<s>
The	O
6309	B-General_Concept
is	O
Hitachi	O
's	O
CMOS	B-Device
version	O
of	O
the	O
Motorola	B-Device
6809	I-Device
microprocessor	B-Architecture
,	O
released	O
in	O
late	O
1982	O
.	O
</s>
<s>
It	O
was	O
initially	O
marketed	O
as	O
a	O
low-power	O
version	O
of	O
the	O
6809	B-Device
,	O
without	O
reference	O
to	O
its	O
many	O
internal	O
improvements	O
.	O
</s>
<s>
While	O
in	O
"	O
Emulation	O
Mode	O
"	O
it	O
is	O
fully	O
compatible	O
with	O
the	O
6809	B-Device
.	O
</s>
<s>
To	O
the	O
6809	B-Device
specifications	O
,	O
it	O
adds	O
higher	O
clock	O
rates	O
,	O
enhanced	O
features	O
,	O
new	O
instructions	O
,	O
and	O
additional	O
registers	B-General_Concept
.	O
</s>
<s>
Most	O
of	O
the	O
new	O
instructions	O
were	O
added	O
to	O
support	O
the	O
additional	O
registers	B-General_Concept
,	O
as	O
well	O
as	O
up	O
to	O
32-bit	O
math	O
,	O
hardware	O
division	O
,	O
bit	O
manipulations	O
,	O
and	O
block	O
transfers	O
.	O
</s>
<s>
The	O
6309	B-General_Concept
is	O
generally	O
30%	O
faster	O
in	O
native	B-Language
mode	I-Language
than	O
the	O
6809	B-Device
.	O
</s>
<s>
FM	O
,	O
a	O
Japanese	O
magazine	O
for	O
Fujitsu	O
personal	O
computer	O
users	O
,	O
contained	O
the	O
first	O
description	O
of	O
the	O
6309	B-General_Concept
's	O
additional	O
capabilities	O
.	O
</s>
<s>
Later	O
,	O
Hirotsugu	O
Kakugawa	O
posted	O
details	O
of	O
the	O
6309	B-General_Concept
's	O
new	O
features	O
and	O
instructions	O
to	O
comp.sys.m6809	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
development	O
of	O
NitrOS-9	B-Operating_System
for	O
the	O
Tandy	B-Device
Color	I-Device
Computer	I-Device
3	O
.	O
</s>
<s>
The	O
6309	B-General_Concept
differs	O
from	O
the	O
6809	B-Device
in	O
several	O
key	O
areas	O
.	O
</s>
<s>
The	O
6309	B-General_Concept
is	O
fabricated	O
in	O
CMOS	B-Device
technology	O
,	O
while	O
the	O
6809	B-Device
is	O
an	O
NMOS	B-Algorithm
device	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
6309	B-General_Concept
requires	O
less	O
power	O
to	O
operate	O
than	O
the	O
6809	B-Device
.	O
</s>
<s>
This	O
is	O
useful	O
for	O
direct	B-General_Concept
memory	I-General_Concept
access	I-General_Concept
as	O
it	O
allows	O
external	O
devices	O
to	O
pause	O
the	O
CPU	O
to	O
release	O
the	O
memory	O
bus	O
,	O
read	O
or	O
write	O
small	O
amounts	O
of	O
memory	O
,	O
and	O
then	O
unpause	O
the	O
CPU	O
again	O
.	O
</s>
<s>
The	O
6309	B-General_Concept
has	O
B	O
(	O
2MHz	O
)	O
versions	O
as	O
the	O
6809	B-Device
does	O
.	O
</s>
<s>
When	O
switched	O
into	O
6309	B-General_Concept
Native	B-Language
Mode	I-Language
(	O
as	O
opposed	O
to	O
the	O
default	O
6809-compatible	O
mode	O
)	O
many	O
key	O
instructions	O
will	O
complete	O
in	O
fewer	O
clock	O
cycles	O
.	O
</s>
<s>
Two	O
8-bit	O
accumulators	B-General_Concept
:	O
'	O
E	O
 '	O
and	O
'	O
F	O
 '	O
.	O
</s>
<s>
These	O
can	O
be	O
concatenated	O
to	O
form	O
16-bit	O
accumulator	B-General_Concept
'	O
W	O
 '	O
.	O
</s>
<s>
The	O
existing	O
6809	B-Device
16-bit	O
accumulator	B-General_Concept
D	O
can	O
be	O
concatenated	O
with	O
W	O
to	O
form	O
32-bit	O
accumulator	B-General_Concept
'	O
Q	O
 '	O
.	O
</s>
<s>
Most	O
