<s>
The	O
Commodore	B-Device
128	I-Device
,	O
also	O
known	O
as	O
the	O
C128	O
,	O
C-128	O
,	O
C	O
=	O
128	O
,	O
is	O
the	O
last	O
8-bit	O
home	O
computer	O
that	O
was	O
commercially	O
released	O
by	O
Commodore	O
Business	O
Machines	O
(	O
CBM	O
)	O
.	O
</s>
<s>
The	O
newer	O
machine	O
has	O
128KB	O
of	O
RAM	B-Architecture
in	O
two	O
64KB	O
banks	O
,	O
and	O
an	O
80-column	O
color	O
video	O
output	O
.	O
</s>
<s>
It	O
has	O
a	O
redesigned	O
case	O
and	O
keyboard	B-Device
.	O
</s>
<s>
Also	O
included	O
is	O
a	O
Zilog	B-General_Concept
Z80	I-General_Concept
CPU	O
which	O
allows	O
the	O
C128	O
to	O
run	O
CP/M	B-Application
,	O
as	O
an	O
alternative	O
to	O
the	O
usual	O
Commodore	B-Language
BASIC	I-Language
environment	O
.	O
</s>
<s>
The	O
presence	O
of	O
the	O
Z80	B-General_Concept
and	O
the	O
huge	O
CP/M	B-Application
software	O
library	O
it	O
brings	O
,	O
coupled	O
with	O
the	O
C64	O
's	O
software	O
library	O
,	O
gave	O
the	O
C128	O
one	O
of	O
the	O
broadest	O
ranges	O
of	O
available	O
software	O
among	O
its	O
competitors	O
.	O
</s>
<s>
The	O
primary	O
hardware	O
designer	O
of	O
the	O
C128	O
was	O
Bil	O
Herd	O
,	O
who	O
had	O
worked	O
on	O
the	O
Plus/4	B-Operating_System
.	O
</s>
<s>
The	O
main	O
Commodore	O
system	O
software	O
was	O
developed	O
by	O
Fred	O
Bowen	O
and	O
Terry	O
Ryan	O
,	O
while	O
the	O
CP/M	B-Application
subsystem	O
was	O
developed	O
by	O
Von	O
Ertwine	O
.	O
</s>
<s>
The	O
C128	O
's	O
keyboard	B-Device
includes	O
four	O
cursor	O
keys	O
,	O
an	O
Alt	B-Device
key	I-Device
,	O
Help	B-Protocol
key	I-Protocol
,	O
Esc	B-Device
key	I-Device
,	O
Tab	O
key	O
and	O
a	O
numeric	B-Device
keypad	I-Device
.	O
</s>
<s>
The	O
lack	O
of	O
a	O
numeric	B-Device
keypad	I-Device
,	O
Alt	B-Device
key	I-Device
,	O
and	O
Esc	B-Device
key	I-Device
on	O
the	O
C64	O
was	O
an	O
issue	O
with	O
some	O
CP/M	B-Application
productivity	B-Application
software	I-Application
when	O
used	O
with	O
the	O
C64	O
's	O
Z80	B-General_Concept
cartridge	O
.	O
</s>
<s>
A	O
keypad	O
was	O
requested	O
by	O
many	O
C64	O
owners	O
who	O
spent	O
long	O
hours	O
entering	O
machine	B-Language
language	I-Language
type-in	O
programs	O
.	O
</s>
<s>
Many	O
of	O
the	O
added	O
keys	O
matched	O
counterparts	O
present	O
on	O
the	O
IBM	B-Device
PC	I-Device
's	O
keyboard	B-Device
and	O
made	O
the	O
new	O
computer	O
more	O
attractive	O
to	O
business	O
software	O
developers	O
.	O
</s>
<s>
While	O
the	O
128	O
's	O
40-column	O
mode	O
closely	O
duplicates	O
that	O
of	O
the	O
C64	O
,	O
an	O
extra	O
1K	O
of	O
color	O
RAM	B-Architecture
is	O
made	O
available	O
to	O
the	O
programmer	O
,	O
as	O
it	O
is	O
multiplexed	O
through	O
memory	B-General_Concept
address	I-General_Concept
1	O
.	O
</s>
<s>
The	O
C128	O
does	O
not	O
perform	O
a	O
system	O
RAM	B-Architecture
test	O
on	O
power-up	O
like	O
previous	O
Commodore	O
machines	O
.	O
</s>
<s>
Instead	O
of	O
the	O
single	O
6510	B-General_Concept
microprocessor	B-Architecture
of	O
the	O
C64	O
,	O
the	O
C128	O
incorporates	O
a	O
two-CPU	O
design	O
.	O
</s>
<s>
The	O
primary	O
CPU	O
,	O
the	O
8502	B-General_Concept
,	O
is	O
a	O
slightly	O
improved	O
version	O
of	O
the	O
6510	B-General_Concept
,	O
capable	O
of	O
being	O
clocked	O
at	O
2MHz	O
.	O
</s>
<s>
The	O
second	O
CPU	O
is	O
a	O
Zilog	B-General_Concept
Z80	I-General_Concept
which	O
is	O
used	O
to	O
run	O
CP/M	B-Application
software	O
,	O
as	O
well	O
as	O
to	O
initiate	O
operating-mode	O
selection	O
at	O
boot	O
time	O
.	O
</s>
<s>
The	O
two	O
processors	O
cannot	O
run	O
concurrently	O
,	O
thus	O
the	O
C128	O
is	O
not	O
a	O
multiprocessing	B-Operating_System
system	O
.	O
</s>
<s>
The	O
C128	O
's	O
complex	O
architecture	O
,	O
includes	O
four	O
differently	O
accessed	O
kinds	O
of	O
RAM	B-Architecture
(	O
128KB	O
main	O
RAM	B-Architecture
,	O
16	O
–	O
64KB	O
VDC	O
video	O
RAM	B-Architecture
,	O
2kNibbles	O
VIC-II	O
Color	O
RAM	B-Architecture
,	O
2-kilobyte	O
floppy-drive	O
RAM	B-Architecture
on	O
C128Ds	O
,	O
0	O
,	O
128	O
or	O
512KB	O
REU	B-General_Concept
RAM	B-Architecture
)	O
,	O
two	O
or	O
three	O
CPUs	O
(	O
main	O
:	O
8502	B-General_Concept
,	O
Z80	B-General_Concept
for	O
CP/M	B-Application
;	O
the	O
128D	O
also	O
incorporates	O
a	O
6502	B-General_Concept
in	O
the	O
disk	O
drive	O
)	O
,	O
and	O
two	O
different	O
video	O
chips	O
(	O
VIC-IIe	O
and	O
VDC	O
)	O
for	O
its	O
various	O
operational	O
modes	O
.	O
</s>
<s>
The	O
C128	O
has	O
three	O
operating	B-General_Concept
modes	I-General_Concept
.	O
</s>
<s>
C128	O
Mode	O
(	O
native	B-Language
mode	I-Language
)	O
runs	O
at	O
1	O
or	O
2MHz	O
with	O
the	O
8502	B-General_Concept
CPU	O
and	O
has	O
both	O
40	O
-	O
and	O
80-column	O
text	B-Application
modes	I-Application
available	O
.	O
</s>
<s>
CP/M	B-Application
Mode	O
uses	O
both	O
the	O
Z80	B-General_Concept
and	O
the	O
8502	B-General_Concept
,	O
and	O
is	O
able	O
to	O
function	O
in	O
both	O
40	O
-	O
or	O
80-column	O
text	B-Application
mode	I-Application
.	O
</s>
<s>
Selection	O
of	O
these	O
modes	O
is	O
implemented	O
via	O
the	O
Z80	B-General_Concept
chip	O
.	O
</s>
<s>
The	O
Z80	B-General_Concept
controls	O
the	O
bus	O
on	O
initial	O
boot-up	O
and	O
checks	O
to	O
see	O
if	O
there	O
is	O
a	O
CP/M	B-Application
disk	O
in	O
the	O
drive	O
,	O
if	O
there	O
are	O
any	O
