<s>
A	O
serial	B-Device
computer	I-Device
is	O
a	O
computer	O
typified	O
by	O
bit-serial	B-General_Concept
architecture	I-General_Concept
i.e.	O
,	O
internally	O
operating	O
on	O
one	O
bit	O
or	O
digit	O
for	O
each	O
clock	O
cycle	O
.	O
</s>
<s>
Machines	O
with	O
serial	O
main	O
storage	O
devices	O
such	O
as	O
acoustic	O
or	O
magnetostrictive	O
delay	O
lines	O
and	O
rotating	B-General_Concept
magnetic	I-General_Concept
devices	I-General_Concept
were	O
usually	O
serial	B-Device
computers	I-Device
.	O
</s>
<s>
Serial	B-Device
computers	I-Device
require	O
much	O
less	O
hardware	O
than	O
their	O
parallel	B-Operating_System
computing	I-Operating_System
counterpart	O
,	O
but	O
are	O
much	O
slower	O
.	O
</s>
<s>
There	O
are	O
modern	O
variants	O
of	O
the	O
serial	B-Device
computer	I-Device
available	O
as	O
a	O
soft	B-Device
microprocessor	I-Device
which	O
can	O
serve	O
niche	O
purposes	O
where	O
size	O
of	O
the	O
CPU	O
is	O
the	O
main	O
constraint	O
.	O
</s>
<s>
The	O
first	O
computer	O
that	O
was	O
not	O
serial	O
(	O
the	O
first	O
parallel	B-Operating_System
computer	I-Operating_System
)	O
was	O
the	O
Whirlwind	B-Device
in	O
1951	O
.	O
</s>
<s>
A	O
serial	B-Device
computer	I-Device
is	O
not	O
necessarily	O
the	O
same	O
as	O
a	O
computer	O
with	O
a	O
1-bit	O
architecture	O
,	O
which	O
is	O
a	O
subset	O
of	O
the	O
serial	B-Device
computer	I-Device
class	O
.	O
</s>
<s>
1-bit	O
computer	O
instructions	O
operate	O
on	O
data	O
consisting	O
of	O
single	O
bits	O
,	O
whereas	O
a	O
serial	B-Device
computer	I-Device
can	O
operate	O
on	O
N-bit	O
data	O
widths	O
,	O
but	O
does	O
so	O
a	O
single	O
bit	O
at	O
a	O
time	O
.	O
</s>
<s>
Most	O
of	O
the	O
early	O
massive	B-Operating_System
parallel	I-Operating_System
processing	I-Operating_System
machines	O
were	O
built	O
out	O
of	O
individual	O
serial	B-General_Concept
processors	I-General_Concept
,	O
including	O
:	O
</s>
