<s>
A	O
disk	B-Application
editor	I-Application
is	O
a	O
computer	B-Application
program	I-Application
that	O
allows	O
its	O
user	O
to	O
read	O
,	O
edit	O
,	O
and	O
write	O
raw	O
data	O
(	O
at	O
character	B-Protocol
or	O
hexadecimal	O
,	O
byte-levels	B-Application
)	O
on	O
disk	O
drives	O
(	O
e.g.	O
,	O
hard	B-Device
disks	I-Device
,	O
USB	O
flash	O
disks	O
or	O
removable	B-Device
media	I-Device
such	O
as	O
a	O
floppy	B-Device
disks	I-Device
)	O
;	O
as	O
such	O
,	O
they	O
are	O
sometimes	O
called	O
sector	B-Application
editors	I-Application
,	O
since	O
the	O
read/write	O
routines	O
built	O
into	O
the	O
electronics	O
of	O
most	O
disk	O
drives	O
require	O
to	O
read/write	O
data	O
in	O
chunks	O
of	O
sectors	B-Application
(	O
usually	O
512	B-Application
bytes	I-Application
)	O
.	O
</s>
<s>
Many	O
disk	B-Application
editors	I-Application
can	O
also	O
be	O
used	O
to	O
edit	O
the	O
contents	O
of	O
a	O
running	O
computer	O
's	O
memory	B-General_Concept
or	O
a	O
disk	B-Application
image	I-Application
.	O
</s>
<s>
Unlike	O
hex	B-Application
editors	I-Application
,	O
which	O
are	O
used	O
to	O
edit	O
files	B-Operating_System
,	O
a	O
disk	B-Application
editor	I-Application
allows	O
access	O
to	O
the	O
underlying	O
disk	B-Device
structures	I-Device
,	O
such	O
as	O
the	O
master	B-Device
boot	I-Device
record	I-Device
(	O
MBR	B-Device
)	O
or	O
GUID	B-Application
Partition	I-Application
Table	I-Application
(	O
GPT	O
)	O
,	O
file	B-Application
system	I-Application
,	O
and	O
directories	B-Application
.	O
</s>
<s>
On	O
some	O
operating	O
systems	O
(	O
like	O
Unix	B-Application
or	O
Unix-like	B-Operating_System
)	O
most	O
hex	B-Application
editors	I-Application
can	O
act	O
as	O
disk	B-Application
editors	I-Application
just	O
opening	O
block	O
devices	O
instead	O
of	O
regular	O
files	B-Operating_System
.	O
</s>
<s>
Programmers	O
can	O
use	O
disk	B-Application
editors	I-Application
to	O
understand	O
these	O
structures	O
and	O
test	O
whether	O
their	O
implementation	O
(	O
e.g.	O
</s>
<s>
of	O
a	O
file	B-Application
system	I-Application
)	O
works	O
correctly	O
.	O
</s>
<s>
Some	O
disk	B-Application
editors	I-Application
include	O
special	O
functions	O
which	O
enable	O
more	O
comfortable	O
ways	O
to	O
edit	O
and	O
fix	O
file	B-Application
systems	I-Application
or	O
other	O
disk	O
specific	O
data	O
structures	O
.	O
</s>
<s>
Furthermore	O
,	O
some	O
include	O
simple	O
file	O
browsers	O
that	O
can	O
present	O
the	O
disk	O
contents	O
for	O
partially	O
corrupted	O
file	B-Application
systems	I-Application
or	O
file	B-Application
systems	I-Application
unknown	O
to	O
the	O
operating	O
system	O
.	O
</s>
<s>
Disk	B-Application
editors	I-Application
for	O
home	O
computers	O
of	O
the	O
1980s	O
were	O
often	O
included	O
as	O
part	O
of	O
utility	B-Application
software	I-Application
packages	O
on	O
floppies	B-Device
or	O
cartridges	B-Protocol
.	O
</s>
<s>
The	O
latter	O
had	O
the	O
advantage	O
of	O
being	O
instantly	O
available	O
at	O
power-on	O
and	O
after	O
resets	O
,	O
instead	O
of	O
having	O
to	O
be	O
loaded	O
or	O
reloaded	O
on	O
the	O
same	O
disk	O
drive	O