C64/C128	O
cartridges	O
present	O
,	O
or	O
if	O
the	O
Commodore	O
key	O
(	O
which	O
serves	O
as	O
the	O
C64-mode	O
selector	O
)	O
is	O
being	O
depressed	O
on	O
boot-up	O
.	O
</s>
<s>
In	O
1984	O
,	O
a	O
year	O
before	O
the	O
release	O
of	O
the	O
Commodore	B-Device
128	I-Device
,	O
Commodore	O
released	O
the	O
Plus/4	B-Operating_System
.	O
</s>
<s>
Although	O
targeted	O
at	O
a	O
low-end	O
business	O
market	O
that	O
could	O
not	O
afford	O
the	O
relatively	O
high	O
cost	O
and	O
training	O
requirements	O
of	O
early	O
IBM	B-Device
PC	I-Device
compatibles	O
,	O
it	O
was	O
perceived	O
by	O
the	O
Commodore	O
press	O
as	O
a	O
follow-up	O
to	O
the	O
64	O
and	O
would	O
be	O
expected	O
to	O
improve	O
upon	O
that	O
model	O
's	O
capabilities	O
.	O
</s>
<s>
While	O
the	O
C64	O
's	O
graphics	O
and	O
sound	O
capabilities	O
were	O
generally	O
considered	O
excellent	O
,	O
the	O
response	O
to	O
the	O
Plus/4	B-Operating_System
was	O
one	O
of	O
disappointment	O
.	O
</s>
<s>
Upon	O
the	O
Plus/4	B-Operating_System
'	O
s	O
introduction	O
,	O
repeated	O
recommendations	O
were	O
made	O
in	O
the	O
Commodore	O
press	O
for	O
a	O
new	O
computer	O
called	O
the	O
"	O
C-128	O
"	O
with	O
increased	O
RAM	B-Architecture
capacity	O
,	O
an	O
80-column	O
display	O
as	O
was	O
standard	O
in	O
business	O
computers	O
,	O
a	O
new	O
BASIC	O
programming	O
language	O
that	O
made	O
it	O
easy	O
for	O
programmers	O
to	O
use	O
the	O
computer	O
's	O
graphics	O
and	O
sound	O
without	O
resorting	O
to	O
PEEK	B-Language
and	I-Language
POKEs	I-Language
,	O
a	O
new	O
disk	O
drive	O
that	O
improved	O
upon	O
the	O
1541	B-Device
's	O
abysmal	O
transfer	O
rate	O
,	O
as	O
well	O
as	O
total	O
C64	O
compatibility	O
.	O
</s>
<s>
A	O
new	O
chip	O
,	O
the	O
VDC	O
,	O
provides	O
the	O
C128	O
with	O
an	O
80-column	O
color	O
CGA-compatible	O
display	O
(	O
also	O
called	O
RGBI	O
for	O
red-green-blue	O
plus	O
intensity	O
)	O
.	O
</s>
<s>
The	O
then-new	O
8502	B-General_Concept
microprocessor	B-Architecture
is	O
completely	O
backward-compatible	O
with	O
the	O
C64	O
's	O
6510	B-General_Concept
,	O
but	O
can	O
run	O
at	O
double	O
the	O
speed	O
if	O
desired	O
.	O
</s>
<s>
The	O
C64	O
's	O
BASIC	B-Language
2.0	I-Language
was	O
replaced	O
with	O
BASIC	B-Language
7.0	I-Language
,	O
which	O
includes	O
structured	B-Language
programming	I-Language
commands	O
from	O
the	O
Plus/4	B-Operating_System
'	O
s	O
BASIC	O
3.5	O
,	O
as	O
well	O
as	O
keywords	O
designed	O
specifically	O
to	O
take	O
advantage	O
of	O
the	O
machine	O
's	O
capabilities	O
.	O
</s>
<s>
A	O
sprite	O
editor	O
and	O
machine	B-General_Concept
language	I-General_Concept
monitor	I-General_Concept
were	O
added	O
.	O
</s>
<s>
The	O
screen-editor	O
part	O
of	O
the	O
Kernal	B-Operating_System
was	O
further	O
improved	O
to	O
support	O
an	O
insert	B-Device
mode	I-Device
and	O
other	O
features	O
accessed	O
through	O
ESC-key	O
combinations	O
,	O
as	O
well	O
as	O
a	O
rudimentary	O
windowing	O
feature	O
,	O
and	O
was	O
relocated	O
to	O
a	O
separate	O
ROM	B-Device
.	O
</s>
<s>
The	O
C128	O
's	O
80-column	O
mode	O
can	O
display	O
lowercase	O
characters	O
along	O
with	O
PETSCII	B-Protocol
graphics	O
characters	O
;	O
40-column	O
mode	O
is	O
subject	O
to	O
the	O
same	O
"	O
upper	O
-	O
and	O
lowercase	O
"	O
or	O
"	O
uppercase-plus-graphics	O
"	O
restriction	O
as	O
earlier	O
Commodores	O
.	O
</s>
<s>
The	O
keyboard	B-Device
,	O
however	O
,	O
was	O
not	O
switched	O
to	O
the	O
Selectric	O
layout	O
as	O
had	O
become	O
standard	O
,	O
instead	O
retaining	O
the	O
same	O
ADM-3A-derived	O
design	O
as	O
on	O
Commodore	O
's	O
prior	O
models	O
.	O
</s>
<s>
The	O
VDC	O
chip	O
is	O
largely	O
useless	O
for	O
gaming	O
since	O
it	O
has	O
no	O
sprites	O
or	O
raster	B-General_Concept
interrupts	I-General_Concept
.	O
</s>
<s>
NTSC	O
C128s	O
will	O
work	O
with	O
any	O
CGA-type	O
monitor	O
(	O
TTL	O
RGB	O
@	O
15kHz/60Hz	O
)	O
such	O
as	O
the	O
IBM	O
5153	O
.	O
</s>
<s>
However	O
,	O
PAL	O
models	O
of	O
the	O
C128	O
operate	O
at	O
50Hz	O
and	O
are	O
n't	O
compatible	O
with	O
most	O
CGA	B-Device
monitors	O
,	O
which	O
expect	O
a	O
60Hz	O
refresh	O
rate	O
.	O
</s>
<s>
Pin	O
7	O
of	O
the	O
VDC	O
output	O
(	O
normally	O
unused	O
on	O
CGA	B-Device
monitors	O
)	O
produces	O
a	O
monochrome	O
NTSC/PAL	O
signal	O
,	O
but	O
no	O
cable	O
was	O
provided	O
for	O
it	O
and	O
interested	O
users	O
had	O
to	O
make	O
their	O
own	O
or	O
purchase	O
one	O
on	O
the	O
aftermarket	O
.	O
</s>
<s>
Two	O
new	O
disk	O
drives	O
were	O
introduced	O
in	O
conjunction	O
with	O
the	O
C128	O
:	O
the	O
short-lived	O
single-sided	O
1570	B-Device
and	O
the	O
double-sided	O
1571	B-Device
.	O
</s>
<s>
A	O
dual-disk	O
1572	B-Device
model	O
was	O
announced	O
but	O
never	O
produced	O
.	O
</s>
<s>
All	O
of	O
these	O
drives	O
are	O
more	O
reliable	O
than	O
the	O
1541	B-Device
and	O
promise	O
much	O
better	O
performance	O
via	O
a	O
new	O
"	O
burst	O
mode	O
"	O
feature	O
.	O
</s>
<s>
The	O
1581	O
drive	O
also	O
has	O
more	O
on-board	O
RAM	B-Architecture
than	O
its	O
predecessors	O
,	O
making	O
it	O
possible	O
to	O
open	O
a	O
larger	O
number	O
of	O
files	O
at	O
one	O
time	O
.	O
</s>
<s>
BASIC	B-Language
7.0	I-Language
includes	O
DLOAD	O
and	O
DSAVE	O
commands	O
to	O
support	O
loading	O
and	O
saving	O
to	O