of	O
the	O
new	O
instructions	O
are	O
modifications	O
of	O
existing	O
instructions	O
to	O
handle	O
the	O
existence	O
of	O
the	O
additional	O
registers	B-General_Concept
,	O
such	O
as	O
load	O
,	O
store	O
,	O
add	O
,	O
and	O
the	O
like	O
.	O
</s>
<s>
Genuine	O
6309	B-General_Concept
additions	O
include	O
inter-register	O
arithmetic	O
,	O
block	O
transfers	O
,	O
hardware	O
division	O
,	O
and	O
bit-level	O
manipulations	O
.	O
</s>
<s>
Further	O
,	O
16	O
bit	O
registers	B-General_Concept
D	O
and	O
W	O
can	O
be	O
target	O
of	O
16	O
bit	O
arithmetic	O
with	O
carry	O
and	O
16	O
bit	O
shift	O
and	O
rotate	O
operations	O
.	O
</s>
<s>
On	O
6809	B-Device
,	O
these	O
operations	O
are	O
limited	O
to	O
8	O
bit	O
operands	O
.	O
</s>
<s>
Despite	O
the	O
user-friendliness	O
of	O
the	O
additional	O
instructions	O
,	O
analysis	O
by	O
6809	B-Device
programming	O
gurus	O
indicates	O
that	O
many	O
of	O
the	O
new	O
instructions	O
are	O
actually	O
slower	O
than	O
the	O
equivalent	O
6809	B-Device
code	O
,	O
especially	O
in	O
tight	O
loops	O
.	O
</s>
<s>
Most	O
of	O
new	O
instructions	O
use	O
prefix	O
opcode	O
and	O
that	O
makes	O
them	O
slower	O
by	O
one	O
cycle	O
when	O
compared	O
to	O
similar	O
6809	B-Device
instruction	O
.	O
</s>
<s>
On	O
other	O
side	O
,	O
6309	B-General_Concept
native	B-Language
mode	I-Language
executes	O
many	O
instructions	O
faster	O
by	O
one	O
or	O
more	O
cycles	O
.	O
</s>
<s>
Here	O
is	O
a	O
timing	O
comparison	O
of	O
an	O
8	O
bit	O
LD	O
instruction	O
for	O
'	O
A	O
 '	O
register	O
and	O
'	O
E	O
 '	O
register	O
on	O
6809	B-Device
and	O
6309	B-General_Concept
:	O
</s>
<s>
Depending	O
on	O
addressing	O
mode	O
and	O
6309	B-General_Concept
mode	O
,	O
equivalent	O
6809	B-Device
code	O
can	O
be	O
faster	O
.	O
</s>
<s>
As	O
table	O
above	O
indicates	O
,	O
exclusive	O
or	O
of	O
16	O
bit	O
register	O
D	O
with	O
immediate	O
parameter	O
can	O
be	O
replaced	O
by	O
two	O
8	O
bit	O
instructions	O
EORA	O
imm	O
,	O
EORB	O
imm	O
and	O
it	O
will	O
execute	O
faster	O
when	O
6309	B-General_Concept
runs	O
in	O
emulation	O
mode	O
.	O
</s>
<s>
Further	O
,	O
when	O
6309	B-General_Concept
is	O
running	O
in	O
native	B-Language
mode	I-Language
,	O
instructions	O
EORA	O
direct	O
,	O
EORB	O
direct	O
take	O
only	O
3	O
cycles	O
,	O
one	O
cycle	O
less	O
than	O
inter-register	O
operation	O
.	O
</s>
<s>
Instead	O
of	O
stacking	O
the	O
PC	O
and	O
CC	O
registers	B-General_Concept
(	O
normal	O
6809	B-Device
behavior	O
)	O
the	O
FIRQ	O
interrupt	O
can	O
be	O
set	O
to	O
stack	O
the	O
entire	O
register	O
set	O
,	O
as	O
the	O
IRQ	O
interrupt	O
does	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
6309	B-General_Concept
has	O
two	O
possible	O
trap	O
modes	O
,	O
one	O
for	O
an	O
illegal	O
instruction	O
fetch	O
and	O
one	O
for	O
division	O
by	O
zero	O
.	O
</s>
<s>
The	O
illegal	O
instruction	O
fetch	O
is	O
not	O
maskable	O
,	O
and	O
many	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
users	O
reported	O
that	O
their	O
6309	B-General_Concept
's	O
were	O
"	O
buggy	O
"	O
when	O
in	O
reality	O
it	O
was	O
an	O
indicator	O
of	O
enhanced	O
and	O
unknown	O
features	O
.	O
</s>
