<s>
The	O
Commodore	B-Device
PET	I-Device
is	O
a	O
line	O
of	O
personal	B-Device
computers	I-Device
produced	O
starting	O
in	O
1977	O
by	O
Commodore	O
International	O
.	O
</s>
<s>
A	O
single	O
all-in-one	O
case	O
combines	O
a	O
MOS	B-General_Concept
Technology	I-General_Concept
6502	I-General_Concept
microprocessor	B-Architecture
,	O
Commodore	B-Language
BASIC	I-Language
in	O
read-only	B-Device
memory	I-Device
,	O
keyboard	O
,	O
monochrome	B-Device
monitor	I-Device
,	O
and	O
,	O
in	O
early	O
models	O
,	O
a	O
cassette	O
deck	O
.	O
</s>
<s>
The	O
name	O
"	O
PET	O
"	O
was	O
suggested	O
by	O
Andre	O
Souson	O
after	O
he	O
saw	O
the	O
Pet	O
Rock	O
in	O
Los	O
Gatos	O
,	O
and	O
stated	O
they	O
were	O
going	O
to	O
make	O
the	O
"	O
pet	B-Device
computer	I-Device
"	O
.	O
</s>
<s>
A	O
series	O
of	O
problems	O
delayed	O
production	O
versions	O
until	O
December	O
1977	O
,	O
by	O
which	O
time	O
the	O
TRS-80	B-Device
and	O
Apple	B-Device
II	I-Device
had	O
already	O
begun	O
deliveries	O
.	O
</s>
<s>
Following	O
the	O
initial	O
PET	B-Device
2001	I-Device
,	O
the	O
design	O
was	O
updated	O
through	O
a	O
series	O
of	O
models	O
with	O
more	O
memory	O
,	O
better	O
keyboard	O
,	O
larger	O
screen	O
,	O
and	O
other	O
modifications	O
.	O
</s>
<s>
TI	O
faced	O
increasing	O
competition	O
from	O
Japanese	O
vertically-integrated	O
companies	O
who	O
were	O
using	O
new	O
CMOS-based	O
processors	O
and	O
had	O
a	O
lower	O
total	O
cost	O
of	O
production	O
.	O
</s>
<s>
Commodore	O
initially	O
responded	O
by	O
beginning	O
their	O
own	O
attempt	O
to	O
form	O
a	O
vertically-integrated	O
calculator	O
line	O
as	O
well	O
,	O
purchasing	O
a	O
vendor	O
in	O
California	O
that	O
was	O
working	O
on	O
a	O
competitive	O
CMOS	B-Device
calculator	O
chip	O
and	O
an	O
LED	O
production	O
line	O
.	O
</s>
<s>
They	O
also	O
went	O
looking	O
for	O
a	O
company	O
with	O
an	O
existing	O
calculator	O
chip	O
line	O
,	O
something	O
to	O
tide	O
them	O
over	O
in	O
the	O
immediate	O
term	O
,	O
and	O
this	O
led	O
them	O
to	O
MOS	B-Architecture
Technology	I-Architecture
.	O
</s>
<s>
MOS	O
had	O
been	O
building	O
calculator	O
chips	O
for	O
some	O
time	O
,	O
but	O
more	O
recently	O
had	O
begun	O
to	O
branch	O
out	O
into	O
new	O
markets	O
with	O
its	O
6502	B-General_Concept
microprocessor	I-General_Concept
design	O
,	O
which	O
they	O
were	O
trying	O
to	O
bring	O
to	O
market	O
.	O
</s>
<s>
Along	O
with	O
the	O
6502	B-General_Concept
came	O
Chuck	O
Peddle	O
's	O
KIM-1	B-Device
design	O
,	O
a	O
small	O
computer	O
kit	O
based	O
on	O
the	O
6502	B-General_Concept
.	O
</s>
<s>
At	O
Commodore	O
,	O
Peddle	O
convinced	O
Jack	O
Tramiel	O
that	O
calculators	O
were	O
a	O
dead-end	O
and	O
that	O
Commodore	O
should	O
explore	O
the	O
burgeoning	O
microcomputer	B-Architecture
market	O
instead	O
.	O
</s>
<s>
At	O
first	O
,	O
they	O
considered	O
purchasing	O
an	O
existing	O
design	O
,	O
and	O
in	O
September	O
1976	O
Peddle	O
got	O
a	O
demonstration	O
of	O
Steve	O
Jobs	O
and	O
Steve	O
Wozniak	O
's	O
Apple	B-Device
II	I-Device
prototype	O
.	O
</s>
<s>
The	O
Commodore	B-Device
PET	I-Device
was	O
officially	O
announced	O
in	O
1976	O
and	O
Jack	O
Tramiel	O
gave	O
Chuck	O
Peddle	O
six	O
months	O
to	O
have	O
the	O
computer	O
ready	O
for	O
the	O
January	O
1977	O
Consumer	O
Electronics	O
Show	O
,	O
with	O
his	O
team	O
including	O
John	O
Feagans	O
,	O
Bill	O
Seiler	O
,	O
two	O
Japanese	O
engineers	O
named	O
Fujiyama	O
and	O
Aoji	O
,	O
and	O
Jack	O
's	O
son	O
Leonard	O
Tramiel	O
,	O
who	O
helped	O
design	O
the	O
PETSCII	B-Protocol
graphic	O
characters	O
and	O
acted	O
as	O
quality	O
control	O
.	O
</s>
<s>
The	O
result	O
was	O
Commodore	O
's	O
first	O
mass-market	O
personal	B-Device
computer	I-Device
,	O
the	O
PET	O
,	O
the	O
first	O
model	O
of	O
which	O
was	O
the	O
PET	B-Device
2001	I-Device
.	O
</s>
<s>
Its	O
6502	B-General_Concept
processor	I-General_Concept
controlled	O
the	O
screen	O
,	O
keyboard	O
,	O
cassette	O
tape	O
recorders	O
and	O
any	O
peripherals	O
connected	O
to	O
one	O
of	O
the	O
computer	O
's	O
several	O
expansion	O
ports	O
.	O
</s>
<s>
The	O
