<s>
The	O
Ping-Pong	B-Application
virus	I-Application
(	O
also	O
called	O
Boot	O
,	O
Bouncing	B-Application
Ball	I-Application
,	O
Bouncing	B-Application
Dot	I-Application
,	O
Italian	O
,	O
Italian-A	O
or	O
VeraCruz	B-Application
)	O
is	O
a	O
boot	B-Device
sector	I-Device
virus	O
discovered	O
on	O
March	O
1	O
,	O
1988	O
,	O
at	O
the	O
Politecnico	O
di	O
Torino	O
(	O
Turin	O
Polytechnic	O
University	O
)	O
in	O
Italy	O
.	O
</s>
<s>
It	O
was	O
likely	O
the	O
most	O
common	O
and	O
best	O
known	O
boot	B-Device
sector	I-Device
virus	O
until	O
outnumbered	O
by	O
the	O
Stoned	B-Application
virus	I-Application
.	O
</s>
<s>
Computers	O
could	O
be	O
contaminated	O
by	O
an	O
infected	O
diskette	B-Device
,	O
showing	O
up	O
as	O
a	O
1	O
KB	O
bad	O
cluster	O
(	O
the	O
last	O
one	O
on	O
the	O
disk	O
,	O
used	O
by	O
the	O
virus	O
to	O
store	O
the	O
original	O
boot	B-Device
sector	I-Device
)	O
to	O
most	O
disk	O
checking	O
programs	O
.	O
</s>
<s>
Due	O
to	O
being	O
labelled	O
as	O
bad	O
cluster	O
,	O
MS-DOS	B-Application
will	O
avoid	O
overwriting	O
it	O
.	O
</s>
<s>
It	O
infects	O
disks	O
on	O
every	O
active	O
drive	O
and	O
will	O
even	O
infect	O
non-bootable	O
partitions	B-Application
on	O
the	O
hard	O
disk	O
.	O
</s>
<s>
The	O
virus	O
would	O
become	O
active	O
if	O
a	O
disk	O
access	O
is	O
made	O
exactly	O
on	O
the	O
half-hour	O
and	O
start	O
to	O
show	O
a	O
small	O
"	O
ball	O
"	O
bouncing	O
around	O
the	O
screen	O
in	O
both	O
text	B-Application
mode	I-Application
(	O
the	O
ASCII	B-Protocol
bullet	O
character	O
"	O
•	O
"	O
)	O
and	O
graphical	O
mode	O
.	O
</s>
<s>
The	O
original	O
Ping	B-Application
Pong	I-Application
virus	I-Application
(	O
Ping-Pong.A	O
)	O
only	O
infects	O
floppy	B-Device
disks	I-Device
.	O
</s>
<s>
Later	O
variants	O
of	O
this	O
virus	O
such	O
as	O
Ping-Pong.B	O
and	O
Ping-Pong.C	O
also	O
infect	O
the	O
hard	O
disk	O
boot	B-Device
sector	I-Device
as	O
well	O
.	O
</s>
<s>
While	O
the	O
virus	O
is	O
active	O
,	O
one	O
cannot	O
replace	O
the	O
boot	B-Device
sector	I-Device
—	O
it	O
either	O
prevents	O
writing	O
to	O
it	O
or	O
it	O
immediately	O
re-infects	O
it	O
.	O
</s>
