<s>
Experix	B-Application
is	O
an	O
open-source	B-License
command	O
interpreter	O
designed	O
for	O
operating	O
laboratory	O
equipment	O
,	O
especially	O
data	B-Algorithm
acquisition	I-Algorithm
devices	O
,	O
and	O
processing	O
,	O
displaying	O
and	O
storing	O
the	O
data	O
from	O
them	O
.	O
</s>
<s>
It	O
is	O
usable	O
now	O
,	O
only	O
under	O
Linux	B-Application
on	O
the	O
x86	B-Operating_System
architecture	I-Operating_System
,	O
but	O
still	O
under	O
development	O
,	O
and	O
users	O
are	O
welcome	O
to	O
participate	O
in	O
extending	O
and	O
improving	O
it	O
.	O
</s>
<s>
commercial	O
data	B-Algorithm
acquisition	I-Algorithm
programs	O
,	O
for	O
example	O
LabVIEW	B-Application
,	O
which	O
model	O
a	O
measurement	O
and	O
control	O
application	O
as	O
a	O
network	O
of	O
operational	O
units	O
represented	O
graphically	O
as	O
boxes	O
with	O
connections	O
that	O
stand	O
for	O
data	O
flow	O
.	O
</s>
<s>
Experix	B-Application
,	O
in	O
contrast	O
,	O
represents	O
the	O
application	O
as	O
a	O
series	O
of	O
operations	O
generally	O
taking	O
place	O
one	O
after	O
another	O
.	O
</s>
<s>
It	O
processes	O
a	O
command	O
line	O
in	O
a	O
sequential	O
way	O
,	O
and	O
numbers	O
,	O
operators	O
,	O
functions	O
and	O
commands	O
in	O
the	O
command	O
line	O
consume	O
and	O
create	O
objects	O
on	O
a	O
stack	B-Application
.	O
</s>
<s>
These	O
objects	O
include	O
integers	O
and	O
floating-point	B-Algorithm
numbers	I-Algorithm
in	O
several	O
sizes	O
,	O
complex	O
and	O
polar	O
numbers	O
,	O
multi-dimensional	O
arrays	O
made	O
from	O
any	O
of	O
the	O
numerical	O
types	O
,	O
several	O
kinds	O
of	O
strings	O
,	O
and	O
pointers	O
to	O
functions	O
,	O
commands	O
and	O
variables	O
(	O
which	O
can	O
be	O
numbers	O
,	O
arrays	O
and	O
strings	O
)	O
.	O
</s>
<s>
A	O
function	O
,	O
command	O
or	O
operator	O
requires	O
certain	O
types	O
of	O
objects	O
on	O
the	O
stack	B-Application
and	O
puts	O
objects	O
on	O
the	O
stack	B-Application
,	O
and	O
may	O
also	O
change	O
values	O
in	O
stack	B-Application
objects	O
and	O
variables	O
,	O
draw	O
graphs	O
,	O
order	O
operations	O
in	O
device	B-Application
drivers	I-Application
,	O
and	O
read	O
and	O
write	O
files	O
.	O
</s>
<s>
Experix	B-Application
is	O
released	O
under	O
the	O
GNU	B-License
GPL	I-License
.	O
</s>
<s>
This	O
sample	O
of	O
command	O
tokens	O
will	O
give	O
an	O
idea	O
of	O
the	O
range	O
of	O
capabilities	O
that	O
experix	B-Application
has	O
.	O
</s>
<s>
>=	O
$9	O
if	O
the	O
value	O
in	O
stack	B-Application
level	O
1	O
is	O
greater	O
than	O
that	O
in	O
level	O
2	O
,	O
command	O
execution	O
branches	O
to	O
label	O
$9	O
:	O
</s>
<s>
Experix	B-Application
provides	O
hardware	O
operations	O
by	O
way	O
of	O
a	O
command-line	O
interface	O
to	O
device	B-Application
drivers	I-Application
.	O
</s>
<s>
An	O
experix	B-Application
driver	O
has	O
a	O
'	O
read	O
 '	O
entry	O
point	O
which	O
functions	O
more	O
like	O
an	O
ioctl	B-Operating_System
.	O
</s>
<s>
It	O
copies	O
the	O
integer	O
array	O
that	O
experix	B-Application
has	O
prepared	O
,	O
finds	O
in	O
it	O
an	O
operation	O
code	O
and	O
supporting	O
information	O
,	O
performs	O
the	O
operation	O
and	O
returns	O
results	O
to	O
the	O
array	O
.	O
</s>
<s>
The	O
driver	O
maintains	O
a	O
control	O
page	O
which	O
experix	B-Application
maps	O
with	O
read-only	O
permission	O
,	O
and	O
a	O
number	O
of	O
data	O
pages	O
which	O
are	O
mapped	O
with	O
read-write	O
permission	O
.	O
</s>
<s>
A	O
data	B-Algorithm
acquisition	I-Algorithm
device	B-Application