PET	B-Device
2001	I-Device
included	O
either	O
(	O
2001-4	O
)	O
or	O
(	O
2001-8	O
)	O
of	O
8-bit	O
RAM	B-Architecture
,	O
and	O
was	O
essentially	O
a	O
single-board	B-Device
computer	I-Device
with	O
discrete	O
logic	O
driving	O
a	O
small	O
built-in	O
monochrome	B-Device
monitor	I-Device
with	O
character	O
graphics	O
,	O
enclosed	O
in	O
a	O
sheet	O
metal	O
case	O
that	O
reflected	O
Commodore	O
's	O
background	O
as	O
a	O
manufacturer	O
of	O
office	O
equipment	O
.	O
</s>
<s>
The	O
machine	O
also	O
included	O
a	O
built-in	O
Datasette	B-Device
for	O
data	O
storage	O
located	O
on	O
the	O
front	O
of	O
the	O
case	O
,	O
which	O
left	O
little	O
room	O
for	O
the	O
keyboard	O
.	O
</s>
<s>
A	O
working	O
PET	B-Device
2001	I-Device
prototype	O
was	O
shown	O
to	O
the	O
public	O
at	O
the	O
Winter	O
CES	O
1977	O
in	O
January	O
1977	O
,	O
and	O
the	O
first	O
hundred	O
units	O
were	O
shipped	O
in	O
October	O
,	O
mostly	O
going	O
to	O
magazines	O
and	O
software	O
developers	O
,	O
while	O
the	O
machine	O
was	O
not	O
generally	O
available	O
to	O
consumers	O
until	O
December	O
.	O
</s>
<s>
However	O
,	O
the	O
PET	O
was	O
back-ordered	O
for	O
months	O
and	O
to	O
ease	O
deliveries	O
,	O
early	O
in	O
1978	O
Commodore	O
decided	O
to	O
cancel	O
the	O
4KB	O
version	O
(	O
also	O
because	O
the	O
user	O
would	O
be	O
left	O
with	O
barely	O
of	O
RAM	B-Architecture
)	O
.	O
</s>
<s>
Commodore	O
was	O
the	O
first	O
company	O
to	O
license	O
Microsoft	O
's	O
6502	B-General_Concept
BASIC	O
,	O
but	O
the	O
agreement	O
nearly	O
drove	O
Microsoft	O
into	O
receivership	O
as	O
Commodore	O
stipulated	O
that	O
they	O
would	O
only	O
pay	O
for	O
it	O
when	O
the	O
PET	O
began	O
shipping	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
the	O
year	O
,	O
Microsoft	O
was	O
saved	O
by	O
Apple	O
's	O
decision	O
to	O
license	O
Microsoft	O
BASIC	O
for	O
the	O
Apple	B-Device
II	I-Device
line	O
.	O
</s>
<s>
The	O
BASIC	O
included	O
on	O
the	O
original	O
PET	B-Device
2001	I-Device
was	O
known	O
as	O
Commodore	B-Language
BASIC	I-Language
1.0	O
;	O
Microsoft	O
supplied	O
Commodore	O
with	O
a	O
source	O
listing	O
for	O
their	O
6502	B-General_Concept
BASIC	O
,	O
essentially	O
a	O
port	O
of	O
BASIC-80	O
,	O
and	O
Commodore	O
performed	O
the	O
rest	O
of	O
the	O
work	O
themselves	O
,	O
including	O
changing	O
the	O
startup	O
screen	O
and	O
prompts	O
,	O
adding	O
I/O	B-General_Concept
support	O
,	O
the	O
SYS	O
command	O
for	O
invoking	O
machine	O
language	O
programs	O
,	O
and	O
fixing	O
bugs	O
.	O
</s>
<s>
The	O
PEEK	B-Language
function	O
would	O
not	O
work	O
on	O
memory	O
locations	O
above	O
49152	O
so	O
as	O
to	O
prevent	O
the	O
user	O
from	O
viewing	O
the	O
copyrighted	O
code	O
in	O
the	O
system	O
ROMs	O
.	O
</s>
<s>
Aside	O
from	O
the	O
8K	O
BASIC	O
ROM	B-Device
,	O
the	O
PET	O
also	O
included	O
a	O
4K	O
character	O
ROM	B-Device
and	O
an	O
8K	O
kernal	O
ROM	B-Device
.	O
</s>
<s>
The	O
first	O
half	O
of	O
the	O
kernal	O
contained	O
screen	O
editor	O
functions	O
(	O
the	O
screen	O
editor	O
on	O
80	O
column	O
PETs	O
differed	O
from	O
40-column	O
models	O
)	O
with	O
the	O
second	O
half	O
containing	O
a	O
number	O
of	O
function	O
calls	O
for	O
tasks	O
such	O
as	O
inputting	O
and	O
outputting	O
data	O
to	O
and	O
from	O
different	O
I/O	B-General_Concept
devices	I-General_Concept
,	O
reading	O
the	O
keyboard	O
,	O
and	O
positioning	O
the	O
cursor	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
kernal	O
ROM	B-Device
received	O
system	O
interrupts	O
and	O
scanned	O
the	O
keyboard	O
.	O
</s>
<s>
The	O
kernel	O
,	O
an	O
idea	O
of	O
John	O
Feagans	O
,	O
was	O
the	O
first	O
personal	B-Device
computer	I-Device
OS	O
ROM	B-Device
to	O
be	O
a	O
distinct	O
entity	O
from	O
BASIC	O
.	O
</s>
<s>
The	O
character	O
ROM	B-Device
was	O
4K	O
in	O
size	O
,	O
containing	O
four	O
different	O
128	O
character	O
tables	O
,	O
the	O
uppercase/graphics	O
character	B-General_Concept
set	I-General_Concept
and	O
upper/lowercase	O
character	B-General_Concept
set	I-General_Concept
,	O
plus	O
reverse	O
video	O
versions	O
of	O
both	O
.	O
</s>
<s>
This	O
