<s>
The	O
Commodore	B-Device
1530	I-Device
(	O
C2N	O
)	O
Datasette	B-Device
,	O
later	O
also	O
Datassette	B-Device
(	O
a	O
portmanteau	O
of	O
data	O
and	O
cassette	O
)	O
,	O
is	O
Commodore	O
's	O
dedicated	O
magnetic	B-Architecture
tape	I-Architecture
data	I-Architecture
storage	I-Architecture
device	O
.	O
</s>
<s>
Using	O
compact	B-Device
cassettes	I-Device
as	O
the	O
storage	B-General_Concept
medium	I-General_Concept
,	O
it	O
provides	O
inexpensive	O
storage	O
to	O
Commodore	O
's	O
8-bit	O
computers	O
,	O
including	O
the	O
PET	B-Device
,	O
VIC-20	B-Device
,	O
and	O
Commodore	O
64	O
.	O
</s>
<s>
A	O
physically	O
similar	O
model	O
,	O
Commodore	B-Device
1531	I-Device
,	O
was	O
made	O
for	O
the	O
Commodore	B-Operating_System
16	I-Operating_System
and	O
Plus/4	B-Operating_System
series	O
computers	O
.	O
</s>
<s>
Typical	O
compact	B-Device
cassette	I-Device
interfaces	O
of	O
the	O
late	O
1970s	O
use	O
a	O
small	O
controller	O
in	O
the	O
computer	O
to	O
convert	O
digital	B-General_Concept
data	I-General_Concept
to	O
and	O
from	O
analog	O
tones	O
.	O
</s>
<s>
The	O
interface	O
is	O
then	O
connected	O
to	O
the	O
cassette	O
deck	O
using	O
normal	O
audio	O
cables	O
like	O
RCA	B-Protocol
jacks	I-Protocol
or	O
3.5mm	B-Device
phone	I-Device
jacks	I-Device
.	O
</s>
<s>
This	O
sort	O
of	O
system	O
was	O
used	O
on	O
the	O
Apple	B-Device
II	I-Device
and	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
,	O
as	O
well	O
as	O
many	O
S-100	B-Architecture
bus	I-Architecture
systems	O
,	O
and	O
allow	O
them	O
to	O
be	O
used	O
with	O
any	O
cassette	O
player	O
with	O
suitable	O
connections	O
.	O
</s>
<s>
In	O
the	O
Datasette	B-Device
,	O
instead	O
of	O
writing	O
two	O
tones	O
to	O
tape	O
to	O
indicate	O
bits	O
,	O
patterns	O
of	O
square	O
waves	O
are	O
used	O
,	O
including	O
a	O
parity	B-Error_Name
bit	I-Error_Name
.	O
</s>
<s>
Programs	O
are	O
written	O
twice	O
to	O
tape	O
for	O
error	B-Error_Name
correction	I-Error_Name
;	O
if	O
an	O
error	O
is	O
detected	O
when	O
reading	O
the	O
first	O
recording	O
,	O
the	O
computer	O
corrects	O
it	O
with	O
data	O
from	O
the	O
second	O
.	O
</s>
<s>
The	O
Datasette	B-Device
has	O
built-in	O
analog-to-digital	O
converters	O
and	O
audio	O
filters	O
to	O
convert	O
the	O
computer	O
's	O
digital	B-General_Concept
data	I-General_Concept
into	O
analog	O
audio	O
and	O
vice	O
versa	O
.	O
</s>
<s>
Connection	O
to	O
the	O
computer	O
is	O
done	O
via	O
a	O
proprietary	O
edge	O
connector	O
(	O
Commodore	B-Device
1530	I-Device
)	O
or	O
mini-DIN	B-Protocol
connector	I-Protocol
(	O
1531	O
)	O
.	O
</s>
<s>
The	O
absence	O
of	O
recordable	O
audio	O
signals	O
on	O
this	O
interface	O
makes	O
the	O
Datasette	B-Device
and	O
clones	O
the	O
only	O
cassette	O
recorders	O
usable	O
