<s>
A	O
floppy	B-Device
disk	I-Device
is	O
a	O
disk	O
storage	O
medium	O
composed	O
of	O
a	O
disk	O
of	O
thin	O
and	O
flexible	O
magnetic	B-Architecture
storage	I-Architecture
medium	O
encased	O
in	O
a	O
rectangular	O
plastic	O
carrier	O
.	O
</s>
<s>
It	O
is	O
read	O
and	O
written	O
using	O
a	O
floppy	B-Device
disk	I-Device
drive	I-Device
(	O
FDD	O
)	O
.	O
</s>
<s>
Floppy	B-Device
disks	I-Device
were	O
an	O
almost	O
universal	O
data	O
format	O
from	O
the	O
1970s	O
into	O
the	O
1990s	O
,	O
used	O
for	O
primary	O
data	O
storage	O
as	O
well	O
as	O
for	O
backup	O
and	O
data	O
transfers	O
between	O
computers	O
.	O
</s>
<s>
In	O
1967	O
,	O
at	O
an	O
IBM	O
facility	O
in	O
San	O
Jose	O
(	O
CA	O
)	O
,	O
work	O
began	O
on	O
a	O
drive	O
that	O
led	O
to	O
the	O
world	O
's	O
first	O
floppy	B-Device
disk	I-Device
and	O
disk	O
drive	O
.	O
</s>
<s>
The	O
more	O
conveniently	O
sized	O
5¼-inch	B-Device
disks	I-Device
were	O
introduced	O
in	O
1976	O
,	O
and	O
became	O
almost	O
universal	O
on	O
dedicated	O
word	B-General_Concept
processing	I-General_Concept
systems	O
and	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
A	O
number	O
of	O
other	O
variant	B-Operating_System
sizes	I-Operating_System
were	O
introduced	O
over	O
time	O
,	O
with	O
limited	O
market	O
success	O
.	O
</s>
<s>
Floppy	B-Device
disks	I-Device
remained	O
a	O
popular	O
medium	O
for	O
nearly	O
40	O
years	O
,	O
but	O
their	O
use	O
was	O
declining	O
by	O
the	O
mid	O
-	O
to	O
late	O
1990s	O
.	O
</s>
<s>
The	O
introduction	O
of	O
high	O
speed	O
computer	B-Architecture
networking	I-Architecture
and	O
formats	O
based	O
on	O
the	O
new	O
NAND	O
flash	O
technique	O
(	O
like	O
USB	O
flash	O
drives	O
and	O
memory	B-Device
cards	I-Device
)	O
led	O
to	O
the	O
eventual	O
disappearance	O
of	O
the	O
floppy	B-Device
disk	I-Device
as	O
a	O
standard	O
feature	O
of	O
microcomputers	B-Architecture
,	O
with	O
a	O
notable	O
point	O
in	O
this	O
conversion	O
being	O
the	O
introduction	O
of	O
the	O
floppy-less	O
iMac	B-Device
in	O
1998	O
.	O
</s>
<s>
After	O
2000	O
,	O
floppy	B-Device
disks	I-Device
were	O
increasingly	O
rare	O
and	O
used	O
primarily	O
with	O
older	O
hardware	O
and	O
especially	O
with	O
legacy	O
industrial	O
computer	O
equipment	O
.	O
</s>
<s>
IBM	O
San	O
Jose	O
's	O
Direct	O
Access	O
Storage	O
Product	O
Manager	O
,	O
Alan	O
Shugart	O
,	O
assigned	O
the	O
job	O
to	O
David	B-Device
L	I-Device
.	I-Device
Noble	I-Device
,	O
who	O
tried	O
to	O
develop	O
a	O
new-style	O
tape	O
for	O
the	O
purpose	O
,	O
but	O
without	O
success	O
.	O
</s>
<s>
The	O
project	O
was	O
reassigned	O
to	O
Donald	O
L	O
.	O
Wartner	O
,	O
23FD	O
Disk	O
Drive	O
manager	O
,	O
and	O
Herbert	O
E	O
.	O
Thompson	O
,	O
23FD	O
Disk	O
manager	O
,	O
along	O
with	O
design	O
engineers	O
Warren	O
L	O
.	O
Dalziel	O
,	O
Jay	O
Brent	O
Nilson	O
,	O
and	O
Ralph	O
Flores	O
;	O
and	O
that	O
team	O
developed	O
the	O
IBM	O
23FD	O
Floppy	B-Device
Disk	I-Device
Drive	I-Device
System	O
(	O
code	O
name	O
Minnow	O
)	O
.	O
</s>
<s>
The	O
disk	O
is	O
a	O
read-only	O
,	O
flexible	O
diskette	B-Device
called	O
the	O
"	O
memory	O
disk	O
"	O
and	O
holding	O
80	O
kilobytes	O
of	O
data	O
.	O
</s>
<s>
The	O
Floppy	B-Device
Disk	I-Device
Patent	O
#3	O
,	O
