<s>
The	O
Michelangelo	B-Application
virus	I-Application
is	O
a	O
computer	O
virus	O
first	O
discovered	O
on	O
4	O
February	O
1991	O
in	O
Australia	O
.	O
</s>
<s>
The	O
virus	O
was	O
designed	O
to	O
infect	O
DOS	B-Device
systems	O
,	O
but	O
did	O
not	O
engage	O
the	O
operating	B-General_Concept
system	I-General_Concept
or	O
make	O
any	O
OS	O
calls	O
.	O
</s>
<s>
Michelangelo	B-Application
,	O
like	O
all	O
boot	B-Device
sector	I-Device
viruses	O
,	O
operated	O
at	O
the	O
BIOS	B-Operating_System
level	O
.	O
</s>
<s>
Each	O
year	O
,	O
the	O
virus	O
remained	O
dormant	O
until	O
March	O
6	O
,	O
the	O
birthday	O
of	O
Renaissance	B-Application
artist	O
Michelangelo	B-Application
.	O
</s>
<s>
Michelangelo	B-Application
is	O
a	O
variant	O
of	O
the	O
already	O
endemic	O
Stoned	B-Application
virus	I-Application
.	O
</s>
<s>
On	O
March	O
6	O
,	O
if	O
the	O
PC	O
is	O
an	O
AT	O
or	O
a	O
PS/2	O
,	O
the	O
virus	O
overwrites	O
the	O
first	O
one	O
hundred	O
sectors	O
of	O
the	O
hard	B-Device
disk	I-Device
with	O
nulls	O
.	O
</s>
<s>
Although	O
all	O
the	O
user	O
's	O
data	O
would	O
still	O
be	O
on	O
the	O
hard	B-Device
disk	I-Device
,	O
it	O
would	O
be	O
irretrievable	O
for	O
the	O
average	O
user	O
.	O
</s>
<s>
On	O
hard	B-Device
disks	I-Device
,	O
the	O
virus	O
moves	O
the	O
original	O
master	B-Device
boot	I-Device
record	I-Device
to	O
cylinder	O
0	O
,	O
head	B-Device
0	O
,	O
sector	B-Application
7	O
.	O
</s>
<s>
On	O
floppy	B-Device
disks	I-Device
,	O
if	O
the	O
disk	O
is	O
360	O
KB	O
,	O
the	O
virus	O
moves	O
the	O
original	O
boot	B-Device
sector	I-Device
to	O
cylinder	O
0	O
,	O
head	B-Device
1	O
,	O
sector	B-Application
3	O
.	O
</s>
<s>
On	O
other	O
disks	O
,	O
the	O
virus	O
moves	O
the	O
original	O
boot	B-Device
sector	I-Device
to	O
cylinder	O
0	O
,	O
head	B-Device
1	O
,	O
sector	B-Application
14	O
.	O
</s>
<s>
Although	O
designed	O
to	O
infect	O
DOS	B-Device
systems	O
,	O
the	O
virus	O
can	O
easily	O
disrupt	O
other	O
operating	B-General_Concept
systems	I-General_Concept
installed	O
on	O
the	O
system	O
since	O
,	O
like	O
many	O
viruses	O
of	O
its	O
era	O
,	O
the	O
Michelangelo	B-Application
infects	O
the	O
master	B-Device
boot	I-Device
record	I-Device
of	O
a	O
hard	B-Device
drive	I-Device
.	O
</s>
<s>
Once	O
a	O
system	O
became	O
infected	O
,	O
any	O
floppy	B-Device
disk	I-Device
inserted	O
into	O
the	O
system	O
(	O
and	O
written	O
to	O
;	O
in	O
1992	O
a	O
PC	O
system	O
could	O
not	O
detect	O
that	O
a	O
floppy	B-Device
had	O
been	O
inserted	O
,	O
so	O
the	O
virus	O
could	O
not	O
infect	O
the	O
floppy	B-Device
until	O
some	O
access	O
to	O
the	O
disk	O
is	O
made	O
)	O
becomes	O
immediately	O
infected	O
as	O
well	O
.	O
</s>
<s>
And	O
because	O
the	O
virus	O
spends	O
most	O
of	O
its	O
time	O
dormant	O
,	O
activating	O
only	O
on	O
March	O
6	O
,	O
it	O
is	O
conceivable	O
that	O
an	O
infected	O
computer	O
could	O
go	O
for	O
years	O
without	O
detection	O
as	O
long	O
as	O
it	O
was	O
n't	O
booted	B-Operating_System
on	O
that	O
date	O
,	O
while	O
infected	O
.	O
</s>
<s>
The	O
virus	O
first	O
came	O
to	O
widespread	O
international	O
attention	O
in	O
January	O
1992	O
,	O
when	O
it	O
was	O
revealed	O
that	O
a	O
few	O
computer	O
and	O
software	O
manufacturers	O
had	O
accidentally	O
shipped	O
products	O
,	O
for	O
example	O
Intel	O
's	O
LANSpool	B-Protocol
print	O
server	O
,	O
infected	O
with	O
the	O
virus	O
.	O
</s>
<s>
Although	O
the	O
infected	O
machines	O
numbered	O
only	O
in	O
the	O
hundreds	O
,	O
the	O
resulting	O
publicity	O
spiraled	O
into	O
"	O
expert	O
"	O
claims	O
,	O
partially	O
led	O
by	O
anti-virus	O
company	O
founder	O
John	O
McAfee	O
,	O
of	O
thousands	O
or	O
even	O
millions	O
of	O
computers	O
infected	O
by	O
Michelangelo	B-Application
.	O
</s>