with	O
Commodore	O
computers	O
,	O
until	O
aftermarket	O
converters	O
made	O
the	O
use	O
of	O
ordinary	O
recorders	O
possible	O
.	O
</s>
<s>
Because	O
of	O
its	O
digital	B-General_Concept
format	I-General_Concept
the	O
Datasette	B-Device
is	O
both	O
more	O
reliable	O
than	O
other	O
data	O
cassette	O
systems	O
and	O
very	O
slow	O
,	O
transferring	O
data	O
at	O
around	O
per	O
second	O
.	O
</s>
<s>
After	O
the	O
Datasette	B-Device
's	O
launch	O
,	O
however	O
,	O
special	O
turbo	O
tape	O
software	O
appeared	O
,	O
providing	O
much	O
faster	O
tape	O
operation	O
(	O
loading	O
and	O
saving	O
)	O
.	O
</s>
<s>
Datasettes	B-Device
can	O
typically	O
store	O
about	O
per	O
side	O
.	O
</s>
<s>
The	O
use	O
of	O
turbo	O
tape	O
and	O
other	O
fast	B-Device
loaders	I-Device
increased	O
this	O
number	O
to	O
roughly	O
.	O
</s>
<s>
The	O
Datasette	B-Device
has	O
only	O
one	O
connection	O
cable	O
,	O
with	O
a	O
spacing	O
PCB	O
edge	O
connector	O
at	O
the	O
computer	O
end	O
.	O
</s>
<s>
All	O
input/output	O
signals	O
to	O
the	O
Datasette	B-Device
are	O
all	O
digital	O
,	O
and	O
so	O
all	O
digital-to-analog	O
conversion	O
,	O
and	O
vice	O
versa	O
,	O
is	O
handled	O
within	O
the	O
unit	O
.	O
</s>
<s>
The	O
pinout	B-Application
is	O
ground	O
,	O
,	O
motor	O
,	O
read	O
,	O
write	O
,	O
key-sense	O
.	O
</s>
<s>
Inside	O
the	O
computer	O
,	O
the	O
first	O
Complex	B-Device
Interface	I-Device
Adapter	I-Device
(	O
6526	B-Device
)	O
in	O
the	O
C64	O
senses	O
when	O
the	O
signal	O
goes	O
from	O
one	O
to	O
zero	O
.	O
</s>
<s>
This	O
event	O
is	O
called	O
trigger	O
and	O
causes	O
an	O
interrupt	B-General_Concept
request	I-General_Concept
.	O
</s>
<s>
Op-amp	O
(	O
4	O
)	O
amplifies	O
the	O
signal	O
into	O
clipping	B-Algorithm
the	O
sine-formed	O
signal	O
.	O
</s>
<s>
The	O
clipped	O
signal	O
therefore	O
fits	O
into	O
the	O
TTL	B-General_Concept
electrical	O
level	O
window	O
of	O
the	O
Schmitt	O
trigger	O
step	O
that	O
in	O
turn	O
feeds	O
the	O
digital	O
cassette	O
port	O
.	O
</s>
<s>
On	O
the	O
PAL	B-Language
version	O
of	O
the	O
C64	O
,	O
the	O
time	O
granularity	O
is	O
(	O
for	O
NTSC	O
)	O
.	O
</s>
<s>
Once	O
the	O
bits	O
can	O
be	O
decoded	O
,	O
they	O
are	O
fed	O
into	O
a	O
shift	B-General_Concept
register	I-General_Concept
and	O
are	O
continuously	O
compared	O
to	O
a	O
special	O
bit	O
sequence	O
.	O
</s>
<s>
There	O
are	O
at	O
least	O
four	O
main	O
models	O
of	O
the	O
1530/C2N	O
Datassette	B-Device
:	O
</s>
<s>
The	O
original	O
modified	O
Sanyo	O
M1540A	O
cassette	O
drive	O
,	O
built	O
into	O
the	O
earliest	O
models	O
of	O
PET	B-Device
in	O
1977	O
.	O
</s>
<s>
The	O
second	O
built-in	O
Datassette	B-Device
in	O
the	O
PET	B-Device
2001	I-Device
:	O
another	O
standard	O
consumer	O
model	O
(	O
sold	O
in	O
some	O
