<s>
The	O
Commodore	B-Device
CBM-II	I-Device
series	O
is	O
a	O
short-lived	O
range	O
of	O
8-bit	O
personal	B-Device
computers	I-Device
from	O
Commodore	O
Business	O
Machines	O
(	O
CBM	O
)	O
,	O
released	O
in	O
1982	O
and	O
intended	O
as	O
a	O
follow-on	O
to	O
the	O
Commodore	B-Device
PET	I-Device
series	O
.	O
</s>
<s>
The	O
CBM-II	B-Device
has	O
two	O
incarnations	O
,	O
the	O
P	O
series	O
(	O
P	O
=	O
personal	O
,	O
or	O
,	O
home	O
use	O
)	O
and	O
the	O
B	O
series	O
(	O
B	O
=	O
business	O
use	O
)	O
.	O
</s>
<s>
The	O
6509	B-General_Concept
CPU	I-General_Concept
runs	O
at	O
1MHz	O
in	O
the	O
P-series	O
due	O
to	O
the	O
use	O
of	O
the	O
VIC-II	O
chip	O
.	O
</s>
<s>
The	O
B-series	O
uses	O
a	O
6545	B-General_Concept
CRTC	I-General_Concept
video	O
chip	O
to	O
give	O
an	O
80-column	O
"	O
green	O
screen	O
"	O
monochrome	O
output	O
more	O
suitable	O
for	O
word	O
processing	O
and	O
other	O
business	O
use	O
than	O
the	O
VIC-II	O
'	O
s	O
40-column	O
display	O
.	O
</s>
<s>
Most	O
models	O
have	O
the	O
Motorola	B-General_Concept
68B45	I-General_Concept
installed	O
which	O
is	O
a	O
pin-compatible	O
variant	O
rather	O
than	O
the	O
MOS	O
6545A1	O
2MHz	O
part	O
.	O
</s>
<s>
On	O
the	O
B-series	O
the	O
6509	B-General_Concept
CPU	I-General_Concept
runs	O
at	O
2MHz	O
.	O
</s>
<s>
CBM-IIs	B-Device
are	O
the	O
only	O
Commodore	O
8-bit	O
machines	O
with	O
an	O
RS-232	O
port	O
instead	O
of	O
the	O
standard	O
user	O
port	O
.	O
</s>
<s>
The	O
I/O	O
registers	O
for	O
the	O
user	O
port	O
are	O
still	O
present	O
(	O
as	O
they	O
're	O
an	O
internal	O
function	O
of	O
the	O
6522	B-Device
chips	O
)	O
but	O
there	O
is	O
no	O
connector	O
for	O
it	O
on	O
the	O
motherboard	O
.	O
</s>
<s>
A	O
cartridge	B-Protocol
slot	O
is	O
also	O
included	O
on	O
the	O
machines	O
;	O
however	O
,	O
no	O
known	O
cartridge	B-Protocol
software	O
was	O
developed	O
.	O
</s>
<s>
The	O
B-series	O
retained	O
the	O
IEEE-488	O
interface	O
from	O
the	O
PET	O
instead	O
of	O
the	O
IEC	B-Protocol
serial	I-Protocol
interface	O
on	O
the	O
VIC-20	B-Device
and	O
C64	O
.	O
</s>
<s>
The	O
small	O
amount	O
of	O
software	O
Commodore	O
developed	O
for	O
the	O
B-series	O
was	O
distributed	O
on	O
500k	O
8050	B-Device
format	O
disks	O
rather	O
than	O
the	O
170k	O
4040/1541	O
format	O
.	O
</s>
<s>
Features	O
common	O
to	O
both	O
the	O
P	O
and	O
B-series	O
included	O
an	O
MOS	B-General_Concept
Technology	I-General_Concept
6509	I-General_Concept
CPU	O
,	O
an	O
enhanced	O
version	O
of	O
the	O
venerable	O
6502	B-General_Concept
,	O
that	O
was	O
capable	O
of	O
addressing	O
up	O
to	O
1	O
megabyte	O
of	O
RAM	B-Architecture
via	O
bank	B-General_Concept
switching	I-General_Concept
(	O