driver	I-Application
has	O
an	O
interrupt	B-General_Concept
handler	I-General_Concept
which	O
uses	O
data	O
from	O
the	O
output	O
pages	O
and	O
stores	O
data	O
in	O
the	O
input	O
pages	O
.	O
</s>
<s>
At	O
designated	O
index	O
values	O
it	O
sends	O
the	O
new	O
data	O
signal	O
to	O
experix	B-Application
.	O
</s>
<s>
The	O
xcd	O
function	O
is	O
used	O
to	O
bind	O
the	O
signal	O
to	O
an	O
experix	B-Application
command	O
string	O
.	O
</s>
<s>
It	O
runs	O
atomically	O
,	O
which	O
means	O
it	O
uses	O
a	O
separate	O
stack	B-Application
and	O
runs	O
uninterrupted	O
between	O
two	O
tokens	O
in	O
whatever	O
user	O
command	O
happens	O
to	O
be	O
in	O
progress	O
.	O
</s>
<s>
Commands	O
,	O
functions	O
and	O
operators	O
are	O
described	O
in	O
help	O
files	O
,	O
which	O
are	O
accessed	O
in	O
experix	B-Application
by	O
the	O
help	O
operators	O
.	O
</s>
<s>
System	O
commands	O
such	O
as	O
cat	O
and	O
grep	B-Application
will	O
show	O
these	O
files	O
with	O
their	O
colorization	O
,	O
and	O
the	O
editor	O
that	O
experix	B-Application
uses	O
for	O
the	O
two-question-mark	O
help	O
operator	O
is	O
nano	O
(	O
from	O
the	O
GNU	B-Operating_System
project	O
)	O
with	O
the	O
escape	O
sequence	O
extension	O
.	O
</s>
<s>
The	O
source	O
files	O
for	O
nano	O
that	O
were	O
changed	O
to	O
provide	O
this	O
extension	O
are	O
available	O
on	O
the	O
experix	B-Application
website	O
.	O
</s>
<s>
Experix	B-Application
users	O
are	O
encouraged	O
to	O
correct	O
and	O
improve	O
help	O
files	O
as	O
they	O
work	O
.	O
</s>
<s>
Currently	O
,	O
experix	B-Application
is	O
only	O
available	O
for	O
Linux	B-Application
and	O
,	O
due	O
to	O
assembly	O
language	O
code	O
,	O
only	O
on	O
the	O
x86	B-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
At	O
present	O
the	O
only	O
graphics	O
support	O
for	O
experix	B-Application
is	O
with	O
the	O
open-source	B-License
SVGALib	B-Application
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
have	O
an	O
experix	B-Application
graphics	O
session	O
in	O
one	O
virtual	O
terminal	O
and	O
text	O
or	O
X	O
sessions	O
in	O
others	O
,	O
and	O
switch	O
between	O
them	O
with	O
the	O
keys	O
.	O
</s>
<s>
Graphics	O
operations	O
are	O
done	O
by	O
a	O
server	O
process	O
,	O
and	O
experix	B-Application
sends	O
commands	O
and	O
data	O
to	O
this	O
process	O
through	O
a	O
fifo	O
.	O
</s>
<s>
It	O
has	O
an	O
execution	O
thread	O
that	O
uses	O
readline	B-Application
(	O
an	O
open-source	B-License
library	O
from	O
the	O
GNU	B-Operating_System
project	O
)	O
to	O
obtain	O
command	O
lines	O
and	O
place	O
them	O
in	O
the	O
execution	O
queue	O
.	O
</s>
<s>
the	O
echo	O
from	O
readline	B-Application
)	O
into	O
graphics	O
server	O
commands	O
.	O
</s>
<s>
Experix	B-Application
can	O
also	O
run	O
in	O
a	O
text	O
screen	O
or	O
X-term	O
without	O
using	O
svgalib	B-Application
at	O
all	O
.	O
</s>
<s>
There	O
is	O
some	O
assembly	O
code	O
and	O
other	O
matters	O
to	O
attend	O
to	O
before	O
it	O
can	O
run	O
on	O
architectures	O
other	O
than	O
x86	B-Operating_System
.	O
</s>
<s>
The	O
range	O
of	O
device	B-Application
drivers	I-Application
and	O
applications	O
available	O
now	O
is	O
extremely	O
limited	O
.	O
</s>
<s>
It	O
runs	O
as	O
root	B-Application
,	O
which	O
is	O
a	O
considerable	O
security	O
hazard	O
on	O
a	O
networked	O
computer	O
.	O
</s>
<s>
It	O
should	O
be	O
possible	O
to	O
run	O
experix	B-Application
without	O
root	B-Application
privileges	I-Application
,	O
but	O
this	O
has	O
not	O
yet	O
been	O
done	O
.	O
</s>
