<s>
Graphics	B-Language
BASIC	I-Language
is	O
a	O
third-party	O
extension	B-Language
to	O
the	O
Commodore	B-Language
BASIC	I-Language
V2.0	I-Language
programming	O
language	O
of	O
the	O
Commodore	O
64	O
computer	O
.	O
</s>
<s>
The	O
program	O
was	O
later	O
extended	O
by	O
Ken	O
Rose	O
and	O
Jack	O
Thornton	O
,	O
and	O
repackaged	O
and	O
sold	O
in	O
1985	O
by	O
Epyx	O
under	O
the	O
title	O
Programmers	O
BASIC	B-Language
Toolkit	I-Language
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
adds	O
over	O
100	O
new	O
commands	O
to	O
the	O
BASIC	B-Language
language	I-Language
,	O
providing	O
an	O
easy-to-use	O
API	B-General_Concept
to	O
the	O
relatively	O
advanced	O
(	O
at	O
the	O
time	O
)	O
graphics	O
and	O
sound	O
hardware	O
capabilities	O
of	O
the	O
Commodore	O
64	O
.	O
</s>
<s>
The	O
only	O
access	O
to	O
these	O
features	O
with	O
Commodore	B-Language
BASIC	I-Language
alone	O
is	O
through	O
the	O
cumbersome	O
use	O
of	O
PEEK	B-Language
and	I-Language
POKE	I-Language
commands	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
was	O
delivered	O
on	O
a	O
single	O
5.25	B-Device
"	I-Device
floppy	B-Device
disk	I-Device
,	O
containing	O
the	O
language	O
itself	O
and	O
numerous	O
,	O
very	O
simple	O
demo	O
programs	O
showing	O
off	O
the	O
new	O
features	O
of	O
the	O
language	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
's	O
main	O
feature	O
is	O
its	O
easy-to-use	O
graphics	O
commands	O
,	O
including	O
commands	O
to	O
draw	O
dots	O
,	O
lines	O
,	O
circles	O
,	O
ellipses	O
,	O
rectangles	O
,	O
and	O
polygons	O
.	O
</s>
<s>
As	O
can	O
be	O
seen	O
from	O
the	O
above	O
,	O
the	O
syntax	O
is	O
somewhat	O
similar	O
to	O
that	O
of	O
GW-BASIC	B-Language
'	O
s	O
or	O
AmigaBASIC	B-Language
's	O
graphics	O
commands	O
,	O
but	O
different	O
enough	O
to	O
prevent	O
source-code	O
compatibility	O
.	O
</s>
<s>
Switching	O
between	O
these	O
is	O
extremely	O
easy	O
in	O
Graphics	B-Language
BASIC	I-Language
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
also	O
allows	O
the	O
screen	O
to	O
be	O
horizontally	O
split	O
between	O
multiple	O
modes	O
.	O
</s>
<s>
One	O
of	O
the	O
more	O
unusual	O
choices	O
of	O
syntax	O
in	O
Graphics	B-Language
BASIC	I-Language
was	O
the	O
setting	O
of	O
graphics	O
colours	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
also	O
provides	O
commands	O
to	O
manipulate	O
the	O
Commodore	O
64	O
's	O
eight	O
sprites	O
.	O
</s>
<s>
The	O
compact	O
syntax	O
of	O
the	O
sprite	O
commands	O
has	O
more	O
in	O
common	O
with	O
the	O
command-line	O
options	O
of	O
Unix	B-Application
programs	O
than	O
conventional	O
programming	O
languages	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
also	O
supports	O
automatic	O
sprite	O
movement	O
(	O
change	O
in	O
place	O
)	O
,	O
animation	O
(	O
change	O
in	O
shape	O
)	O
,	O
and	O
collision	O
detection	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
also	O
provides	O
various	O
commands	O
to	O
control	O
the	O
Commodore	O
64	O
's	O
built-in	O
audio	O
synthesizer	O
,	O
allowing	O
the	O
selection	O
of	O
waveform	O
type	O
,	O
tone	O
(	O
frequency	O
)	O
,	O
and	O
amplitude	O
envelopes	O
.	O
</s>
<s>
In	O
addition	O
to	O
graphics	O
and	O
sound	O
commands	O
,	O
Graphics	B-Language
BASIC	I-Language
also	O
provides	O
various	O
other	O
useful	O
commands	O
such	O
as	O
DIR	O
to	O
list	O
the	O
file	O
directory	O
of	O
a	O
device	O
,	O
JOY	O
to	O
return	O
the	O
position	O
of	O
a	O
joystick	O
,	O
KEY	O
to	O
program	O
function	O
keys	O
,	O
REN	O
to	O
renumber	O
the	O
current	O
program	O
line	O
numbers	O
.	O
</s>
<s>
Graphics	B-Language
BASIC	I-Language
also	O
added	O
an	O
ON	O
ERROR	O
command	O
to	O
perform	O
error	O
capturing	O
,	O
a	O
PROCEDURE	O
command	O
that	O
allowed	O
variables	O
to	O
be	O
passed	O
to	O
subroutines	O
,	O
and	O
added	O
ELSE	O
to	O
the	O
IF/THEN	O
command	O
.	O
</s>