however	O
,	O
no	O
CBM-II	B-Device
model	O
came	O
with	O
more	O
than	O
256	O
kilobytes	O
of	O
RAM	B-Architecture
)	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
CBM-II	B-Device
has	O
an	O
industry-standard	O
RS-232	O
serial	O
interface	O
and	O
an	O
IEEE-488	O
parallel	O
bus	O
(	O
for	O
use	O
by	O
disk	O
drives	O
and	O
printers	O
)	O
just	O
like	O
the	O
PET/CBM	O
series	O
.	O
</s>
<s>
The	O
CBM-II	B-Device
'	O
s	O
built-in	O
operating	O
system	O
uses	O
an	O
enhanced	O
version	O
of	O
CBM	B-Language
BASIC	I-Language
version	O
4.0	O
.	O
</s>
<s>
An	O
optional	O
Intel	O
8088-based	O
coprocessor	B-General_Concept
board	O
allows	O
the	O
CBM-II	B-Device
series	O
to	O
run	O
CP/M	B-Application
-86	O
1.1	O
and	O
MS-DOS	O
1.25	O
;	O
however	O
,	O
the	O
computers	O
were	O
not	O
IBM	O
PC	O
compatible	O
and	O
very	O
little	O
,	O
if	O
any	O
,	O
software	O
taking	O
advantage	O
of	O
this	O
capability	O
ever	O
appeared	O
.	O
</s>
<s>
The	O
coprocessor	B-General_Concept
board	O
only	O
runs	O
on	O
high-profile	O
machines	O
due	O
to	O
power	O
supply	O
and	O
mechanical	O
spacing	O
requirements	O
.	O
</s>
<s>
A	O
Z80	B-General_Concept
card	O
was	O
also	O
announced	O
if	O
the	O
user	O
wished	O
to	O
run	O
CP/M	B-Application
-80	I-Application
,	O
as	O
well	O
as	O
a	O
Zilog	B-Device
Z8001	I-Device
board	O
,	O
but	O
none	O
are	O
known	O
to	O
exist	O
.	O
</s>
<s>
The	O
8088	B-Device
board	O
never	O
reached	O
production	O
apparently	O
because	O
of	O
difficulties	O
getting	O
it	O
to	O
work	O
with	O
the	O
system	O
.	O
</s>
<s>
The	O
CBM-II	B-Device
line	O
uses	O
a	O
complicated	O
RAM	B-Architecture
banking	B-General_Concept
scheme	O
.	O
</s>
<s>
Bank	O
0	O
contains	O
the	O
video	O
RAM	B-Architecture
on	O
P-series	O
machines	O
and	O
is	O
empty	O
on	O
B-series	O
machines	O
.	O
</s>
<s>
Banks	O
1-4	O
contain	O
the	O
main	O
system	O
RAM	B-Architecture
,	O
with	O
Bank	O
15	O
containing	O
the	O
system	O
ROMs	O
,	O
cartridge	B-Protocol
ROM	O
,	O
I/O	O
registers	O
,	O
video	O
RAM	B-Architecture
on	O
B-series	O
machines	O
,	O
and	O
a	O
small	O
amount	O
of	O
RAM	B-Architecture
to	O
store	O
system	O
variables	O
.	O
</s>
<s>
However	O
,	O
unlike	O
the	O
later	O
released	O
Commodore	B-Device
128	I-Device
,	O
the	O
CBM-IIs	B-Device
do	O
not	O
have	O
the	O
system	O
ROMs	O
mapped	O
into	O
banks	O
other	O
than	O
15	O
,	O
which	O
has	O
very	O
limited	O
program	O
RAM	B-Architecture
(	O
1k	O
free	O
,	O
plus	O
a	O
4k	O
expander	O
board	O
could	O
be	O
installed	O
)	O
.	O
</s>
<s>
This	O
meant	O
that	O
software	O
had	O
to	O
include	O
its	O
own	O
OS	O
routines	O
to	O
handle	O
device	O
I/O	O
and	O
interrupts	B-Application
,	O
as	O
it	O
is	O
not	O
