<s>
The	O
UMC	B-Device
Green	I-Device
CPU	I-Device
was	O
an	O
x86-compatible	O
microprocessor	B-Architecture
produced	O
by	O
UMC	O
,	O
a	O
Taiwanese	O
semiconductor	O
company	O
,	O
in	O
the	O
early	O
-	O
to	O
mid-1990s	O
.	O
</s>
<s>
It	O
was	O
offered	O
as	O
an	O
alternative	O
to	O
the	O
Intel	B-General_Concept
80486	I-General_Concept
with	O
which	O
it	O
was	O
pin	O
compatible	O
,	O
enabling	O
it	O
to	O
be	O
installed	O
in	O
most	O
80486	B-General_Concept
motherboards	O
.	O
</s>
<s>
The	O
UMC	B-Device
Green	I-Device
CPU	I-Device
was	O
available	O
with	O
different	O
features	O
,	O
physical	O
characteristics	O
and	O
clock	O
speeds	O
.	O
</s>
<s>
All	O
models	O
feature	O
an	O
8KB	O
level	B-General_Concept
1	I-General_Concept
cache	I-General_Concept
and	O
operate	O
at	O
clock	O
speeds	O
of	O
25MHz	O
,	O
33MHz	O
,	O
or	O
40MHz	O
.	O
</s>
<s>
Model	O
FPU	O
Package	O
Voltage	O
Notes	O
U5S	O
No	O
CPGA	B-Algorithm
5	O
V	O
Compatible	O
with	O
the	O
486SX	O
.	O
</s>
<s>
U5D	O
Yes	O
Compatible	O
with	O
the	O
486DX	B-General_Concept
,	O
very	O
few	O
were	O
produced	O
.	O
</s>
<s>
U5SX	O
No	O
CPGA	B-Algorithm
,	O
PPGA	B-Algorithm
,	O
PQFP	O
Identical	O
to	O
the	O
U5S	O
,	O
the	O
QFP	B-Algorithm
version	O
was	O
available	O
as	O
an	O
embedded	O
solution	O
or	O
attached	O
to	O
a	O
PGA	B-Algorithm
adapter	O
.	O
</s>
<s>
U5SD	O
CPGA	B-Algorithm
Few	O
were	O
produced	O
.	O
</s>
<s>
Functionally	O
identical	O
to	O
U5S	O
and	O
U5SX	O
but	O
with	O
486DX	B-General_Concept
pinout	O
.	O
</s>
<s>
U5SLV	O
3.3	O
V	O
Low-voltage	O
version	O
U5FLV	O
Low-voltage	O
version	O
,	O
often	O
embedded	O
on	O
the	O
motherboard	O
.	O
</s>
<s>
The	O
U5SD	O
does	O
not	O
contain	O
a	O
floating	O
point	O
unit	O
and	O
is	O
indistinguishable	O
from	O
other	O
U5S	O
chips	O
in	O
operation	O
,	O
though	O
it	O
is	O
unusual	O
because	O
it	O
features	O
a	O
486DX	B-General_Concept
pinout	O
as	O
opposed	O
to	O
the	O
more	O
common	O
486SX	O
pinout	O
versions	O
.	O
</s>
<s>
This	O
would	O
allow	O
installation	O
into	O
certain	O
older	O
motherboards	O
which	O
may	O
have	O
had	O
upgrade	O
sockets	O
hardwired	O
to	O
fit	O
only	O
486DX	B-General_Concept
chips	O
.	O
</s>
<s>
All	O
available	O
models	O
of	O
Green	O
CPU	O
were	O
produced	O
on	O
a	O
0.6μm	O
CMOS	B-Device
process	O
.	O
</s>
<s>
These	O
processors	O
were	O
designed	O
to	O
compete	O
with	O
other	O
clock	O
doubling	O
solutions	O
such	O
as	O
the	O
Intel	B-Device
80486DX2	I-Device
,	O
AMD	B-Device
Am486DX2	I-Device
and	O
Cyrix	O
Cx486DX2	O
,	O
but	O
due	O
to	O
ongoing	O
legal	O
troubles	O
UMC	O
withdrew	O
the	O
U486DX2	O
from	O
production	O
.	O
</s>
<s>
The	O
processor	O
was	O
only	O
ever	O
produced	O
as	O
an	O
engineering	O
sample	O
and	O
never	O
made	O
it	O
to	O
market	O
,	O
it	O
was	O
manufactured	O
with	O
a	O
0.35μm	O
CMOS	B-Device
process	O
and	O
is	O
contained	O
within	O
a	O
ceramic	O
package	O
.	O
</s>
<s>
In	O
1994	O
,	O
Intel	O
alleged	O
that	O
UMC	O
had	O
infringed	O
upon	O
its	O
patent	O
for	O
the	O
80486	B-General_Concept
microprocessor	B-Architecture
and	O
filed	O
complaints	O
against	O
UMC	O
and	O
it	O
's	O
distributors	O
.	O
</s>
<s>
UMC	O
countered	O
the	O
claims	O
with	O
an	O
anti-trust	O
suit	O
and	O
the	O
case	O
was	O
eventually	O
settled	O
out	O
of	O
court	O
with	O
UMC	O
withdrawing	O
their	O
product	O
and	O
ceasing	O
production	O
of	O
80486-compatible	O
microprocessors	B-Architecture
.	O
</s>