668,658	O
was	O
issued	O
on	O
June	O
6	O
,	O
1972	O
,	O
with	O
named	O
inventors	O
Ralph	O
Flores	O
and	O
Herbert	O
E	O
.	O
Thompson	O
.	O
</s>
<s>
The	O
Floppy	B-Device
Disk	I-Device
Drive	I-Device
Patent	O
#3	O
,	O
678,481	O
was	O
issued	O
July	O
18	O
,	O
1972	O
with	O
named	O
inventors	O
Warren	O
L	O
.	O
Dalziel	O
,	O
Jay	O
.	O
</s>
<s>
IBM	O
introduced	O
the	O
diskette	B-Device
commercially	O
in	O
1971	O
.	O
</s>
<s>
Internally	O
IBM	O
used	O
another	O
device	O
,	O
code	O
named	O
Mackerel	O
,	O
to	O
write	O
floppy	B-Device
disks	I-Device
for	O
distribution	O
to	O
the	O
field	O
.	O
</s>
<s>
Shugart	O
,	O
by	O
then	O
at	O
Memorex	O
shipped	O
the	O
Memorex	O
650	O
in	O
1972	O
,	O
the	O
first	O
commercially	O
available	O
read-write	O
floppy	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
Most	O
early	O
8	B-Device
"	I-Device
disks	O
were	O
hard	O
sectored	O
,	O
meaning	O
that	O
they	O
had	O
a	O
fixed	O
number	O
of	O
disk	O
sectors	O
(	O
usually	O
8	O
,	O
16	O
,	O
or	O
32	O
)	O
,	O
marked	O
by	O
physical	O
holes	O
punched	O
around	O
the	O
disk	O
hub	O
,	O
and	O
the	O
drive	O
required	O
the	O
correct	O
media	O
type	O
for	O
its	O
controller	O
.	O
</s>
<s>
The	O
33FD	O
first	O
shipped	O
in	O
May	O
1973	O
as	O
a	O
component	O
of	O
the	O
3740	B-Device
Data	I-Device
Entry	I-Device
System	I-Device
,	O
designed	O
to	O
directly	O
replace	O
IBM	O
's	O
punched	B-Architecture
card	I-Architecture
(	O
"	O
keypunch	O
"	O
)	O
data	O
entry	O
machines	O
.	O
</s>
<s>
The	O
medium	O
sold	O
separately	O
as	O
"	O
Diskette	B-Device
1	O
"	O
.	O
</s>
<s>
It	O
was	O
designed	O
to	O
hold	O
the	O
same	O
amount	O
of	O
data	O
as	O
3000	O
punch	B-Architecture
cards	I-Architecture
.	O
</s>
<s>
In	O
1973	O
,	O
Shugart	O
founded	O
Shugart	O
Associates	O
which	O
went	O
on	O
to	O
become	O
the	O
dominant	O
manufacturer	O
of	O
8-inch	B-Device
floppy	I-Device
disk	O
drives	O
.	O
</s>
<s>
In	O
1976	O
,	O
media	O
supplier	O
Information	O
Terminals	O
Corporation	O
enhanced	O
resilience	O
further	O
by	O
adding	O
a	O
Teflon	O
coating	O
to	O
the	O
magnetic	B-Architecture
disk	I-Architecture
itself	O
.	O
</s>
<s>
When	O
the	O
first	O
microcomputers	B-Architecture
were	O
being	O
developed	O
in	O
the	O
1970s	O
,	O
the	O
8-inch	B-Device
floppy	I-Device
found	O
a	O
place	O
on	O
them	O
as	O
one	O
of	O
the	O
few	O
"	O
high	O
speed	O
,	O
mass	O
storage	O
"	O
devices	O
that	O
were	O
even	O
remotely	O
affordable	O
to	O
the	O
target	O
market	O
(	O
individuals	O
and	O
small	O
businesses	O
)	O
.	O
</s>
<s>
The	O
first	O
microcomputer	B-Architecture
operating	B-General_Concept
system	I-General_Concept
,	O
CP/M	B-Application
,	O
originally	O
shipped	O
on	O
8-inch	O
disks	O
.	O
</s>
<s>
However	O
,	O
the	O
drives	O
were	O
still	O
expensive	O
,	O
typically	O
costing	O
more	O
than	O
the	O
computer	O
they	O
were	O
attached	O
to	O
in	O
early	O
days	O
,	O
so	O
most	O
machines	O
of	O
the	O
era	O
used	O
cassette	B-Device
tape	I-Device
instead	O
.	O
</s>
<s>
Other	O
8-inch	B-Device
floppy	I-Device
disk	O
formats	O
such	O
as	O
the	O
Burroughs	O
1MB	O
unit	O
failed	O
to	O
achieve	O
any	O
market	O
presence	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
1978	O
the	O
typical	O
floppy	B-Device
