<s>
Background	O
debug	O
mode	O
(	O
BDM	O
)	O
interface	O
is	O
an	O
electronic	O
interface	O
that	O
allows	O
debugging	O
of	O
embedded	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
Specifically	O
,	O
it	O
provides	O
in-circuit	B-Application
debugging	I-Application
functionality	O
in	O
microcontrollers	O
.	O
</s>
<s>
No	O
special	O
hardware	O
is	O
required	O
in	O
the	O
host	O
;	O
a	O
simple	O
bidirectional	O
I/O	B-Architecture
pin	I-Architecture
is	O
sufficient	O
.	O
</s>
<s>
Tri-states	B-Device
its	O
output	O
,	O
allowing	O
the	O
target	O
to	O
drive	O
the	O
line	O
.	O
</s>
<s>
This	O
capability	O
,	O
implemented	O
in	O
various	O
processors	O
under	O
such	O
names	O
as	O
background	O
debug	O
mode	O
(	O
BDM	O
)	O
,	O
JTAG	O
and	O
on-chip	O
in-circuit	B-Application
emulation	I-Application
,	O
puts	O
basic	O
debugging	O
functions	O
on	O
the	O
chip	O
itself	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
in-circuit	B-Application
debugging	I-Application
.	O
</s>
<s>
Furthermore	O
,	O
most	O
new	O
MCUs	O
have	O
nonvolatile	O
memory	O
such	O
as	O
flash	B-Device
memory	I-Device
so	O
that	O
programming	O
code	O
on	O
the	O
target	O
system	O
is	O
also	O
required	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
in-circuit	B-Device
programming	I-Device
.	O
</s>
<s>
To	O
support	O
in-circuit	B-Application
debugging	I-Application
and	O
programming	O
requirements	O
,	O
the	O
HC08	O
Family	O
has	O
the	O
monitor	O
mode	O
and	O
the	O
HCS08	O
and	O
RS08	O
utilize	O
a	O
background	O
debug	O
mode	O
(	O
BDM	O
)	O
.	O
</s>
<s>
The	O
register	O
holds	O
a	O
value	O
indicating	O
an	O
address	B-General_Concept
in	O
memory	O
.	O
</s>