disk	O
without	O
using	O
the	O
,	O
8	O
or	O
other	O
device	O
number	O
,	O
and	O
also	O
a	O
DIRECTORY	O
command	O
that	O
reads	O
a	O
disk	O
's	O
catalog	O
information	O
directly	O
to	O
screen	O
memory	O
without	O
overwriting	O
BASIC	O
memory	O
as	O
in	O
BASIC	B-Language
2.0	I-Language
.	O
</s>
<s>
Users	O
no	O
longer	O
have	O
to	O
type	O
LOAD	B-Device
"	I-Device
*	I-Device
"	I-Device
,	I-Device
8	I-Device
,	I-Device
1	I-Device
.	O
</s>
<s>
All	O
1571	B-Device
drives	O
will	O
normally	O
start	O
up	O
in	O
native	B-Language
mode	I-Language
on	O
the	O
C128	O
.	O
</s>
<s>
If	O
the	O
user	O
switches	O
to	O
C64	O
mode	O
by	O
typing	O
"	O
GO	O
64	O
"	O
,	O
the	O
drive	O
remains	O
in	O
native	B-Language
mode	I-Language
.	O
</s>
<s>
But	O
if	O
C64	O
mode	O
is	O
activated	O
by	O
holding	O
the	O
Commodore	O
key	O
down	O
when	O
powering-up	O
,	O
the	O
1571	B-Device
then	O
goes	O
into	O
1541	B-Device
mode	O
.	O
</s>
<s>
The	O
C128	O
has	O
twice	O
the	O
RAM	B-Architecture
of	O
the	O
C64	O
,	O
a	O
far	O
higher	O
proportion	O
of	O
which	O
is	O
available	O
for	O
BASIC	O
programming	O
,	O
due	O
to	O
the	O
new	O
MMU	B-General_Concept
bank-switching	O
chip	O
.	O
</s>
<s>
This	O
allows	O
BASIC	O
program	O
code	O
to	O
be	O
stored	O
separately	O
from	O
variables	O
,	O
greatly	O
enhancing	O
the	O
machine	O
's	O
ability	O
to	O
handle	O
complex	O
programs	O
,	O
speeding	O
garbage	B-General_Concept
collection	I-General_Concept
and	O
easing	O
debugging	O
for	O
the	O
programmer	O
.	O
</s>
<s>
An	O
executing	O
program	O
can	O
be	O
STOPped	O
,	O
its	O
code	O
edited	O
,	O
variable	O
values	O
inspected	O
or	O
altered	O
in	O
direct	B-Application
mode	I-Application
,	O
and	O
program	O
execution	O
resumed	O
with	O
the	O
variable	O
table	O
intact	O
using	O
BASIC	O
's	O
GOTO	O
command	O
.	O
</s>
<s>
BASIC	B-Language
7.0	I-Language
has	O
a	O
full	O
complement	O
of	O
graphics	O
and	O
sound-handling	O
commands	O
,	O
as	O
well	O
as	O
BASIC	O
4.0	O
'	O
s	O
disk	O
commands	O
and	O
improved	O
garbage	O
cleanup	O
,	O
and	O
support	O
for	O
structured	B-Language
programming	I-Language
via	O
IF	O
...	O
THEN	O
ELSE	O
...	O
,	O
DO	O
...	O
WHILE	O
,	O
and	O
WHILE	O
...	O
WEND	O
loops	O
.	O
</s>
<s>
Programmable	O
characters	O
are	O
still	O
however	O
not	O
supported	O
,	O
so	O
the	O
programmer	O
will	O
have	O
to	O
manipulate	O
them	O
with	O
PEEK	B-Language
and	I-Language
POKE	I-Language
as	O
on	O
the	O
VIC-20	O
and	O
C64	O
.	O
</s>
<s>
On	O
the	O
downside	O
,	O
BASIC	B-Language
7.0	I-Language
ran	O
considerably	O
slower	O
than	O
BASIC	B-Language
2.0	I-Language
unless	O
2MHz	O
mode	O
was	O
used	O
due	O
to	O
its	O
28KB	O
size	O
(	O
a	O
250%	O
increase	O
over	O
BASIC	B-Language
2.0	I-Language
)	O
and	O
having	O
to	O
bank	O
switch	O
to	O
access	O
program	O
variables	O
and	O
BASIC	O
program	O
text	O
(	O
if	O
greater	O
than	O
16k	O
in	O
length	O
)	O
.	O
</s>
<s>
The	O
128	O
's	O
ROM	B-Device
contains	O
an	O
easter	O
egg	O
:	O
Entering	O
the	O
command	O
SYS	O
32800	O
,	O
123	O
,	O
45	O
,	O
6	O
in	O
native	B-Language
mode	I-Language
reveals	O
a	O
screen	O
with	O
a	O
listing	O
of	O
the	O
machine	O
's	O
main	O
developers	O
followed	O
by	O
the	O
message	O
Link	O
arms	O
,	O
do	O
n't	O
make	O
them.	O
"	O
</s>
<s>
These	O
commands	O
are	O
holdovers	O
from	O
the	O
BASIC	O
interpreter	O
intended	O
for	O
a	O
planned	O
but	O
never-produced	O
LCD	B-Device
portable	I-Device
computer	I-Device
and	O
had	O
been	O
intended	O
to	O
exit	O
from	O
the	O
BASIC	O
interpreter	O
and	O
to	O
ignore	O
keyboard	B-Device
input	O
during	O
sensitive	O
program	O
execution	O
,	O
respectively	O
.	O
</s>
<s>
The	O
C128	O
's	O
greater	O
hardware	O
capabilities	O
,	O
especially	O
the	O
increased	O
RAM	B-Architecture
,	O
screen	O
display	O
resolution	O
,	O
and	O
serial	O
bus	O
speed	O
,	O
made	O
it	O
a	O
more	O
capable	O
platform	O
than	O
the	O
C64	O
for	O
running	O
the	O
GEOS	B-Device
graphical	O
operating	O
system	O
.	O
</s>
<s>
The	O
second	O
of	O
the	O
C128	O
's	O
two	O
CPUs	O
is	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
,	O
which	O
allows	O
the	O
C128	O
to	O
run	O
CP/M	B-Application
.	O
</s>
<s>
The	O
C128	O
was	O
shipped	O
with	O
CP/M	B-Application
3.0	O
(	O
a.k.a.	O
</s>
<s>
CP/M	B-Application
Plus	O
,	O
which	O
is	O
backward-compatible	O
with	O
CP/M	B-Application
2.2	O
)	O
and	O
ADM31/3A	O
terminal	B-General_Concept
emulation	O
.	O
</s>
<s>
A	O
CP/M	B-Application
cartridge	O
had	O
been	O
available	O
for	O
the	O
C64	O
,	O
but	O
it	O
was	O
expensive	O
and	O
of	O
limited	O
use	O
since	O
the	O
1541	B-Device
drive	O
cannot	O
read	O
the	O
MFM-formatted	O
disks	O
that	O
CP/M	B-Application
software	O
was	O
distributed	O
on	O
.	O
</s>
<s>
Software	O
had	O
to	O
be	O
made	O
available	O
on	O
Commodore-specific	O
disks	O
formatted	O
using	O
the	O
GCR	B-Device
encoding	I-Device
scheme	O
.	O
</s>
<s>
Commodore	O
made	O
versions	O
of	O
PerfectCalc	O
and	O
the	O
EMACS-derived	O
PerfectWriter	O
available	O
,	O
and	O
Commodore	O
user	O
groups	O
sometimes	O
had	O
a	O
selection	O
of	O
CP/M	B-Application
diskettes	O
,	O
but	O
the	O
limited	O
software	O
availability	O
negated	O
one	O
of	O
CP/M	B-Application
'	O
s	O
chief	O
attractions	O
—	O
its	O
huge	O
software	O
library	O
.	O
</s>
<s>
Since	O