included	O
a	O
number	O
of	O
graphics	O
characters	O
for	O
creating	O
pseudographics	B-Data_Structure
on	O
the	O
screen	O
as	O
well	O
as	O
playing	O
card	O
symbols	O
(	O
reportedly	O
because	O
Jack	O
Tramiel	O
's	O
sons	O
wanted	O
to	O
play	O
card	O
games	O
on	O
the	O
computer	O
)	O
.	O
</s>
<s>
On	O
the	O
original	O
PET	B-Device
2001	I-Device
,	O
the	O
uppercase/graphics	O
character	B-General_Concept
set	I-General_Concept
and	O
upper/lowercase	O
character	B-General_Concept
set	I-General_Concept
were	O
reversed	O
compared	O
to	O
how	O
they	O
would	O
be	O
on	O
later	O
machines	O
;	O
PET	O
owners	O
who	O
upgraded	O
their	O
machines	O
to	O
the	O
BASIC	B-Language
2.0	I-Language
ROMs	O
often	O
also	O
swapped	O
out	O
the	O
character	O
ROMs	O
for	O
the	O
newer	O
version	O
.	O
</s>
<s>
Although	O
the	O
machine	O
was	O
moderately	O
successful	O
,	O
there	O
were	O
frequent	O
complaints	O
about	O
the	O
tiny	O
calculator-like	O
keyboard	O
,	O
often	O
referred	O
to	O
as	O
a	O
"	O
chiclet	B-Device
keyboard	I-Device
"	O
because	O
the	O
keys	O
resembled	O
the	O
chewing	O
gum	O
it	O
was	O
named	O
after	O
.	O
</s>
<s>
Reliability	O
was	O
fairly	O
poor	O
,	O
although	O
that	O
was	O
common	O
in	O
many	O
early	O
microcomputers	B-Architecture
.	O
</s>
<s>
The	O
PET	O
had	O
somewhat	O
of	O
a	O
competitive	O
advantage	O
over	O
its	O
Apple	B-Device
II	I-Device
and	O
TRS-80	B-Device
rivals	O
as	O
both	O
were	O
using	O
relatively	O
primitive	O
integer	O
BASICs	O
for	O
their	O
first	O
six	O
months	O
on	O
the	O
market	O
while	O
the	O
PET	O
had	O
a	O
full-featured	O
BASIC	O
with	O
floating	O
point	O
support	O
,	O
a	O
sophisticated	O
screen	O
editor	O
,	O
and	O
lowercase	O
letters	O
,	O
the	O
last	O
being	O
a	O
feature	O
that	O
the	O
two	O
competing	O
platforms	O
would	O
not	O
have	O
for	O
a	O
few	O
years	O
.	O
</s>
<s>
In	O
1979	O
,	O
Commodore	O
replaced	O
the	O
original	O
PET	B-Device
2001	I-Device
with	O
an	O
improved	O
model	O
known	O
as	O
the	O
2001-N	O
(	O
the	O
N	O
was	O
short	O
for	O
"	O
New	O
"	O
)	O
.	O
</s>
<s>
The	O
kernel	O
ROM	B-Device
was	O
upgraded	O
to	O
add	O
support	O
for	O
Commodore	O
's	O
newly-introduced	O
disk	O
drive	O
line	O
.	O
</s>
<s>
Finally	O
,	O
Commodore	O
added	O
a	O
machine-language	O
monitor	O
to	O
the	O
kernel	O
ROM	B-Device
that	O
could	O
be	O
accessed	O
by	O
jumping	O
to	O
any	O
memory	O
location	O
with	O
a	O
BRK	B-General_Concept
instruction	O
.	O
</s>
<s>
Commodore	O
contacted	O
Microsoft	O
to	O
upgrade	O
BASIC	O
for	O
the	O
new	O
machines	O
;	O
this	O
resulted	O
in	O
the	O
soon-to-be-familiar	O
BASIC	B-Language
2.0	I-Language
which	O
removed	O
the	O
256	O
element	O
array	O
limitation	O
and	O
had	O
a	O
rearranged	O
zero	O
page	O
.	O
</s>
<s>
The	O
PEEK	B-Language
function	O
was	O
unblocked	O
for	O
memory	O
locations	O
above	O
49152	O
.	O
</s>
<s>
BASIC	B-Language
2.0	I-Language
also	O
included	O
an	O
easter	O
egg	O
that	O
Bill	O
Gates	O
personally	O
coded	O
,	O
which	O
would	O
cause	O
"	O
MICROSOFT	O
!	O
"	O
</s>
<s>
to	O
appear	O
if	O
the	O
user	O
typed	O
WAIT	O
6502	B-General_Concept
,	O
x	O
(	O
x	O
being	O
the	O
number	O
of	O
times	O
to	O
display	O
the	O
message	O
)	O
;	O
this	O
was	O
reportedly	O
due	O
to	O
a	O
dispute	O
with	O
Commodore	O
over	O
ownership	O
of	O
BASIC	O
(	O
years	O
later	O
,	O
when	O
Microsoft	O
developed	O
BASIC	O
for	O
the	O
Amiga	B-Device
,	O
one	O
of	O
their	O
conditions	O
was	O
that	O
Commodore	O
credit	O
the	O
original	O
authors	O
of	O
BASIC	O
,	O
so	O
BASIC	B-Language
7.0	I-Language
on	O
the	O
Commodore	B-Device
128	I-Device
displayed	O
a	O
Microsoft	O
copyright	O
notice	O
)	O
.	O
</s>
<s>
These	O
included	O
the	O
enhanced	O
BASIC	O
4.0	O
,	O
which	O
added	O
commands	O
for	O
disk	O
functions	O
and	O
significantly	O
improved	O
garbage	B-General_Concept
cleanup	O
.	O
</s>
<s>
By	O
this	O
point	O
,	O
Commodore	O
discovered	O
that	O
people	O
were	O
buying	O
cheaper	O
and	O
models	O
of	O
the	O
3000-series	O
and	O
upgrading	O
the	O
RAM	B-Architecture
rather	O
than	O
paying	O
extra	O
for	O
the	O
model	O
.	O
</s>
<s>
Used	O
wisely	O
