<s>
HP-GL	B-Language
,	O
short	O
for	O
Hewlett-Packard	B-Language
Graphics	I-Language
Language	I-Language
and	O
often	O
written	O
as	O
HPGL	B-Language
,	O
is	O
a	O
printer	O
control	O
language	O
created	O
by	O
Hewlett-Packard	O
(	O
HP	O
)	O
.	O
</s>
<s>
HP-GL	B-Language
was	O
the	O
primary	O
printer	O
control	O
language	O
used	O
by	O
HP	O
plotters	B-Operating_System
.	O
</s>
<s>
It	O
was	O
introduced	O
with	O
the	O
plotter	B-Operating_System
in	O
1977	O
and	O
became	O
a	O
standard	O
for	O
almost	O
all	O
plotters	B-Operating_System
.	O
</s>
<s>
Hewlett-Packard	O
'	O
s	O
printers	O
also	O
usually	O
support	O
HP-GL/2	O
in	O
addition	O
to	O
PCL	B-Language
.	O
</s>
<s>
When	O
first	O
introduced	O
,	O
HP-GL	B-Language
contained	O
the	O
following	O
commands	O
:	O
</s>
<s>
Typical	O
HP-GL	B-Language
files	O
start	O
with	O
a	O
few	O
setup	O
commands	O
,	O
followed	O
by	O
a	O
long	O
string	O
of	O
graphics	O
commands	O
.	O
</s>
<s>
The	O
file	O
was	O
in	O
ASCII	B-Protocol
(	O
text	B-General_Concept
file	I-General_Concept
)	O
format	O
,	O
for	O
instance	O
:	O
</s>
<s>
The	O
coordinate	O
system	O
was	O
based	O
on	O
the	O
smallest	O
units	O
one	O
of	O
the	O
HP	O
plotters	B-Operating_System
could	O
support	O
,	O
and	O
was	O
set	O
to	O
25µm	O
(	O
i.e.	O
</s>
<s>
The	O
coordinate	O
space	O
was	O
positive	O
or	O
negative	O
floating	B-Algorithm
point	I-Algorithm
numbers	I-Algorithm
,	O
specifically	O
±230	O
.	O
</s>
<s>
The	O
original	O
HP-GL	B-Language
language	O
did	O
not	O
support	O
definition	O
of	O
line	O
width	O
,	O
as	O
this	O
parameter	O
was	O
determined	O
by	O
the	O
pens	O
loaded	O
into	O
the	O
plotter	B-Operating_System
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
first	O
inkjet	O
plotters	B-Operating_System
,	O
line	O
width	O
for	O
the	O
"	O
pens	O
"	O
specified	O
within	O
the	O
HP-GL	B-Language
files	O
had	O
to	O
be	O
set	O
at	O
the	O
printer	O
so	O
it	O
would	O
know	O
what	O
line	O
width	O
to	O
print	O
for	O
each	O
pen	O
,	O
a	O
cumbersome	O
and	O
error-prone	O
process	O
.	O
</s>
<s>
With	O
Hewlett-Packard	O
Graphics	O
Language/2	O
aka	O
HP-GL/2	O
,	O
definition	O
of	O
line	O
width	O
was	O
introduced	O
into	O
the	O
language	O
and	O
allowed	O
for	O
elimination	O
of	O
this	O
step	O
.	O
</s>
<s>
HP-GL	B-Language
is	O
related	O
to	O
AGL	O
(	O
A	B-Language
Graphics	I-Language
Language	I-Language
)	O
,	O
an	O
extension	O
of	O
the	O
BASIC	O
programming	O
language	O
.	O
</s>
<s>
AGL	O
was	O
implemented	O
on	O
Hewlett-Packard	O
minicomputers	B-Architecture
to	O
simplify	O
controlling	O
a	O
plotter	B-Operating_System
.	O
</s>
<s>
AGL	O
commands	O
describe	O
the	O
desired	O
graphics	O
plotting	O
function	O
,	O
which	O
the	O
computer	O
relays	O
as	O
several	O
HP-GL	B-Language
instructions	O
to	O
the	O
plotter	B-Operating_System
.	O
</s>
