<s>
It	O
was	O
designed	O
for	O
data	B-Operating_System
centers	I-Operating_System
,	O
where	O
it	O
replaced	O
line	O
printers	O
attached	O
to	O
mainframe	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
1981	O
:	O
The	O
first	O
small	O
personal	O
computer	O
designed	O
for	O
office	O
use	O
,	O
the	O
Xerox	B-Operating_System
Star	I-Operating_System
8010	I-Operating_System
,	O
reached	O
market	O
.	O
</s>
<s>
The	O
system	O
used	O
a	O
desktop	B-Application
metaphor	I-Application
that	O
was	O
unsurpassed	O
in	O
commercial	O
sales	O
,	O
until	O
the	O
Apple	B-Device
Macintosh	I-Device
.	O
</s>
<s>
1985	O
:	O
Apple	O
introduced	O
the	O
LaserWriter	O
(	O
also	O
based	O
on	O
the	O
Canon	O
CX	O
engine	O
)	O
,	O
but	O
used	O
the	O
newly	O
released	O
PostScript	B-Language
page-description	O
language	O
(	O
up	O
until	O
this	O
point	O
,	O
each	O
manufacturer	O
used	O
its	O
own	O
proprietary	O
page-description	O
language	O
,	O
making	O
the	O
supporting	O
software	O
complex	O
and	O
expensive	O
)	O
.	O
</s>
<s>
PostScript	B-Language
allowed	O
the	O
use	O
of	O
text	O
,	O
fonts	O
,	O
graphics	O
,	O
images	O
,	O
and	O
color	O
largely	O
independent	O
of	O
the	O
printer	O
's	O
brand	O
or	O
resolution	O
.	O
</s>
<s>
PageMaker	B-Operating_System
,	O
developed	O
by	O
Aldus	O
for	O
the	O
Macintosh	B-Device
and	O
LaserWriter	O
,	O
was	O
also	O
released	O
in	O
1985	O
and	O
the	O
combination	O
became	O
very	O
popular	O
for	O
desktop	O
publishing	O
.	O
</s>
<s>
A	O
laser	O
beam	O
(	O
typically	O
,	O
an	O
aluminium	O
gallium	O
arsenide	O
(	O
AlGaAs	O
)	O
semiconductor	O
laser	O
)	O
that	O
can	O
emit	O
red	O
or	O
infrared	O
light	O
)	O
projects	O
an	O
image	O
of	O
the	O
page	O
to	O
be	O
printed	O
onto	O
an	O
electrically	O
charged	O
,	O
selenium-coated	O
,	O
rotating	O
,	O
cylindrical	O
drum	O
(	O
or	O
,	O
more	O
commonly	O
in	O
subsequent	O
versions	O
,	O
a	O
drum	O
called	O
an	O
organic	O
photoconductor	O
made	O
of	O
N-vinylcarbazole	O
,	O
an	O
organic	O
monomer	O
)	O
.	O
</s>
<s>
The	O
document	O
to	O
be	O
printed	O
is	O
encoded	O
in	O
a	O
page	O
description	O
language	O
such	O
as	O
PostScript	B-Language
,	O
Printer	B-Language
Command	I-Language
Language	I-Language
(	O
PCL	B-Language
)	O
,	O
or	O
Open	B-Device
XML	I-Device
Paper	I-Device
Specification	I-Device
(	O
OpenXPS	B-Device
)	O
.	O
</s>
<s>
The	O
raster	B-Algorithm
image	I-Algorithm
processor	O
(	O
RIP	O
)	O
converts	O
the	O
page	O
description	O
into	O
a	O
bitmap	O
which	O
is	O
stored	O
in	O
the	O
printer	O
's	O
raster	B-Algorithm
memory	O
.	O
</s>
<s>
Each	O
horizontal	O
strip	O
of	O
dots	O
across	O
the	O
page	O
is	O
known	O
as	O
a	O
raster	B-Algorithm
line	O
or	O
scan	B-Algorithm
line	I-Algorithm
.	O
</s>
<s>
To	O
avoid	O
a	O
buffer	O
underrun	O
(	O
where	O
the	O
laser	O
reaches	O
a	O
point	O
on	O
the	O
