<s>
The	O
Motorola	O
MC68010	B-Device
processor	O
is	O
a	O
16/32	O
-bit	O
microprocessor	B-Architecture
from	O
Motorola	O
,	O
released	O
in	O
1982	O
as	O
the	O
successor	O
to	O
the	O
Motorola	B-Device
68000	I-Device
.	O
</s>
<s>
It	O
fixes	O
several	O
small	O
flaws	O
in	O
the	O
68000	B-Device
,	O
and	O
adds	O
a	O
few	O
features	O
.	O
</s>
<s>
The	O
68010	B-Device
is	O
pin-compatible	O
with	O
the	O
68000	B-Device
,	O
but	O
is	O
not	O
100%	O
software	O
compatible	O
.	O
</s>
<s>
This	O
means	O
that	O
the	O
68010	B-Device
meets	O
Popek	B-Architecture
and	I-Architecture
Goldberg	I-Architecture
virtualization	I-Architecture
requirements	I-Architecture
.	O
</s>
<s>
Because	O
the	O
68000	B-Device
offers	O
an	O
unprivileged	O
MOVE	O
from	O
SR	O
,	O
it	O
does	O
not	O
meet	O
them	O
.	O
</s>
<s>
It	O
can	O
recover	O
from	O
bus	O
faults	O
,	O
and	O
re-run	O
the	O
last	O
instruction	O
,	O
allowing	O
it	O
to	O
implement	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
The	O
exception	B-General_Concept
stack	O
frame	O
is	O
different	O
.	O
</s>
<s>
It	O
introduced	O
a	O
22-bit	O
Vector	O
Base	O
Register	O
(	O
VBR	O
)	O
that	O
holds	O
A[31:10]	O
of	O
the	O
1	O
KiB-aligned	O
base	O
address	O
for	O
the	O
exception	B-General_Concept
vector	O
table	O
.	O
</s>
<s>
The	O
68000	B-Device
vector	O
table	O
was	O
always	O
based	O
at	O
address	O
zero	O
.	O
</s>
<s>
The	O
two-instruction	O
mini-loop	O
opcodes	O
are	O
prefetched	O
and	O
held	O
in	O
the	O
6-byte	O
instruction	O
cache	O
while	O
subsequent	O
memory	B-General_Concept
read/write	O
cycles	O
are	O
only	O
needed	O
for	O
the	O
data	O
operands	O
for	O
the	O
duration	O
of	O
the	O
loop	O
.	O
</s>
<s>
In	O
practice	O
,	O
the	O
overall	O
speed	O
gain	O
over	O
a	O
68000	B-Device
at	O
the	O
same	O
frequency	O
is	O
less	O
than	O
10%	O
.	O
</s>
<s>
The	O
68010	B-Device
could	O
be	O
used	O
with	O
the	O
68451	B-Device
MMU	B-General_Concept
.	O
</s>
<s>
However	O
,	O
aspects	O
of	O
its	O
design	O
,	O
such	O
as	O
its	O
1	O
clock	O
memory	B-General_Concept
access	O
penalty	O
,	O
made	O
this	O
configuration	O
unpopular	O
.	O
</s>
<s>
Some	O
vendors	O
used	O
their	O
own	O
MMU	B-General_Concept
designs	O
,	O
such	O
as	O
Sun	O
Microsystems	O
in	O
their	O
Sun-2	B-Device
workstation	B-Device
and	O
Convergent	O
Technologies	O
in	O
the	O
AT&T	O
UNIX	O
PC/3B1	O
.	O
</s>
<s>
The	O
68010	B-Device
was	O
never	O
as	O
popular	O
as	O
the	O
68000	B-Device
.	O
</s>
<s>
However	O
,	O
due	O
to	O
the	O
68010	B-Device
's	O
small	O
speed	O
boost	O
over	O
the	O
68000	B-Device
and	O
its	O
support	O
for	O
