<s>
In	O
computer	B-Application
software	I-Application
,	O
a	O
time	B-General_Concept
bomb	I-General_Concept
is	O
part	O
of	O
a	O
computer	B-Application
program	I-Application
that	O
has	O
been	O
written	O
so	O
that	O
it	O
will	O
start	O
or	O
stop	O
functioning	O
after	O
a	O
predetermined	O
date	O
or	O
time	O
is	O
reached	O
.	O
</s>
<s>
The	O
term	O
"	O
time	B-General_Concept
bomb	I-General_Concept
"	O
does	O
not	O
refer	O
to	O
a	O
program	B-Application
that	O
stops	O
functioning	O
a	O
specific	O
number	O
of	O
days	O
after	O
it	O
is	O
installed	O
;	O
instead	O
,	O
the	O
term	O
"	O
trialware	O
"	O
applies	O
.	O
</s>
<s>
Time	B-General_Concept
bombs	I-General_Concept
are	O
commonly	O
used	O
in	O
beta	O
(	O
pre-release	O
)	O
software	B-Application
when	O
the	O
manufacturer	O
of	O
the	B-Application
software	I-Application
does	O
not	O
want	O
the	O
beta	O
version	O
being	O
used	O
after	O
the	O
final	O
release	O
date	O
.	O
</s>
<s>
One	O
example	O
of	O
time	B-General_Concept
bomb	I-General_Concept
software	B-Application
would	O
be	O
Microsoft	O
's	O
Windows	O
Vista	O
Beta	O
2	O
,	O
which	O
was	O
programmed	O
to	O
expire	O
on	O
May	O
31	O
,	O
2007	O
.	O
</s>
<s>
The	O
time	O
limits	O
on	O
time	B-General_Concept
bomb	I-General_Concept
software	B-Application
are	O
not	O
usually	O
as	O
heavily	O
enforced	O
as	O
they	O
are	O
on	O
trial	O
software	B-Application
,	O
since	O
time	B-General_Concept
bomb	I-General_Concept
software	B-Application
does	O
not	O
usually	O
implement	O
secure	O
clock	O
functions	O
.	O
</s>
<s>
The	O
main	O
differences	O
between	O
logic	O
bombs	O
and	O
time	B-General_Concept
bombs	I-General_Concept
is	O
that	O
a	O
logic	O
bomb	O
may	O
have	O
a	O
timing	O
function	O
implemented	O
into	O
it	O
as	O
a	O
failsafe	O
if	O
the	O
conditions	O
are	O
not	O
met	O
in	O
a	O
certain	O
time	O
period	O
(	O
it	O
may	O
delete	O
itself	O
or	O
activate	O
its	O
payload	O
using	O
the	O
timing	O
system	O
)	O
,	O
while	O
time	B-General_Concept
bombs	I-General_Concept
only	O
use	O
timing	O
functions	O
to	O
(	O
de	O
)	O
activate	O
themselves	O
.	O
</s>
<s>
Time	B-General_Concept
bombs	I-General_Concept
,	O
once	O
activated	O
,	O
will	O
unload	O
their	O
payload	O
(	O
which	O
may	O
be	O
malicious	O
)	O
in	O
a	O
similar	O
way	O
logic	O
bombs	O
deliver	O
their	O
payloads	O
to	O
the	O
target	O
.	O
</s>
<s>
The	O
main	O
difference	O
between	O
both	O
time	O
and	O
logic	O
bombs	O
,	O
and	O
fork	B-Operating_System
bombs	I-Operating_System
,	O
is	O
that	O
a	O
fork	B-Operating_System
bomb	I-Operating_System
has	O
no	O
payload	O
per	O
se	O
,	O
and	O
instead	O
does	O
its	O
damage	O
by	O
continually	O
replicating	O
itself	O
to	O
deplete	O
available	O
system	O
resources	O
.	O
</s>
<s>
The	O
first	O
use	O
of	O
a	O
time	B-General_Concept
bomb	I-General_Concept
in	O
software	B-Application
may	O
have	O
been	O
in	O
1979	O
with	O
the	O
Scribe	B-Protocol
markup	I-Protocol
language	I-Protocol
and	O
word	O
processing	O
system	O
,	O
developed	O
by	O
Brian	O
Reid	O
.	O
</s>
<s>
Reid	O
sold	O
Scribe	B-Protocol
to	O
a	O
software	B-Application
company	O
called	O
Unilogic	O
(	O
later	O
renamed	O
Scribe	B-Protocol
Systems	O
)	O
,	O
and	O
agreed	O
to	O
insert	O
a	O
set	O
of	O
time-dependent	O
functions	O
(	O
called	O
"	O
time	B-General_Concept
bombs	I-General_Concept
"	O
)	O
that	O
would	O
deactivate	O
freely	O
copied	O
versions	O
of	O
the	O
program	B-Application
after	O
a	O
90-day	O
expiration	O
date	O
.	O
</s>
<s>
To	O
avoid	O
deactivation	O
,	O
users	O
paid	O
the	B-Application
software	I-Application
company	O
,	O
which	O
then	O
issued	O
a	O
code	O
that	O
defused	O
the	O
internal	O
time	B-General_Concept
bomb	I-General_Concept
feature	O
.	O
</s>
