<s>
A	O
memory	B-General_Concept
buffer	I-General_Concept
register	I-General_Concept
(	O
MBR	O
)	O
or	O
memory	B-General_Concept
data	I-General_Concept
register	I-General_Concept
(	O
MDR	O
)	O
is	O
the	O
register	B-General_Concept
in	O
a	O
computer	O
's	O
CPU	B-General_Concept
that	O
stores	O
the	O
data	O
being	O
transferred	O
to	O
and	O
from	O
the	O
immediate	O
access	O
storage	O
.	O
</s>
<s>
It	O
contains	O
a	O
copy	O
of	O
the	O
value	O
in	O
the	O
memory	O
location	O
specified	O
by	O
the	O
memory	B-General_Concept
address	I-General_Concept
register	I-General_Concept
.	O
</s>
<s>
It	O
acts	O
as	O
a	O
buffer	B-General_Concept
,	O
allowing	O
the	O
processor	O
and	O
memory	B-Architecture
units	I-Architecture
to	O
act	O
independently	O
without	O
being	O
affected	O
by	O
minor	O
differences	O
in	O
operation	O
.	O
</s>
<s>
This	O
register	B-General_Concept
holds	O
the	O
contents	O
of	O
the	O
memory	O
which	O
are	O
to	O
be	O
transferred	O
from	O
memory	O
to	O
other	O
components	O
or	O
vice	O
versa	O
.	O
</s>
<s>
A	O
word	O
to	O
be	O
stored	O
must	O
be	O
transferred	O
to	O
the	O
MBR	O
,	O
from	O
where	O
it	O
goes	O
to	O
the	O
specific	O
memory	O
location	O
,	O
and	O
the	O
arithmetic	O
data	O
to	O
be	O
processed	O
in	O
the	O
ALU	B-General_Concept
first	O
goes	O
to	O
MBR	O
and	O
then	O
to	O
accumulated	O
register	B-General_Concept
,	O
and	O
then	O
it	O
is	O
processed	O
in	O
the	O
ALU	B-General_Concept
.	O
</s>
<s>
The	O
MDR	O
is	O
a	O
two-way	O
register	B-General_Concept
.	O
</s>
<s>
When	O
there	O
is	O
a	O
write	O
instruction	O
,	O
the	O
data	O
to	O
be	O
written	O
is	O
placed	O
into	O
the	O
MDR	O
from	O
another	O
CPU	B-General_Concept
register	I-General_Concept
,	O
which	O
then	O
puts	O
the	O
data	O
into	O
memory	O
.	O
</s>
<s>
The	O
memory	B-General_Concept
data	I-General_Concept
register	I-General_Concept
is	O
half	O
of	O
a	O
minimal	O
interface	O
between	O
a	O
microprogram	B-Device
and	O
computer	B-General_Concept
storage	I-General_Concept
;	O
the	O
other	O
half	O
is	O
a	O
memory	B-General_Concept
address	I-General_Concept
register	I-General_Concept
(	O
MAR	O
)	O
.	O
</s>