possible	O
to	O
"	O
far	O
call	O
"	O
code	O
across	O
different	O
memory	O
banks	O
.	O
</s>
<s>
In	O
theory	O
,	O
if	O
Banks	O
5	O
–	O
14	O
were	O
filled	O
,	O
up	O
to	O
1MB	O
of	O
RAM	B-Architecture
could	O
be	O
installed	O
,	O
but	O
in	O
practice	O
the	O
computer	O
is	O
limited	O
to	O
256KB	O
as	O
the	O
PLA	O
chip	O
does	O
not	O
have	O
enough	O
address	O
lines	O
for	O
it	O
.	O
</s>
<s>
Passing	O
data	O
between	O
different	O
banks	O
requires	O
use	O
of	O
the	O
register	O
at	O
$0	O
which	O
selects	O
the	O
banks	O
to	O
be	O
read	O
from	O
and	O
written	O
to	O
via	O
LDA	O
(	O
zero	O
page	O
)	O
,	O
Y	O
and	O
STA	O
(	O
zero	O
page	O
)	O
,	O
Y	O
CPU	O
opcodes	B-Language
.	O
</s>
<s>
The	O
BASIC	O
included	O
with	O
the	O
CBM-II	B-Device
series	O
is	O
known	O
as	O
BASIC	O
4.0	O
+	O
.	O
</s>
<s>
Commodore	O
had	O
plans	O
for	O
a	O
wide	O
variety	O
of	O
RAM	B-Architecture
configurations	O
as	O
well	O
as	O
slimline	O
and	O
"	O
high	O
profile	O
"	O
models	O
.	O
</s>
<s>
Both	O
slimline	O
and	O
high-profile	O
models	O
have	O
a	O
connector	O
for	O
internal	O
floppy	O
drives	O
and	O
coprocessor	B-General_Concept
boards	O
,	O
although	O
only	O
the	O
latter	O
have	O
physical	O
room	O
in	O
the	O
case	O
and	O
a	O
sufficient	O
power	O
supply	O
for	O
them	O
.	O
</s>
<s>
No	O
production	O
machines	O
had	O
internal	O
floppy	O
drives	O
,	O
however	O
these	O
likely	O
would	O
have	O
been	O
a	O
half-height	O
variant	O
of	O
the	O
8050	B-Device
.	O
</s>
<s>
Most	O
of	O
the	O
planned	O
CBM-II	B-Device
models	O
never	O
made	O
it	O
past	O
the	O
prototype	O
stage	O
.	O
</s>
<s>
In	O
the	O
end	O
,	O
the	O
only	O
CBM-II	B-Device
models	O
to	O
enter	O
production	O
and	O
be	O
sold	O
to	O
end	O
users	O
were	O
the	O
B128/600	O
,	O
B256/700	O
,	O
CBM-128/710	O
,	O
and	O
PAL	B-Language
model	O
P500s	O
.	O
</s>
<s>
The	O
B128	B-Device
and	O
P500	O
were	O
slimline	O
models	O
with	O
no	O
internal	O
disk	O
drives	O
or	O
attached	O
monitor	O
while	O
the	O
CBM	O
128	O
and	O
B256	O
were	O
high-profile	O
models	O
.	O
</s>
<s>
The	O
B128	B-Device
was	O
the	O
biggest	O
selling	O
of	O
the	O
three	O
.	O
</s>
<s>
The	O
production	O
naming	O
within	O
the	O
United	O
States	O
and	O
Canada	O
was	O
the	O
B128/B256	O
and	O
CBM128-80/CBM	O
256-80	O
while	O
in	O
Europe	O
they	O
were	O
known	O
as	O
the	O
600	O
and	O
700	O
series	O
respectively	O
(	O
no	O
"	O
B	O
"	O
in	O
front	O
of	O
the	O
model	O
number	O
)	O
.	O
</s>
<s>
There	O
are	O
prototype	O
models	O
though	O
such	O
as	O
the	O
B500	O
(	O
earlier	O
B128	B-Device
design	O
)	O
and	O
B700	O
(	O
earlier	O
CBM	O
128-80/CBM	O
256-80	O
design	O
)	O
known	O
to	O
exist	O
.	O
</s>
<s>
The	O
most	O
common	O
of	O