they	O
were	O
also	O
incompatible	O
with	O
the	O
C128	O
,	O
the	O
design	O
team	O
decided	O
to	O
support	O
CP/M	B-Application
by	O
putting	O
the	O
Z80	B-General_Concept
on	O
the	O
main	O
system	B-Device
board	I-Device
.	O
</s>
<s>
The	O
C128	O
runs	O
CP/M	B-Application
noticeably	O
slower	O
than	O
most	O
dedicated	O
CP/M	B-Application
systems	O
,	O
as	O
the	O
Z80	B-General_Concept
processor	O
runs	O
at	O
an	O
effective	O
speed	O
of	O
only	O
.	O
</s>
<s>
These	O
CPUs	O
handle	O
data	O
and	O
memory	B-General_Concept
addressing	I-General_Concept
very	O
differently	O
from	O
the	O
Z80	B-General_Concept
.	O
</s>
<s>
CP/M	B-Application
also	O
ran	O
more	O
slowly	O
due	O
to	O
the	O
reasons	O
mentioned	O
below	O
,	O
such	O
as	O
needing	O
to	O
pass	O
control	O
to	O
the	O
8502	B-General_Concept
for	O
any	O
I/O	O
or	O
interrupt	O
processing	O
.	O
</s>
<s>
For	O
these	O
reasons	O
,	O
few	O
users	O
actually	O
ran	O
CP/M	B-Application
software	O
on	O
the	O
C128	O
.	O
</s>
<s>
When	O
the	O
C128	O
is	O
powered	O
on	O
,	O
the	O
Z80	B-General_Concept
is	O
active	O
first	O
and	O
executes	O
a	O
small	O
boot	O
loader	O
ROM	B-Device
at	O
$	O
0-	O
$FFF	O
to	O
check	O
for	O
the	O
presence	O
of	O
a	O
CP/M	B-Application
disk	O
.	O
</s>
<s>
If	O
one	O
is	O
not	O
detected	O
,	O
control	O
is	O
passed	O
to	O
the	O
8502	B-General_Concept
and	O
C128	O
native	B-Language
mode	I-Language
is	O
started	O
.	O
</s>
<s>
CP/M	B-Application
mode	O
in	O
practice	O
requires	O
a	O
1571	B-Device
or	O
1581	O
drive	O
to	O
be	O
useful	O
,	O
since	O
a	O
1541	B-Device
cannot	O
read	O
MFM	O
disks	O
and	O
will	O
run	O
much	O
slower	O
due	O
to	O
not	O
supporting	O
the	O
C128	O
's	O
burst	O
mode	O
.	O
</s>
<s>
CP/M	B-Application
boot	O
disks	O
nonetheless	O
must	O
be	O
in	O
the	O
drive	O
's	O
native	O
GCR	B-Device
format	I-Device
;	O
MFM	O
disks	O
cannot	O
be	O
booted	O
from	O
,	O
only	O
read	O
once	O
the	O
user	O
is	O
already	O
in	O
CP/M	B-Application
.	O
</s>
<s>
In	O
addition	O
,	O
80-column	O
mode	O
is	O
generally	O
required	O
since	O
most	O
CP/M	B-Application
software	O
expects	O
an	O
80-column	O
screen	O
.	O
</s>
<s>
The	O
C128	O
emulates	O
an	O
ADM-3A	B-Device
terminal	B-General_Concept
in	O
CP/M	B-Application
mode	O
,	O
so	O
software	O
will	O
have	O
to	O
be	O
set	O
up	O
for	O
that	O
.	O
</s>
<s>
Aside	O
from	O
the	O
standard	O
ADM-3A	B-Device
terminal	B-General_Concept
commands	O
,	O
a	O
number	O
of	O
extra	O
ones	O
are	O
available	O
to	O
use	O
the	O
VIC-II	O
and	O
VDC	O
's	O
features	O
,	O
including	O
setting	O
the	O
text	O
and	O
background	O
color	O
.	O
</s>
<s>
The	O
CP/M	B-Application
command	O
interpreter	O
(	O
although	O
not	O
application	O
software	O
)	O
includes	O
a	O
safeguard	O
to	O
prevent	O
the	O
user	O
from	O
issuing	O
a	O
control	O
code	O
to	O
make	O
the	O
text	O
and	O
background	O
the	O
same	O
color	O
,	O
which	O
would	O
render	O
text	O
invisible	O
and	O
force	O
the	O
user	O
to	O
reset	O
the	O
computer	O
.	O
</s>
<s>
In	O
CP/M	B-Application
mode	O
,	O
it	O
is	O
possible	O
to	O
run	O
MBASIC	O
,	O
Microsoft	O
's	O
release	O
of	O
BASIC-80	B-Language
for	O
CP/M	B-Application
.	O
</s>
<s>
Compared	O
with	O
the	O
native	B-Language
mode	I-Language
BASIC	B-Language
7.0	I-Language
,	O
MBASIC	O
is	O
terse	O
and	O
limited	O
in	O
its	O
capabilities	O
,	O
requiring	O
the	O
use	O
of	O
terminal-style	O
key	O
combinations	O
to	O
edit	O
program	O
lines	O
or	O
move	O
the	O
text	O
cursor	O
and	O
lacking	O
any	O
sound	O
or	O
graphics	O
features	O
.	O
</s>
<s>
Although	O
MBASIC	O
has	O
mathematical	O
and	O
calculation	O
features	O
that	O
BASIC	B-Language
7.0	I-Language
lacks	O
such	O
as	O
integer	O
and	O
double	O
precision	O
variable	O
support	O
,	O
any	O
speed	O
advantage	O
gained	O
by	O
the	O
use	O
of	O
integer	O
variables	O
is	O
rendered	O
moot	O
by	O
the	O
extremely	O
slow	O
performance	O
of	O
the	O
computer	O
in	O
CP/M	B-Application
mode	O
.	O
</s>
<s>
Moreover	O
,	O
Commodore	B-Language
BASIC	I-Language
has	O
40-bit	O
floating	O
point	O
which	O
serves	O
as	O
a	O
middle	O
ground	O
between	O
MBASIC	O
's	O
32-bit	O
floating	O
point	O
and	O
64-bit	O
double	O
precision	O
variables	O
.	O
</s>
<s>
MBASIC	O
also	O
offers	O
only	O
34k	O
of	O
free	O
program	O
space	O
against	O
BASIC	B-Language
7.0	I-Language
'	O
s	O
approximately	O
90k	O
.	O
</s>
<s>
Other	O
CP/M	B-Application
software	O
such	O
as	O
Wordstar	O
and	O
Supercalc	O
will	O
also	O
be	O
significantly	O
outperformed	O
by	O
native	B-Language
mode	I-Language
C128	O
equivalents	O
like	O
PaperClip	B-Protocol
,	O
which	O
also	O
have	O
an	O
easier	O
to	O
use	O
interface	O
.	O
</s>
<s>
The	O
CP/M	B-Application
CBIOS	B-Operating_System
(	O
the	O
part	O
of	O
CP/M	B-Application
that	O
interfaces	O
with	O
the	O
hardware	O
)	O
does	O
not	O
directly	O
interface	O
with	O
the	O
hardware	O
like	O
on	O
most	O
CP/M	B-Application
implementations	O
,	O
rather	O
it	O
calls	O
the	O
kernal	B-Operating_System
routines	O
for	O
interrupt	O
handing	O
and	O
I/O	O
—	O
when	O
the	O
kernal	B-Operating_System
needs	O
to	O
be	O
used	O
,	O
the	O
Z80	B-General_Concept
uses	O
routines	O
at	O
-	O
to	O
pass	O
parameter	O
data	O
to	O
the	O
8502	B-General_Concept
,	O
which	O
is	O
then	O
activated	O
and	O
the	O
Z80	B-General_Concept
