<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
a	O
memory	B-General_Concept
map	I-General_Concept
is	O
a	O
structure	O
of	O
data	O
(	O
which	O
usually	O
resides	O
in	O
memory	O
itself	O
)	O
that	O
indicates	O
how	O
memory	O
is	O
laid	O
out	O
.	O
</s>
<s>
The	O
term	O
"	O
memory	B-General_Concept
map	I-General_Concept
"	O
can	O
have	O
different	O
meanings	O
in	O
different	O
contexts	O
.	O
</s>
<s>
It	O
is	O
the	O
fastest	O
and	O
most	O
flexible	O
cache	B-General_Concept
organization	O
that	O
uses	O
an	O
associative	B-Data_Structure
memory	I-Data_Structure
.	O
</s>
<s>
The	O
associative	B-Data_Structure
memory	I-Data_Structure
stores	O
both	O
the	O
address	O
and	O
content	O
of	O
the	O
memory	O
word	O
.	O
</s>
<s>
In	O
the	O
boot	B-Operating_System
process	I-Operating_System
,	O
a	O
memory	B-General_Concept
map	I-General_Concept
is	O
passed	O
on	O
from	O
the	O
firmware	B-Application
in	O
order	O
to	O
instruct	O
an	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
about	O
memory	O
layout	O
.	O
</s>
<s>
In	O
virtual	B-Architecture
memory	I-Architecture
implementations	O
and	O
memory	B-General_Concept
management	I-General_Concept
units	I-General_Concept
,	O
a	O
memory	B-General_Concept
map	I-General_Concept
refers	O
to	O
page	B-General_Concept
tables	I-General_Concept
or	O
hardware	B-General_Concept
registers	I-General_Concept
,	O
which	O
store	O
the	O
mapping	O
between	O
a	O
certain	O
process	O
's	O
virtual	B-Architecture
memory	I-Architecture
layout	O
and	O
how	O
that	O
space	O
relates	O
to	O
physical	O
memory	O
addresses	O
.	O
</s>
<s>
In	O
native	O
debugger	B-Application
programs	O
,	O
a	O
memory	B-General_Concept
map	I-General_Concept
refers	O
to	O
the	O
mapping	O
between	O
loaded	O
executable(or )	O
library	O
files	O
and	O
memory	O
regions	O
.	O
</s>
<s>
These	O
memory	B-Architecture
maps	I-Architecture
are	O
used	O
to	O
resolve	O
memory	O
addresses	O
(	O
such	O
as	O
function	B-Language
pointers	I-Language
)	O
to	O
actual	O
symbols	O
.	O
</s>
<s>
BIOS	B-Operating_System
for	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
and	O
compatibles	O
provides	O
a	O
set	O
of	O
routines	O
that	O
can	O
be	O
used	O
by	O
operating	B-General_Concept
system	I-General_Concept
or	O
applications	O
to	O
get	O
the	O
memory	O
layout	O
.	O
</s>
<s>
BIOS	B-Operating_System
Function	O
:	O
INT	O
0x15	O
,	O
AX	O
=	O
0xE801	O
:	O
</s>
<s>
This	O
BIOS	B-Operating_System
interrupt	O
call	O
is	O
used	O
to	O
get	O
the	O
memory	O
size	O
for	O
64MB+	O
configurations	O
.	O
</s>
<s>
BIOS	B-Operating_System
Function	O
:	O
INT	O
0x15	O
,	O
AX	O
=	O
0xE820	O
-	O
GET	O
SYSTEM	O
MEMORY	B-General_Concept
MAP	I-General_Concept
:	O
</s>
<s>
Offset	O
Size	O
Value	O
description	O
0	O
QWORD	O
(	O
8	O
bytes	O
)	O
Base	O
address	O
of	O
memory	B-General_Concept
map	I-General_Concept
region	O
referred	O
to	O
by	O
EBX	O
.	O
</s>
<s>
How	O
used	O
:	O
The	O
operating	B-General_Concept
system	I-General_Concept
shall	O
allocate	O
an	O
SMAP	O
buffer	O
in	O
memory	O
(	O
20	O
bytes	O
buffer	O
)	O
.	O
</s>
<s>
If	O
no	O
error	O
,	O
the	O
interrupt	O
call	O
returns	O
with	O
CF	O
clear	O
and	O
the	O
buffer	O
filled	O
with	O
data	O
representing	O
first	O
region	O
of	O
the	O
memory	B-General_Concept
map	I-General_Concept
.	O
</s>
<s>
EBX	O
is	O
updated	O
by	O
BIOS	B-Operating_System
so	O
that	O
when	O
the	O
OS	O
calls	O
the	O
routine	O
again	O
,	O
The	O
next	O
region	O
is	O
returned	O
in	O
the	O
buffer	O
.	O
</s>
<s>
BIOS	B-Operating_System
sets	O
EBX	O
to	O
zero	O
if	O
all	O
done	O
.	O
</s>
