<s>
In	O
personal	B-Device
computing	I-Device
,	O
a	O
tower	O
is	O
a	O
form	O
factor	O
of	O
desktop	B-Device
computer	I-Device
case	I-General_Concept
whose	O
height	O
is	O
much	O
greater	O
than	O
its	O
width	O
,	O
thus	O
having	O
the	O
appearance	O
of	O
an	O
upstanding	O
tower	O
block	O
,	O
as	O
opposed	O
to	O
a	O
traditional	O
"	O
pizza	B-General_Concept
box	I-General_Concept
"	O
computer	B-General_Concept
case	I-General_Concept
whose	O
width	O
is	O
greater	O
than	O
its	O
height	O
and	O
appears	O
lying	O
flat	O
.	O
</s>
<s>
Compared	O
to	O
a	O
pizza	B-General_Concept
box	I-General_Concept
case	I-General_Concept
,	O
the	O
tower	O
tends	O
to	O
be	O
larger	O
and	O
offers	O
more	O
potential	O
for	O
internal	O
volume	O
for	O
the	O
same	O
desk	O
area	O
occupied	O
,	O
and	O
therefore	O
allows	O
more	O
hardware	B-Architecture
installation	O
and	O
theoretically	O
better	O
airflow	O
for	O
cooling	B-General_Concept
.	O
</s>
<s>
Although	O
the	O
traditional	O
layout	O
for	O
a	O
tower	O
system	O
is	O
to	O
have	O
the	O
case	O
placed	O
on	O
top	O
of	O
the	O
desk	O
alongside	O
the	O
monitor	B-Device
and	O
other	O
peripherals	O
,	O
a	O
far	O
more	O
common	O
configuration	O
is	O
to	O
place	O
the	O
case	O
on	O
the	O
floor	O
below	O
the	O
desk	O
or	O
in	O
an	O
under-desk	O
compartment	O
,	O
in	O
order	O
to	O
free	O
up	O
desktop	B-Device
space	O
for	O
other	O
items	O
.	O
</s>
<s>
Computer	O
systems	O
housed	O
in	O
the	O
horizontal	O
"	O
pizza	B-General_Concept
box	I-General_Concept
"	O
form	O
factor	O
—	O
once	O
popularized	O
by	O
the	O
IBM	B-Device
PC	I-Device
in	O
the	O
1980s	O
but	O
fallen	O
out	O
of	O
mass	O
use	O
since	O
the	O
late	O
1990s	O
—	O
have	O
been	O
given	O
the	O
term	O
desktops	O
to	O
contrast	O
them	O
with	O
the	O
often	O
underdesk-situated	O
towers	O
.	O
</s>
<s>
Tower	B-General_Concept
cases	I-General_Concept
are	O
often	O
categorized	O
as	O
mini-tower	O
,	O
midi-tower	O
,	O
mid-tower	O
,	O
or	O
full-tower	O
.	O
</s>
<s>
For	O
case	B-Architecture
modding	I-Architecture
enthusiasts	O
and	O
gamers	O
wanting	O
to	O
play	O
the	O
most	O
technically	O
challenging	O
video	O
games	O
,	O
the	O
full-tower	O
case	O
also	O
makes	O
for	O
an	O
ideal	O
gaming	B-Device
PC	I-Device
case	O
because	O
of	O
their	O
ability	O
to	O
accommodate	O
extensive	O
water	O
cooling	B-General_Concept
setups	O
and	O
larger	O
case	B-Application
fans	I-Application
.	O
</s>
<s>
Traditionally	O
,	O
full-tower	O
systems	O
had	O
between	O
four	O
and	O
six	O
externally	O
accessible	O
half-height	B-Device
5.25-inch	O
drive	B-Device
bays	I-Device
and	O
up	O
to	O
ten	O
3.5-inch	O
drive	B-Device
bays	I-Device
.	O
</s>
<s>
However	O
,	O
as	O
modern	O
computing	O
technology	O
has	O
moved	O
away	O
from	O
mechanical	O
removable	B-Device
media	I-Device
drives	O
toward	O