disk	I-Device
price	O
per	O
piece	O
was	O
$5	O
(	O
)	O
to	O
$8	O
(	O
)	O
.	O
</s>
<s>
The	O
8	B-Device
"	I-Device
floppy	B-Device
disk	I-Device
drive	I-Device
interface	O
standard	O
as	O
developed	O
from	O
the	O
Shugart	O
Associates	O
drives	O
involved	O
a	O
50-pin	O
interface	O
and	O
a	O
spindle	O
motor	O
that	O
ran	O
directly	O
from	O
the	O
A/C	O
line	O
and	O
spun	O
constantly	O
.	O
</s>
<s>
In	O
a	O
1976	O
meeting	O
,	O
An	O
Wang	O
of	O
Wang	O
Laboratories	O
informed	O
Jim	O
Adkisson	O
and	O
Don	O
Massaro	O
of	O
Shugart	O
Associates	O
that	O
the	O
8-inch	O
format	O
was	O
simply	O
too	O
large	O
and	O
expensive	O
for	O
the	O
desktop	O
word	B-General_Concept
processing	I-General_Concept
machines	O
he	O
was	O
developing	O
at	O
the	O
time	O
,	O
and	O
argued	O
for	O
a	O
US$100	O
drive	O
(	O
)	O
.	O
</s>
<s>
The	O
5¼	O
drive	O
was	O
considerably	O
less	O
expensive	O
than	O
8-inch	O
drives	O
,	O
and	O
soon	O
started	O
appearing	O
on	O
CP/M	B-Application
machines	O
.	O
</s>
<s>
Shugart	O
's	O
initial	O
5.25	B-Device
"	I-Device
drive	O
was	O
the	O
35-track	O
,	O
single-sided	O
SA-400	O
,	O
which	O
was	O
widely	O
used	O
in	O
many	O
early	O
microcomputers	B-Architecture
,	O
and	O
which	O
introduced	O
the	O
34-pin	O
interface	O
that	O
would	O
become	O
an	O
industry	O
standard	O
.	O
</s>
<s>
It	O
could	O
be	O
used	O
with	O
either	O
a	O
hard	O
or	O
soft	B-Device
sectored	I-Device
controller	O
,	O
and	O
storage	O
capacity	O
was	O
listed	O
as	O
90k	O
(	O
single	O
density	O
)	O
or	O
113k	O
(	O
double	O
density	O
)	O
.	O
</s>
<s>
(	O
later	O
called	O
Verbatim	O
)	O
,	O
had	O
approximately	O
35	O
percent	O
of	O
the	O
estimated	O
$135	O
million	O
floppy	B-Device
disk	I-Device
market	O
and	O
sold	O
5¼-inch	B-Device
disks	I-Device
in	O
large	O
quantities	O
for	O
$1.50	O
each	O
(	O
)	O
.	O
</s>
<s>
Apple	O
purchased	O
bare	O
SA-400	O
drive	O
mechanisms	O
for	O
their	O
Disk	B-Device
II	I-Device
drive	O
,	O
which	O
was	O
then	O
equipped	O
with	O
a	O
custom	O
Apple	O
controller	O
board	O
and	O
the	O
faceplate	O
stamped	O
with	O
the	O
Apple	O
logo	O
.	O
</s>
<s>
Steve	O
Wozniak	O
developed	O
a	O
recording	O
scheme	O
known	O
as	O
Group	B-Device
Coded	I-Device
Recording	I-Device
which	O
allowed	O
140k	O
of	O
storage	O
,	O
well	O
above	O
the	O
standard	O
90	O
–	O
113k	O
,	O
although	O
the	O
price	O
of	O
double	O
density	O
controllers	O
fell	O
not	O
long	O
after	O
the	O
Disk	B-Device
II	I-Device
's	O
introduction	O
.	O
</s>
<s>
GCR	B-Device
recording	O
used	O
software	O
means	O
of	O
detecting	O
the	O
track	O
and	O
sector	O
being	O
accessed	O
,	O
hence	O
there	O
was	O
no	O
need	O
of	O
hard	O
sectored	O
disks	O
or	O
even	O
the	O
index	O
hole	O
.	O
</s>
<s>
Commodore	O
also	O
elected	O
to	O
use	O
GCR	B-Device
recording	O
(	O
although	O
a	O
different	O
variation	O
not	O
compatible	O
with	O
Apple	O
's	O
format	O
)	O
in	O
their	O
disk	O
drive	O
line	O
.	O
</s>
<s>
Tandy	O
however	O
used	O
industry-standard	O
FM	B-Protocol
on	O
the	O
TRS-80	O
'	O
s	O
disk	O
drives	O
,	O
with	O
stock	O
Shugart	O
SA-400s	O
,	O
and	O
so	O
had	O
a	O
mere	O
85k	O
of	O
storage	O
.	O
</s>
<s>
This	O
was	O
considered	O
risky	O
by	O
some	O
as	O
single	B-Architecture
sided	I-Architecture
