7/23/2019 Ergonomics for a computer
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r The
prototype
computer. 2
The
latestveÍsion redesigned
'l
t
I
according to ergonomic
principles.
uexen
E M I ElectronicsLtd.
'|
|
i
reset
from
one
problem
to solve
another;
easeofopera-
tion
and
avoidance
of
operator
mistakes
are therefore
essential.
Such
mistakes
are
far more
troublesome
han
loss of speedor machine inaccuracy'
A correct
setting,
but
on
a
wrong
potentiometer
-
or a switch
left
in the
wrong
position
-
can
ruin
the solution
of a
problem
and
cause
much
delay
while
the fault
is found.
Even
worse,
the
error
in the
solution
may
not be
discovered.
Therefore
the risk
of
these
mistakes
must
be reduced
to the
minimum
by
proper
attention
to ergonomlc
factors.
During
the
redesign
of EMIAC
II,
at
EMI
Elec-
tronics
Ltd,
advice
from
the
firm's
engineering
psychology laboratory
was sought
on
various
aspects
f
the operational
layout;
the
prototype, r,
was
already
fairly
satisfactory,
but
the
project
team
wished
to
make
every possible mprovement.
Ergonomics
for
a,
Gomputer
AN
ANALocuE
coMPUTER
s
an assembly
of many,
similar,
electronic
'building
bricks'
which
can
be
con-
nected
together
in a multitude
of different
ways.
The
input and output leads of the amplifiers, integrators,
and
function
potentiometers are
all brought
out sepa-
rately
to sockets
on the
'patch
panel',
which
is thus
very
similar
to a telephone
exchange
switchboard.
By
mak-
ing the
appropriate
interconnections
the operator
can
'patch
up'
the computer
to
solve
most
problems
which
can be
defined
in
suitable
mathematical
terms.
Analogue
computers
are
particularly
useful
to simu-
late
and optimize
the
design
and working
of complex
devices
with several
interdependent
variables,
such
as
suspension systems
of motor
cars
or
chemical
pro-
cessing factories
with
continuous
flow.
Flexibility
is an
important
feature
of
an analogue
computer,
so
that it can
quickly
and
accurately be
DÉSIGN
I2O
7/23/2019 Ergonomics for a computer
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t È
ElïfIAC
I
I
panel
major
problem in this
study
was the
panel
of
z4
potent io-
all of
which
may have
to be selected
one
at a t ime
by
an
switch
and adjusted
very carefully
to an
exact
value
meter.
Unless the layout is clear and simple, there is a risk
up the
wrong
potent iometer
or of start ing
to
adiust one
already
been
set, with
consequent
annoyance
and risk
the
prototype, to economise
in space,
the
potent iometers
staggered
at
45"
to
each other
and the
jack
sockets,
through
electrical
connect ion
is
made
to the
potent iometers' were
them.
The
result
is somewhat
confusing
and there
for numbers
to
ident ify
each
iack
socket,
3.
Despite
electronic
complicat ion
and sl ight
increase
in
panel
size
it
agreed
to use
push-pull switches
with
a number on
the knob
iack
sockets;
the design
problem therefore
was to
a
layout with
which
the sequence
of operations
-
frsr,
find
the switch,
second,
frnd
the
potentiometer,
third,
it, and,
ourth,
turn off
the switch
-
would
be done
most
and
with the
least
error.
method of
tackling
this,
as with all
ergonomic
problems,
was
I2 O
f irst to
refer to
results of
all relevant
research
;
it was
found,
how-
ever,
that the
evidence
in the
literature
was
not adequate
to allow
of
reliable
extrapolat ion
to
solve the
problem.
Therefore
an
expcri-
ment2, had to be made which resulted in the optimum layout, 4.
I t was suggested
init ial ly
that
a rotary selector
switch
should
be
used
instead of
the
iack
sockets.
This
proved impract ical
electroni-
cally,
but
the discussion
and explanat ion
brought
to l ight
a way in
which
part
ofthe
basic engineering
circuit
could be
improved.
This
is
quite
a common
experience
during
ergonomic
redesign
studies;
explaining the
machine
to
someone
with
a dif ferent
specialist
approach
st imulates
the engineering
team
to reconsider
it s
system
from a fresh
viewPoint.
r See
for instance:
Applied experinental
psycholggy,,
. Chapanis'
\ í . R. Garner
and
C. T.
Mbrgan. Chapman
and
Hall
Ltd,
f,z
tz s
Hwnan
engineering
gtide
fot
equipnent
designets'
W. E.
Woodson' CUP
{ r
6s.