,	O
the	O
port	O
could	O
be	O
used	O
as	O
a	O
simple	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
and	O
allowed	O
printers	O
and	O
disk	O
drives	O
(	O
which	O
were	O
then	O
very	O
expensive	O
)	O
to	O
be	O
shared	O
among	O
all	O
of	O
the	O
machines	O
in	O
the	O
classroom	O
.	O
</s>
<s>
Unlike	O
later	O
Commodore	O
machines	O
,	O
PETs	O
had	O
no	O
kernel	O
ROM	B-Device
functions	O
for	O
the	O
IEEE-488	O
port	O
and	O
users	O
had	O
to	O
write	O
their	O
own	O
for	O
using	O
peripherals	O
such	O
as	O
modems	O
.	O
</s>
<s>
First	O
year	O
4000-series	O
PETs	O
retained	O
the	O
same	O
video	O
hardware	O
as	O
the	O
PET	O
2001/3000	O
,	O
but	O
in	O
1981	O
this	O
was	O
replaced	O
by	O
the	O
12-inch	O
screen	O
and	O
6845-based	O
hardware	O
.	O
</s>
<s>
Numbers	O
were	O
exclusively	O
on	O
the	O
numeric	B-Device
keypad	I-Device
and	O
the	O
row	O
above	O
the	O
alphabet	O
keys	O
had	O
only	O
punctuation	O
symbols	O
.	O
</s>
<s>
A	O
large	O
line	O
of	O
5.25-inch	O
and	O
8-inch	O
floppy	O
drives	O
were	O
made	O
for	O
the	O
PET	O
family	O
,	O
and	O
even	O
5	O
and	O
7MB	O
external	O
hard	B-Device
disks	I-Device
.	O
</s>
<s>
While	O
they	O
became	O
fairly	O
popular	O
for	O
business	O
use	O
in	O
Europe	O
,	O
they	O
failed	O
to	O
make	O
much	O
impact	O
on	O
the	O
US	O
market	O
in	O
part	O
because	O
the	O
6502-based	O
PETs	O
could	O
not	O
run	O
CP/M	B-Application
,	O
which	O
had	O
become	O
the	O
standard	O
for	O
business	O
software	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
PET	O
's	O
of	O
memory	O
was	O
a	O
disadvantage	O
against	O
the	O
Apple	B-Device
II	I-Device
and	O
TRS-80	B-Device
,	O
both	O
of	O
which	O
could	O
accommodate	O
.	O
</s>
<s>
The	O
8000-series	O
PETs	O
had	O
a	O
motherboard	O
connector	O
for	O
a	O
daughterboard	O
that	O
added	O
an	O
additional	O
64K	O
of	O
RAM	B-Architecture
for	O
96K	O
total	O
;	O
this	O
was	O
a	O
standard	O
feature	O
on	O
the	O
8096	O
.	O
</s>
<s>
A	O
register	O
at	O
is	O
used	O
to	O
set	O
the	O
RAM	B-Architecture
configuration	O
.	O
</s>
<s>
The	O
extra	O
RAM	B-Architecture
is	O
banked	O
in	O
four	O
16K	O
blocks	O
,	O
the	O
first	O
two	O
blocks	O
are	O
switched	O
into	O
-	O
and	O
the	O
second	O
two	O
in	O
-	O
.	O
</s>
<s>
Normally	O
,	O
banking	O
in	O
the	O
expansion	O
RAM	B-Architecture
will	O
swap	O
out	O
the	O
video	O
RAM	B-Architecture
,	O
I/O	B-General_Concept
registers	O
,	O
and	O
system	O
ROMs	O
,	O
so	O
interrupts	O
must	O
be	O
turned	O
off	O
first	O
,	O
but	O
it	O
is	O
also	O
possible	O
to	O
set	O
the	O
video	O
RAM	B-Architecture
and	O
I/O	B-General_Concept
registers	O
to	O
"	O
peek	B-Language
"	O
through	O
.	O
</s>
<s>
The	O
expansion	O
RAM	B-Architecture
cannot	O
be	O
seen	O
by	O
BASIC	O
and	O
machines	O
equipped	O
with	O
the	O
RAM	B-Architecture
board	O
will	O
still	O
report	O
the	O
standard	O
31,743	O
bytes	O
free	O
on	O
power	O
up	O
.	O
</s>
<s>
On	O
2001/3000	O
PETs	O
,	O
there	O
was	O
a	O
register	O
which	O
when	O
enabled	O
did	O
not	O
allow	O
reading/writing	O
of	O
the	O
video	O
RAM	B-Architecture
except	O
during	O
the	O
vertical	O
blanking	O
in	O
order	O
to	O
prevent	O
snow	O
on	O
the	O
screen	O
,	O
caused	O
by	O
the	O
CPU	B-General_Concept
and	O
video	O
controller	O
trying	O
to	O
access	O
the	O
VRAM	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
This	O
feature	O
was	O
used	O
because	O
of	O
the	O
extremely	O
slow	O
6550	O
SRAMs	O
in	O
the	O
PET	B-Device
2001	I-Device
,	O
although	O
it	O
ceased	O
to	O
be	O
a	O
problem	O
on	O
3000-series	O
PETs	O
since	O
they	O
used	O
faster	O
2114	O
SRAMs	O
for	O
the	O
video	O
memory	O
instead	O
.	O
</s>
<s>
PETs	O
with	O
12-inch	O
displays	O
(	O
all	O
8000s	O
and	O
later	O
4000s	O
)	O
used	O
a	O
video	O
controller	O
based	O
on	O
the	O
Motorola	B-General_Concept
6845	I-General_Concept
CRTC	O
chip	O
(	O
unlike	O
the	O
TTL	O
logic	O
circuit	O
in	O
2001/3000s/early	O
4000s	O
)	O
that	O
eliminated	O
the	O
snow	O
problem	O
,	O
but	O
also	O
placed	O
a	O
CRT	O
control	O
register	O
in	O
place	O
of	O
where	O
the	O
VBLANK	O
flag	O
had	O
been	O
on	O
the	O
2001/3000	O
.	O
</s>
<s>
