and
is)
were
to
write
in
logy.
an
represents
an effort to
binary
render a
point
thorough
'software'
of
the
modern
computer.
the
problem
unnecessary,
and
t h a t t h i s is a s t e p i n a d o u b t f u l
we
direction'.
Thinking along the s a m e lines, the
sity
of
Manchester
computer
all
a
programming
instructions
group
of
adopted
32
were
Univer-
for their
code
in
constructed
teleprinter
feel
first
which
from
characters.
a
Thus
t h e s e q u e n c e of instructions for c a l c u l a t i n g
a
sum
+
a 16 b u
of
the
form
ai bi
a2 b2
the
languages,
of
offered
perhaps
not
This
simplified
which
began
difficulties
be
Fortran
for
however,
of c o m p u t e r s
customers.
of
were
Gradually,
led
to
in 1957) h a s b e e n o n e of t h e m o s t s u c c e s s ful.
164
The
sequence
of
instructions
given
The
user
electric
of
Institute of
such
typewriter
a
project
Techno-
system
which
is
sits
at
connected
programs
ignoring
electronic
ly
typewriters.
non-numerical
providing
rapidly
a
similar
In
servicing
If
be
from
one
connected
to
make
language
into
suitable
equip-
ment, they can read printed text or
control
tools.
The
to
programmed
only
from
seems
speed
lie
limit
to
their
their finite —
in
and
the
but
programme
them.
everydata
(in t h e f o r m of p u n c h e d c a r d s or p e r f o r a t e d
p a p e r tape) a r e usually p l a c e d in a
which
they
wait
The
until
results
'backing-store'
printed.
The
delay
constitutes
delay
many
is
not
computer
by
the
users
to
other
computer
acceptable.
is
sequence,
between
long ;
a
and
no
existence
typing
reply
a
request
becomes
computer
could
at
provide
and
intolerably
present
an
s e r v i c e to all of t h e 250 or so p e o p l e
who
use
day.
the
main
Perhaps
big
CERN
there
enough
computer
never
and
fast
will
each
be
computers
enough
to
provide
this k i n d of o n - l i n e s e r v i c e to all w h o
to
use
them.
continue
to
If
become
and
cheaper,
may
become
the
small
simultaneously
use
the
of
a
want
computers
big
exception
faster
computer
rather
than
future
be
these
see
example,
development,
a
continuing
hoped-for
merely
but
and
the
will
the
ciently
we
the
skill
relief
happen
shall
increase
'substitution
for
for
What
this
in
adequate
by
hours.
For
delay
equitably
in
t h e rule. B u t w h a t e v e r t h e d i r e c t i o n of
'turn-around-time',
applications,
time
the
be
large-
until they c a n
often a m o u n t i n g to several
For
generated
introduced
the
queue
can
may also queue on s o m e
capacity
queues
they
its
receiving
storage
intellectual
o n e ' s p r o g r a m at o n c e , p r o g r a m s a n d
in
sharing
service
fact,
the
can
translations
programs
(introduced
Massachusetts
indifferent g a m e of chess. T h e y c a n
poor
of
programming
objection
time-sharing
them.
processed.
the
a
users,
to
discouraging
of the
arithmetic
Since a computer cannot execute
retained
of
between
T
Manches-
introduction
U n f o r t u n a t e l y , if t h e r e a r e t o o m a n y
Computers
limitations of t h o s e w h o
was
the
a
result ?
play a g o o d g a m e of draughts, but only an
tasks.
£ E Q G
computer
the
do
also perform
to
might
development
quickly, could
—
whether
prospective
that
ever-increasing
code
receiving a printed
t h e f a c t t h a t t h e c o m p u t e r is s i m u l t a n e o u s -
to
capacity,
manufacturers
programming
realized
invented
/ U U F
commercially !
wonder
soon
machine
programming
University
was
computer,
Gap
capabilities, apart
w h e n e n g i n e e r e d versions of t h e
ter
It
Communication
O i l l :
E / /
sale
The
another.