disks	I-Architecture
were	O
only	O
certified	O
by	O
the	O
manufacturer	O
for	O
single-sided	O
use	O
.	O
</s>
<s>
Although	O
hard	O
sectored	O
disks	O
were	O
used	O
on	O
some	O
early	O
8	B-Device
"	I-Device
drives	O
prior	O
to	O
the	O
IBM	O
33FD	O
(	O
May	O
1973	O
)	O
,	O
they	O
were	O
never	O
widely	O
used	O
in	O
5¼-inch	O
form	O
,	O
although	O
North	O
Star	O
clung	O
to	O
the	O
format	O
until	O
they	O
went	O
bankrupt	O
in	O
1984	O
.	O
</s>
<s>
Tandon	O
introduced	O
a	O
double-sided	B-Architecture
drive	O
in	O
1978	O
,	O
doubling	O
the	O
capacity	O
,	O
and	O
this	O
new	O
“	O
double	O
sided	O
double	O
density	O
”	O
(	O
DSDD	O
)	O
format	O
increased	O
capacity	O
to	O
360KB	O
.	O
</s>
<s>
By	O
1979	O
,	O
there	O
were	O
also	O
77-track	O
5¼-inch	O
drives	O
available	O
,	O
mostly	O
used	O
in	O
CP/M	B-Application
and	O
other	O
professional	O
computers	O
,	O
and	O
also	O
found	O
in	O
some	O
of	O
Commodore	O
's	O
disk	O
drive	O
line	O
.	O
</s>
<s>
In	O
addition	O
,	O
more	O
compact	O
half-height	O
disk	O
drives	O
began	O
to	O
appear	O
,	O
as	O
well	O
as	O
double-sided	B-Architecture
drives	O
,	O
although	O
the	O
cost	O
of	O
them	O
meant	O
that	O
single-sided	O
remained	O
the	O
standard	O
for	O
most	O
home	O
computers	O
,	O
and	O
80-track	O
drives	O
known	O
as	O
"	O
quad	O
density	O
"	O
.	O
</s>
<s>
For	O
most	O
of	O
the	O
1970s	O
and	O
1980s	O
,	O
the	O
floppy	B-Device
drive	I-Device
was	O
the	O
primary	O
storage	O
device	O
for	O
word	B-General_Concept
processors	I-General_Concept
and	O
microcomputers	B-Architecture
.	O
</s>
<s>
Since	O
these	O
machines	O
had	O
no	O
hard	O
drive	O
,	O
the	O
OS	B-General_Concept
was	O
usually	O
booted	O
from	O
one	O
floppy	B-Device
disk	I-Device
,	O
which	O
was	O
then	O
removed	O
and	O
replaced	O
by	O
another	O
one	O
containing	O
the	O
application	O
.	O
</s>
<s>
Some	O
machines	O
using	O
two	O
disk	O
drives	O
(	O
or	O
one	O
dual	O
drive	O
)	O
allowed	O
the	O
user	O
to	O
leave	O
the	O
OS	B-General_Concept
disk	O
in	O
place	O
and	O
simply	O
change	O
the	O
application	O
disks	O
as	O
needed	O
,	O
or	O
to	O
copy	O
data	O
from	O
one	O
floppy	B-Device
to	O
another	O
.	O
</s>
<s>
RX50	O
was	O
another	O
proprietary	O
format	O
,	O
used	O
by	O
Digital	O
Equipment	O
Corporation	O
's	O
Rainbow	B-Device
100	I-Device
,	O
DECmate	O
II	O
,	O
and	O
Professional	B-Device
300	I-Device
Series	I-Device
.	O
</s>
<s>
Floppy	B-Device
disks	I-Device
were	O
supported	O
on	O
IBM	O
's	O
PC	B-Operating_System
DOS	I-Operating_System
and	O
Microsoft	O
's	O
MS-DOS	B-Application
from	O
their	O
beginning	O
on	O
the	O
original	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
With	O
version	O
1.0	O
of	O
PCDOS	B-Operating_System
(	O
1981	O
)	O
,	O
only	O
single-sided	O
160KB	O
floppies	B-Device
were	O
supported	O
.	O
</s>
<s>
Version	O
1.1	O
the	O
next	O
year	O
saw	O
support	O
expand	O
to	O
double-sided	B-Architecture
320KB	O
disks	O
.	O
</s>
<s>
Finally	O
,	O
in	O
1983	O
,	O
DOS	B-Device
2.0	O
supported	O
9	O
sectors	O
per	O
track	O
rather	O
than	O
8	O
,	O
providing	O
180KB	O
on	O
a	O
(	O
formatted	O
)	O
single-sided	B-Architecture
disk	I-Architecture
and	O
360KB	O
on	O
a	O
double-sided	B-Architecture
.	O
</s>
<s>
In	O
1984	O
,	O
IBM	O