deactivated	O
.	O
</s>
<s>
After	O
the	O
kernal	B-Operating_System
routine	O
is	O
finished	O
executing	O
,	O
control	O
is	O
passed	O
back	O
to	O
the	O
Z80	B-General_Concept
.	O
</s>
<s>
It	O
was	O
reported	O
that	O
the	O
programmer	O
in	O
charge	O
of	O
porting	O
CP/M	B-Application
to	O
the	O
C128	O
had	O
intended	O
to	O
have	O
the	O
CBIOS	B-Operating_System
interface	O
with	O
the	O
hardware	O
directly	O
in	O
Z80	B-General_Concept
machine	B-Language
language	I-Language
,	O
but	O
had	O
great	O
difficulty	O
with	O
the	O
VDU	O
chips	O
as	O
they	O
were	O
prone	O
to	O
overheating	O
and	O
self-destructing	O
.	O
</s>
<s>
The	O
VDU	O
also	O
underwent	O
numerous	O
hardware	O
revisions	O
while	O
the	O
C128	O
was	O
in	O
development	O
and	O
the	O
CP/M	B-Application
programmer	O
was	O
unable	O
to	O
get	O
his	O
code	O
working	O
properly	O
,	O
so	O
the	O
C128	O
engineering	O
team	O
requested	O
instead	O
that	O
he	O
simply	O
rewrite	O
the	O
CBIOS	B-Operating_System
to	O
pass	O
function	O
calls	O
to	O
the	O
8502	B-General_Concept
.	O
</s>
<s>
CP/M	B-Application
mode	O
is	O
very	O
different	O
from	O
the	O
operating	O
environments	O
familiar	O
to	O
Commodore	O
users	O
.	O
</s>
<s>
While	O
Commodore	B-Device
DOS	I-Device
is	O
built	O
into	O
the	O
ROM	B-Device
of	O
Commodore	O
disk	O
drives	O
and	O
is	O
usually	O
accessed	O
through	O
BASIC	O
,	O
CP/M	B-Application
requires	O
the	O
use	O
of	O
a	O
boot	O
diskette	O
and	O
requires	O
entry	O
of	O
terse	O
commands	O
inherited	O
from	O
minicomputer	B-Architecture
platforms	O
.	O
</s>
<s>
CP/M	B-Application
programs	O
tend	O
to	O
lack	O
the	O
user-friendly	B-General_Concept
nature	O
of	O
most	O
Commodore	O
applications	O
.	O
</s>
<s>
Intended	O
to	O
give	O
the	O
new	O
computer	O
a	O
large	O
library	O
of	O
professional-grade	O
business	O
software	O
that	O
Commodore	O
lacked	O
,	O
CP/M	B-Application
was	O
long	O
past	O
its	O
prime	O
by	O
the	O
mid-1980s	O
,	O
and	O
so	O
it	O
was	O
seldom	O
used	O
on	O
the	O
C128	O
.	O
</s>
<s>
By	O
incorporating	O
the	O
original	O
C64	O
BASIC	O
and	O
Kernal	B-Operating_System
ROMs	O
in	O
their	O
entirety	O
(	O
16KB	O
total	O
)	O
,	O
the	O
C128	O
achieves	O
almost	O
100	O
percent	O
compatibility	O
with	O
the	O
Commodore	O
64	O
.	O
</s>
<s>
prompt	O
,	O
in	O
BASIC	B-Language
7.0	I-Language
.	O
</s>
<s>
This	O
feature	O
faithfully	O
duplicates	O
the	O
C64	O
's	O
behavior	O
when	O
a	O
cartridge	O
(	O
such	O
as	O
Simons	B-Language
 '	I-Language
BASIC	I-Language
)	O
is	O
plugged	O
into	O
the	O
port	O
and	O
asserts	O
either	O
of	O
these	O
lines	O
but	O
,	O
unlike	O
an	O
actual	O
C64	O
,	O
where	O
the	O
memory-map-changing	O
action	O
of	O
these	O
lines	O
is	O
implemented	O
directly	O
in	O
hardware	O
,	O
the	O
C128	O
's	O
Z80	B-General_Concept
firmware	O
startup	O
code	O
polls	O
these	O
lines	O
on	O
power-up	O
and	O
then	O
switches	O
modes	O
as	O
necessary	O
.	O
</s>
<s>
C128	O
native-mode	B-Language
cartridges	O
are	O
recognized	O
and	O
started	O
by	O
the	O
kernal	B-Operating_System
polling	O
defined	O
locations	O
in	O
the	O
memory	O
map	O
.	O
</s>
<s>
The	O
MMU	B-General_Concept
,	O
Z80	B-General_Concept
,	O
and	O
IEC	O
burst	O
mode	O
are	O
disabled	O
in	O
C64	O
mode	O
,	O
however	O
all	O
other	O
C128	O
hardware	O
features	O
including	O
the	O
VDU	O
and	O
2MHz	O
mode	O
are	O
still	O
accessible	O
.	O
</s>
<s>
The	O
extended	O
keys	O
of	O
the	O
C128	O
keyboard	B-Device
may	O
be	O
read	O
from	O
machine	B-Language
language	I-Language
,	O
although	O
the	O
kernal	B-Operating_System
routines	O
only	O
recognize	O
the	O
keys	O
that	O
exist	O
on	O
the	O
C64	O
.	O
</s>
<s>
On	O
North	O
American	O
C128s	O
,	O
when	O
in	O
C64	O
mode	O
,	O
even	O
the	O
character	O
(	O
font	O
)	O
ROM	B-Device
changes	O
from	O
that	O
of	O
C128	O
mode	O
.	O
</s>
<s>
Early	O
C128	O
prototypes	O
had	O
a	O
single	O
ROM	B-Device
,	O
with	O
a	O
slightly	O
improved	O
character	O
set	O
over	O
that	O
of	O
the	O
C64	O
.	O
</s>
<s>
But	O
some	O
C64	O
programs	O
read	O
the	O
character	O
ROM	B-Device
as	O
data	O
,	O
and	O
will	O
fail	O
in	O
various	O
ways	O
on	O
a	O
C128	O
.	O
</s>
<s>
Thus	O
,	O
the	O
C128	O
was	O
given	O
a	O
double-sized	O
character	O
ROM	B-Device
,	O
which	O
delivers	O
the	O
C128	O
font	O
in	O
C128	O
mode	O
,	O
and	O
the	O
C64	O
font	O
in	O
C64	O
mode	O
.	O
</s>
<s>
International	O
models	O
of	O
the	O
C128	O
use	O
the	O
unmodified	O
C64	O
font	O
in	O
both	O
modes	O
,	O
since	O
the	O
second	O
half	O
of	O
the	O
character	O
ROM	B-Device
is	O
instead	O
dedicated	O
to	O
the	O
international	O
font	O
(	O
containing	O
such	O
things	O
as	O
accented	O
characters	O
or	O
German	O
umlauts	O
)	O
.	O
</s>
<s>
Some	O
of	O
the	O
few	O
C64	O
programs	O
that	O
fail	O
on	O
a	O
C128	O
will	O
run	O
correctly	O
when	O
the	O
caps	B-Device
lock	I-Device
key	I-Device
is	O
pressed	O
down	O
(	O
or	O
the	O
ASCII/National	O
key	O
on	O
international	O
C128	O
models	O
)	O
.	O
</s>
<s>
Whereas	O
the	O
SHIFT	O
LOCK	O
key	O
found	O
on	O
both	O
C64	O
and	O
C128	O
is	O
simply	O
a	O
mechanical	O
latch	O
for	O
the	O
left	O
SHIFT	O
key	O
,	O
the	O
CAPS	B-Device
LOCK	I-Device
key	I-Device
on	O
the	O
C128	O
can	O
be	O
read	O
via	O
the	O
8502	B-General_Concept
's	O
built-in	O
I/O	O
port	O
.	O
</s>
<s>
A	O
few	O
C64	O