solid-state	O
devices	O
such	O
as	O
USB	O
flash	O
drives	O
,	O
solid-state	B-Device
drives	I-Device
(	O
SSDs	B-Device
)	O
and	O
large-capacity	O
external	B-Device
storage	I-Device
as	O
well	O
as	O
cloud	O
storage	O
,	O
such	O
an	O
abundance	O
of	O
internal	O
and	O
external	O
drive	B-Device
bays	I-Device
is	O
less	O
common	O
.	O
</s>
<s>
More	O
recent	O
full-tower	O
cases	O
instead	O
only	O
have	O
one	O
or	O
two	O
external	O
drive	B-Device
bays	I-Device
,	O
or	O
none	O
at	O
all	O
,	O
with	O
the	O
internal	O
bays	O
moved	O
elsewhere	O
in	O
the	O
case	O
to	O
free	O
up	O
room	O
and	O
improve	O
airflow	O
.	O
</s>
<s>
Full-tower	O
cases	O
readily	O
fit	O
full-size	O
ATX	B-Architecture
motherboards	I-Architecture
but	O
may	O
also	O
accommodate	O
smaller	O
microATX	B-Device
motherboards	B-Device
due	O
to	O
the	O
former	O
standard	O
's	O
interoperability	O
in	O
mounting	O
holes	O
.	O
</s>
<s>
Full-tower	O
cases	O
may	O
also	O
have	O
increased	O
dimensional	O
depth	O
and	O
length	O
over	O
their	O
shorter	O
counterparts	O
,	O
allowing	O
them	O
to	O
accommodate	O
Extended	B-Architecture
ATX	I-Architecture
motherboards	B-Device
,	O
larger	O
graphics	B-Device
cards	I-Device
and	O
heatsinks	O
.	O
</s>
<s>
Since	O
the	O
2010s	O
,	O
full-tower	O
cases	O
are	O
commonly	O
used	O
by	O
enthusiasts	O
as	O
showpiece	O
cases	O
with	O
custom	O
water	O
cooling	B-General_Concept
,	O
RGB	O
LED	O
lighting	O
,	O
and	O
tempered	O
glass	O
or	O
acrylics	O
side	O
panel	O
.	O
</s>
<s>
They	O
may	O
also	O
hold	O
two	O
motherboards	B-Device
(	O
as	O
is	O
the	O
case	O
with	O
the	O
Corsair	O
1000D	O
)	O
and	O
dual	O
power	O
supplies	O
(	O
Corsair	O
900D	O
)	O
.	O
</s>
<s>
Mid-tower	O
cases	O
,	O
usually	O
between	O
and	O
in	O
height	O
,	O
are	O
the	O
most	O
common	O
form	O
factor	O
of	O
personal	B-Device
computer	I-Device
towers	O
.	O
</s>
<s>
Before	O
the	O
late	O
2010s	O
,	O
mid-towers	O
contained	O
between	O
three	O
and	O
four	O
5.25-inch	O
drive	B-Device
bays	I-Device
and	O
an	O
equivalent	O
number	O
of	O
3.5-inch	O
bays	O
to	O
house	O
optical	O
disc	O
drives	O
,	O
floppy	B-Device
disk	I-Device
drives	I-Device
and	O
hard	B-Device
disk	I-Device
drives	I-Device
,	O
leaving	O
just	O
enough	O
room	O
for	O
a	O
standard	O
ATX	B-Architecture
motherboard	I-Architecture
and	O
power	O
supply	O
unit	O
.	O
</s>
<s>
Since	O
the	O
widespread	O
adoption	O
of	O
USB	O
flash	O
drives	O
,	O
solid-state	B-Device
drives	I-Device
(	O
which	O
take	O
up	O
far	O
less	O
space	O
than	O
spinning	O
hard	B-Device
disk	I-Device
drives	I-Device
)	O
and	O
the	O
declining	O
usage	O
of	O
internal	O
optical	O
drives	O
,	O
the	O
number	O
of	O
drive	B-Device
bays	I-Device
has	O
become	O
less	O
of	O
a	O
concern	O
to	O
the	O
contemporary	O
computer	O
user	O
,	O
the	O
internal	O
space	O
of	O
mid-towers	O