introduced	O
the	O
5¼	O
high	O
density	O
disk	O
format	O
with	O
its	O
new	O
IBM	B-Operating_System
AT	I-Operating_System
machines	O
.	O
</s>
<s>
The	O
5¼	O
HD	O
drive	O
was	O
essentially	O
a	O
scaled-down	O
8	B-Device
"	I-Device
drive	O
,	O
using	O
the	O
same	O
rotation	O
speed	O
and	O
bit	O
rate	O
,	O
and	O
it	O
provided	O
almost	O
three	O
times	O
as	O
much	O
storage	O
as	O
the	O
360k	B-Device
format	O
,	O
but	O
had	O
compatibility	O
issues	O
with	O
the	O
older	O
drives	O
due	O
to	O
the	O
narrower	O
read/write	O
head	O
.	O
</s>
<s>
Except	O
for	O
labeling	O
,	O
5¼-inch	O
high-density	B-Device
disks	I-Device
were	O
externally	O
identical	O
to	O
their	O
double-density	O
counterparts	O
.	O
</s>
<s>
By	O
the	O
end	O
of	O
the	O
1980s	O
,	O
the	O
5¼-inch	B-Device
disks	I-Device
had	O
been	O
superseded	O
by	O
the	O
3½-inch	O
disks	O
.	O
</s>
<s>
The	O
main	O
community	O
of	O
users	O
was	O
primarily	O
those	O
who	O
still	O
owned	O
1980s	O
legacy	O
machines	O
(	O
PCs	B-Device
running	O
DOS	B-Device
or	O
home	O
computers	O
)	O
that	O
had	O
no	O
3½-inch	O
drive	O
;	O
the	O
advent	O
of	O
Windows	B-Application
95	I-Application
(	O
not	O
even	O
sold	O
in	O
stores	O
in	O
a	O
5¼-inch	O
version	O
;	O
a	O
coupon	O
had	O
to	O
be	O
obtained	O
and	O
mailed	O
in	O
)	O
and	O
subsequent	O
phaseout	O
of	O
stand-alone	O
MS-DOS	B-Application
with	O
version	O
6.22	O
forced	O
many	O
of	O
them	O
to	O
upgrade	O
their	O
hardware	O
.	O
</s>
<s>
By	O
the	O
mid-1990s	O
,	O
the	O
drives	O
had	O
virtually	O
disappeared	O
as	O
the	O
3½-inch	O
disk	O
became	O
the	O
predominant	O
floppy	B-Device
disk	I-Device
.	O
</s>
<s>
During	O
the	O
development	O
of	O
the	O
Apple	B-Device
Lisa	I-Device
,	O
Apple	O
developed	O
a	O
disk	O
format	O
codenamed	O
Twiggy	O
,	O
and	O
officially	O
known	O
as	O
FileWare	B-Device
.	O
</s>
<s>
The	O
drive	O
was	O
also	O
present	O
in	O
prototypes	O
of	O
the	O
original	O
Apple	B-Device
Macintosh	I-Device
computer	I-Device
,	O
but	O
was	O
removed	O
in	O
both	O
the	O
Mac	B-Device
and	O
later	O
versions	O
of	O
the	O
Lisa	B-Device
in	O
favor	O
of	O
the	O
-inch	O
floppy	B-Device
disk	I-Device
from	O
Sony	O
.	O
</s>
<s>
They	O
all	O
shared	O
a	O
number	O
of	O
advantages	O
over	O
the	O
older	O
format	O
,	O
including	O
a	O
small	O
form	O
factor	O
and	O
a	O
rigid	O
case	O
with	O
a	O
slideable	O
write	B-Device
protect	I-Device
catch	O
.	O
</s>
<s>
Some	O
of	O
these	O
formats	O
included	O
Dysan	O
and	O
Shugart	O
's	O
-inch	O
floppy	B-Device
disk	I-Device
,	O
the	O
later	O
ubiquitous	O
Sony	O
-inch	O
disk	O
and	O
the	O
3-inch	O
format	O
:	O
</s>
<s>
the	O
Mitsumi	O
Quick	O
Disk	O
3-inch	O
floppies	B-Device
.	O
</s>
<s>
The	O
3-inch	O
floppy	B-Device
drive	I-Device
itself	O
was	O
manufactured	O
by	O
Hitachi	O
,	O
Matsushita	O
and	O
Maxell	O
.	O
</s>
<s>
Similarly	O
,	O
only	O
three	O
manufacturers	O
of	O
media	O
(	O
Maxell	O
,	O
Matsushita	O
and	O
Tatung	O
)	O
are	O
known	O
(	O
sometimes	O
also	O
branded	O
Yamaha	O
,	O
Amsoft	B-Device
,	O
Panasonic	O
,	O
Schneider	O
,	O
Tandy	O
,	O
Godexco	O
and	O
Dixons	O
)	O
,	O
but	O
"	O
no-name	O
"	O
disks	O
with	O
questionable	O
quality	O
have	O
been	O
seen	O
in	O
circulation	O
.	O
</s>
<s>
Amstrad	O
included	O
a	O
3-inch	O