programs	O
are	O
confused	O
by	O
this	O
extra	O
I/O	O
bit	O
;	O
keeping	O
the	O
CAPS	B-Device
LOCK	I-Device
key	I-Device
in	O
the	O
down	O
position	O
will	O
force	O
the	O
I/O	O
line	O
low	O
,	O
matching	O
the	O
C64	O
's	O
configuration	O
and	O
resolving	O
the	O
issue	O
.	O
</s>
<s>
'	O
s	O
Gazette	O
published	O
a	O
type-in	O
program	O
that	O
exploited	O
this	O
difference	O
by	O
using	O
a	O
raster	B-General_Concept
interrupt	I-General_Concept
to	O
enable	O
fast	O
mode	O
when	O
the	O
bottom	O
of	O
the	O
visible	O
screen	O
was	O
reached	O
,	O
and	O
then	O
disable	O
it	O
when	O
screen	O
rendering	O
began	O
again	O
at	O
the	O
top	O
.	O
</s>
<s>
An	O
easy	O
way	O
to	O
differentiate	O
between	O
a	O
hardware	O
C64	O
and	O
a	O
C128	O
operating	O
in	O
C64	O
mode	O
,	O
typically	O
used	O
from	O
within	O
a	O
running	O
program	O
,	O
is	O
to	O
write	O
a	O
value	O
different	O
from	O
$FF	O
(	O
255	O
)	O
to	O
memory	B-General_Concept
address	I-General_Concept
$D02F	O
(	O
53295	O
)	O
,	O
a	O
register	O
which	O
is	O
used	O
to	O
decode	O
the	O
extra	O
keys	O
of	O
the	O
C128	O
(	O
the	O
numerical	B-Device
keypad	I-Device
and	O
some	O
other	O
keys	O
)	O
.	O
</s>
<s>
On	O
the	O
C64	O
this	O
memory	B-General_Concept
location	I-General_Concept
will	O
always	O
contain	O
the	O
value	O
$FF	O
no	O
matter	O
what	O
is	O
written	O
to	O
it	O
,	O
but	O
on	O
a	O
C128	O
in	O
C64	O
mode	O
the	O
value	O
of	O
the	O
location	O
—	O
a	O
memory-mapped	O
register	O
—	O
can	O
be	O
changed	O
.	O
</s>
<s>
To	O
handle	O
the	O
relatively	O
large	O
amounts	O
of	O
ROM	B-Device
and	O
RAM	B-Architecture
(	O
tenfold	O
the	O
size	O
of	O
8502	B-General_Concept
's	O
address	O
space	O
)	O
the	O
C128	O
uses	O
the	O
8722	O
MMU	B-General_Concept
chip	O
to	O
create	O
different	O
memory	O
maps	O
,	O
in	O
which	O
different	O
combinations	O
of	O
RAM	B-Architecture
and	O
ROM	B-Device
would	O
appear	O
according	O
to	O
bit	O
patterns	O
written	O
into	O
the	O
MMU	B-General_Concept
's	O
configuration	O
register	O
at	O
memory	B-General_Concept
address	I-General_Concept
.	O
</s>
<s>
Another	O
feature	O
of	O
the	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
is	O
to	O
allow	O
relocation	O
of	O
zero	B-General_Concept
page	I-General_Concept
and	O
the	O
stack	B-Application
.	O
</s>
<s>
Although	O
the	O
C128	O
can	O
theoretically	O
support	O
256k	O
of	O
RAM	B-Architecture
in	O
four	O
blocks	O
,	O
the	O
PCB	O
has	O
no	O
provisions	O
to	O
add	O
this	O
extra	O
RAM	B-Architecture
,	O
nor	O
can	O
the	O
MMU	B-General_Concept
actually	O
access	O
more	O
than	O
128k	O
.	O
</s>
<s>
Therefore	O
,	O
if	O
the	O
MMU	B-General_Concept
is	O
programmed	O
to	O
access	O
blocks	O
2	O
or	O
3	O
,	O
all	O
that	O
results	O
is	O
a	O
mirror	O
of	O
the	O
RAM	B-Architecture
in	O
blocks	O
0	O
and	O
1	O
.	O
</s>
<s>
Since	O
the	O
I/O	O
registers	O
and	O
system	O
ROMs	O
can	O
be	O
disabled	O
or	O
enabled	O
freely	O
,	O
as	O
well	O
as	O
being	O
locatable	O
in	O
either	O
RAM	B-Architecture
bank	O
and	O
the	O
VIC-II	O
set	O
to	O
use	O
either	O
bank	O
for	O
its	O
memory	O
space	O
,	O
up	O
to	O
256	O
memory	O
configurations	O
are	O
possible	O
,	O
although	O
the	O
vast	O
majority	O
of	O
them	O
are	O
useless	O
(	O
for	O
example	O
,	O
unworkable	O
combinations	O
like	O
the	O
kernal	B-Operating_System
ROM	B-Device
in	O
bank	O
0	O
and	O
the	O
I/O	O
registers	O
in	O
bank	O
1	O
are	O
possible	O
)	O
.	O
</s>
<s>
The	O
top	O
and	O
bottom	O
1k	O
of	O
RAM	B-Architecture
(	O
–	O
and	O
-	O
)	O
are	O
"	O
shared	O
"	O
RAM	B-Architecture
,	O
visible	O
from	O
both	O
blocks	O
.	O
</s>
<s>
The	O
MMU	B-General_Concept
allows	O
either	O
to	O
be	O
expanded	O
in	O
increments	O
up	O
to	O
16k	O
.	O
</s>
<s>
The	O
–	O
range	O
contains	O
the	O
zero	B-General_Concept
page	I-General_Concept
and	O
stack	B-Application
while	O
-	O
contains	O
the	O
MMU	B-General_Concept
registers	O
and	O
reset	O
vectors	O
.	O
</s>
<s>
These	O
areas	O
are	O
always	O
shared	O
and	O
cannot	O
be	O
switched	O
to	O
non-shared	O
RAM	B-Architecture
.	O
</s>
<s>
Shared	O
RAM	B-Architecture
is	O
always	O
the	O
opposite	O
bank	O
from	O
the	O
one	O
currently	O
being	O
used	O
by	O
the	O
CPU	O
,	O
thus	O
if	O
bank	O
0	O
is	O
selected	O
,	O
any	O
read	O
or	O
write	O
to	O
shared	O
RAM	B-Architecture
will	O
refer	O
to	O
the	O
corresponding	O
locations	O
in	O
bank	O
1	O
and	O
vice	O
versa	O
.	O
</s>
<s>
The	O
VIC-II	O
can	O
be	O
set	O
to	O
use	O
either	O
RAM	B-Architecture
bank	O
and	O
from	O
there	O
,	O
its	O
normal	O
16k	O
window	O
.	O
</s>
<s>
While	O
on	O
the	O
C64	O
,	O
the	O
VIC-II	O
can	O
only	O
see	O
the	O
character	O
ROM	B-Device
in	O
banks	O
2	O
and	O
4	O
of	O
its	O
memory	O
space	O
,	O
the	O
C128	O
,	O
on	O
the	O
other	O
hand	O
,	O
makes	O
it	O
possible	O
to	O
enable	O
or	O
disable	O
the	O
character	O
ROM	B-Device
for	O
any	O
VIC-II	O
bank	O
via	O
the	O
register	O
at	O
.	O
</s>
<s>
Also	O
,	O
there	O
are	O
two	O
sets	O
of	O
color	O
RAM	B-Architecture
—	O
one	O
visible	O
to	O
the	O
CPU	O
,	O
the	O
other	O
to	O
the	O
VIC-II	O
and	O
the	O
user	O
may	O
select	O
what	O
chip	O
sees	O
what	O
.	O
</s>
<s>
In	O
CP/M	B-Application
mode	O
,	O
the	O
Program	O
Segment	O
Prefix	O
and	O
Transient	O
Program	O
Area	O
reside	O
in	O
Bank	O
1	O
and	O
the	O
I/O	O
registers	O
and	O
