<s>
Pure	B-Language
Data	I-Language
(	O
Pd	O
)	O
is	O
a	O
visual	B-Language
programming	I-Language
language	I-Language
developed	O
by	O
Miller	O
Puckette	O
in	O
the	O
1990s	O
for	O
creating	O
interactive	O
computer	B-Application
music	I-Application
and	O
multimedia	O
works	O
.	O
</s>
<s>
While	O
Puckette	O
is	O
the	O
main	O
author	O
of	O
the	O
program	O
,	O
Pd	O
is	O
an	O
open-source	B-Application
project	O
with	O
a	O
large	O
developer	O
base	O
working	O
on	O
new	O
extensions	O
.	O
</s>
<s>
It	O
is	O
released	O
under	O
BSD-3-Clause	B-Operating_System
.	O
</s>
<s>
It	O
runs	O
on	O
Linux	B-Application
,	O
MacOS	B-Application
,	O
iOS	B-Application
,	O
Android	B-Application
and	O
Windows	O
.	O
</s>
<s>
Ports	O
exist	O
for	O
FreeBSD	B-Operating_System
and	O
IRIX	B-Operating_System
.	O
</s>
<s>
Pd	O
is	O
very	O
similar	O
in	O
scope	O
and	O
design	O
to	O
Puckette	O
's	O
original	O
Max	B-Application
program	O
,	O
developed	O
while	O
he	O
was	O
at	O
IRCAM	O
,	O
and	O
is	O
to	O
some	O
degree	O
interoperable	O
with	O
Max/MSP	B-Application
,	O
the	O
commercial	O
predecessor	O
to	O
the	O
Max	B-Application
language	O
.	O
</s>
<s>
They	O
may	O
be	O
collectively	O
discussed	O
as	O
members	O
of	O
the	O
Patcher	B-Application
family	O
of	O
languages	O
.	O
</s>
<s>
With	O
the	O
addition	O
of	O
the	O
Graphics	B-Language
Environment	I-Language
for	I-Language
Multimedia	I-Language
(	O
GEM	O
)	O
external	O
,	O
and	O
externals	O
designed	O
to	O
work	O
with	O
it	O
(	O
like	O
Pure	B-Language
Data	I-Language
Packet	O
/	O
PiDiP	O
for	O
Linux	B-Application
,	O
)	O
,	O
framestein	O
for	O
Windows	O
,	O
GridFlow	O
(	O
as	O
n-dimensional	O
matrix	O
processing	O
,	O
for	O
Linux	B-Application
,	O
,	O
Windows	O
)	O
,	O
it	O
is	O
possible	O
to	O
create	O
and	O
manipulate	O
video	O
,	O
OpenGL	B-Application
graphics	O
,	O
images	O
,	O
etc.	O
,	O
in	O
realtime	O
with	O
extensive	O
possibilities	O
for	O
interactivity	O
with	O
audio	O
,	O
external	O
sensors	O
,	O
etc	O
.	O
</s>
<s>
Pd	O
uses	O
FUDI	B-Protocol
as	O
a	O
networking	O
protocol	O
.	O
</s>
<s>
Pure	B-Language
Data	I-Language
and	O
Max	B-Application
are	O
both	O
examples	O
of	O
dataflow	B-Application
programming	I-Application
languages	I-Application
.	O
</s>
<s>
Dataflow	B-Application
languages	I-Application
model	O
a	O
program	O
as	O
a	O
directed	O
graph	O
of	O
the	O
data	O
flowing	O
between	O
operations	O
.	O
</s>
<s>
In	O
Pure	B-Language
Data	I-Language
and	O
Max	B-Application
,	O
functions	O
or	O
"	O
objects	O
"	O
are	O
linked	O
or	O
"	O
patched	O
"	O
together	O
in	O
a	O
graphical	B-Application
environment	I-Application
which	O
models	O
the	O
flow	O
of	O
the	O
control	O
and	O
audio	O
.	O
</s>
<s>
Unlike	O
the	O
original	O
version	O
of	O
Max	B-Application
,	O
however	O
,	O
Pd	O
was	O
always	O
designed	O
to	O
do	O
control-rate	O
and	O
audio	O
processing	O
on	O
the	O
host	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
,	O
rather	O
than	O
offloading	O
the	O
sound	O
synthesis	O
and	O
signal	O
processing	O
to	O
a	O
digital	B-Architecture
signal	I-Architecture
processor	I-Architecture
(	O
DSP	B-General_Concept
)	O
board	O
(	O
such	O
as	O
the	O
Ariel	O
ISPW	B-General_Concept
which	O
was	O
used	O
for	O
Max/FTS	O
)	O
.	O
</s>
<s>
Pd	O
code	O
forms	O
the	O
basis	O
of	O
David	O
Zicarelli	O
's	O
MSP	O
extensions	O
to	O
the	O
Max	B-Application
language	O
to	O
do	O
software	O
audio	O
processing	O
.	O
</s>
<s>
Like	O
Max	B-Application
,	O
Pd	O
has	O
a	O
modular	B-Architecture
code	O
base	O
of	O
externals	O
or	O
objects	O
which	O
are	O
used	O
as	O
building	O
blocks	O
for	O
programs	O
written	O
in	O
the	O
software	O
.	O
</s>
<s>
This	O
makes	O
the	O
program	O
arbitrarily	O
extensible	O
through	O
a	O
public	O
API	B-General_Concept
,	O
and	O
encourages	O
developers	O
to	O
add	O
their	O
own	O
control	O
and	O
audio	O