page	O
before	O
it	O
has	O
the	O
dots	O
to	O
draw	O
there	O
)	O
,	O
a	O
laser	O
printer	O
typically	O
needs	O
enough	O
raster	B-Algorithm
memory	O
to	O
hold	O
the	O
bitmap	O
image	O
of	O
an	O
entire	O
page	O
.	O
</s>
<s>
1	O
megabyte	O
=	O
1,048,576	O
bytes	O
,	O
or	O
8,388,608	O
bits	O
,	O
which	O
is	O
just	O
large	O
enough	O
to	O
hold	O
the	O
entire	O
page	O
at	O
300	O
dpi	O
,	O
leaving	O
about	O
100	O
kilobytes	O
to	O
spare	O
for	O
use	O
by	O
the	O
raster	B-Algorithm
image	I-Algorithm
processor	O
.	O
</s>
<s>
One	O
version	O
uses	O
amorphous	O
silicon	O
containing	O
hydrogen	O
as	O
the	O
light-receiving	O
layer	O
,	O
boron	O
nitride	O
as	O
a	O
charge	O
leakage	O
barrier	O
layer	O
,	O
as	O
well	O
as	O
a	O
surface	O
layer	O
of	O
doped	B-Algorithm
silicon	I-Algorithm
,	O
notably	O
silicon	O
with	O
oxygen	O
or	O
nitrogen	O
which	O
at	O
sufficient	O
concentration	O
resembles	O
machining	O
silicon	O
nitride	O
.	O
</s>
<s>
The	O
laser	O
is	O
aimed	O
at	O
a	O
rotating	O
polygonal	O
mirror	O
which	O
directs	O
the	O
light	O
beam	O
through	O
a	O
system	O
of	O
lenses	O
and	O
mirrors	O
onto	O
the	O
photoreceptor	O
drum	O
,	O
writing	O
pixels	B-Algorithm
at	O
rates	O
up	O
to	O
sixty-five	O
million	O
times	O
per	O
second	O
.	O
</s>
<s>
Once	O
the	O
raster	B-Algorithm
image	I-Algorithm
generation	O
is	O
complete	O
,	O
all	O
steps	O
of	O
the	O
printing	O
process	O
can	O
occur	O
one	O
after	O
the	O
other	O
in	O
rapid	O
succession	O
.	O
</s>
<s>
,	O
low-end	O
monochrome	O
laser	O
printers	O
can	O
sell	O
for	O
less	O
than	O
$75	O
,	O
and	O
while	O
these	O
printers	O
tend	O
to	O
lack	O
onboard	O
processing	O
and	O
rely	O
on	O
the	O
host	O
computer	O
to	O
generate	O
a	O
raster	B-Algorithm
image	I-Algorithm
,	O
they	O
nonetheless	O
outperform	O
the	O
1984	O
LaserJet	O
in	O
nearly	O
all	O
situations	O
.	O
</s>
<s>
Color	O
laser	O
printers	O
use	O
colored	O
toner	O
(	O
dry	O
ink	O
)	O
,	O
typically	O
cyan	O
,	O
magenta	B-Algorithm
,	O
yellow	O
,	O
and	O
black	O
(	O
CMYK	O
)	O
.	O
</s>
<s>
2-part	O
Color	O
laser	O
transfers	O
are	O
part	O
of	O
a	O
two-step	O
process	O
whereby	O
the	O
color	O
laser	O
printers	O
use	O
colored	O
toner	O
(	O
dry	O
ink	O
)	O
,	O
typically	O
cyan	O
,	O
magenta	B-Algorithm
,	O
yellow	O
,	O
and	O
black	O
(	O
CMYK	O
)	O
;	O
however	O
,	O
newer	O
printers	O
designed	O
to	O
print	O
on	O
dark	O
T-shirts	O
utilize	O
a	O
special	O
white	O
toner	O
allowing	O
them	O
to	O
make	O
transfers	O
for	O
dark	O
garments	O
or	O
dark	O
business	O
products	O
.	O
</s>
<s>
Many	O
modern	O
color	O
laser	O
printers	O
mark	O
printouts	O
by	O
a	O
nearly	O
invisible	O
dot	O
raster	B-Algorithm
,	O
for	O
the	O
purpose	O
of	O
traceability	O
.	O
</s>
<s>
The	O
dots	O
are	O
yellow	O
and	O
about	O
in	O
size	O
,	O
with	O
a	O
raster	B-Algorithm
of	O
about	O
.	O
</s>
