<s>
The	O
Am5x86	B-Device
processor	O
is	O
an	O
x86-compatible	O
CPU	B-General_Concept
announced	O
in	O
November	O
of	O
1995	O
by	O
AMD	O
for	O
use	O
in	O
486-class	O
computer	O
systems	O
.	O
</s>
<s>
The	O
Am5x86	B-Device
(	O
also	O
known	O
as	O
the	O
5x86-133	O
,	O
Am5x86	B-Device
,	O
X5-133	O
,	O
and	O
sold	O
under	O
various	O
3rd-party	O
labels	O
such	O
as	O
the	O
Kingston	O
Technology	O
"	O
Turbochip	O
"	O
)	O
is	O
an	O
Enhanced	O
Am486	B-Device
processor	O
with	O
an	O
internally	O
set	O
multiplier	O
of	O
4	O
,	O
allowing	O
it	O
to	O
run	O
at	O
133	O
MHz	O
on	O
systems	O
without	O
official	O
support	O
for	O
clock-multiplied	O
DX2	B-Device
or	O
DX4	B-Device
486	I-Device
processors	O
.	O
</s>
<s>
Like	O
all	O
Enhanced	O
Am486	B-Device
,	O
the	O
Am5x86	B-Device
featured	O
write-back	O
L1	O
cache	B-General_Concept
,	O
and	O
unlike	O
all	O
but	O
a	O
few	O
,	O
a	O
generous	O
16	O
kilobytes	O
rather	O
than	O
the	O
more	O
common	O
8	O
KB	O
.	O
</s>
<s>
Since	O
having	O
a	O
clock	O
multiplier	O
of	O
four	O
is	O
not	O
part	O
of	O
the	O
original	O
Socket	B-General_Concept
3	I-General_Concept
design	O
(	O
and	O
that	O
the	O
486	B-General_Concept
only	O
have	O
a	O
single	O
CLKMUL	O
pin	O
anyway	O
)	O
,	O
AMD	O
made	O
the	O
5x86	O
accept	O
a	O
2x	O
setting	O
from	O
the	O
motherboard	O
and	O
instead	O
operate	O
at	O
a	O
rate	O
of	O
4x	O
.	O
</s>
<s>
When	O
using	O
an	O
Am5x86	B-Device
,	O
the	O
motherboard	O
must	O
be	O
set	O
to	O
the	O
2x	O
setting	O
.	O
</s>
<s>
The	O
chip	O
will	O
actually	O
physically	O
fit	O
into	O
an	O
older	O
486	B-General_Concept
socket	B-General_Concept
such	O
as	O
a	O
socket	B-Device
1	I-Device
or	O
2	O
or	O
the	O
original	O
168-pin	O
80486	B-General_Concept
socket	B-General_Concept
,	O
but	O
doing	O
this	O
requires	O
a	O
replacement	O
voltage	B-Device
regulator	O
,	O
since	O
the	O
AMD	O
chip	O
runs	O
at	O
3.45	O
volts	O
.	O
</s>
<s>
The	O
combination	O
of	O
clock	O
speed	O
and	O
the	O
relatively	O
large	O
16	O
KB	O
write-back	O
L1	O
cache	B-General_Concept
allows	O
the	O
5x86	O
to	O
equal	O
or	O
slightly	O
exceed	O
an	O
Intel	B-General_Concept
Pentium	I-General_Concept
75	O
MHz	O
processor	O
in	O
integer	O
arithmetic	O
in	O
benchmarks	O
.	O
</s>
<s>
Real	O
world	O
performance	O
varies	O
,	O
however	O
,	O
with	O
later	O
Windows	O
operating	O
systems	O
and	O
many	O
FPU-sensitive	O
games	O
favoring	O
the	O
Pentium	B-General_Concept
75	O
MHz	O
.	O
</s>
<s>
Because	O
it	O
is	O
based	O
on	O
a	O
pure	O
486	B-General_Concept
design	O
,	O
it	O
is	O
compatible	O
with	O
older	O
systems	O
,	O
something	O
its	O
slightly	O
faster	O
rival	O
,	O
the	O
Cyrix	B-Device
Cx5x86	I-Device
,	O
has	O
trouble	O
with	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
is	O
commonly	O
