<s>
The	O
Atari	B-Device
810	I-Device
is	O
the	O
official	O
floppy	B-Device
disk	I-Device
drive	I-Device
for	O
the	O
Atari	O
400	O
and	O
800	O
,	O
the	O
first	O
two	O
models	O
in	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
of	O
home	O
computers	O
.	O
</s>
<s>
Third-party	O
enhancements	O
such	O
as	O
the	O
Happy	B-Device
810	I-Device
address	O
these	O
problems	O
as	O
do	O
replacement	O
drives	O
like	O
the	O
Indus	B-Device
GT	I-Device
with	O
more	O
storage	O
and	O
other	O
features	O
.	O
</s>
<s>
The	O
810	O
was	O
replaced	O
by	O
the	O
Atari	B-Device
1050	I-Device
with	O
the	O
release	O
of	O
the	O
XL	O
series	O
machines	O
in	O
1983	O
.	O
</s>
<s>
It	O
was	O
replaced	O
in	O
turn	O
in	O
1987	O
by	O
the	O
XF551	B-Device
with	O
a	O
double-sided	O
,	O
double-density	O
360kB	O
mode	O
.	O
</s>
<s>
The	O
machines	O
that	O
emerged	O
as	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
had	O
originally	O
been	O
designed	O
as	O
part	O
of	O
a	O
project	O
to	O
develop	O
a	O
driver	O
chipset	O
for	O
a	O
new	O
games	O
console	O
.	O
</s>
<s>
During	O
the	O
time	O
the	O
chips	O
were	O
being	O
developed	O
,	O
the	O
Apple	B-Device
II	I-Device
became	O
very	O
popular	O
and	O
propelled	O
Apple	O
Computer	O
into	O
one	O
of	O
the	O
largest	O
initial	O
public	O
offerings	O
of	O
its	O
era	O
.	O
</s>
<s>
One	O
of	O
the	O
key	O
reasons	O
for	O
the	O
Apple	B-Device
II	I-Device
's	O
success	O
was	O
the	O
Disk	B-Device
II	I-Device
,	O
introduced	O
in	O
June	O
1978	O
at	O
the	O
very	O
low	O
(	O
for	O
the	O
era	O
)	O
price	O
of	O
$495	O
(	O
)	O
plus	O
the	O
interface	O
card	O
.	O
</s>
<s>
The	O
interface	O
was	O
based	O
on	O
a	O
system	O
Steve	O
Wozniak	O
had	O
previously	O
built	O
while	O
working	O
at	O
Hewlett-Packard	O
to	O
control	O
a	O
Shugart	O
Associates	O
SA-400	O
floppy	B-Device
drive	I-Device
.	O
</s>
<s>
Atari	O
was	O
determined	O
to	O
make	O
a	O
plug-and-play	O
system	O
that	O
connected	O
directly	O
to	O
the	O
television	O
,	O
like	O
the	O
Atari	B-Application
VCS	I-Application
.	O
</s>
<s>
This	O
precluded	O
the	O
idea	O
of	O
having	O
expansion	B-Device
slots	I-Device
that	O
could	O
be	O
connected	O
to	O
external	O
equipment	O
,	O
like	O
on	O
the	O
Apple	O
,	O
as	O
the	O
openings	O
would	O
be	O
difficult	O
to	O
shield	O
property	O
to	O
avoid	O
RF	O
leakage	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
introduction	O
of	O
the	O
SIO	B-Architecture
serial	O
bus	O
,	O
a	O
system	O
that	O
allowed	O
devices	O
to	O
be	O
daisy	O
chained	O
to	O
a	O
single	O
port	O
.	O
</s>
<s>
Using	O
a	O
cable	O
made	O
shielding	O
to	O
the	O
required	O
levels	O
much	O
easier	O
,	O
but	O
also	O
required	O
the	O
external	O