The	O
PET	B-Device
2001	I-Device
and	O
2001-8N	O
had	O
a	O
register	O
that	O
would	O
disable	O
the	O
video	O
output	O
;	O
this	O
was	O
also	O
used	O
as	O
output	O
for	O
the	O
IEEE-488	O
interface	O
,	O
so	O
screen	O
flicker	O
would	O
occur	O
during	O
disk	O
drive	O
or	O
printer	O
use	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
basic	O
CBM	O
8000	O
hardware	O
,	O
the	O
9000	O
added	O
a	O
second	O
CPU	B-General_Concept
in	O
the	O
form	O
of	O
the	O
Motorola	B-Device
6809	I-Device
,	O
more	O
RAM	B-Architecture
and	O
included	O
a	O
number	O
of	O
programming	O
languages	O
including	O
a	O
BASIC	O
in	O
ROM	B-Device
for	O
the	O
6502	B-General_Concept
and	O
a	O
separate	O
ANSI	O
Minimal	O
BASIC-compatible	O
BASIC	O
for	O
the	O
6809	B-Device
,	O
along	O
with	O
APL	B-Language
,	O
COBOL	B-Application
,	O
FORTRAN	B-Application
,	O
Pascal	B-Application
and	O
a	O
6809	B-Device
assembler	O
on	O
floppies	O
.	O
</s>
<s>
It	O
also	O
included	O
microEDITOR	O
,	O
a	O
text	O
editor	O
for	O
use	O
in	O
writing	O
and	O
maintaining	O
programs	O
for	O
any	O
of	O
the	O
6809	B-Device
languages	O
.	O
</s>
<s>
Also	O
included	O
was	O
a	O
terminal	B-Application
program	I-Application
which	O
allowed	O
the	O
machine	O
to	O
be	O
used	O
as	O
a	O
"	O
smart	O
terminal	B-Application
"	O
as	O
well	O
,	O
so	O
this	O
single	O
machine	O
could	O
replace	O
many	O
of	O
the	O
boxes	O
currently	O
in	O
use	O
at	O
the	O
university	O
.	O
</s>
<s>
Additionally	O
this	O
machine	O
became	O
a	O
remote	O
development	O
environment	O
where	O
the	O
user	O
could	O
later	O
upload	O
their	O
creation	O
to	O
a	O
mainframe	B-Architecture
after	O
completing	O
development	O
and	O
testing	O
on	O
the	O
SuperPET	O
.	O
</s>
<s>
The	O
8296	O
had	O
a	O
completely	O
redesigned	O
motherboard	O
and	O
handled	O
expansion	O
RAM	B-Architecture
in	O
a	O
different	O
fashion	O
than	O
the	O
8096	O
.	O
</s>
<s>
While	O
on	O
the	O
8096	O
,	O
the	O
expansion	O
RAM	B-Architecture
cannot	O
be	O
accessed	O
at	O
all	O
without	O
switching	O
out	O
the	O
OS	O
ROMs	O
and	O
video	O
RAM	B-Architecture
,	O
the	O
8296	O
has	O
a	O
setup	O
closer	O
to	O
that	O
of	O
the	O
Commodore	O
64	O
where	O
writing	O
to	O
the	O
memory	O
locations	O
with	O
the	O
OS	O
ROMs	O
accesses	O
the	O
RAM	B-Architecture
underneath	O
,	O
but	O
reading	O
from	O
those	O
locations	O
will	O
read	O
back	O
the	O
ROMs	O
instead	O
.	O
</s>
<s>
The	O
8296	O
also	O
differs	O
from	O
the	O
8096	O
in	O
that	O
it	O
has	O
jumpers	B-Device
on	O
the	O
PCB	O
to	O
select	O
the	O
power-on	O
memory	O
configuration	O
for	O
-	O
.	O
</s>
<s>
The	O
factory	O
default	O
configuration	O
was	O
to	O
have	O
the	O
I/O	B-General_Concept
registers	O
,	O
video	O
RAM	B-Architecture
,	O
and	O
ROMs	O
occupying	O
-	O
.	O
</s>
<s>
By	O
setting	O
the	O
jumpers	B-Device
,	O
one	O
could	O
swap	O
out	O
any	O
8K	O
region	O
of	O
upper	O
memory	O
for	O
RAM	B-Architecture
,	O
and	O
it	O
was	O
even	O
possible	O
to	O
have	O
everything	O
switched	O
out	O
and	O
convert	O
the	O
entire	O
-	O
to	O
RAM	B-Architecture
,	O
although	O
such	O
a	O
machine	O
would	O
be	O
useless	O
with	O
no	O
I/O	B-General_Concept
or	O
system	O
ROMs	O
accessible	O
.	O
</s>
<s>
Like	O
with	O
the	O
8096	O
,	O
the	O
user	O
could	O
also	O
manipulate	O
the	O
register	O
at	O
to	O
control	O
which	O
RAM	B-Architecture
banks	O
occupied	O
upper	O
memory	O
.	O
</s>
<s>
The	O
8296	O
's	O
RAM	B-Architecture
is	O
banked	O
in	O
16K	O
chunks	O
like	O
the	O
8096	O
,	O
although	O
since	O
it	O
has	O
128K	O
,	O
there	O
are	O
six	O
possible	O
banks	O
instead	O
of	O
four	O
,	O
three	O
that	O
can	O
go	O
into	O
-	O
and	O
three	O
that	O
can	O
go	O
into	O
-	O
,	O
and	O
like	O
with	O
the	O
8096	O
,	O
the	O
video	O
RAM	B-Architecture
and	O
I/O	B-General_Concept
registers	O
can	O
be	O
set	O
to	O
"	O
peek	B-Language
"	O
through	O
.	O
</s>
<s>
The	O
motherboard	O
also	O
sported	O
"	O
user	O
"	O
jumpers	B-Device
which	O
"	O
connected	O
"	O
the	O
RAM	B-Architecture
banking	O
to	O
the	O
user	O
port	O
,	O
these	O
required	O
soldering	O
to	O
enable	O
.	O
</s>
<s>
The	O
IEEE-488	O
–	O