CP/M	B-Application
system	O
code	O
in	O
Bank	O
0	O
.	O
</s>
<s>
The	O
C128	O
's	O
RAM	B-Architecture
is	O
expandable	O
from	O
the	O
standard	O
128KB	O
to	O
256	O
,	O
512	O
or	O
even	O
1,024	O
KB	O
,	O
either	O
by	O
using	O
commercial	O
memory	O
expansion	O
modules	O
,	O
or	O
by	O
making	O
one	O
based	O
on	O
schematics	O
available	O
on	O
the	O
internet	O
.	O
</s>
<s>
Commodore	O
's	O
RAM	B-General_Concept
Expansion	I-General_Concept
Units	I-General_Concept
use	O
an	O
external	O
8726	O
DMA	B-General_Concept
controller	I-General_Concept
to	O
transfer	O
data	O
between	O
the	O
C128	O
's	O
RAM	B-Architecture
and	O
the	O
RAM	B-Architecture
in	O
the	O
expansion	O
unit	O
.	O
</s>
<s>
Late	O
in	O
1985	O
,	O
Commodore	O
released	O
a	O
new	O
version	O
of	O
the	O
C128	O
with	O
a	O
redesigned	O
chassis	O
resembling	O
the	O
Amiga	B-Device
1000	I-Device
.	O
</s>
<s>
Called	O
the	O
Commodore	O
128D	O
,	O
this	O
new	O
European	O
model	O
featured	O
a	O
plastic	O
chassis	O
with	O
a	O
carrying	O
handle	O
on	O
the	O
side	O
,	O
incorporated	O
a	O
1571	B-Device
disk	O
drive	O
into	O
the	O
main	O
chassis	O
,	O
replaced	O
the	O
built-in	O
keyboard	B-Device
with	O
a	O
detachable	O
one	O
,	O
and	O
added	O
a	O
cooling	B-General_Concept
fan	I-General_Concept
.	O
</s>
<s>
The	O
keyboard	B-Device
also	O
featured	O
two	O
folding	O
legs	O
for	O
changing	O
the	O
typing	O
angle	O
.	O
</s>
<s>
The	O
DCR	O
model	O
features	O
a	O
stamped-steel	O
chassis	O
in	O
place	O
of	O
the	O
plastic	O
version	O
of	O
the	O
C128D	O
(	O
with	O
no	O
carrying	O
handle	O
)	O
,	O
a	O
modular	O
switched-mode	O
power	O
supply	O
similar	O
to	O
that	O
of	O
the	O
C128D	O
,	O
retaining	O
that	O
model	O
's	O
detachable	O
keyboard	B-Device
and	O
internal	O
1571	B-Device
floppy	O
drive	O
.	O
</s>
<s>
A	O
number	O
of	O
components	O
on	O
the	O
mainboard	B-Device
were	O
consolidated	O
to	O
reduce	O
production	O
costs	O
and	O
,	O
as	O
an	O
additional	O
cost-reduction	O
measure	O
,	O
the	O
cooling	B-General_Concept
fan	I-General_Concept
that	O
was	O
fitted	O
to	O
the	O
D	O
model	O
's	O
power	O
supply	O
was	O
removed	O
.	O
</s>
<s>
A	O
significant	O
improvement	O
introduced	O
with	O
the	O
DCR	O
model	O
was	O
the	O
replacement	O
of	O
the	O
8563	O
video	O
display	O
controller	O
(	O
VDC	O
)	O
with	O
the	O
more	O
technically	O
advanced	O
8568	O
VDC	O
and	O
equipping	O
it	O
with	O
64	O
kilobytes	O
of	O
video	O
RAM	B-Architecture
—	O
the	O
maximum	O
amount	O
addressable	O
by	O
the	O
device	O
.	O
</s>
<s>
The	O
four-fold	O
increase	O
in	O
video	O
RAM	B-Architecture
over	O
that	O
installed	O
in	O
the	O
"	O
flat	O
"	O
C128	O
made	O
it	O
possible	O
,	O
among	O
other	O
things	O
,	O
to	O
maintain	O
multiple	O
text	O
screens	O
in	O
support	O
of	O
a	O
true	O
windowing	O
system	O
,	O
or	O
generate	O
higher-resolution	O
graphics	O
with	O
a	O
more	O
flexible	O
color	O
palette	O
.	O
</s>
<s>
The	O
new	O
ROMs	O
address	O
a	O
number	O
of	O
bugs	B-Error_Name
that	O
are	O
present	O
in	O
the	O
original	O
ROMs	O
,	O
including	O
an	O
infamous	O
off-by-one	B-Error_Name
error	I-Error_Name
in	O
the	O
keyboard	B-Device
decoding	O
table	O
,	O
in	O
which	O
the	O
'	O
Q	O
 '	O
character	O
would	O
remain	O
lower	O
case	O
when	O
CAPS	B-Device
LOCK	I-Device
was	O
active	O
.	O
</s>
<s>
Despite	O
the	O
DCR	O
's	O
improved	O
RGB	O
video	O
capabilities	O
,	O
Commodore	O
did	O
not	O
enhance	O
BASIC	B-Language
7.0	I-Language
with	O
the	O
ability	O
to	O
manipulate	O
RGB	O
graphics	O
.	O
</s>
<s>
Driving	O
the	O
VDC	O
in	O
graphics	O
mode	O
continues	O
to	O
require	O
the	O
use	O
of	O
calls	O
to	O
screen-editor	O
ROM	B-Device
primitives	B-Language
or	O
their	O
assembly	B-Language
language	I-Language
equivalents	O
,	O
or	O
by	O
using	O
third-party	O
BASIC	O
language	O
extensions	O
,	O
such	O
as	O
Free	O
Spirit	O
Software	O
's	O
"	O
BASIC	B-Language
8	I-Language
"	O
,	O
which	O
adds	O
high-resolution	O
VDC	O
graphics	O
commands	O
to	O
BASIC	B-Language
7.0	I-Language
.	O
</s>
<s>
Because	O
the	O
128	O
would	O
run	O
virtually	O
all	O
64	O
software	O
,	O
and	O
because	O
the	O
next-generation	O
32/16	O
-bit	O
home	O
computers	O
—	O
primarily	O
the	O
Commodore	B-Device
Amiga	I-Device
and	O
Atari	B-Device
ST	I-Device
—	O
represented	O
the	O
latest	O
technology	O
,	O
relatively	O
little	O
software	O
for	O
the	O
C128	O
's	O
native	B-Language
mode	I-Language
appeared	O
(	O
probably	O
on	O
the	O
order	O
of	O
100	O
–	O
200	O
commercial	O
titles	O
,	O
plus	O
the	O
usual	O
share	O
of	O
public	O
domain	O
and	O
magazine	O
type-in	O
programs	O
)	O
,	O
leading	O
some	O
users	O
to	O
regret	O
their	O
purchase	O
.	O
</s>
<s>
Some	O
C64	O
software	O
such	O
as	O
Bard	B-Application
's	I-Application
Tale	I-Application
III	I-Application
and	O
Kid	B-Application
Niki	I-Application
ran	O
in	O
128	O
mode	O
without	O
stating	O
this	O
in	O
the	O
documentation	O
,	O
using	O
the	O
autoboot	O
and	O
the	O
1571	B-Device
's	O
faster	O
disk	O
access	O
.	O
</s>
<s>
Some	O
C64	O
games	O
were	O
ported	O
to	O
native	B-Language
mode	I-Language
like	O
Kikstart	B-Application
2	I-Application
and	O
The	B-Application
Last	I-Application
V8	I-Application
from	O
Mastertronic	O
,	O
which	O
had	O
separate	O
C128	O
versions	O
,	O
and	O
Ultima	B-Application
V	I-Application