devices	O
to	O
host	O
the	O
interface	O
circuitry	O
that	O
would	O
normally	O
be	O
placed	O
on	O
an	O
expansion	B-Device
card	I-Device
inside	O
the	O
machine	O
.	O
</s>
<s>
To	O
offset	O
this	O
as	O
much	O
as	O
possible	O
,	O
Atari	O
used	O
discarded	O
MOS	B-General_Concept
6507	I-General_Concept
chips	O
from	O
the	O
VCS	O
production	O
line	O
.	O
</s>
<s>
Atari	O
had	O
long	O
relied	O
on	O
Signetic	O
's	O
6507s	B-General_Concept
being	O
rated	O
for	O
1MHz	O
but	O
most	O
of	O
them	O
actually	O
being	O
able	O
to	O
run	O
at	O
a	O
slightly	O
higher	O
1.1MHz	O
that	O
the	O
VCS	O
worked	O
at	O
.	O
</s>
<s>
Atari	O
arranged	O
a	O
deal	O
with	O
MPI	O
for	O
their	O
mechanisms	O
and	O
designed	O
their	O
own	O
controller	O
to	O
drive	O
it	O
,	O
combining	O
the	O
6507	B-General_Concept
running	O
at	O
500kHz	O
with	O
a	O
standard	O
FM	B-Protocol
encoding	I-Protocol
drive	O
controller	O
,	O
the	O
Western	B-Device
Digital	I-Device
FD1771	I-Device
.	O
</s>
<s>
In	O
spite	O
of	O
these	O
efforts	O
,	O
the	O
resulting	O
drive	O
was	O
still	O
more	O
expensive	O
than	O
the	O
Disk	B-Device
II	I-Device
,	O
listed	O
at	O
$599	O
when	O
it	O
was	O
introduced	O
in	O
1979	O
.	O
</s>
<s>
It	O
also	O
had	O
the	O
disadvantage	O
of	O
running	O
more	O
slowly	O
than	O
the	O
Disk	B-Device
II	I-Device
;	O
although	O
the	O
underlying	O
SIO	B-Architecture
bus	O
was	O
running	O
at	O
19.2kbps	O
,	O
the	O
effective	O
data	O
rate	O
was	O
generally	O
around	O
6kbps	O
,	O
compared	O
to	O
about	O
15kbps	O
for	O
the	O
Disk	B-Device
II	I-Device
.	O
</s>
<s>
This	O
is	O
one	O
reason	O
the	O
machine	O
was	O
never	O
considered	O
seriously	O
in	O
the	O
business	O
market	O
;	O
applications	O
like	O
VisiCalc	B-Application
were	O
not	O
competitive	O
with	O
the	O
Apple	B-Device
II	I-Device
when	O
run	O
on	O
the	O
Atari	O
or	O
Commodore	O
64	O
.	O
</s>
<s>
Initial	O
units	O
shipped	O
with	O
Atari	B-Operating_System
DOS	I-Operating_System
1.0	O
,	O
sometimes	O
known	O
as	O
DOS	O
I	O
.	O
</s>
<s>
While	O
the	O
8-bit	O
machines	O
were	O
first	O
being	O
introduced	O
,	O
the	O
first	O
MFM	B-Protocol
double-density	O
drive	O
controllers	O
were	O
appearing	O
,	O
allowing	O
the	O
same	O
disks	O
to	O
store	O
twice	O
as	O
much	O
data	O
,	O
180kB	O
.	O
</s>
<s>
Early	O
advertising	O
for	O
the	O
new	O
machines	O
often	O
showed	O
the	O
815	O
,	O
which	O
combined	O
two	O
drives	O
in	O
a	O
single	O
case	O
and	O
used	O
MFM	B-Protocol
encoding	I-Protocol
.	O
</s>
<s>
The	O
controller	O
was	O
custom	O
and	O
only	O
supported	O
MFM	B-Protocol
,	O
making	O
the	O
815	O
incompatible	O
with	O
disks	O
used	O
in	O
the	O
810	O
.	O
</s>
<s>
Third	O
parties	O
exploring	O
the	O