based	O
PET	O
disk	O
drive	O
line	O
was	O
also	O
updated	O
;	O
the	O
large	O
,	O
heavy	O
metal-cased	O
drives	O
were	O
replaced	O
by	O
smaller	O
units	O
in	O
1541	B-Device
cases	O
;	O
they	O
looked	O
almost	O
identical	O
to	O
a	O
1541	B-Device
drive	O
except	O
for	O
the	O
back	O
sporting	O
an	O
IEEE-488	O
connector	O
instead	O
of	O
the	O
two	O
IEC	O
DIN	O
connectors	O
.	O
</s>
<s>
Of	O
the	O
previously	O
extensive	O
PET	O
disk	O
drive	O
line	O
,	O
the	O
only	O
drives	O
that	O
returned	O
were	O
the	O
2031-LP	O
and	O
SFD-1001	B-Device
(	O
basically	O
a	O
2040	O
and	O
an	O
8250	O
repackaged	O
in	O
a	O
1541-style	O
case	O
with	O
half-height	O
drive	O
mechanisms	O
)	O
.	O
</s>
<s>
The	O
resurrected	O
PET	O
was	O
sold	O
through	O
1986	O
and	O
then	O
finally	O
retired	O
for	O
good	O
,	O
having	O
been	O
superseded	O
by	O
the	O
Commodore	B-Device
128	I-Device
,	O
1571	B-Device
,	O
and	O
1581	O
.	O
</s>
<s>
Although	O
not	O
officially	O
a	O
member	O
of	O
the	O
PET	O
series	O
,	O
in	O
1983	O
Commodore	O
packaged	O
C64	O
motherboards	O
in	O
plastic	O
cases	O
similar	O
to	O
the	O
PET	O
4000-series	O
in	O
order	O
to	O
create	O
the	O
Educator	B-Device
64	I-Device
.	O
</s>
<s>
This	O
was	O
an	O
attempt	O
to	O
retake	O
some	O
of	O
the	O
education	O
market	O
they	O
had	O
largely	O
lost	O
by	O
then	O
to	O
the	O
Apple	B-Device
IIe	I-Device
.	O
</s>
<s>
In	O
the	O
home	O
computer	O
market	O
,	O
the	O
PET	O
line	O
was	O
soon	O
outsold	O
by	O
machines	O
that	O
supported	O
high-resolution	O
color	O
graphics	O
and	O
sound	O
,	O
mainly	O
the	O
Apple	B-Device
II	I-Device
(	O
which	O
shipped	O
in	O
June	O
1977	O
)	O
,	O
Atari	B-Device
400/800	I-Device
(	O
1979	O
)	O
,	O
and	O
,	O
in	O
particular	O
,	O
Commodore	O
's	O
own	O
bestselling	O
VIC-20	B-Device
(	O
1980/81	O
)	O
.	O
</s>
<s>
Commodore	O
released	O
a	O
High	O
Resolution	O
Graphic	O
board	O
for	O
the	O
PET	O
using	O
the	O
Thomson	B-Device
EF936x	I-Device
graphics	O
chip	O
with	O
a	O
resolution	O
of	O
512×512	O
pixels	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
Apple	B-Device
II	I-Device
,	O
TRS-80	B-Device
Model	I-Device
I	I-Device
,	O
and	O
Atari	O
400	O
(	O
via	O
3rd	O
party	O
expansions	O
)	O
/800	O
could	O
all	O
be	O
expanded	O
to	O
a	O
maximum	O
of	O
48KB	O
of	O
RAM	B-Architecture
while	O
the	O
PET	O
was	O
limited	O
to	O
32KB	O
.	O
</s>
<s>
Without	O
the	O
High	O
Resolution	O
Graphic	O
board	O
,	O
the	O
PET	O
's	O
graphics	O
capabilities	O
were	O
limited	O
to	O
a	O
character	B-General_Concept
set	I-General_Concept
hardwired	O
in	O
ROM	B-Device
,	O
similar	O
to	O
the	O
Apple	B-Device
II	I-Device
in	O
text	O
mode	O
.	O
</s>
<s>
On	O
many	O
of	O
the	O
PET	O
range	O
's	O
home	O
computer	O
rivals	O
,	O
the	O
look-up	O
address	O
of	O
the	O
character	O
graphics	O
could	O
be	O
changed	O
and	O
pointed	O
to	O
RAM	B-Architecture
,	O
where	O
new	O
characters	O
could	O
be	O
defined	O
by	O
a	O
programmer	O
to	O
create	O
custom	O
graphics	O
shapes	O
.	O
</s>
<s>
From	O
a	O
programming	O
point	O
of	O
view	O
,	O
this	O
was	O
a	O
relatively	O
simple	O
method	O
of	O
producing	O
good-looking	O
graphics	O
,	O
which	O
used	O
negligibly	O
more	O
RAM	B-Architecture
than	O
a	O
standard	O
character	O
display	O
,	O
and	O
significantly	O
less	O
RAM	B-Architecture
than	O
bitmap	O
graphics	O
.	O
</s>
<s>
The	O
PET	O
's	O
lack	O
of	O
a	O
remappable	O
character	B-General_Concept
set	I-General_Concept
is	O
a	O
major	O
weakness	O
in	O
the	O
machine	O
's	O
design	O
.	O
</s>
<s>
Somewhat	O
offsetting	O
this	O
drawback	O
,	O
the	O
PET	O
's	O
ROM-restricted	O
character	B-General_Concept
set	I-General_Concept
an	O
ASCII-1963	O
deviation	O
known	O
as	O
PETSCII	B-Protocol
was	O
one	O
of	O
the	O
most	O
varied	O
and	O
flexible	O
of	O
the	O
era	O
.	O
</s>
<s>
It	O
allowed	O
PET	O
games	O
with	O
rudimentary	O
graphics	O
to	O
be	O
created	O
,	O
exemplified	O
by	O
clones	O
of	O
video	O
games	O
such	O
as	O
Space	B-Application
Invaders	I-Application
and	O
Lunar	B-Application
Lander	I-Application
.	O
</s>
<s>
The	O
PETSCII	B-Protocol
character	B-General_Concept
