<s>
In	O
computing	O
,	O
a	O
pizza	O
box	O
is	O
a	O
style	O
of	O
case	B-General_Concept
design	O
for	O
desktop	B-Device
computers	I-Device
or	O
network	B-Protocol
switches	I-Protocol
.	O
</s>
<s>
Pizza	B-General_Concept
box	I-General_Concept
cases	I-General_Concept
tend	O
to	O
be	O
wide	O
and	O
flat	O
,	O
normally	O
in	O
height	O
,	O
resembling	O
pizza	O
delivery	O
boxes	O
and	O
thus	O
the	O
name	O
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
a	O
tower	B-General_Concept
system	O
,	O
whose	O
case	B-General_Concept
height	O
is	O
much	O
greater	O
than	O
the	O
width	O
and	O
has	O
an	O
"	O
upright	O
"	O
appearance	O
.	O
</s>
<s>
In	O
modern	O
usage	O
,	O
the	O
term	O
"	O
pizza	O
box	O
"	O
is	O
normally	O
reserved	O
for	O
very	O
flat	O
cases	O
with	O
height	O
no	O
more	O
than	O
,	O
while	O
those	O
taller	O
than	O
2	O
inches	O
are	O
referred	O
to	O
as	O
desktop	B-General_Concept
cases	I-General_Concept
instead	O
.	O
</s>
<s>
The	O
common	O
setup	O
of	O
a	O
pizza	O
box	O
system	O
is	O
to	O
have	O
the	O
display	B-Device
monitor	I-Device
placed	O
directly	O
on	O
top	O
of	O
the	O
case	B-General_Concept
,	O
which	O
serves	O
as	O
a	O
podium	B-Protocol
to	O
elevate	O
the	O
monitor	O
more	O
towards	O
the	O
user	O
's	O
eye	O
level	O
,	O
and	O
to	O
have	O
other	O
peripherals	O
placed	O
in	O
front	O
and	O
alongside	O
the	O
case	B-General_Concept
.	O
</s>
<s>
Occasionally	O
,	O
the	O
pizza	O
box	O
may	O
be	O
laid	O
on	O
its	O
sides	O
in	O
a	O
tower-like	O
orientation	O
.	O
</s>
<s>
Data	O
General	O
's	O
Aviion	B-Device
Unix	B-Application
server	B-Application
was	O
the	O
first	O
to	O
coin	O
the	O
expression	O
when	O
it	O
advertised	O
in	O
1991	O
with	O
the	O
tagline	O
"	O
Who	O
just	O
fit	O
mainframe	O
power	O
in	O
a	O
pizza	O
box	O
?	O
</s>
<s>
"	O
,	O
but	O
most	O
computers	O
generally	O
referred	O
to	O
as	O
pizza	O
box	O
systems	O
were	O
high-end	O
desktop	O
systems	O
such	O
as	O
Sun	O
Microsystems	O
workstations	B-Device
sold	O
in	O
the	O
1990s	O
,	O
most	O
notably	O
the	O
SPARCstation	O
1	O
and	O
SPARCstation	O
5	O
.	O
</s>
<s>
Other	O
notable	O
examples	O
have	O
been	O
among	O
the	O
highest-performing	O
desktop	B-Device
computers	I-Device
of	O
their	O
generations	O
,	O
including	O
the	O
SGI	O
Indy	O
,	O
the	O
NeXTstation	B-Device
,	O
and	O
the	O
Amiga	B-Device
1000	I-Device
,	O
but	O
the	O
form	O
factor	O
was	O
also	O
seen	O
in	O
budget	O
and	O
lower-end	O
lines	O
such	O
as	O
the	O
Macintosh	B-Device
LC	I-Device
family	I-Device
.	O
</s>
<s>
The	O
original	O
SPARCstation1	O
design	O
included	O
an	O
expansion	B-Device
bus	I-Device
technology	O
,	O
SBus	B-Architecture
,	O
expressly	O
designed	O
for	O
the	O
form	O
factor	O
;	O
expansion	B-Device
cards	I-Device
were	O
small	O
,	O
especially	O
in	O
comparison	O
to	O
other	O
expansion	B-Device
cards	I-Device
in	O
use	O
at	O
the	O
time	O
such	O
as	O
VMEbus	B-Architecture
,	O
and	O
were	O
mounted	O
horizontally	O
instead	O
of	O
vertically	O
.	O
</s>
<s>
PC-compatible	O
computers	O
in	O
this	O
type	O
of	O
case	B-General_Concept
typically	O
use	O
the	O
PCI	B-Protocol
expansion	B-Device
bus	I-Device
and	O
are	O
usually	O
either	O
a	O
)	O
limited	O
to	O
one	O
or	O
two	O
horizontally	O
placed	O
expansion	B-Device
cards	I-Device
or	O
b	O
)	O
require	O
special	O
low-profile	O
expansion	B-Device
cards	I-Device
,	O
shorter	O
than	O
the	O
PCIcards	O
regular	O
PCs	B-Device
use	O
.	O
</s>
<s>
The	O
density	O
of	O
computing	O
power	O
and	O
stackability	O
of	O
pizza	O
box	O
systems	O
also	O
made	O
them	O
attractive	O
for	O
use	O
in	O
data	B-Operating_System
centers	I-Operating_System
.	O
</s>
<s>
Systems	O
originally	O
designed	O
for	O
desktop	O
use	O
were	O
placed	O
on	O
shelves	O
inside	O
of	O
19-inch	B-Application
racks	I-Application
,	O
sometimes	O
requiring	O
that	O
part	O
of	O
their	O
cases	O
be	O
cut	O
off	O
in	O
order	O
for	O
them	O
to	O
fit	O
.	O
</s>
<s>
Since	O
the	O
late	O
1990s	O
,	O
pizza	O
boxes	O
have	O
been	O
a	O
common	O
form	O
factor	O
in	O
office	O
cubicles	O
,	O
data	B-Operating_System
centers	I-Operating_System
or	O
industrial	O
applications	O
,	O
where	O
desktop	O
space	O
,	O
rack	O
room	O
and	O
density	O
are	O
critical	O
.	O
</s>
<s>
Servers	O
in	O
this	O
form	O
factor	O
,	O
as	O
well	O
as	O
higher-end	O
Ethernet	B-Protocol
switches	I-Protocol
,	O
are	O
now	O
designed	O
for	O
rack	O
mounting	O
.	O
</s>
<s>
Rack	B-Application
mount	I-Application
1U	O
computers	O
come	O
in	O
all	O
types	O
of	O
configurations	O
and	O
depths	O
.	O
</s>
<s>
The	O
pizza	B-General_Concept
box	I-General_Concept
form	I-General_Concept
factor	I-General_Concept
for	O
smaller	O
personal	O
systems	O
and	O
thin	O
clients	O
remains	O
in	O
use	O
well	O
into	O
the	O
21st	O
century	O
,	O
though	O
it	O
is	O
increasingly	O
being	O
superseded	O
by	O
laptops	B-Device
,	O
nettops	B-Protocol
or	O
All-in-One	B-Device
PC	I-Device
designs	O
that	O
embed	O
the	O
already	O
size-reduced	O
computer	O
onto	O
the	O
keyboard	B-Device
or	O
display	B-Device
monitor	I-Device
.	O
</s>
