<s>
The	O
Cyrix	B-Device
5x86	I-Device
was	O
a	O
line	O
of	O
x86	B-Operating_System
microprocessors	I-Operating_System
designed	O
by	O
Cyrix	O
and	O
released	O
on	O
June	O
5	O
of	O
1995	O
.	O
</s>
<s>
The	O
line	O
came	O
out	O
about	O
5	O
months	O
before	O
the	O
more	O
famous	O
Cyrix	B-General_Concept
6x86	I-General_Concept
.	O
</s>
<s>
The	O
Cyrix	B-Device
5x86	I-Device
was	O
one	O
of	O
the	O
fastest	O
CPUs	O
ever	O
produced	O
for	O
Socket	B-General_Concept
3	I-General_Concept
computer	O
systems	O
.	O
</s>
<s>
With	O
better	O
performance	O
in	O
most	O
applications	O
than	O
an	O
Intel	B-General_Concept
Pentium	I-General_Concept
processor	O
at	O
75MHz	O
,	O
the	O
Cyrix	B-Device
Cx5x86	I-Device
filled	O
a	O
gap	O
by	O
providing	O
a	O
medium-performance	O
processor	O
option	O
for	O
486	B-General_Concept
Socket3	O
motherboards	B-Device
(	O
which	O
are	O
incapable	O
of	O
handling	O
Intel	O
's	O
Pentium	B-General_Concept
CPUs	O
,	O
apart	O
from	O
the	O
Pentium	B-Device
Overdrive	I-Device
)	O
.	O
</s>
<s>
The	O
IBM	B-Device
5x86C	I-Device
is	O
an	O
IBM	O
branded	O
and	O
produced	O
version	O
of	O
the	O
Cyrix-designed	O
Cyrix	B-Device
Cx5x86	I-Device
CPU	B-General_Concept
.	O
</s>
<s>
Previous	O
IBM	O
x86	B-Operating_System
processors	O
,	O
IBM	B-Device
386SLC	I-Device
and	O
IBM	O
486SLC	O
,	O
were	O
based	O
on	O
modified	O
Intel	O
designs	O
.	O
</s>
<s>
The	O
Cyrix	B-Device
5x86	I-Device
processor	O
,	O
codename	O
"	O
M1sc	O
"	O
,	O
was	O
based	O
on	O
a	O
scaled-down	O
version	O
of	O
the	O
"	O
M1	O
"	O
core	O
used	O
in	O
the	O
Cyrix	B-General_Concept
6x86	I-General_Concept
,	O
which	O
provided	O
80%	O
of	O
the	O
performance	O
for	O
a	O
50%	O
decrease	O
in	O
transistors	B-Application
over	O
the	O
6x86	B-General_Concept
design	O
.	O
</s>
<s>
It	O
had	O
the	O
32-bit	O
memory	O
bus	O
of	O
an	O
ordinary	O
486	B-General_Concept
processor	I-General_Concept
,	O
but	O
internally	O
had	O
much	O
more	O
in	O
common	O
with	O
fifth-generation	O
processors	O
such	O
as	O
the	O
Cyrix	B-General_Concept
6x86	I-General_Concept
,	O
the	O
AMD	O
K5	O
,	O
and	O
the	O
Intel	B-General_Concept
Pentium	I-General_Concept
,	O
and	O
even	O
the	O
sixth-generation	O
Intel	B-Device
Pentium	I-Device
Pro	I-Device
.	O
</s>
<s>
The	O
chip	O
featured	O
near-complete	O
support	O
for	O
i486	B-General_Concept
instructions	O
,	O
but	O
very	O
limited	O
support	O
for	O
Pentium	B-General_Concept
instructions	O
.	O
</s>
<s>
Some	O
performance-enhancing	O
features	O
of	O
the	O
CPU	B-General_Concept
were	O
intentionally	O
disabled	O
due	O
to	O
potentially	O
stability-threatening	O
bugs	B-Error_Name