set	I-General_Concept
was	O
even	O
flexible	O
enough	O
to	O
allow	O
for	O
the	O
creation	O
of	O
simple	O
3D	O
games	O
such	O
as	O
Labyrinth	O
.	O
</s>
<s>
This	O
flexibility	O
was	O
achieved	O
by	O
the	O
use	O
of	O
two	O
switchable	O
character	B-General_Concept
sets	I-General_Concept
,	O
allowing	O
the	O
choice	O
of	O
either	O
mixed-case	O
characters	O
,	O
or	O
uppercase	O
with	O
graphics	O
;	O
either	O
could	O
also	O
be	O
displayed	O
as	O
a	O
reverse	O
field	O
,	O
negative	O
image	O
.	O
</s>
<s>
For	O
specialized	O
applications	O
,	O
alternative	O
character	B-General_Concept
sets	I-General_Concept
could	O
be	O
programmed	O
into	O
an	O
EPROM	B-General_Concept
inserted	O
in	O
the	O
character	B-General_Concept
set	I-General_Concept
ROM	B-Device
socket	O
.	O
</s>
<s>
Alternative	O
character	B-General_Concept
set	I-General_Concept
EPROMs	B-General_Concept
with	O
diacritics	O
and	O
mathematical	O
symbols	O
were	O
available	O
in	O
the	O
aftermarket	O
.	O
</s>
<s>
A	O
2001-8B	O
model	O
with	O
katakana	O
keyboard	O
and	O
character	B-General_Concept
set	I-General_Concept
was	O
sold	O
in	O
Japan	O
.	O
</s>
<s>
In	O
2012	O
,	O
Commodore	O
enthusiast	O
Steve	O
Gray	O
began	O
a	O
project	O
to	O
convert	O
the	O
Commodore	B-Device
PET	I-Device
to	O
colour	O
.	O
</s>
<s>
The	O
result	O
is	O
16	O
colours	O
for	O
foreground	O
and	O
background	O
,	O
The	O
colour	O
RAM	B-Architecture
is	O
located	O
at	O
$8800	O
which	O
is	O
not	O
used	O
in	O
regular	O
PET	O
machines	O
.	O
</s>
<s>
In	O
addition	O
,	O
it	O
was	O
common	O
for	O
commercial	O
programs	O
to	O
include	O
a	O
copy	B-Application
protection	I-Application
ROM	B-Device
that	O
had	O
to	O
be	O
installed	O
prior	O
to	O
running	O
the	O
application	O
;	O
something	O
of	O
an	O
inconvenience	O
to	O
users	O
owning	O
multiple	O
applications	O
protected	O
in	O
this	O
way	O
,	O
as	O
the	O
chips	O
would	O
have	O
to	O
be	O
swapped	O
in	O
order	O
to	O
run	O
their	O
respective	O
programs	O
.	O
</s>
<s>
+	O
Commodore	B-Device
PET	I-Device
model	O
specifications	O
PET	O
20012001-N	O
and	O
2001-B	O
seriesCBM	O
3000	O
series	O
PET	O
4000	O
seriesCBM	O
8000	O
series	O
SuperPET	O
SP9000	O
Image	O
x160pxPET	O
2001	O
x160pxCBM	O
4032	O
x160pxSuperPET	O
SP9000	O
CPUMOS	O
6502	B-General_Concept
,	O
1	O
MHzMOS	O
6502	B-General_Concept
,	O
1	O
MHzMOS	O
6502	B-General_Concept
and	O
Motorola	B-Device
6809	I-Device
,	O
1	O
MHz	O
RAM4	O
or	O
8	O
KB	O
/	O
8	O
,	O
16	O
,	O
or	O
32	O
KB8	O
,	O
16	O
,	O
or	O
32	O
KB	O
/	O
32	O
or	O
96	O
KB96	O
KB	O
ROM18	O
KB	O
,	O
including	O
BASIC	O
1.0	O
,	O
or	O
20	O
KB	O
,	O
including	O
BASIC	B-Language
2.0	I-Language
(	O
disk	O
drives	O
not	O
supported	O
on	O
the	O
original	O
2001	O
)	O
20	O
KB	O
,	O
including	O
BASIC	O
4.048	O
KB	O
,	O
including	O
BASIC	O
4.0	O
and	O
other	O
programming	O
languages	O
(	O
Waterloo	O
microAPL	O
,	O
microFORTRAN	O
,	O
microBASIC	O
,	O
microPASCAL	O
,	O
microCOBOL	O
)	O
,	O
and	O
microEDITOR	O
a	O
modal	O
text	O
editor	O
VideoDiscrete	O
TTL	O
video	O
circuit	O
,	O
9	O
"	O
monochrome	B-Device
monitor	I-Device
(	O
white	O
phosphor	O
on	O
the	O
original	O
2001	O
,	O
green	O
on	O
2001-N	O
PETs	O
)	O
,	O
40×25	O
character	O
display9-inch	O
as	O
3000	O
or	O
MOS	O
6545	O
12-inch	O
/	O
12-inch	O
monochrome	B-Device
monitor	I-Device
,	O
40×25	O
or	O
80×25	O
character	O
displayMOS	O
6545	O
,	O
12-inch	O
monochrome	B-Device
monitor	I-Device
,	O
80×25	O
character	O
display	O
SoundNone	O
or	O
single	O
piezo	O
"	O
beeper	O
"	O
(	O
optional	O
external	O
speaker	O
driven	O
by	O
MOS	O
6522	O
CB2	O
pin	O
)	O
Single	O
piezo	O
"	O
beeper	O
"	O
(	O
optional	O
external	O
speaker	O
driven	O
by	O
MOS	O
6522	O
CB2	O
pin	O
)	O
Ports2	O
MOS	O
6520	O
PIA	O
,	O
MOS	O
6522	O
VIA	O
,	O
2×	O
Datassette	B-Device
(	O
1	O
used	O
and	O
1	O
on	O
the	O
back	O
)	O
,	O
1×	O
IEEE-4882	O
MOS	O
6520	O
PIA	O
,	O
MOS	O
6522	O
VIA	O
,	O
2	O
Datassette	B-Device
ports	O
(	O
1	O
on	O
the	O
back	O
)	O
,	O
1×	O
IEEE-488MOS	O
6520	O
PIA	O
,	O
MOS	O
6522	O
VIA	O
,	O
MOS	O
6551	O
ACIA	O
,	O
1	O
RS-232	O
,	O
2	O
Datassette	B-Device
ports	O
(	O
1	O