that	O
later	O
would	O
hold	O
the	O
floppy	B-Device
to	O
be	O
edited	O
(	O
the	O
majority	O
of	O
home	O
computer	O
users	O
possessed	O
only	O
one	O
floppy	B-Device
disk	I-Device
drive	I-Device
at	O
that	O
time	O
)	O
.	O
</s>
<s>
Having	O
the	O
disk	B-Application
editor	I-Application
on	O
cartridge	B-Protocol
also	O
helped	O
the	O
user	O
avoid	O
editing/damaging	O
the	O
disk	B-Application
editor	I-Application
application	O
disk	O
by	O
mistake	O
.	O
</s>
<s>
All	O
disk	B-Application
editors	I-Application
strive	O
to	O
be	O
better	O
than	O
DEBUG	B-Device
contained	O
in	O
all	O
DOS	B-Device
versions	O
.	O
</s>
<s>
DEBUG	B-Device
can	O
load	O
,	O
edit	O
,	O
and	O
write	O
one	O
or	O
more	O
sectors	B-Application
from	O
a	O
floppy	B-Device
or	O
hard	B-Device
disk	I-Device
based	O
on	O
the	O
BIOS	B-Operating_System
.	O
</s>
<s>
This	O
permits	O
simple	O
disk	O
editing	O
tasks	O
such	O
as	O
saving	O
and	O
restoring	O
the	O
master	B-Device
boot	I-Device
record	I-Device
and	O
other	O
critical	O
sectors	B-Application
,	O
or	O
even	O
changing	O
the	O
active	O
(=	O
boot	O
)	O
partition	B-Application
in	O
the	O
MBR	B-Device
.	O
</s>
<s>
In	O
an	O
NTVDM	O
under	O
Windows	B-Device
NT	I-Device
DEBUG	B-Device
cannot	O
access	O
the	O
physical	O
drive	O
with	O
the	O
MBR	B-Device
of	O
the	O
operating	O
system	O
and	O
is	O
in	O
essence	O
useless	O
as	O
disk	B-Application
editor	I-Application
for	O
the	O
system	O
drive	O
.	O
</s>
<s>
The	O
Resource	O
Kit	O
and	O
the	O
support	O
tools	O
for	O
some	O
Windows	B-Device
NT	I-Device
versions	O
contain	O
DSKPROBE	O
as	O
a	O
very	O
simple	O
disk	B-Application
editor	I-Application
supporting	O
the	O
use	O
and	O
modification	O
of	O
the	O
partition	B-Application
table	O
in	O
the	O
MBR	B-Device
and	O
related	O
tasks	O
.	O
</s>
<s>
A	O
partition	B-Application
editor	O
(	O
also	O
called	O
partitioning	B-Application
utility	O
)	O
is	O
a	O
kind	O
of	O
utility	B-Application
software	I-Application
designed	O
to	O
view	O
,	O
create	O
,	O
modify	O
or	O
delete	O
disk	B-Application
partitions	I-Application
.	O
</s>
<s>
A	O
disk	B-Application
partition	I-Application
is	O
a	O
logical	O
segment	O
of	O
the	O
storage	O
space	O
on	O
a	O
storage	O
device	O
.	O
</s>
<s>
By	O
partitioning	B-Application
a	O
large	O
device	O
into	O
several	O
partitions	B-Application
,	O
it	O
is	O
possible	O
to	O
isolate	O
various	O
types	O
of	O
data	O
from	O
one	O
another	O
,	O
and	O
allow	O
the	O
coexistence	O
of	O
two	O
or	O
more	O
operating	O
systems	O
simultaneously	O
.	O
</s>
<s>
Features	O
and	O
capabilities	O
of	O
partition	B-Application
editors	O
vary	O
,	O
but	O
generally	O
they	O
can	O
create	O
several	O
partition	B-Application
on	O
a	O
disk	O
,	O
or	O
one	O
contiguous	O
partition	B-Application
on	O
several	O
disks	O
,	O
at	O
the	O
discretion	O
of	O
the	O
user	O
.	O
</s>
<s>
They	O
can	O
also	O
,	O
shrink	O
a	O
partition	B-Application
to	O
allow	O
more	O
partitions	B-Application
created	O
on	O
a	O
storage	O
device	O
,	O
or	O
delete	O
one	O
and	O
expand	O
an	O
adjacent	O
partition	B-Application
into	O
the	O
available	O
space	O
.	O
</s>