overclocked	O
to	O
160	O
MHz	O
,	O
thereby	O
giving	O
performance	O
similar	O
to	O
that	O
of	O
a	O
Pentium	B-General_Concept
90MHz	O
system	O
.	O
</s>
<s>
There	O
are	O
four	O
main	O
versions	O
of	O
the	O
socketed	O
version	O
of	O
this	O
CPU	B-General_Concept
,	O
manufactured	O
in	O
different	O
locations	O
.	O
</s>
<s>
The	O
later	O
models	O
were	O
the	O
preferred	O
versions	O
of	O
the	O
chip	O
,	O
because	O
they	O
were	O
rated	O
for	O
higher	O
temperatures	O
and	O
thus	O
more	O
forgiving	O
of	O
overclocking	B-Application
.	O
</s>
<s>
The	O
Am5x86	B-Device
made	O
the	O
first-ever	O
use	O
of	O
the	O
controversial	O
PR	O
rating	O
.	O
</s>
<s>
Because	O
the	O
5x86	O
is	O
the	O
equal	O
of	O
a	O
Pentium	B-General_Concept
75MHz	O
processor	O
in	O
benchmarks	O
,	O
AMD	O
later	O
marketed	O
the	O
chip	O
as	O
"	O
Am5x86-P75	O
"	O
.	O
</s>
<s>
Sales	O
of	O
the	O
Am5x86	B-Device
were	O
an	O
important	O
source	O
of	O
revenue	O
for	O
AMD	O
at	O
a	O
time	O
when	O
lengthy	O
delays	O
in	O
bringing	O
the	O
AMD	O
K5	O
to	O
production	O
were	O
threatening	O
the	O
company	O
's	O
profitability	O
.	O
</s>
<s>
AMD	O
manufactured	O
the	O
Am5x86	B-Device
processor	O
for	O
ordinary	O
PC	O
systems	O
until	O
1999	O
.	O
</s>
<s>
It	O
was	O
popular	O
for	O
entry-level	O
desktop	O
systems	O
,	O
appeared	O
in	O
many	O
different	O
notebook	O
models	O
,	O
and	O
also	O
sold	O
separately	O
as	O
an	O
upgrade	O
processor	O
for	O
older	O
486	B-General_Concept
systems	O
.	O
</s>
<s>
Several	O
companies	O
made	O
upgrade	O
kits	O
with	O
an	O
AMD	B-Device
5x86	I-Device
with	O
a	O
voltage	B-Device
regulator	O
and	O
socket	B-General_Concept
converter	O
,	O
which	O
allows	O
its	O
use	O
on	O
virtually	O
every	O
socketed	O
486	B-General_Concept
motherboard	O
ever	O
produced	O
.	O
</s>
<s>
Several	O
companies	O
also	O
provided	O
upgrades	O
for	O
older	O
486	B-General_Concept
notebooks	O
by	O
replacing	O
soldered	O
486	B-General_Concept
CPUs	O
.	O
</s>
<s>
The	O
chips	O
were	O
even	O
used	O
on	O
later	O
Acorn	B-Device
RiscPC	I-Device
"	O
PC	O
card	O
"	O
second	O
processors	O
.	O
</s>
<s>
The	O
RiscPC	B-Device
's	O
OpenBus	O
memory	O
interface	O
was	O
only	O
32	O
bit	O
,	O
which	O
meant	O
that	O
the	O
Pentium	B-General_Concept
could	O
not	O
be	O
easily	O
interfaced	O
to	O
it	O
.	O
</s>
<s>
Intel	O
's	O
expensive	O
Pentium	B-Device
Overdrive	I-Device
for	O
486	B-General_Concept
systems	O
is	O
a	O
troublesome	O
CPU	B-General_Concept
,	O
with	O
many	O
compatibility	O
issues	O
,	O
and	O
so	O
is	O
not	O
used	O
.	O
</s>
<s>
The	O
5x86	O
therefore	O
provided	O
the	O
acme	O
of	O
RiscPC	B-Device
Windows	O
performance	O
.	O
</s>
<s>
CPU	B-General_Concept
Model	O
number	O
Frequency	O
L1	O
Cache	B-General_Concept
FSB	B-Architecture
Mult	O
.	O
</s>