capabilities	O
of	O
the	O
810	O
system	O
soon	O
demonstrated	O
that	O
the	O
19.2kbps	O
speed	O
of	O
the	O
SIO	B-Architecture
communications	O
could	O
be	O
easily	O
doubled	O
.	O
</s>
<s>
It	O
was	O
later	O
revealed	O
that	O
the	O
speed	O
was	O
not	O
a	O
limitation	O
of	O
the	O
SIO	B-Architecture
port	O
,	O
but	O
the	O
maximum	O
speed	O
of	O
the	O
logic	O
analyzer	O
available	O
in	O
the	O
lab	O
where	O
it	O
was	O
being	O
developed	O
.	O
</s>
<s>
Best	O
known	O
among	O
the	O
many	O
products	O
was	O
the	O
Happy	B-Device
810	I-Device
,	O
introduced	O
in	O
1982	O
.	O
</s>
<s>
It	O
added	O
a	O
buffer	O
able	O
to	O
cache	O
one	O
entire	O
track	O
of	O
data	O
,	O
and	O
along	O
with	O
the	O
associated	O
Warp	O
Speed	O
software	O
,	O
increased	O
read	O
performance	O
about	O
three	O
times	O
,	O
making	O
it	O
very	O
competitive	O
with	O
the	O
Apple	B-Device
II	I-Device
.	O
</s>
<s>
The	O
performance	O
and	O
reliability	O
problems	O
with	O
the	O
810	O
also	O
led	O
to	O
a	O
thriving	O
market	O
for	O
third-party	O
drives	O
like	O
the	O
Rana	O
1000	O
and	O
Indus	B-Device
GT	I-Device
,	O
along	O
with	O
a	O
wide	O
selection	O
of	O
replacements	O
for	O
Atari	B-Operating_System
DOS	I-Operating_System
.	O
</s>
<s>
Changes	O
to	O
the	O
plans	O
led	O
to	O
only	O
one	O
of	O
these	O
designs	O
being	O
released	O
as	O
the	O
1200XL	B-Device
.	O
</s>
<s>
Initially	O
this	O
included	O
the	O
Atari	B-Device
1010	I-Device
cassette	O
deck	O
,	O
the	O
Atari	B-Device
1020	I-Device
plotter	O
,	O
and	O
1025	O
printers	O
.	O
</s>
<s>
When	O
the	O
1200XL	B-Device
was	O
introduced	O
at	O
the	O
Winter	O
Consumer	O
Electronics	O
Show	O
in	O
December	O
1982	O
,	O
there	O
was	O
no	O
sign	O
of	O
a	O
new	O
floppy	B-Device
drive	I-Device
.	O
</s>
<s>
This	O
prediction	O
came	O
true	O
;	O
when	O
the	O
1200XL	B-Device
finally	O
reached	O
the	O
market	O
in	O
June	O
1983	O
,	O
it	O
was	O
accompanied	O
by	O
the	O
new	O
Atari	B-Device
1050	I-Device
.	O
</s>
<s>
The	O
back	O
of	O
the	O
case	O
had	O
two	O
SIO	B-Architecture
ports	O
to	O
allow	O
daisy-chaining	O
,	O
a	O
ring	O
jack	O
for	O
the	O
external	O
power	O
supply	O
,	O
and	O
two	O
pin	O
switches	O
to	O
select	O
the	O
drive	O
number	O
from	O
1	O
to	O
4	O
.	O
</s>
<s>
These	O
versions	O
added	O
an	O
External	O
Data	O
Separator	O
Board	O
which	O
plugged	O
into	O
the	O
socket	O
for	O
the	O
FD1771	B-Device
chip	O
,	O
providing	O
more	O
separation	O
between	O
the	O
signals	O
and	O
improving	O
read	O
reliability	O
.	O
</s>
<s>
This	O
added	O
an	O
entirely	O
new	O
card	O
,	O
the	O
Power	O
Supply	O
Board	O
,	O
which	O
included	O
a	O
tachometer	B-Device
that	O
finally	O
solved	O
the	O
speed	O
problems	O
.	O
</s>