the	O
B-series	O
was	O
the	O
low-profile	O
B128	B-Device
(	O
called	O
the	O
CBM	O
610	O
in	O
Europe	O
)	O
,	O
which	O
had	O
128	O
kilobytes	O
of	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
B128	B-Device
did	O
not	O
sell	O
well	O
,	O
and	O
ultimately	O
Commodore	O
's	O
inventory	O
was	O
liquidated	O
by	O
Protecto	O
Enterprizes	O
,	O
a	O
large	O
Commodore	O
mail	O
order	O
dealer	O
based	O
in	O
Chicago	O
,	O
Illinois	O
.	O
</s>
<s>
The	O
Protecto	O
ads	O
for	O
the	O
B128	B-Device
bundle	O
,	O
including	O
a	O
dual	O
disk	O
drive	O
,	O
monitor	O
and	O
printer	O
,	O
appeared	O
in	O
various	O
computer	O
magazines	O
for	O
several	O
years	O
.	O
</s>
<s>
The	O
CBM-II	B-Device
line	O
sold	O
poorly	O
and	O
ended	O
up	O
being	O
extremely	O
expensive	O
to	O
manufacture	O
,	O
as	O
well	O
as	O
difficult	O
to	O
develop	O
software	O
for	O
.	O
</s>
<s>
Commodore	O
did	O
not	O
release	O
any	O
sales	O
figures	O
or	O
an	O
official	O
discontinuation	O
date	O
,	O
however	O
the	O
B128/600	O
is	O
the	O
most	O
common	O
model	O
in	O
the	O
lineup	O
.	O
</s>
<s>
CBM-IIs	B-Device
were	O
still	O
being	O
sold	O
in	O
Germany	O
up	O
to	O
1987	O
.	O
</s>
<s>
The	O
exact	O
number	O
of	O
CBM-IIs	B-Device
produced	O
is	O
unclear	O
,	O
however	O
serial	O
numbers	O
indicate	O
that	O
at	O
least	O
10,000	O
B128s	B-Device
were	O
shipped	O
along	O
with	O
a	O
few	O
dozen	O
to	O
a	O
few	O
thousand	O
of	O
the	O
other	O
models	O
.	O
</s>
<s>
After	O
discontinuing	O
the	O
CBM-II	B-Device
range	O
,	O
Commodore	O
handed	O
its	O
documentation	O
,	O
schematics	O
,	O
and	O
all	O
other	O
information	O
over	O
to	O
CBUG	O
,	O
the	O
Chicago	O
B128	B-Device
Users	O
Group	O
.	O
</s>
<s>
Among	O
these	O
materials	O
was	O
a	O
prototype	O
motherboard	O
using	O
an	O
Intel	B-Device
8088	I-Device
processor	O
,	O
which	O
hints	O
at	O
the	O
possibility	O
the	O
line	O
could	O
have	O
been	O
made	O
IBM	O
compatible	O
if	O
production	O
had	O
continued	O
.	O
</s>
<s>
Its	O
library	O
,	O
however	O
,	O
paled	O
in	O
comparison	O
to	O
the	O
large	O
software	O
libraries	O
enjoyed	O
by	O
the	O
Commodore	O
64	O
and	O
VIC-20	B-Device
.	O
</s>
<s>
The	O
rounded	O
case	O
design	O
of	O
the	O
high-profile	O
CBM-II	B-Device
series	O
would	O
later	O
be	O
used	O
in	O
redesigned	O
versions	O
of	O
the	O
original	O
PET/CBM	O
computers	O
,	O
(	O
such	O
as	O
the	O
CBM8296	O
)	O
that	O
the	O
CBM-II	B-Device
line	O
was	O
designed	O
to	O
replace	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
memory	O
banking	B-General_Concept
scheme	O
of	O
the	O
CBM-II	B-Device
would	O
be	O
reused	O
on	O
the	O
Commodore	B-Device
128	I-Device
with	O
a	O
few	O
slight	O
modifications	O
.	O
</s>