markets	O
as	O
CCE	O
CCT1020	O
)	O
modified	O
with	O
a	O
Commodore	O
PCB	O
.	O
</s>
<s>
The	O
first	O
two	O
external	O
models	O
were	O
made	O
as	O
PET	B-Device
peripherals	O
,	O
and	O
styled	O
after	O
the	O
PET	B-Device
2001	I-Device
built-in	O
tape	O
drive	O
.	O
</s>
<s>
The	O
latter	O
two	O
were	O
styled	O
and	O
marketed	O
for	O
the	O
VIC-20	B-Device
and	O
C64	O
.	O
</s>
<s>
All	O
1530s	O
are	O
compatible	O
with	O
all	O
those	O
computers	O
,	O
as	O
well	O
as	O
the	O
C128	B-Device
.	O
</s>
<s>
A	O
small	O
screwdriver	O
can	O
thus	O
easily	O
be	O
used	O
to	O
affect	O
the	O
adjustment	O
without	O
disassembling	O
the	O
Datassette	B-Device
's	O
chassis	O
.	O
</s>
<s>
Confusingly	O
,	O
the	O
Datassette	B-Device
at	O
various	O
times	O
was	O
sold	O
both	O
as	O
the	O
C2N	O
DATASETTE	B-Device
UNIT	O
Model	O
1530	O
and	O
as	O
the	O
1530	O
DATASSETTE	B-Device
UNIT	O
Model	O
C2N	O
.	O
</s>
<s>
Like	O
Datasette	B-Device
models	O
,	O
the	O
recording	O
format	O
is	O
compatible	O
across	O
computers	O
;	O
the	O
VIC	O
,	O
for	O
example	O
,	O
can	O
read	O
PET	B-Device
cassettes	O
.	O
</s>
<s>
Similar	O
in	O
physical	O
appearance	O
to	O
the	O
1530/C2N	O
models	O
is	O
the	O
Commodore	B-Device
1531	I-Device
,	O
made	O
for	O
the	O
Commodore	B-Operating_System
16	I-Operating_System
and	O
Plus/4	B-Operating_System
series	O
computers	O
.	O
</s>
<s>
This	O
has	O
a	O
Mini-DIN	B-Protocol
connector	I-Protocol
in	O
place	O
of	O
the	O
PCB	O
edge	O
connector	O
.	O
</s>
<s>
The	O
Datasette	B-Device
was	O
more	O
popular	O
outside	O
than	O
inside	O
the	O
United	O
States	O
.	O
</s>
<s>
Computer	O
Gaming	O
World	O
reported	O
in	O
1986	O
that	O
British	O
cassette-based	O
software	O
had	O
failed	O
in	O
the	O
United	O
States	O
because	O
"	O
97%	O
of	O
the	O
Commodore	O
systems	O
in	O
the	O
USA	O
have	O
disk	B-General_Concept
drives	I-General_Concept
"	O
;	O
by	O
contrast	O
,	O
MicroProse	O
reported	O
in	O
1987	O
that	O
80%	O
of	O
its	O
100,000	O
sales	O
of	O
Gunship	B-Application
in	O
the	O
UK	O
were	O
on	O
cassette	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
disk	B-General_Concept
drives	I-General_Concept
quickly	O
became	O
standard	O
,	O
despite	O
the	O
1541	O
costing	O
roughly	O
five	O
times	O
as	O
much	O
as	O
a	O
Datasette	B-Device
.	O
</s>
<s>
In	O
most	O
parts	O
of	O
Europe	O
,	O
the	O
Datasette	B-Device
was	O
the	O
medium	O
of	O
choice	O
for	O
several	O
years	O
after	O
its	O
launch	O
,	O
although	O
floppy	O
disk	B-General_Concept
drives	I-General_Concept
were	O
generally	O
available	O
.	O
</s>
<s>
The	O
inexpensive	O
and	O
widely	O
available	O
audio	B-Device
cassettes	I-Device
made	O
the	O
Datasette	B-Device
a	O
good	O
choice	O
for	O
the	O
budget-aware	O
home	O
computer	O
mass	O
market	O
.	O
</s>
