<s>
A	O
diagnostic	B-Application
program	I-Application
(	O
also	O
known	O
as	O
a	O
Test	O
Mode	O
)	O
is	O
an	O
automatic	B-Application
computer	I-Application
program	I-Application
sequence	O
that	O
determines	O
the	O
operational	O
status	O
within	O
the	O
software	B-Architecture
,	O
hardware	B-Architecture
,	O
or	O
any	O
combination	O
thereof	O
in	O
a	O
component	O
,	O
a	O
system	B-General_Concept
,	O
or	O
a	O
network	O
of	O
systems	O
.	O
</s>
<s>
Diagnostic	B-Application
programs	I-Application
ideally	O
provide	O
the	O
user	O
with	O
guidance	O
regarding	O
any	O
issues	O
or	O
problems	O
found	O
during	O
its	O
operation	O
.	O
</s>
<s>
Diagnostic	B-Application
programs	I-Application
are	O
also	O
inserted	O
into	O
consumer	O
electronic	O
products	O
and	O
electronic	O
games	O
.	O
</s>
<s>
Sometimes	O
if	O
the	O
owner	O
of	O
an	O
electronic	O
device	O
asks	O
the	O
manufacturer	O
how	O
to	O
access	O
the	O
hidden	O
diagnostic	B-Application
program	I-Application
,	O
they	O
may	O
reply	O
to	O
the	O
consumer	O
saying	O
that	O
the	O
information	O
is	O
considered	O
to	O
be	O
"	O
proprietary	O
"	O
and	O
cannot	O
be	O
shared	O
.	O
</s>
<s>
Early	O
diagnostics	O
programs	O
were	O
procedural	O
instructions	O
performed	O
by	O
humans	O
,	O
not	O
by	O
computer	B-Application
programs	I-Application
.	O
</s>
<s>
See	O
Built-in	O
test	O
equipment	O
that	O
enabled	O
system	B-General_Concept
operators	O
to	O
perform	O
testing	O
and	O
diagnostics	O
.	O
</s>
<s>
As	O
computers	O
became	O
smaller	O
,	O
more	O
mobile	O
,	O
computer	B-Application
programs	I-Application
were	O
used	O
to	O
perform	O
diagnostics	O
tasks	O
.	O
</s>
<s>
In	O
the	O
late	O
1960s	O
,	O
Volkswagen	O
introduced	O
the	O
first	O
on-board	O
computer	O
system	B-General_Concept
with	O
diagnostics	O
provisions	O
.	O
</s>
<s>
The	O
diagnostics	O
program	O
for	O
a	O
device	O
or	O
system	B-General_Concept
may	O
be	O
independently	O
located	O
or	O
integrated	O
within	O
.	O
</s>
<s>
Background	O
monitoring	O
of	O
system	B-General_Concept
indicators	O
,	O
for	O
statistical	O
analysis	O
of	O
trends	O
,	O
and	O
for	O
recording	O
abnormal	O
events	O
.	O
</s>
<s>
Integrated	O
background	O
diagnostics	O
,	O
that	O
perform	O
testing	O
of	O
system	B-General_Concept
components	O
during	O
idle-time	O
of	O
a	O
system	B-General_Concept
.	O
</s>
<s>
Operation-interleaved	O
diagnostics	O
,	O
that	O
incorporate	O
diagnostics	O
into	O
the	O
normal	O
operation	O
of	O
a	O
system	B-General_Concept
component	O
,	O
thus	O
any	O
marginal	O
operating	O
mode	O
is	O
immediately	O
diagnosed	O
.	O
</s>
<s>
Examples	O
of	O
hardware	B-Architecture
components	O
with	O
features	O
that	O
assist	O
a	O
diagnostic	B-Application
program	I-Application
are	O
:	O
</s>
<s>
Modular	B-Architecture
diagnostic	O
,	O
which	O
combines	O
sets	O
of	O
single-purpose	O
diagnostics	O
,	O
Lego-like	O
,	O
into	O
an	O
environment	O
easily	O
tailored	O
to	O
particular	O
industry	O
requirements	O
.	O
</s>
<s>
Key	O
to	O
its	O
design	O
is	O
its	O
reusable	O
hardware	B-Architecture
and	O
software	B-Architecture
operating	B-General_Concept
system	I-General_Concept
that	O
performs	O
all	O
of	O
its	O
diagnostics	O
programs	O
.	O
</s>
<s>
Knowledge-Driven	O
diagnostic	O
system	B-General_Concept
(	O
such	O
as	O
a	O
technician	O
or	O
diagnostician	O
)	O
where	O
the	O
knowledge	O
acquired	O
over	O
time	O
is	O
used	O
as	O
a	O
"	O
mental	O
model	O
"	O
of	O
the	O
system	B-General_Concept
's	O
operation	O
and	O
informs	O
the	O
diagnostic	O
system	B-General_Concept
through	O
logical	O
reasoning	O
to	O
one	O
or	O
more	O
possible	O
or	O
likely	O
causes	O
for	O
a	O
situation	O
to	O
exist	O
.	O
</s>
<s>
The	O
1996	O
Onboard	O
Diagnostics	O
II	O
system	B-General_Concept
(	O
OBD	O
II	O
)	O
that	O
standardized	O
the	O
diagnostics	O
port	O
across	O
all	O
models	O
of	O
cars	O
and	O
light	O
trucks	O
allowing	O
vehicle	O
owners	O
and	O
repair	O
technicians	O
access	O
to	O
the	O
vehicle	O
's	O
error	O
code	O
and	O
emissions	O
history	O
.	O
</s>
<s>
Personal	O
computer	O
users	O
have	O
diagnostics	O
options	O
from	O
both	O
software	B-Architecture
and	O
hardware	B-Architecture
sources	O
,	O
e.g.	O
,	O
Hewlett-Packard	O
'	O
s	O
(	O
HP	O
's	O
)	O
diagnostics	O
guide	O
for	O
confirming	O
hardware	B-Architecture
failures	O
.	O
</s>