virtual	B-Architecture
memory	I-Architecture
,	O
it	O
can	O
be	O
found	O
in	O
a	O
number	O
of	O
smaller	O
Unix	B-Application
systems	I-Application
,	O
both	O
with	O
the	O
68451	B-Device
MMU	B-General_Concept
(	O
for	O
example	O
in	O
the	O
Torch	B-Device
Triple	I-Device
X	I-Device
)	O
,	O
and	O
with	O
a	O
custom	O
MMU	B-General_Concept
(	O
such	O
as	O
the	O
Sun-2	B-Device
Workstation	B-Device
,	O
AT&T	O
UNIX	O
PC/3B1	O
,	O
Convergent	O
Technologies	O
MiniFrame	O
,	O
NCR	O
Tower	O
XP	O
,	O
Apollo	O
Computer	O
's	O
DN300	B-Device
and	I-Device
DN320	I-Device
,	O
and	O
HP	B-Device
9000	I-Device
Model	O
310	O
)	O
and	O
various	O
research	O
machines	O
.	O
</s>
<s>
Most	O
other	O
vendors	O
(	O
such	O
as	O
Apple	O
Computer	O
)	O
stayed	O
with	O
the	O
68000	B-Device
until	O
the	O
68020	B-Device
was	O
introduced	O
.	O
</s>
<s>
Atari	O
Games	O
used	O
the	O
68010	B-Device
in	O
some	O
of	O
their	O
arcade	O
boards	O
such	O
as	O
the	O
Atari	B-Application
System	I-Application
1	I-Application
.	O
</s>
<s>
Some	O
owners	O
of	O
Amiga	B-Device
and	O
Atari	B-Device
ST	I-Device
computers	O
and	O
Sega	B-Operating_System
Genesis	I-Operating_System
game	O
consoles	O
replaced	O
their	O
system	O
's	O
68000	B-Device
CPU	O
with	O
a	O
68010	B-Device
to	O
gain	O
a	O
small	O
speed	O
boost	O
.	O
</s>
<s>
The	O
Motorola	O
MC68012	O
processor	O
is	O
a	O
16/32	O
-bit	O
microprocessor	B-Architecture
from	O
the	O
early	O
1980s	O
.	O
</s>
<s>
It	O
is	O
an	O
84-pin	O
PGA	B-Algorithm
version	O
of	O
the	O
Motorola	B-Device
68010	I-Device
.	O
</s>
<s>
The	O
memory	B-General_Concept
space	O
was	O
extended	O
to	O
2GB	O
,	O
and	O
a	O
read-modify-write	O
cycle	O
(	O
RMC	O
)	O
pin	O
,	O
indicating	O
that	O
an	O
indivisible	O
read-modify-write	O
cycle	O
in	O
progress	O
,	O
was	O
added	O
,	O
in	O
order	O
to	O
help	O
the	O
design	O
of	O
multiprocessor	O
systems	O
with	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
All	O
other	O
processors	O
had	O
to	O
hold	O
off	O
memory	B-General_Concept
accesses	O
until	O
the	O
cycle	O
was	O
complete	O
.	O
</s>
<s>
All	O
other	O
features	O
of	O
the	O
MC68010	B-Device
were	O
preserved	O
.	O
</s>
<s>
The	O
expansion	O
of	O
the	O
memory	B-General_Concept
space	O
caused	O
an	O
issue	O
for	O
any	O
programs	O
that	O
used	O
the	O
high	O
byte	O
of	O
an	O
address	O
to	O
store	O
data	O
,	O
a	O
programming	O
trick	O
that	O
was	O
successful	O
with	O
those	O
processors	O
that	O
only	O
have	O
a	O
24-bit	O
address	O
bus	O
(	O
68000	B-Device
and	O
68010	B-Device
)	O
.	O
</s>
<s>
A	O
similar	O
problem	O
affected	O
the	O
68020	B-Device
.	O
</s>