is	O
now	O
used	O
more	O
commonly	O
for	O
closed-loop	O
water	O
coolers	O
,	O
dual	O
graphics	B-Device
cards	I-Device
,	O
and	O
tightly	O
stacked	O
SSDs	B-Device
.	O
</s>
<s>
Mini-tower	O
cases	O
,	O
between	O
and	O
in	O
height	O
,	O
slot	O
between	O
the	O
Mini-ITX	B-Architecture
specification	O
for	O
small-form-factor	B-Device
PCs	I-Device
and	O
the	O
archetypal	O
mid-tower	O
.	O
</s>
<s>
Mini-towers	O
typically	O
will	O
only	O
accommodate	O
microATX	B-Device
motherboards	B-Device
and	O
for	O
this	O
reason	O
sell	O
in	O
fewer	O
numbers	O
in	O
the	O
consumer	O
market	O
than	O
the	O
other	O
size	O
classes	O
of	O
computer	B-General_Concept
towers	I-General_Concept
.	O
</s>
<s>
Traditionally	O
,	O
mini-towers	O
had	O
only	O
one	O
or	O
two	O
disk	O
drive	B-Device
bays	I-Device
(	O
either	O
5.25-inch	O
or	O
3.5-inch	O
)	O
.	O
</s>
<s>
The	O
tower	O
form	O
factor	O
may	O
be	O
seen	O
as	O
a	O
proportional	O
miniaturization	O
of	O
mainframe	B-Architecture
computers	I-Architecture
and	O
minicomputers	B-Architecture
,	O
some	O
of	O
which	O
comprise	O
massive	O
tall	O
enclosures	O
standing	O
almost	O
to	O
the	O
ceiling	O
.	O
</s>
<s>
In	O
the	O
advent	O
of	O
the	O
microcomputer	B-Architecture
era	O
,	O
most	O
systems	O
were	O
configured	O
with	O
the	O
keyboard	B-Device
built	I-Device
into	I-Device
the	I-Device
same	I-Device
chassis	I-Device
that	O
the	O
main	O
system	O
circuit	O
board	O
resides	O
.	O
</s>
<s>
Such	O
computers	O
were	O
also	O
termed	O
home	O
computers	O
and	O
counted	O
such	O
popular	O
systems	O
as	O
the	O
Apple	B-Device
II	I-Device
,	O
TRS-80	B-Device
,	O
VIC-20	B-Device
,	O
and	O
Commodore	O
64	O
,	O
among	O
others	O
.	O
</s>
<s>
In	O
1981	O
,	O
IBM	O
introduced	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
,	O
a	O
system	O
which	O
was	O
met	O
widespread	O
adoption	O
in	O
both	O
enterprises	O
and	O
home	O
businesses	O
within	O
a	O
couple	O
years	O
and	O
set	O
a	O
new	O
de	O
facto	O
standard	O
for	O
the	O
physical	O
configuration	O
of	O
microcomputers	B-Architecture
.	O
</s>
<s>
The	O
IBM	B-Device
PC	I-Device
and	O
successors	O
housed	O
the	O
system	B-Device
board	I-Device
and	O
expansion	B-Device
cards	I-Device
in	O
a	O
separate	O
horizontal	O
unit	O
,	O
with	O
the	O
keyboard	O
usually	O
in	O
front	O
and	O
the	O
prescribed	O
CRT	B-Device
monitor	I-Device
resting	O
on	O
top	O
of	O
the	O
system	B-General_Concept
unit	I-General_Concept
;	O
the	O
front	O
of	O
the	O
system	B-General_Concept
unit	I-General_Concept
houses	O
one	O
or	O
more	O
disk	O
drives	O
.	O
</s>
<s>
In	O
1982	O
,	O
NCR	O
introduced	O
the	O
Tower	O
series	O
of	O
workstation	B-Device
computers	I-Device
,	O
named	O
so	O
for	O
their	O
tall	O
,	O
upright	O
configuration	O
,	O
intended	O
to	O
be	O
stowed	O
away	O
under	O
a	O
desk	O
.	O
</s>
<s>