single-sided	O
,	O
double-density	O
(	O
180KB	O
)	O
drive	O
in	O
their	O
CPC	B-Device
and	O
some	O
models	O
of	O
PCW	B-Device
.	O
</s>
<s>
The	O
PCW	B-Device
8512	O
included	O
a	O
double-sided	B-Architecture
,	O
quad-density	O
(	O
720KB	O
)	O
drive	O
as	O
the	O
second	O
drive	O
,	O
and	O
later	O
models	O
,	O
such	O
as	O
the	O
PCW	B-Device
9512	O
,	O
used	O
quad-density	O
even	O
for	O
the	O
first	O
drive	O
.	O
</s>
<s>
The	O
Oric-1	O
and	O
Atmos	O
systems	O
from	O
Oric	O
International	O
also	O
used	O
the	O
3-inch	O
floppy	B-Device
drives	I-Device
,	O
originally	O
shipping	O
with	O
the	O
Atmos	O
,	O
but	O
also	O
supported	O
on	O
the	O
older	O
Oric-1	O
.	O
</s>
<s>
Since	O
all	O
3-inch	O
media	O
were	O
double-sided	B-Architecture
in	O
nature	O
,	O
single-sided	O
drive	O
owners	O
were	O
able	O
to	O
flip	O
the	O
disk	O
over	O
to	O
use	O
the	O
other	O
side	O
.	O
</s>
<s>
The	O
disk	O
format	O
itself	O
had	O
no	O
more	O
capacity	O
than	O
the	O
more	O
popular	O
(	O
and	O
cheaper	O
)	O
-inch	O
floppies	B-Device
.	O
</s>
<s>
Unlike	O
-inch	O
or	O
-inch	O
disks	O
,	O
the	O
3-inch	O
disks	O
were	O
designed	O
to	O
be	O
reversible	O
and	O
sported	O
two	O
independent	O
write-protect	B-Device
switches	O
.	O
</s>
<s>
3-inch	O
drives	O
were	O
also	O
used	O
on	O
a	O
number	O
of	O
exotic	O
and	O
obscure	O
CP/M	B-Application
systems	O
such	O
as	O
the	O
Tatung	B-Operating_System
Einstein	I-Operating_System
and	O
occasionally	O
on	O
MSX	B-Operating_System
systems	O
in	O
some	O
regions	O
.	O
</s>
<s>
However	O
,	O
the	O
final	O
tip	O
of	O
the	O
scale	O
was	O
when	O
Sony	O
in	O
1984	O
convinced	O
Apple	O
Computer	O
to	O
use	O
the	O
-inch	O
drives	O
in	O
the	O
Macintosh	B-Device
128K	I-Device
model	O
,	O
effectively	O
making	O
the	O
-inch	O
drive	O
a	O
de	O
facto	O
standard	O
.	O
</s>
<s>
The	O
Quick	O
Disk	O
uses	O
a	O
2.8-inch	O
magnetic	B-Architecture
media	I-Architecture
,	O
break-off	O
write-protection	B-Device
tabs	O
(	O
one	O
for	O
each	O
side	O
)	O
,	O
and	O
contains	O
a	O
see-through	O
hole	O
near	O
center	O
spindle	O
(	O
used	O
to	O
ensure	O
spindle	O
clamping	O
)	O
.	O
</s>
<s>
Nintendo	O
packaged	O
the	O
2.8-inch	O
magnetic	B-Architecture
media	I-Architecture
in	O
a	O
3-inch	O
×	O
4-inch	O
housing	O
,	O
while	O
others	O
packaged	O
the	O
same	O
media	O
in	O
a	O
3inch×3inch	O
square	O
housing	O
.	O
</s>
<s>
The	O
Quick	O
Disk	O
's	O
most	O
successful	O
use	O
was	O
in	O
Nintendo	O
's	O
Famicom	B-Device
Disk	I-Device
System	I-Device
(	O
FDS	O
)	O
.	O
</s>
<s>
Mitsumi	O
's	O
"	O
3-inch	O
"	O
Quick	O
Disk	O
media	O
were	O
also	O
used	O
in	O
a	O
3-inch	O
×	O
3-inch	O
housing	O
for	O
many	O
Smith	O
Corona	O
word	B-General_Concept
processors	I-General_Concept
.	O
</s>
<s>
Another	O
non-inclusive	O
list	O
of	O
Quick	O
Disk	O
versions	O
:	O
QDM-01	O
,	O
QDD	O
(	O
Quick	O
Disk	O
Drive	O
)	O
on	O
French	O
Thomson	O
micro-computers	B-Architecture
,	O
in	O
the	O
Casio	O
QD-7	O
drive	O
,	O
in	O
a	O
peripheral	O
for	O
the	O
Sharp	O
MZ-700	O
&	O
MZ-800	O
system	O
,	O
in	O
the	O
DPQ-280	O
Quickdisk	O
for	O
the	O
Daewoo/Dynadata	O
MSX1	O
DPC-200	O
,	O
in	O
the	O
Dragon	B-Device
32/64	I-Device
machine	O
,	O
in	O
the	O
Crescent	O
Quick	O
Disk	O
128	O
,	O
128i	O
