<s>
MemTest86	B-Application
and	O
Memtest86+	B-Application
are	O
memory	O
test	O
software	O
programs	O
designed	O
to	O
test	O
and	O
stress	O
test	O
an	O
x86	B-Operating_System
architecture	I-Operating_System
computer	O
's	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
for	O
errors	O
,	O
by	O
writing	O
test	O
patterns	O
to	O
most	O
memory	O
addresses	O
,	O
reading	O
back	O
the	O
data	O
,	O
and	O
comparing	O
for	O
errors	O
.	O
</s>
<s>
Each	O
tries	O
to	O
verify	O
that	O
the	O
RAM	B-Architecture
will	O
accept	O
and	O
correctly	O
retain	O
arbitrary	O
patterns	O
of	O
data	O
written	O
to	O
it	O
,	O
that	O
there	O
are	O
no	O
errors	O
where	O
different	O
bits	O
of	O
memory	O
interact	O
,	O
and	O
that	O
there	O
are	O
no	O
conflicts	O
between	O
memory	O
addresses	O
.	O
</s>
<s>
MemTest86	B-Application
was	O
developed	O
by	O
Chris	O
Brady	O
in	O
1994	O
.	O
</s>
<s>
After	O
MemTest86	B-Application
remained	O
at	O
version	O
3.0	O
(	O
2002	O
release	O
)	O
for	O
two	O
years	O
,	O
Samuel	O
Demeulemeester	O
created	O
the	O
Memtest86+	B-Application
fork	O
to	O
add	O
support	O
for	O
newer	O
CPUs	O
and	O
chipsets	B-Device
.	O
</s>
<s>
the	O
latest	O
version	O
of	O
Memtest86+	B-Application
is	O
6.10	O
.	O
</s>
<s>
MemTest86	B-Application
is	O
written	O
in	O
C	B-Language
and	O
x86	B-Operating_System
assembly	B-Language
.	O
</s>
<s>
The	O
source	O
code	O
of	O
MemTest86	B-Application
(	O
BIOS	O
version	O
)	O
and	O
of	O
the	O
MemTest86+	B-Application
fork	O
is	O
released	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
<s>
The	O
bootloading	O
code	O
was	O
originally	O
derived	O
from	O
Linux	B-Operating_System
1.2.1	I-Operating_System
.	O
</s>
<s>
The	O
program	O
is	O
compiled	O
as	O
position-independent	B-Operating_System
code	I-Operating_System
so	O
as	O
to	O
be	O
able	O
to	O
move	O
itself	O
around	O
and	O
test	O
all	O
the	O
memory	O
regions	O
.	O
</s>
<s>
Both	O
versions	O
now	O
support	O
current	O
multi-core	B-Architecture
processors	I-Architecture
and	O
the	O
corresponding	O
chipsets	B-Device
.	O
</s>
<s>
Starting	O
from	O
MemTest86	B-Application
2.3	O
and	O
Memtest86+	B-Application
1.60	O
,	O
the	O
program	O
can	O
output	O
a	O
list	O
of	O
bad	O
RAM	B-Architecture
regions	O
in	O
the	O
format	O
expected	O
by	O
the	O
BadRAM	O
patch	O
for	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
GRUB2	O
is	O
able	O
to	O
supply	O
this	O
same	O
information	O
to	O
an	O
unpatched	O
kernel	B-Operating_System
,	O
making	O
the	O
BadRAM	O
patch	O
unnecessary	O
.	O
</s>
<s>
In	O
February	O
2013	O
,	O
the	O
original	O
MemTest86	B-Application
was	O
sold	O
to	O
PassMark	O
.	O
</s>
<s>
The	O
BIOS	O
version	O
was	O
updated	O
under	O
GPL	B-License
until	O
version	O
4.3.7	O
.	O
</s>
<s>
MemTest86	B-Application
Version	O
5.0	O
(	O
3	O
December	O
2013	O
)	O
was	O
rewritten	O
for	O
UEFI	B-Architecture
booting	O
,	O
allowing	O
for	O
secure	O
boot	O
approval	O
and	O
mouse	O
support	O
.	O
</s>
<s>
All	O
UEFI	B-Architecture
versions	O
are	O
released	O
under	O
a	O
proprietary	B-Application
freeware	O
license	O
.	O
</s>
<s>
When	O
UEFI	B-Architecture
is	O
not	O
available	O
,	O
Version	O
5.0	O
(	O
and	O
later	O
)	O
fall	O
back	O
to	O
BIOS	O