The	O
first	O
,	O
the	O
Tower	O
1632	O
,	O
is	O
29	O
inches	O
tall	O
and	O
featured	O
a	O
Motorola	B-Device
68000	I-Device
microprocessor	I-Device
.	O
</s>
<s>
Costing	O
upwards	O
of	O
$12	O
,	O
500	O
,	O
the	O
1632	O
is	O
meant	O
to	O
run	O
Unix	B-Application
and	O
supports	O
up	O
to	O
16	O
simultaneous	O
networked	O
users	O
.	O
</s>
<s>
In	O
1983	O
,	O
Tandy	O
Corporation	O
offered	O
their	O
Tandy	B-Device
2000	I-Device
with	O
an	O
optional	O
floor	O
stand	O
,	O
turning	O
the	O
normally	O
horizontal	O
desktop	B-General_Concept
case	I-General_Concept
on	O
its	O
side	O
and	O
allowing	O
it	O
to	O
be	O
stashed	O
under-desk	O
;	O
the	O
square	O
badge	O
on	O
the	O
Tandy	B-Device
2000	I-Device
can	O
be	O
removed	O
and	O
rotated	O
upright	O
in	O
turn	O
.	O
</s>
<s>
IBM	O
followed	O
suit	O
with	O
their	O
PC/AT	B-Operating_System
in	O
1984	O
,	O
which	O
included	O
an	O
optional	O
"	O
floor-standing	O
enclosure	O
"	O
for	O
$165	O
.	O
</s>
<s>
Of	O
the	O
three	O
initial	O
entrants	O
in	O
the	O
company	O
's	O
RT	B-Device
PC	I-Device
line	O
in	O
1986	O
,	O
two	O
were	O
tower	O
units	O
,	O
while	O
the	O
other	O
was	O
a	O
traditional	O
horizontal	O
case	O
like	O
the	O
AT	O
and	O
the	O
PCs	B-Device
before	O
it	O
.	O
</s>
<s>
In	O
1987	O
,	O
IBM	O
introduced	O
the	O
PS/2	B-Device
Model	I-Device
60	I-Device
,	O
an	O
initial	O
entry	O
in	O
the	O
company	O
's	O
Personal	B-Device
System/2	I-Device
line	O
of	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
It	O
was	O
IBM	O
's	O
first	O
Intel-based	O
PC	O
built	O
entirely	O
into	O
a	O
tower	B-General_Concept
case	I-General_Concept
.	O
</s>
<s>
The	O
PS/2	B-Device
Model	I-Device
60	I-Device
was	O
comparable	O
in	O
technical	O
specification	O
to	O
its	O
sibling	O
the	O
PS/2	B-Device
Model	O
50	O
,	O
which	O
sported	O
a	O
horizontal	O
desktop	B-Device
form	O
factor	O
.	O
</s>
<s>
Whereas	O
the	O
Model	O
50	O
had	O
only	O
four	O
expansion	B-Device
slots	I-Device
and	O
three	O
drive	B-Device
bays	I-Device
,	O
however	O
,	O
the	O
Model	O
60	O
featured	O
eight	O
expansion	B-Device
slots	I-Device
and	O
four	O
drive	B-Device
bays	I-Device
.	O
</s>
<s>
Because	O
of	O
the	O
latter	O
's	O
increased	O
potential	O
for	O
connectivity	O
and	O
multitasking	O
,	O
technology	O
journalists	O
envisioned	O
the	O
PS/2	B-Device
Model	I-Device
60	I-Device
as	O
a	O
multiuser	O
machine	O
,	O
although	O
multiuser	O
operating	O
systems	O
supporting	O
the	O
80286	B-General_Concept
processor	O
of	O
both	O
the	O
Models	O
50	O
and	O
60	O
were	O
hard	O
to	O
come	O
by	O
in	O
1987	O
.	O
</s>
<s>
IBM	O
followed	O
up	O
with	O
the	O
tower-based	O
PS/2	B-Device
Model	I-Device
80	I-Device
later	O
that	O
year	O
,	O
their	O
first	O
PC	O
powered	O
by	O
an	O
i386	B-General_Concept
processor	O
.	O
</s>
<s>
According	O
to	O
The	O
New	O