Data on
hunpn
perJornnnce
fot
engineeting
designers,
K.
F. H. Murrell'
reprint
from Ezgineering,
3s
Y'f
{r:if:;o,'"r;9*ÊWÍ,ïi;*h.3X'J""f
L'Y;i;.51'ïX'
H. K. Lewis & Co Ltd, dr Is .
zAnote
on
Danel
layout
for
nuntbets
of ident ical
irerts,
B, Shackel,
to be
publ ished
iÁ Ergononics.
Taylor and
Francis
Lt d
continued
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I i rgonomics lbr
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Patch
panel
r \ l t housh appr rcn t l l ' con iusing i rnd c l cn l ï i r rh t cn ing
to
rh c
u n i n i t i a t c t l , r h i s
p a n c l , 5 ,
s i m p l v
c o n s i s t so i i n p u r a n d o u r p u r
sockets i r r thc t8 ampl i i ic rs and z-1
potcnt iometers .
r i ong
rr i t l r
som ' intc rconncct ing
iunc t ion
l incs.
' l 'hc
brs ic
eroup ine
into t8
b locks oi r lmos t
i t l cn t i ca l
sockcts ,along l i th thc : ;pcc ialss i tching
gr ( )up
r t thc lc { t h i r r r t l cnd. rcc lui rcei
ex t ra cmplrrs is . ó, t r i cnsure
cas l 'sc lcc t ion ol t hc r iqht so ckct cvcn
uhcn
manv
plugs
obscurc
nuch oi thc
panc l
sur lacc .
( l obur -coc i i ng
*as cons idcrcd,bu t
rbout s ix c l i f lc rcnt hucs uould bc nccdcd; th e rcsul t ing dazz lc
n
l c ro r r , dc r l r ca uou ld
probab l l , bc
rnorc o1 r i i is tmct ion than
hc lp . l Lar ion l l i s l ti on o1 a numbc r o l r l c t r i l s t o m in i r l i se rhc r i s kol
crror c tn bc
scen
bt eomplp j l l g t hc l r vo l l t ouTs .
1 " - i * I * f f i w . * . : .
"í *
8
l ) l i s t ( i \ I 2 0
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panel
Íul l
opcrat ing
sequcncc
must
bc
knorvn
belbrc
clccidirrg
rm _
panel
layouts;
only bv
analysing
thc
various
sub-rourrncs
elated
controls
bc
properly
grouped
together.
Crit ical
adjust_
and
master
controll ing
act ions
arc usuallv
made
with
th c
hand
(thc
right
hand
for
most
of the populat ion;
an d
such
conrrols
should
be
placed
casily
for
the
right
hancl,
associatcd
less
crit ical
switchcs
to
thc leÍ i.
that the
main
changc,
T
ancl
g,
u,as
to
intcrchange
Meter
F
S D switch
and
the
accuratc potcnt iometcr
with rhe
graduated
dial ;
p rev ious ly
the
opc ra to r
rvou ld
t cnd ro
opcratc
th c
metcr
switch
u' ith
thc
lelt hand,
thus
obscuring
the
meter
he
wa s
about
to read,
so as
to use
his
right
hand
Íbr
crit ical
adjustmcnt.
Thc
master
control
is
Rorv
A switch
and
is thercforc
in
thc corrccr
posit ion;
thc
ot lter
groups
of amplif iers
are
usually
undcr
it s
control,
and
thercfore
Row
B
and
Row
C switchcs
arc
in thc
less
rmportant
corncrs
of the pancl.
Other
changes
in
dctails
improvc
thc idcnt if icat ion
of su' i tch posit ions
and group
rclated
ircms
togethcr.
, t* :
"s_
ri
$eï
n*Brulf
*
r&
'-fr
)
_$t
1::'J
l
Pt}'
tt ï
{il"
RÓlV Á
Some
time
after
the
study
had
finishcd
an
opportunity
arose
to
ask
the recipient
of the prototvpe
model,
the
Hawker
Siddeley
Nuclear
Porvcr
Co
Ltd,
íor
crit ic isms
of its
operat ion.
I t rvas
pleasing,
if
not
unexpected,
to
f ind that
comments
from
at
least
three months' operat ing of the machine had all been predicted by
rhe
ergonomic
redes ign
study.
px:{
\ '
gE
brief
example
of how an
electronic
machine
is
studied
rn
o improve
the
ergonomic
aspects
of i ts
design,
only the
obvious
points
have
becn
mentioned.
To
the design
engi_
technologists,
who
are at
prcsent
the
chief users
of this
of machine, some of the more detailed aspects u, i l l be
rom
the i l lustrat ions,
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