I U K
change
or data a n d receives b a c k results,
V E Q O
/
This
+
became
minor
t o a l a r g e c o m p u t e r a n d t y p e s in
m a t h e m a t i c a l u n d e r s t a n d i n g of at least p a r t
of
a
c o n s o l e system similar to the M A C
the-scenes
floating-point
floating
algebra
In p r i n c i p l e , t h e a n s w e r to t h i s
lies
programs which constitute the vital'behind-
built-in
The
simple
do
to
making
formula and
against
providing
to
hours
the complicated compilers and
arithmetic:
wants
between
Goldstine presented the following argument
supervisory
who
b y c o m p u t e r if h e m u s t w a i t s e v e r a l
full-time
business
But
do
of
of
of
the
when
human
intellect
relieved
remains
in
Babbage's
machinery,
the
human
human
the
be
not
hand,
intellect'.
human
have
to
the
presumably
been
seen.
hand
suffi-
C
0
S s
Indication of
& ft
0 0 Variables Variables change in the
Acted Receiving Value on
0
Upon
0
9
8
Results
% %
Statement of Results
any
Variable
i
I
fF,='F,)
VF.-'F,/
I
X %
X %
2
-
-
3
+ % + 'F, F. • • fF,='F,l =
I'F, = F J
4
+
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'F, . •
= 8«
fF,='F,| = s « - 1
I'F, ='FJ
0
0
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1
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0
2
0
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4
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0
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n
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2
n
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!
%
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!
F, V
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'F,
r
10
X
'F„
x %%
II
+ % + 'F,>%•
•
12
-
•
13
r
T
%•
•
fF,='F,l =
I'F, =7,/
fFi
l
= Vi\
•
.
.
.
fF„ = 'F„1 =
V
%
-
%
fF^'F.l
'F, • • I'F, = ' M =
f'F, ='F,1 =
i'F, = 'F j
«-2(=2)
2?!-
•
•
•
.
-
16
i)
i8<
/
'F,
x % %.
'F,
-
+ \ + F, V
!
19
'F,
20
\ 'F,
21
X
22
i
23
'F, *F,.
'F»
T
'7, % •
x%
%.
x %V
.
.
.
0
0
0
n
2
, 1
.
2»-
0
::
- - - - - -
3
2n — 2
2
-
- - - - - - - - -
•
,
- - - -
2
• •
-
1
- -
. fF,='F,l
272
- -
VFn-'Fj " 2 "
= 'FJ
a
„
I
21! - 2 ^
3 ' 4 "
2?! 2 f i -
2 3
I
-
3
2»- 2
%-'F,
(% = 'F,,1
• I'Fi-'F,/ = « - 3 ( = i ) .
.
+%
+
%•
I
3
!(
3
- -
.
25
+ 'F,
+ 'F, 'Fi •
-
-
0
H-y
-
1
4
/2l! 21J~
0
W
3 ' 4
1
.
ft-3
-
I
2* 3
2
in-
2 4
0
0
1 2n- 1
.
~?27+T^
j I 2 1 2 - 1 ^ 212J
1 2 * 212 + I
21
1 1
4
-- - -
»+ i
Q
-
2
k
212-2
I
t
-
. 1
ff
4
212 212-
• •
.
1
in - 1
0
• f F ^ ' F , , ! = B;
rF = 'FJ
I'F, ='F,\ = 12 + 1 = 4 + 1 = 5
' F , ='FJ
. 'F, ='F, by a Variable-card
I'F, ='F, by a Variable-card
+
0
3
Here follows a repetition of Operations thirteen to twenty-three
24
- I
i~
. .
.
1 2fl
2 ' in
2 ™
4
fF„ = ' W
•IV'FJ =^ +^ +M.
0
0
0
I
2B- 2
in-
20 -
0
+ I
in - 1
-- - - -
=!F,1 2 f l - 2
4
fF,
2B
2
1
%
0
n-
-
--- - - -
I
%
0
+ I
2B-
fF,='M
• VF, = FJ = 3 + i = 4 •
0
0
0
%
0
0
• 1
.
.
% + % 'Fa-
V
2H
I
"a'
fF
0
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in
in
3
f'F^'F.I
• I'F, ='F,I =
•
0
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hi
-
1
211 212 -
•
-
-
.
I
2 + 1 = 3
2(1-
fF,='F,l
'F, • • l'F,='F,J
+ %±%
0
0
0
817
D
- - • - - - - - in
.
;
15
0
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_ _
2
fF„ = F ) = B , . - = U
. .
l'Fu = ' F j
2
2»- I
2fl
fF = 'Fol = -- 1,——
+ !>!.- .
2 212+1
2
K-'FJ
I
•
2 + 0 = 2
-5-4,
%
% + 'F, %
I
%
0
1 2 8 - 1
u
9
14
1 2!-
I'F, = 7 , / a " an + i
• fF =%i
l
l'F„ = ' W
fF.^F.1
= » - ! ( = 3) • •
•
I'F, ='KJ
.
in
0
in +1
•
8 + 'F, + 'F, %.
>F,
S»- I
•h=»Fj
D
- --
X
0
V, % %
%
0
1
2» + I
!
5
6
Result Variables
Working Variables
Data
1
0
'F ...
I(
0
0
0
0
h

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