routines	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
,	O
or	O
with	O
the	O
help	O
of	O
other	O
externals	O
,	O
in	O
Python	B-Language
,	O
Scheme	B-Language
,	O
Lua	B-Language
,	O
Tcl	B-Operating_System
,	O
and	O
many	O
others	O
.	O
</s>
<s>
Modular	B-Architecture
,	O
reusable	O
units	O
of	O
code	O
written	O
natively	O
in	O
Pd	O
,	O
called	O
"	O
patches	O
"	O
or	O
"	O
abstractions	O
"	O
,	O
are	O
used	O
as	O
standalone	O
programs	O
and	O
freely	O
shared	O
among	O
the	O
Pd	O
user	O
community	O
,	O
and	O
no	O
other	O
programming	O
skill	O
is	O
required	O
to	O
use	O
Pd	O
effectively	O
.	O
</s>
<s>
Like	O
Max	B-Application
,	O
Pd	O
is	O
a	O
dataflow	B-Application
programming	I-Application
language	I-Application
.	O
</s>
<s>
As	O
with	O
most	O
DSP	B-General_Concept
software	O
,	O
there	O
are	O
two	O
primary	O
rates	O
at	O
which	O
data	O
is	O
passed	O
:	O
sample	O
(	O
audio	O
)	O
rate	O
,	O
usually	O
at	O
44,100	O
samples	O
per	O
second	O
,	O
and	O
control	O
rate	O
,	O
at	O
1	O
block	O
per	O
64	O
samples	O
.	O
</s>
<s>
Atoms	O
are	O
the	O
most	O
basic	O
unit	O
of	O
data	O
in	O
Pd	O
,	O
and	O
they	O
consist	O
of	O
either	O
a	O
float	B-Algorithm
,	O
a	O
symbol	O
,	O
or	O
a	O
pointer	O
to	O
a	O
data	B-General_Concept
structure	I-General_Concept
(	O
in	O
Pd	O
,	O
all	O
numbers	O
are	O
stored	O
as	O
32-bit	O
floats	B-Algorithm
)	O
.	O
</s>
<s>
Pd	O
's	O
native	O
objects	O
range	O
from	O
the	O
basic	O
mathematical	O
,	O
logical	O
,	O
and	O
bitwise	O
operators	O
found	O
in	O
every	O
programming	O
language	O
to	O
general	O
and	O
specialized	O
audio-rate	O
DSP	B-General_Concept
functions	O
(	O
designated	O
by	O
a	O
tilde	O
(	O
~	O
)	O
symbol	O
)	O
,	O
such	O
as	O
wavetable	O
oscillators	O
,	O
the	O
Fast	O
Fourier	O
transform	O
(	O
fft	O
~	O
)	O
,	O
and	O
a	O
range	O
of	O
standard	O
filters	O
.	O
</s>
<s>
Data	O
can	O
be	O
loaded	O
from	O
file	O
,	O
read	O
in	O
from	O
an	O
audio	O
board	O
,	O
MIDI	O
,	O
via	O
Open	O
Sound	O
Control	O
(	O
OSC	O
)	O
through	O
a	O
FireWire	B-Protocol
,	O
USB	B-Protocol
,	O
or	O
network	O
connection	O
,	O
or	O
generated	O
on	O
the	O
fly	O
,	O
and	O
stored	O
in	O
tables	O
,	O
which	O
can	O
then	O
be	O
read	O
back	O
and	O
used	O
as	O
audio	O
signals	O
or	O
control	O
data	O
.	O
</s>
<s>
One	O
of	O
the	O
key	O
innovations	O
in	O
Pd	O
over	O
its	O
predecessors	O
has	O
been	O
the	O
introduction	O
of	O
graphical	O
data	B-General_Concept
structures	I-General_Concept
.	O
</s>
<s>
These	O
can	O
be	O
used	O
in	O
a	O
large	O
variety	O
of	O
ways	O
,	O
from	O
composing	O
musical	O
scores	O
,	O
sequencing	O
events	O
,	O
to	O
creating	O
visuals	O
to	O
accompany	O
Pd	O
patches	O
or	O
even	O
extending	O
Pd	O
's	O
GUI	B-Application
.	O
</s>
<s>
Living	O
up	O
to	O
Pd	O
's	O
name	O
,	O
data	B-General_Concept
structures	I-General_Concept
enable	O
Pd	O
users	O
to	O
create	O
arbitrarily	O
complex	O
static	O
as	O
well	O
as	O
dynamic	O
or	O
animated	O
graphical	O
representations	O
of	O
musical	O
data	O
.	O
</s>
<s>
Much	O
like	O
C	B-Language
structs	O
,	O
Pd	O
's	O
structs	O
are	O
composed	O
of	O
any	O
combination	O
of	O
floats	B-Algorithm
,	O
symbols	O
,	O
and	O
array	O
data	O
that	O
can	O
be	O
used	O
as	O
parameters	O
to	O
describe	O
the	O
visual	O
appearance	O
of	O
the	O
data	B-General_Concept
structure	I-General_Concept
or	O
,	O
conversely	O
,	O
to	O
control	O
messages	O
and	O
audio	O
signals	O
in	O
a	O
Pd	O
patch	O
.	O
</s>
<s>
Pure	B-Language
Data	I-Language
has	O
been	O
used	O
as	O
the	O
basis	O
of	O
a	O
number	O
of	O
projects	O
,	O
as	O
a	O
prototyping	O
language	O
and	O
a	O
sound	O
engine	O
.	O
</s>
<s>
The	O
table	O
interface	O
called	O
the	O
Reactable	O
and	O
the	O
abandoned	O
iPhone	O
app	O
RjDj	B-Application
both	O
embed	O
Pd	O
as	O
a	O
sound	O
engine	O
.	O
</s>
<s>
It	O
has	O
also	O
been	O
embedded	O
into	O
EA	O
Spore	B-Application
.	O
</s>