booting	O
and	O
loads	O
the	O
old	O
version	O
4.3.7	O
.	O
</s>
<s>
Version	O
6.0.0	O
(	O
13	O
Feb	O
2015	O
)	O
adds	O
support	O
for	O
DDR4	O
RAM	B-Architecture
,	O
and	O
a	O
row-hammer	B-General_Concept
test	O
based	O
on	O
research	O
from	O
Yoongu	O
Kim	O
,	O
et	O
al	O
..	O
</s>
<s>
Version	O
10	O
states	O
only	O
UEFI	B-Architecture
boot	O
and	O
will	O
not	O
boot	O
on	O
non-UEFI	O
systems	O
,	O
requiring	O
separate	O
download	O
of	O
the	O
older	O
4.3.7	O
version	O
which	O
is	O
also	O
maintained	O
on	O
the	O
official	O
website	O
downloads	O
for	O
that	O
purpose	O
.	O
</s>
<s>
MemTest86+	B-Application
6.0	O
was	O
released	O
in	O
October	O
2022	O
,	O
being	O
rewritten	O
for	O
UEFI	B-Architecture
support	O
,	O
DDR4	O
and	O
DDR5	O
RAM	B-Architecture
,	O
and	O
supporting	O
all	O
current	O
AMD	O
and	O
Intel	O
chipsets	B-Device
and	O
CPUs	O
.	O
</s>
<s>
There	O
are	O
two	O
development	O
streams	O
of	O
Memtest86	B-Application
.	O
</s>
<s>
The	O
original	O
is	O
simply	O
known	O
as	O
MemTest86	B-Application
.	O
</s>
<s>
The	O
other	O
,	O
known	O
as	O
Memtest86+	B-Application
,	O
is	O
a	O
development	O
fork	O
of	O
the	O
original	O
MemTest86	B-Application
.	O
</s>
<s>
However	O
,	O
version	O
5	O
of	O
MemTest86	B-Application
added	O
a	O
mouse-driven	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
and	O
UEFI	B-Architecture
support	O
.	O
</s>
<s>
Each	O
new	O
release	O
adds	O
support	O
for	O
newer	O
processors	O
and	O
chipsets	B-Device
.	O
</s>
<s>
MemTest86( +	O
)	O
is	O
designed	O
to	O
run	O
as	O
a	O
stand-alone	O
,	O
self-contained	O
program	O
from	O
a	O
bootable	O
USB	O
flash	O
drive	O
,	O
CD-ROM	B-Device
,	O
floppy	B-Device
disk	I-Device
,	O
or	O
from	O
a	O
suitable	O
boot	O
manager	O
without	O
an	O
operating	B-General_Concept
system	I-General_Concept
present	O
.	O
</s>
<s>
This	O
is	O
because	O
the	O
program	O
must	O
directly	O
control	O
the	O
hardware	O
being	O
tested	O
and	O
leave	O
as	O
much	O
of	O
the	O
RAM	B-Architecture
space	O
as	O
possible	O
for	O
examination	O
.	O
</s>
<s>
MemTest86( +	O
)	O
'	O
s	O
testing	O
is	O
very	O
comprehensive	O
,	O
so	O
it	O
can	O
find	O
otherwise	O
hidden	O
problems	O
on	O
machines	O
that	O
appear	O
to	O
work	O
normally	O
.	O
</s>
<s>
With	O
many	O
chipsets	B-Device
,	O
MemTest86	B-Application
allows	O
counting	O
of	O
failures	O
even	O
in	O
error-correcting	O
ECC	B-Error_Name
DRAM	O
(	O
without	O
special	O
handling	O
,	O
error	O
correcting	O
memory	O
circuits	O
can	O
mask	O
problems	O
with	O
the	O
underlying	O
memory	O
chips	O
)	O
.	O
</s>
<s>
MemTest86+	B-Application
is	O
a	O
part	O
of	O
many	O
Linux	B-Application
distributions	I-Application
,	O
including	O
Debian	O
,	O
the	O
derived	O
Ubuntu	B-Operating_System
,	O
and	O
Arch	O
Linux	B-Operating_System
.	O
</s>
<s>
Ubuntu	B-Operating_System
includes	O
it	O
as	O
part	O
of	O
the	O
default	O
installation	O
if	O
the	O
machine	O
is	O
booting	O
in	O
BIOS	O
mode	O
;	O
it	O
is	O
available	O
from	O
the	O
GRUB	B-Application
OS-select	O
menu	O
.	O
</s>
<s>
For	O
example	O
,	O
Debian	O
has	O
patches	O
that	O
update	O
the	O
makefile	O
for	O
GCC	B-Application
version	O
5	O
and	O
makes	O
the	O
program	O
Multiboot	O
compliant	O
.	O
</s>
