<s>
Form	O
was	O
a	O
boot	B-Device
sector	I-Device
virus	O
isolated	O
in	O
Switzerland	B-Protocol
in	O
the	O
summer	O
of	O
1990	O
which	O
became	O
very	O
common	O
worldwide	O
.	O
</s>
<s>
The	O
origin	O
of	O
Form	O
is	O
widely	O
listed	O
as	O
Switzerland	B-Protocol
,	O
but	O
this	O
may	O
be	O
an	O
assumption	O
based	O
on	O
its	O
isolation	O
locale	O
.	O
</s>
<s>
The	O
only	O
notable	O
characteristics	O
of	O
Form	O
are	O
that	O
it	O
infects	O
the	O
boot	B-Device
sector	I-Device
instead	O
of	O
the	O
Master	B-Device
Boot	I-Device
Record	I-Device
(	O
MBR	O
)	O
and	O
the	O
clicking	O
noises	O
associated	O
with	O
some	O
infections	O
.	O
</s>
<s>
Form	O
infects	O
the	O
boot	B-Device
sector	I-Device
.	O
</s>
<s>
When	O
a	O
computer	O
is	O
booted	O
from	O
an	O
infected	O
sector	O
,	O
Form	O
goes	O
resident	O
,	O
hooks	O
the	O
interrupt	B-General_Concept
vector	I-General_Concept
table	I-General_Concept
,	O
and	O
runs	O
the	O
original	O
boot	B-Device
sector	I-Device
which	O
it	O
has	O
hidden	O
in	O
an	O
area	O
it	O
flags	O
as	O
defective	O
.	O
</s>
<s>
However	O
,	O
this	O
payload	O
very	O
rarely	O
appears	O
on	O
modern	O
computers	O
,	O
as	O
it	O
will	O
not	O
execute	O
if	O
a	O
keyboard	O
driver	B-Application
is	O
installed	O
.	O
</s>
<s>
Form	O
consumes	O
2KB	O
of	O
memory	O
,	O
and	O
the	O
DOS	B-Device
MEM	O
command	O
will	O
report	O
that	O
this	O
memory	O
is	O
unavailable	O
.	O
</s>
<s>
On	O
floppy	B-Device
disks	I-Device
,	O
1	O
KB	O
(	O
2	O
bad	O
sectors	O
)	O
will	O
be	O
reported	O
.	O
</s>
<s>
Form	O
makes	O
the	O
assumption	O
that	O
the	O
active	O
partition	O
is	O
a	O
DOS	B-Device
FAT	B-Application
partition	I-Application
.	O
</s>
<s>
If	O
this	O
is	O
not	O
true	O
,	O
such	O
as	O
under	O
Windows	B-Device
NT	I-Device
,	O
Form	O
will	O
overwrite	O
in	O
a	O
way	O
that	O
may	O
result	O
in	O
irreversible	O
data	O
loss	O
.	O
</s>
<s>
Since	O
the	O
advent	O
of	O
Windows	B-Application
,	O
boot	O
viruses	O
have	O
become	O
increasingly	O
uncommon	O
,	O
including	O
Form	O
.	O
</s>
<s>
Generally	O
,	O
Form	O
infections	O
are	O
due	O
to	O
the	O
use	O
of	O
floppy	B-Device
disks	I-Device
infected	O
during	O
the	O
original	O
pandemic	O
that	O
have	O
since	O
been	O
taken	O
out	O
of	O
storage	O
.	O
</s>