:	I-Application
Warriors	I-Application
of	I-Application
Destiny	I-Application
from	O
Origin	O
Systems	O
,	O
which	O
used	O
extra	O
RAM	B-Architecture
for	O
music	O
if	O
running	O
on	O
the	O
C128	O
.	O
</s>
<s>
Star	B-Application
Fleet	I-Application
I	I-Application
:	I-Application
The	I-Application
War	I-Application
Begins	I-Application
from	O
Interstel	O
had	O
separate	O
versions	O
,	O
and	O
took	O
advantage	O
of	O
80-column	O
display	O
on	O
the	O
C128	O
.	O
</s>
<s>
By	O
contrast	O
,	O
many	O
C64	O
productivity	B-Application
software	I-Application
titles	O
were	O
ported	O
to	O
the	O
C128	O
,	O
including	O
the	O
popular	O
PaperClip	B-Protocol
and	O
Paperback	O
Writer	O
series	O
.	O
</s>
<s>
This	O
software	O
used	O
the	O
extra	O
memory	O
,	O
80-column	O
screen	O
,	O
enhanced	O
keyboard	B-Device
and	O
large-capacity	O
disk	O
drives	O
to	O
provide	O
features	O
that	O
were	O
considered	O
essential	O
for	O
business	O
use	O
.	O
</s>
<s>
With	O
its	O
advanced	O
BASIC	O
programming	O
language	O
,	O
CP/M	B-Application
compatibility	O
and	O
"	O
user-friendly	B-General_Concept
"	O
native	B-Language
software	I-Language
packages	O
such	O
as	O
Jane	B-Application
,	O
Commodore	O
attempted	O
to	O
create	O
a	O
low-end	O
business	O
market	O
for	O
the	O
C128	O
similar	O
to	O
its	O
strategy	O
with	O
the	O
Plus/4	B-Operating_System
,	O
even	O
distancing	O
itself	O
from	O
the	O
home	O
computer	O
label	O
by	O
branding	O
the	O
C128	O
a	O
"	O
Personal	O
Computer	O
"	O
on	O
the	O
case	O
.	O
</s>
<s>
Significantly	O
,	O
the	O
C128	O
was	O
the	O
first	O
Commodore	O
computer	O
to	O
advertise	O
its	O
use	O
of	O
Microsoft	B-Language
BASIC	I-Language
,	O
where	O
the	O
Microsoft	O
name	O
would	O
have	O
been	O
a	O
competitive	O
asset	O
.	O
</s>
<s>
People	O
who	O
wanted	O
business	O
machines	O
bought	O
IBM	B-Device
PC	I-Device
clones	O
almost	O
exclusively	O
by	O
the	O
time	O
the	O
C128	O
was	O
released	O
.	O
</s>
<s>
The	O
availability	O
of	O
low-cost	O
IBM	O
compatibles	O
like	O
the	O
Leading	B-Device
Edge	I-Device
Model	I-Device
D	I-Device
and	O
Tandy	O
1000	O
that	O
,	O
in	O
some	O
cases	O
,	O
sold	O
for	O
less	O
than	O
a	O
complete	O
C128	O
system	O
derailed	O
Commodore	O
's	O
small	O
business	O
computer	O
strategy	O
.	O
</s>
<s>
There	O
was	O
a	O
professional-level	O
CAD	B-Application
program	I-Application
,	O
Home	O
Designer	O
by	O
BRiWALL	O
,	O
but	O
again	O
,	O
most	O
of	O
this	O
work	O
was	O
done	O
on	O
PCs	O
by	O
the	O
C128	O
's	O
era	O
.	O
</s>
<s>
When	O
the	O
C128( 	O
D/DCR	O
)	O
was	O
discontinued	O
in	O
1989	O
,	O
it	O
was	O
reported	O
to	O
cost	O
nearly	O
as	O
much	O
to	O
manufacture	O
as	O
the	O
Amiga	B-Device
500	I-Device
,	O
even	O
though	O
the	O
C128D	O
had	O
to	O
sell	O
for	O
several	O
hundred	O
dollars	O
less	O
to	O
keep	O
the	O
Amiga	B-Device
's	O
high-end	O
marketing	O
image	O
intact	O
.	O
</s>
<s>
Some	O
form	O
of	O
compatibility	O
was	O
always	O
intended	O
after	O
Herd	O
was	O
approached	O
at	O
the	O
Plus/4	B-Operating_System
'	O
s	O
introduction	O
by	O
a	O
woman	O
who	O
was	O
disappointed	O
that	O
the	O
educational	O
software	O
package	O
she	O
had	O
written	O
for	O
the	O
C64	O
would	O
not	O
run	O
on	O
Commodore	O
's	O
new	O
computer	O
,	O
but	O
when	O
Commodore	O
's	O
marketing	O
department	O
learned	O
of	O
this	O
,	O
they	O
independently	O
announced	O
total	O
compatibility	O
.	O
</s>
<s>
Herd	O
gave	O
the	O
reason	O
for	O
the	O
128	O
's	O
inclusion	O
of	O
a	O
Z80	B-General_Concept
processor	O
as	O
ensuring	O
this	O
"	O
100%	O
compatibility	O
"	O
claim	O
,	O
since	O
supporting	O
the	O
C64	O
's	O
Z80	B-General_Concept
cartridge	O
would	O
have	O
meant	O
the	O
C128	O
supplying	O
additional	O
power	O
to	O
the	O
cartridge	O
port	O
.	O
</s>
<s>
He	O
also	O
stated	O
that	O
the	O
VDC	O
video	O
chip	O
and	O
Z80	B-General_Concept
were	O
sources	O
of	O
trouble	O
during	O
the	O
machine	O
's	O
design	O
.	O
</s>
<s>
Herd	O
added	O
that	O
"	O
I	O
only	O
expected	O
the	O
C128	O
to	O
be	O
sold	O
for	O
about	O
a	O
year	O
,	O
we	O
figured	O
a	O
couple	O
of	O
million	O
would	O
be	O
nice	O
and	O
of	O
course	O
it	O
would	O
n’t	O
undercut	O
Amiga	B-Device
or	O
even	O
the	O
C64	O
"	O
.	O
</s>
<s>
MOS	O
8563	O
VDC	O
(	O
or	O
,	O
in	O
C128DCR	O
,	O
the	O
8568	O
)	O
for	O
80-column	O
digital	O
RGBI	O
component	O
video	O
,	O
compatible	O
with	O
IBM	B-Device
PC	I-Device
CGA	B-Device
monitors	O
,	O
monochrome	O
display	O
also	O
possible	O
on	O
composite	O
video	O
monitors	O
;	O
usable	B-General_Concept
with	O
TV	O
sets	O
only	O
when	O
the	O
set	O
has	O
SCART	B-Protocol
and/or	O
baseband	O
video-in	O
sockets	O
in	O
addition	O
to	O
the	O
antenna	O
connector	O
.	O
</s>
<s>
Color	O
is	O
possible	O
through	O
SCART	B-Protocol
,	O
only	O
monochrome	O
through	O
baseband	O
video-in	O
.	O
</s>
<s>
RGBI	O
video	O
output	O
(	O
DE9-connector	O
)	O
logically	O
similar	O
to	O
the	O
IBM	B-Device
PC	I-Device
CGA	B-Device
connector	O
,	O
but	O
with	O
an	O
added	O
monochrome	O
composite	O
signal	O
.	O
</s>
<s>
This	O
added	O
signal	O
causes	O
a	O
minor	O
incompatibility	O
with	O
certain	O
CGA	B-Device
monitors	O
that	O
can	O
be	O
rectified	O
by	O
removing	O
pin	O
7	O
from	O
the	O
plug	O
at	O
one	O
end	O
of	O
the	O
connecting	O
cable	O
.	O
</s>