on	O
the	O
back	O
)	O
,	O
1×	O
IEEE-488	O
Notes69	O
key	O
chiclet	B-Device
keyboard	I-Device
and	O
built-in	O
Datassette	B-Device
/	O
full-sized	O
,	O
full-travel	O
keyboard	O
,	O
no	O
built-in	O
DatassetteBasically	O
an	O
upgraded	O
2001	O
.	O
</s>
<s>
The	O
8000	O
series	O
was	O
basically	O
a	O
4000	O
with	O
80	O
columns	O
and	O
a	O
slightly	O
different	O
keyboard	O
with	O
a	O
smaller	O
,	O
11-key	O
numeric	O
pad.Basically	O
an	O
8000	O
with	O
ROMs	O
for	O
programming	O
languages	O
,	O
it	O
also	O
had	O
three	O
character	B-General_Concept
sets	I-General_Concept
,	O
and	O
an	O
RS-232	O
for	O
use	O
as	O
a	O
terminal	B-Application
.	O
</s>
<s>
Later	O
(	O
near	O
the	O
end	O
of	O
the	O
PET	O
's	O
lifespan	O
)	O
,	O
single-unit	O
2031	O
and	O
SFD-1001	B-Device
drives	O
were	O
produced	O
that	O
used	O
the	O
same	O
case	O
as	O
the	O
1540/1541	O
,	O
but	O
sported	O
the	O
PET	O
's	O
parallel	O
interface	O
instead	O
of	O
the	O
VIC-20/C64	O
IEC	B-Protocol
serial	I-Protocol
interface	O
.	O
</s>
<s>
The	O
4040/2031	O
used	O
the	O
same	O
format	O
as	O
the	O
1541	B-Device
and	O
is	O
read	O
compatible	O
(	O
although	O
software	O
that	O
performs	O
low-level	O
drive	O
access	O
will	O
not	O
work	O
,	O
and	O
a	O
one	O
byte	O
sector	O
–	O
header	O
size	O
difference	O
makes	O
the	O
formats	O
write-incompatible	O
)	O
.	O
</s>
<s>
8050	O
and	O
8250	O
drives	O
had	O
an	O
incompatible	O
higher	O
density	O
/	O
format	O
,	O
but	O
were	O
popular	O
well	O
into	O
the	O
1980s	O
as	O
server/BBS	O
storage	O
devices	O
because	O
of	O
their	O
large	O
capacity	O
.	O
</s>
<s>
In	O
addition	O
,	O
Commodore	O
had	O
8-inch	O
8060	O
,	O
8061	O
,	O
8062	O
,	O
and	O
8280	O
drives	O
which	O
used	O
MFM	B-Protocol
encoding	I-Protocol
instead	O
of	O
the	O
GCR	B-Device
used	O
on	O
their	O
other	O
disk	O
drives	O
and	O
was	O
mainly	O
intended	O
to	O
allow	O
PET	O
users	O
to	O
read	O
disks	O
written	O
on	O
IBM	O
mainframes/minicomputers	O
.	O
</s>
<s>
and	O
hard	B-Device
disks	I-Device
were	O
produced	O
as	O
well	O
.	O
</s>
<s>
All	O
PET	O
peripherals	O
will	O
work	O
on	O
VIC-20/C64/Plus-4/C128	O
machines	O
with	O
a	O
IEEE-488	O
parallel	O
to	O
IEC	B-Protocol
serial	I-Protocol
adapter	O
(	O
reverse	O
IEC	B-Protocol
serial	I-Protocol
to	O
IEEE-488	O
parallel	O
adapters	O
were	O
also	O
made	O
)	O
,	O
and	O
as	O
mentioned	O
above	O
,	O
using	O
these	O
adapters	O
,	O
8050/8250	O
drives	O
were	O
sometimes	O
used	O
on	O
C64s	O
for	O
BBS	B-Application
service	O
because	O
of	O
their	O
large	O
capacity	O
and	O
faster	O
interface	O
.	O
</s>
<s>
Unlike	O
the	O
Commodore	O
units	O
,	O
it	O
did	O
not	O
use	O
the	O
IEEE-488	O
interface	O
,	O
but	O
instead	O
required	O
an	O
extra	O
circuit	O
board	O
to	O
be	O
installed	O
inside	O
the	O
PET	O
,	O
connected	O
to	O
the	O
PET	O
's	O
expansion	O
connector	O
,	O
which	O
used	O
a	O
Western	O
Digital	O
floppy	O
controller	O
chip	O
to	O
provide	O
a	O
standard	O
Shugart	B-Architecture
interface	O
.	O
</s>
<s>
The	O
board	O
also	O
held	O
extra	O
RAM	B-Architecture
for	O
use	O
as	O
a	O
disk	O
transfer	O
buffer	O
,	O
and	O
ROM	B-Device
containing	O
the	O
disk	O
operating	O
software	O
.	O
</s>
<s>
ETI	O
Canada	O
wrote	O
that	O
the	O
Commodore	B-Device
PET	I-Device
was	O
revolutionary	O
in	O
helping	O
to	O
bring	O
personal	B-Device
computers	I-Device
to	O
widespread	O
use	O
,	O
noting	O
the	O
company	O
's	O
marketing	O
and	O
its	O
targeting	O
of	O
inexperienced	O
computer	O
users	O
with	O
the	O
computer	O
's	O
simple	O
design	O
.	O
</s>
<s>
His	O
machine	O
had	O
three	O
faulty	O
RAM	B-Architecture
chips	I-Architecture
and	O
after	O
some	O
difficulty	O
contacting	O
Commodore	O
,	O
was	O
mailed	O
a	O
set	O
of	O
replacement	O
chips	O
and	O
installation	O
instructions	O
by	O
John	O
Feagans	O
.	O
</s>
<s>
Fylstra	O
described	O
the	O
PET	B-Device
2001	I-Device
as	O
a	O
versatile	O
"	O
appliance	O
"	O
computer	O
most	O
suitable	O
for	O
casual	O
users	O
and	O
computer	O
hobbyists	O
,	O
calling	O
it	O
a	O
"	O
strong	O
contender	O
"	O
in	O
the	O
personal	B-Device
computer	I-Device
market	O
.	O
</s>