and	O
256	O
peripherals	O
for	O
the	O
ZX	O
Spectrum	O
,	O
and	O
in	O
the	O
Triton	O
Quick	O
Disk	O
peripheral	O
also	O
for	O
the	O
ZX	O
Spectrum	O
.	O
</s>
<s>
The	O
World	O
of	O
Spectrum	O
FAQ	O
reveals	O
that	O
the	O
drives	O
did	O
come	O
in	O
different	O
sizes	O
:	O
128	O
to	O
256kB	O
in	O
Crescent	O
's	O
incarnation	O
,	O
and	O
in	O
the	O
Triton	O
system	O
,	O
with	O
a	O
density	O
of	O
4410	O
bits	O
per	O
inch	O
,	O
data	O
transmission	O
rate	O
of	O
101.6	O
kbit/s	O
,	O
a	O
2.8-inch	O
double	B-Architecture
sided	I-Architecture
disk	I-Architecture
type	O
and	O
a	O
capacity	O
of	O
up	O
to	O
20	O
sectors	O
per	O
side	O
at	O
2.5kB	O
per	O
sector	O
,	O
up	O
to	O
100kB	O
per	O
disk	O
.	O
</s>
<s>
Quick	O
Disk	O
as	O
used	O
in	O
the	O
Famicom	B-Device
Disk	I-Device
System	I-Device
holds	O
64kB	O
of	O
data	O
per	O
side	O
,	O
requiring	O
a	O
manual	O
turn-over	O
to	O
access	O
the	O
second	O
side	O
.	O
</s>
<s>
In	O
1981	O
,	O
Sony	O
introduced	O
their	O
-inch	O
floppy	B-Device
disk	I-Device
cartridge	O
(	O
90.0mm	O
×	O
94.0mm	O
)	O
having	O
a	O
single	O
sided	O
unformatted	O
capacity	O
of	O
218.8	O
KB	O
and	O
a	O
formatted	O
capacity	O
of	O
161.2	O
KB	O
.	O
</s>
<s>
Other	O
than	O
Hewlett-Packard	O
'	O
s	O
HP-150	B-Device
of	O
1983	O
and	O
Sony	O
's	O
MSX	B-Operating_System
computers	O
that	O
year	O
,	O
this	O
format	O
suffered	O
from	O
a	O
similar	O
fate	O
as	O
the	O
other	O
new	O
formats	O
;	O
the	O
-inch	O
format	O
simply	O
had	O
too	O
much	O
market	O
share	O
.	O
</s>
<s>
The	O
first	O
single-sided	O
drives	O
compatible	O
with	O
this	O
new	O
media	O
specification	O
shipped	O
in	O
early	O
1983	O
,	O
followed	O
immediately	O
in	O
1984	O
by	O
double-sided	B-Architecture
compatible	O
versions	O
.	O
</s>
<s>
In	O
1984	O
,	O
Apple	O
Computer	O
selected	O
the	O
format	O
for	O
their	O
new	O
Macintosh	B-Device
computers	I-Device
.	O
</s>
<s>
Then	O
,	O
in	O
1985	O
,	O
Atari	O
adopted	O
it	O
for	O
their	O
new	O
ST	B-Device
line	I-Device
,	O
and	O
Commodore	O
for	O
their	O
new	O
Amiga	B-Device
.	O
</s>
<s>
In	O
South	O
Africa	O
,	O
the	O
-inch	O
format	O
was	O
generally	O
called	O
a	O
stiffy	B-Device
disk	I-Device
,	O
to	O
distinguish	O
it	O
from	O
the	O
flexible	O
-inch	O
format	O
.	O
</s>
<s>
When	O
the	O
disk	O
was	O
inserted	O
,	O
a	O
part	O
inside	O
the	O
drive	O
moved	O
the	O
metal	O
cover	O
aside	O
,	O
giving	O
the	O
drive	O
's	O
read/write	O
heads	O
the	O
necessary	O
access	O
to	O
the	O
magnetic	B-Architecture
recording	I-Architecture
surfaces	O
.	O
</s>
<s>
3.5	B-Device
"	I-Device
drives	O
included	O
several	O
other	O
advantages	O
over	O
the	O
older	O
drive	O
types	O
,	O
including	O
not	O
requiring	O
a	O
terminating	O
resistor	O
pack	O
,	O
and	O
no	O
need	O
of	O
an	O
index	O
hole	O
.	O
</s>
<s>
When	O
Apple	O
introduced	O
the	O
Macintosh	B-Device
in	O
1984	O
,	O
it	O
used	O
single-sided	O
-inch	O
disk	O
drives	O
with	O
an	O
advertised	O
capacity	O
of	O
400KB	O
.	O
</s>
<s>
The	O
encoding	O
technique	O
used	O
by	O
these	O
drives	O
was	O
known	O
as	O
GCR	B-Device
,	O
or	O
Group	B-Device
Coded	I-Device
Recording	I-Device
(	O
similar	O
recording	O
methods	O
were	O
used	O
by	O
Commodore	O
on	O
its	O
-inch	O
drives	O
and	O
Sirius	O
Systems	O
