<s>
In	O
computing	O
,	O
a	O
POST	B-Device
card	I-Device
is	O
a	O
plug-in	O
diagnostic	O
interface	B-Device
card	I-Device
that	O
displays	O
progress	O
and	O
error	O
codes	O
generated	O
during	O
power-on	B-Device
self-test	I-Device
(	O
POST	O
)	O
of	O
a	O
computer	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
troubleshoot	O
computers	O
that	O
do	O
not	O
start	B-Operating_System
up	I-Operating_System
.	O
</s>
<s>
At	O
a	O
minimum	O
,	O
if	O
the	O
CPU	B-Device
,	O
BIOS	B-Operating_System
,	O
and	O
the	O
I/O	B-General_Concept
interface	I-General_Concept
upon	O
which	O
the	O
POST	B-Device
card	I-Device
relies	O
on	O
are	O
all	O
working	O
,	O
a	O
POST	B-Device
card	I-Device
can	O
be	O
used	O
to	O
monitor	O
the	O
system	O
's	O
Power-On	B-Device
Self	I-Device
Test	I-Device
(	O
POST	O
)	O
,	O
or	O
to	O
diagnose	O
problems	O
with	O
it	O
.	O
</s>
<s>
The	O
system	O
introduced	O
on	O
IBM	B-Device
PC	I-Device
computers	O
sends	O
8-bit	O
byte	O
codes	O
(	O
usually	O
displayed	O
as	O
two	O
hexadecimal	O
digits	O
)	O
to	O
a	O
specified	O
I/O	B-General_Concept
port	I-General_Concept
(	O
usually	O
80hex	O
)	O
during	O
startup	O
,	O
some	O
indicating	O
a	O
stage	O
in	O
the	O
startup	O
procedure	O
,	O
others	O
identifying	O
errors	O
.	O
</s>
<s>
The	O
description	O
for	O
each	O
code	O
must	O
be	O
looked	O
up	O
in	O
a	O
table	O
for	O
the	O
particular	O
BIOS	B-Operating_System
.	O
</s>
<s>
For	O
example	O
,	O
for	O
the	O
1984	O
IBM	B-Operating_System
PC/AT	I-Operating_System
code	O
1D	O
is	O
issued	O
when	O
about	O
to	O
Determine	O
Memory	O
Size	O
Above	O
1024K	O
,	O
and	O
code	O
2D	O
in	O
the	O
event	O
of	O
8042	O
Keyboard	O
Controller	O
Failure	O
,	O
105	O
System	O
Error	O
.	O
</s>
<s>
POST	B-Device
cards	I-Device
provide	O
information	O
even	O
when	O
a	O
standard	O
display	O
is	O
not	O
available	O
,	O
either	O
because	O
connecting	O
a	O
monitor	O
is	O
impractical	O
,	O
or	O
because	O
the	O
failure	O
occurs	O
before	O
the	O
video	O
subsystem	O
is	O
operational	O
.	O
</s>
<s>
POST	B-Device
cards	I-Device
are	O
inserted	O
into	O
an	O
expansion	B-Device
slot	I-Device
,	O
and	O
are	O
available	O
with	O
connectors	O
for	O
the	O
ISA	B-Architecture
(	O
also	O
supporting	O
EISA	B-Device
)	O
,	O
PCI	B-Protocol
,	O
PCI	B-Protocol
Express	O
,	O
Mini	O
PCIe	O
(	O
for	O
laptops	O
)	O
,	O
Universal	B-Protocol
Serial	I-Protocol
Bus	I-Protocol
,	O
or	O
Low	O
Pin	O
Count	O
bus	O
,	O
or	O
for	O
a	O
parallel	O
port	O
.	O
</s>
<s>
A	O
typical	O
card	O
for	O
desktop	O
computers	O
has	O
a	O
different	O
bus	O
interface	O
on	O
each	O
edge	O
;	O
a	O
card	O
for	O
laptop	O
computers	O
may	O
have	O
both	O
a	O
miniPCI	O
and	O
a	O
parallel	O
port	O
connector	O
(	O
plus	O
USB	B-Protocol
to	O
supply	O
power	O
)	O
.	O
</s>
<s>
Modern	O
motherboards	O
often	O
do	O
not	O
broadcast	O
POST	B-Device
codes	I-Device
to	O
their	O
PCI	B-Protocol
Express	O
slots	O
(	O
PCIe	O
switches	O
only	O
pass	O
on	O
transactions	O
after	O
having	O
been	O
configured	O
to	O
do	O
so	O
by	O
the	O
BIOS	B-Operating_System
)	O
.	O
</s>
<s>
On	O
such	O
motherboards	O
,	O
the	O
Low	O
Pin	O
Count	O
(	O
LPC	O
)	O
bus	O
,	O
an	O
ISA	B-Architecture
variant	O
normally	O
used	O
to	O
connect	O
a	O
Trusted	O
Platform	O
Module	O
(	O
TPM	O
)	O
,	O
may	O
be	O
the	O
only	O
bus	O
where	O
POST	O
messages	O
can	O
still	O
be	O
seen	O
.	O
</s>
<s>
However	O
LPC	O
connectors	O
are	O
not	O
standardized	O
,	O
with	O
between	O
9	O
and	O
19	O
pins	O
and	O
both	O
2.54	O
mm	O
and	O
2	O
mm	O
pin	B-Protocol
headers	I-Protocol
commonly	O
used	O
.	O
</s>
<s>
Therefore	O
,	O
an	O
LPC	O
POST	B-Device
card	I-Device
may	O
have	O
to	O
auto-detect	O
first	O
the	O
pin	O
assignment	O
used	O
.	O
</s>
<s>
Another	O
option	O
are	O
USB	B-Protocol
POST	B-Device
cards	I-Device
such	O
as	O
,	O
which	O
use	O
the	O
.	O
</s>
<s>
Information	O
on	O
the	O
meaning	O
of	O
POST	B-Device
codes	I-Device
for	O
different	O
BIOSes	O
is	O
needed	O
to	O
interpret	O
the	O
codes	O
.	O
</s>
<s>
POST	B-Device
cards	I-Device
for	O
PCs	O
,	O
while	O
originally	O
high-priced	O
,	O
cost	O
from	O
just	O
a	O
few	O
US	O
dollars	O
upwards	O
in	O
the	O
21st	O
century	O
.	O
</s>
<s>
Such	O
motherboards	O
make	O
POST	B-Device
cards	I-Device
less	O
necessary	O
.	O
</s>
<s>
Motherboards	O
were	O
rarely	O
repaired	O
,	O
but	O
replaced	O
;	O
the	O
main	O
purpose	O
of	O
a	O
POST	B-Device
card	I-Device
is	O
to	O
determine	O
that	O
parts	O
mounted	O
on	O
the	O
motherboard	O
itself	O
,	O
rather	O
than	O
plugged-in	O
video	O
cards	O
,	O
RAM	O
,	O
etc	O
.	O
</s>