York	O
Times	O
in	O
1988	O
,	O
the	O
PS/2	B-Device
Models	O
60	O
and	O
80	O
started	O
the	O
trend	O
of	O
computer	O
manufacturers	O
offering	O
PC	O
compatibles	O
in	O
optional	O
tower	O
form	O
factors	O
:	O
</s>
<s>
A	O
countertrend	O
is	O
to	O
take	O
PCs	B-Device
off	O
the	O
desk	O
and	O
put	O
them	O
on	O
the	O
floor	O
.	O
</s>
<s>
IBM	O
started	O
it	O
with	O
the	O
tower	O
configuration	O
for	O
its	O
PS/2	B-Device
Models	O
60	O
and	O
80	O
,	O
and	O
at	O
least	O
a	O
dozen	O
companies	O
were	O
showing	O
floor-standing	O
PCs	B-Device
at	O
Comdex	O
.	O
</s>
<s>
Freed	O
from	O
the	O
need	O
to	O
fit	O
on	O
a	O
desk	O
,	O
some	O
of	O
the	O
tower	O
models	O
are	O
actually	O
getting	O
bigger	O
to	O
accommodate	O
large	O
disk	O
drives	O
,	O
a	O
variety	O
of	O
floppy	B-Device
drives	I-Device
and	O
backup	O
devices	O
,	O
and	O
room	O
for	O
up	O
to	O
a	O
dozen	O
slots	O
for	O
plug-in	O
boards	O
.	O
</s>
<s>
Aftermarket	O
floor	O
stands	O
,	O
allowing	O
existing	O
horizontal	O
desktop	B-Device
computers	I-Device
to	O
be	O
stored	O
upright	O
on	O
the	O
floor	O
,	O
were	O
sold	O
in	O
the	O
late	O
1980s	O
by	O
companies	O
such	O
as	O
Curtis	O
Computer	O
Products	O
.	O
</s>
<s>
The	O
transition	O
in	O
dominance	O
from	O
horizontal	O
desktop	B-Device
computers	I-Device
to	O
towers	O
was	O
mostly	O
complete	O
by	O
1994	O
,	O
according	O
to	O
a	O
period	O
article	O
in	O
PC	O
Week	O
.	O
</s>
<s>
Computer	B-General_Concept
cases	I-General_Concept
or	O
pre-built	O
systems	O
offered	O
in	O
the	O
traditional	O
horizontal	O
form	O
factor	O
have	O
since	O
been	O
separately	O
categorized	O
as	O
desktops	O
,	O
to	O
contrast	O
them	O
with	O
the	O
usually-floor-situated	O
towers	O
.	O
</s>
<s>
Brian	O
Benchoff	O
of	O
Hackaday	O
argued	O
that	O
the	O
popularity	O
of	O
the	O
Macintosh	B-Device
Quadra	I-Device
700	I-Device
was	O
the	O
turning	O
point	O
for	O
computer	O
manufacturers	O
to	O
move	O
over	O
to	O
the	O
tower	O
form	O
factor	O
en	O
masse	O
.	O
</s>
<s>
The	O
tower	O
form	O
factor	O
of	O
the	O
Quadra	B-Device
700	I-Device
was	O
by	O
necessity	O
:	O
common	O
peripherals	O
of	O
the	O
Quadra	O
were	O
the	O
relatively	O
extremely	O
heavy	O
color	O
CRT	B-Device
monitors	I-Device
offered	O
by	O
Apple	O
(	O
those	O
whose	O
screens	O
measured	O
20	O
inches	O
and	O
over	O
diagonally	O
could	O
weigh	O
80lbs	O
or	O
more	O
)	O
favored	O
by	O
the	O
desktop	B-Device
publishing	O
industry	O
during	O
the	O
1990s	O
.	O
</s>
<s>
Such	O
monitors	O
threatened	O
to	O
crush	O
the	O
plastic	O
frames	O
of	O
the	O
Macintosh	B-Device
IIcx	I-Device
and	O
Macintosh	B-Device
IIci	I-Device
;	O
customers	O
might	O
have	O
been	O
tempted	O
to	O
fit	O
such	O
heavy	O
monitors	O
atop	O
the	O
IIcx	O
and	O
IIci	B-Device
because	O
of	O
their	O
horizontal	O
form	O
factor	O
.	O
</s>