which	O
were	O
not	O
fixed	O
before	O
release	O
time	O
(	O
these	O
features	O
can	O
be	O
enabled	O
with	O
freely	O
downloadable	O
software	O
utilities	O
;	O
see	O
below	O
)	O
.	O
</s>
<s>
The	O
similarly	O
named	O
SGS-Thomson	O
(	O
STMicroelectronics	O
)	O
ST5x86	O
and	O
IBM	B-Device
5x86C	I-Device
were	O
licensed	O
rebrandings	O
of	O
the	O
Cyrix	O
design	O
(	O
IBM	O
and	O
ST	O
physically	O
produced	O
Cyrix	O
's	O
CPUs	O
for	O
them	O
)	O
,	O
marketed	O
separately	O
but	O
identical	O
for	O
practical	O
purposes	O
,	O
apart	O
from	O
the	O
availability	O
of	O
a	O
75MHz	O
edition	O
which	O
Cyrix	O
did	O
not	O
bring	O
to	O
market	O
,	O
and	O
slight	O
differences	O
in	O
voltage	O
requirements	O
.	O
</s>
<s>
The	O
Cyrix	B-Device
5x86	I-Device
design	O
,	O
however	O
,	O
should	O
not	O
be	O
confused	O
with	O
the	O
similarly	O
named	O
AMD	B-Device
Am5x86	I-Device
which	O
was	O
essentially	O
a	O
clock-quadrupled	O
486	B-General_Concept
(	O
not	O
an	O
all-new	O
design	O
like	O
the	O
Cyrix	O
part	O
)	O
but	O
which	O
had	O
broadly	O
similar	O
performance	O
,	O
used	O
the	O
same	O
Socket	B-General_Concept
3	I-General_Concept
,	O
and	O
was	O
introduced	O
at	O
the	O
end	O
of	O
the	O
same	O
year	O
.	O
</s>
<s>
It	O
is	O
likely	O
Cyrix	O
could	O
have	O
continued	O
to	O
successfully	O
sell	O
processors	O
based	O
on	O
Socket	B-General_Concept
3	I-General_Concept
,	O
but	O
canned	O
the	O
5x86	O
so	O
that	O
it	O
would	O
not	O
compete	O
with	O
its	O
then	O
new	O
6x86	B-General_Concept
offerings	O
.	O
</s>
<s>
The	O
official	O
Cyrix	B-Device
5x86	I-Device
website	O
boasted	O
about	O
several	O
features	O
of	O
the	O
chip	O
that	O
were	O
disabled	O
by	O
default	O
in	O
the	O
final	O
versions	O
.	O
</s>
<s>
The	O
most	O
controversial	O
of	O
these	O
features	O
was	O
the	O
"	O
branch-prediction	O
"	O
feature	O
,	O
which	O
was	O
enabled	O
in	O
the	O
benchmarks	O
results	O
on	O
the	O
company	O
website	O
when	O
comparing	O
the	O
chip	O
to	O
Intel	O
's	O
Pentium	B-General_Concept
processor	O
.	O
</s>
<s>
There	O
are	O
also	O
many	O
rumours	O
surrounding	O
a	O
133MHz	O
,	O
clock-quadrupled	O
version	O
of	O
the	O
Cyrix	B-Device
5x86	I-Device
.	O
</s>
<s>
IBM	B-Device
5x86C	I-Device
was	O
available	O
as	O
75MHz	O
and	O
100MHz	O
parts	O
.	O
</s>
<s>
IBM	O
continued	O
to	O
produce	O
5x86C	O
at	O
least	O
until	O
late	O
1998	O
(	O
QFP	B-Algorithm
only	O
)	O
,	O
whereas	O
Cyrix	O
's	O
own	O
part	O
was	O
discontinued	O
in	O
1996	O
.	O
</s>
<s>
capable	O
edition	O
for	O
40MHz	O
(	O
40×3	O
)	O
and	O
33MHz	O
(	O
33×4	O
)	O
front	B-Architecture
side	I-Architecture
bus	I-Architecture
.	O
</s>