Technology	O
in	O
its	O
Victor	B-Device
9000	I-Device
non-PC-compatible	O
MS-DOS	B-Application
machine	O
)	O
.	O
</s>
<s>
Somewhat	O
later	O
,	O
PC-compatible	O
machines	O
began	O
using	O
single-sided	O
-inch	O
disks	O
with	O
an	O
advertised	O
capacity	O
of	O
360KB	O
(	O
the	O
same	O
as	O
a	O
double-sided	B-Architecture
-inch	O
disk	O
)	O
,	O
and	O
a	O
different	O
,	O
incompatible	O
recording	O
format	O
called	O
MFM	B-Protocol
(	O
Modified	B-Protocol
Frequency	I-Protocol
Modulation	I-Protocol
)	O
.	O
</s>
<s>
GCR	B-Device
and	O
MFM	B-Protocol
drives	O
(	O
and	O
their	O
formatted	O
disks	O
)	O
were	O
incompatible	O
,	O
although	O
the	O
physical	O
disks	O
were	O
the	O
same	O
.	O
</s>
<s>
In	O
1986	O
,	O
Apple	O
introduced	O
double-sided	B-Architecture
,	O
800	O
KB	O
disks	O
,	O
still	O
using	O
GCR	B-Device
,	O
and	O
soon	O
after	O
,	O
IBM	O
began	O
using	O
720KB	O
double-sided	B-Architecture
double-density	O
MFM	B-Protocol
disks	O
in	O
PCs	B-Device
like	O
the	O
IBM	B-Device
PC	I-Device
Convertible	I-Device
.	O
</s>
<s>
IBM	B-Device
PC	I-Device
compatibles	O
adopted	O
it	O
too	O
,	O
while	O
the	O
Amiga	B-Device
used	O
MFM	B-Protocol
encoding	I-Protocol
on	O
the	O
same	O
disks	O
to	O
give	O
a	O
capacity	O
of	O
1MB	O
(	O
880KB	O
available	O
once	O
formatted	O
)	O
.	O
</s>
<s>
An	O
MFM-based	O
,	O
"	O
high-density	O
"	O
format	O
,	O
displayed	O
as	O
"	O
HD	O
"	O
on	O
the	O
disks	O
themselves	O
and	O
typically	O
advertised	O
as	O
"	O
1.44MB	O
"	O
was	O
introduced	O
in	O
1987	O
;	O
the	O
most	O
common	O
formatted	O
capacity	O
was	O
1,474,560	O
bytes	O
(	O
or	O
1440KiB	O
)	O
,	O
double	O
that	O
of	O
the	O
720KiB	O
variant	O
.	O
</s>
<s>
These	O
HD	O
disks	O
had	O
an	O
extra	O
hole	O
in	O
the	O
case	O
on	O
the	O
opposite	O
side	O
of	O
the	O
write-protect	B-Device
notch	O
.	O
</s>
<s>
IBM	O
used	O
this	O
format	O
on	O
their	O
PS/2	B-Device
series	O
introduced	O
in	O
1987	O
.	O
</s>
<s>
Apple	O
started	O
using	O
"	O
HD	O
"	O
in	O
1988	O
,	O
on	O
the	O
Macintosh	B-Device
IIx	I-Device
,	O
and	O
the	O
HD	O
floppy	B-Device
drive	I-Device
soon	O
became	O
universal	O
on	O
virtually	O
all	O
Macintosh	B-Device
and	O
PC	O
hardware	O
.	O
</s>
<s>
Apple	O
's	O
FDHD	B-Device
(	O
Floppy	B-Device
Disk	I-Device
High	O
Density	O
)	O
drive	O
was	O
capable	O
of	O
reading	O
and	O
writing	O
both	O
GCR	B-Device
and	O
MFM	B-Protocol
formatted	O
disks	O
,	O
and	O
thus	O
made	O
it	O
relatively	O
easy	O
to	O
exchange	O
files	O
with	O
PC	O
users	O
.	O
</s>
<s>
Apple	O
later	O
marketed	O
this	O
drive	O
as	O
the	O
SuperDrive	B-Device
.	O
</s>
<s>
Amiga	B-Device
included	O
"	O
HD	O
"	O
floppy	B-Device
drives	I-Device
relatively	O
late	O
,	O
with	O
releasing	O
of	O
Amiga	B-Device
4000	I-Device
in	O
1992	O
,	O
and	O
was	O
able	O
to	O
store	O
1760KB	O
on	O
it	O
,	O
with	O
ability	O
in	O
software	O
to	O
read/write	O
PC	O
's	O
1440KB/720KB	O
formats	O
.	O
</s>
<s>
Another	O
advance	O
in	O
the	O
oxide	O
coatings	O
allowed	O
for	O
a	O
new	O
"	O
extra-high	B-Device
density	I-Device
"	O
(	O
"	O
ED	O
"	O
)	O
format	O
at	O
2880KB	O
introduced	O
in	O
1990	O
on	O
the	O
NeXTcube	B-Device
,	O
NeXTstation	B-Device
and	O
IBM	B-Device
PS/2	I-Device
model	I-Device
57	I-Device
.	O
</s>
