<s>
A	O
test	B-General_Concept
register	I-General_Concept
,	O
in	O
the	O
Intel	B-General_Concept
80386	I-General_Concept
and	O
Intel	B-General_Concept
80486	I-General_Concept
processor	O
,	O
was	O
a	O
register	O
used	O
by	O
the	O
processor	O
,	O
usually	O
to	O
do	O
a	O
self-test	O
.	O
</s>
<s>
The	O
test	B-General_Concept
registers	I-General_Concept
were	O
named	O
TR3	O
to	O
TR7	O
.	O
</s>
<s>
With	O
the	O
Pentium	B-General_Concept
,	O
the	O
test	B-General_Concept
registers	I-General_Concept
were	O
replaced	O
by	O
a	O
variety	O
of	O
model-specific	B-General_Concept
registers	I-General_Concept
(	O
MSRs	O
)	O
.	O
</s>
<s>
In	O
the	O
80386	B-General_Concept
,	O
two	O
test	B-General_Concept
registers	I-General_Concept
,	O
TR6	O
and	O
TR7	O
,	O
were	O
provided	O
for	O
the	O
purpose	O
of	O
TLB	O
testing	O
.	O
</s>
<s>
The	O
80486	B-General_Concept
provided	O
three	O
additional	O
registers	O
,	O
TR3	O
,	O
TR4	O
and	O
TR5	O
,	O
for	O
testing	O
of	O
the	O
L1	O
cache	O
.	O
</s>
<s>
A	O
test	B-General_Concept
register	I-General_Concept
may	O
either	O
be	O
the	O
source	O
operand	O
or	O
the	O
destination	O
operand	O
.	O
</s>
<s>
The	O
MOV	O
instructions	O
are	O
defined	O
in	O
both	O
real-address	B-Application
mode	I-Application
and	O
protected	B-Application
mode	I-Application
.	O
</s>
<s>
The	O
test	B-General_Concept
registers	I-General_Concept
are	O
privileged	O
resources	O
.	O
</s>
<s>
In	O
protected	B-Application
mode	I-Application
,	O
the	O
MOV	O
instructions	O
that	O
access	O
them	O
can	O
only	O
be	O
executed	O
at	O
privilege	B-Device
level	I-Device
0	O
.	O
</s>
<s>
An	O
attempt	O
to	O
read	O
or	O
write	O
the	O
test	B-General_Concept
registers	I-General_Concept
when	O
executing	O
at	O
any	O
other	O
privilege	B-Device
level	I-Device
causes	O
a	O
general	O
protection	O
exception	O
.	O
</s>
<s>
Also	O
,	O
those	O
instructions	O
generate	O
invalid	O
opcode	O
exception	O
on	O
most	O
CPUs	O
newer	O
than	O
80486	B-General_Concept
.	O
</s>
<s>
Moving	O
data	O
from	O
a	O
general	O
purpose	O
register	O
into	O
a	O
test	B-General_Concept
register	I-General_Concept
is	O
encoded	O
as	O
0F	O
26	O
/r	O
(	O
with	O
r/m	O
being	O
the	O
GPR	O
,	O
and	O
reg	O
being	O
the	O
test	B-General_Concept
register	I-General_Concept
)	O
.	O
</s>
<s>
from	O
the	O
test	B-General_Concept
register	I-General_Concept
into	O
a	O
general	O
purpose	O
register	O
)	O
is	O
encoded	O
as	O
0F	O
24	O
/r	O
(	O
with	O
r/m	O
being	O
the	O
GPR	O
,	O
and	O
reg	O
being	O
the	O
test	B-General_Concept
register	I-General_Concept
)	O
.	O
</s>
<s>
The	O
test	B-General_Concept
registers	I-General_Concept
and/or	O
associated	O
opcodes	O
were	O
supported	O
in	O
the	O
following	O
x86	B-Operating_System
processors	O
:	O
</s>
