<s>
Jiffy	B-Operating_System
can	O
be	O
an	O
informal	O
term	O
for	O
any	O
unspecified	O
short	O
period	O
,	O
as	O
in	O
"	O
I	O
will	O
be	O
back	O
in	O
a	B-Operating_System
jiffy	I-Operating_System
"	O
.	O
</s>
<s>
The	O
earliest	O
technical	O
usage	O
for	O
jiffy	B-Operating_System
was	O
defined	O
by	O
Gilbert	O
Newton	O
Lewis	O
(	O
1875	O
–	O
1946	O
)	O
.	O
</s>
<s>
He	O
proposed	O
in	O
1926	O
a	O
unit	O
of	O
time	O
called	O
the	O
"	O
jiffy	B-Operating_System
"	O
which	O
was	O
equal	O
to	O
the	O
time	O
it	O
takes	O
light	O
to	O
travel	O
one	O
centimeter	O
in	O
a	O
vacuum	O
(	O
approximately	O
33.3564	O
picoseconds	O
)	O
.	O
</s>
<s>
In	O
electronics	O
,	O
a	B-Operating_System
jiffy	I-Operating_System
is	O
the	O
period	O
of	O
an	O
alternating	O
current	O
power	O
cycle	O
,	O
1/60	O
or	O
1/50	O
of	O
a	O
second	O
in	O
most	O
mains	O
power	O
supplies	O
.	O
</s>
<s>
In	O
computing	O
,	O
a	B-Operating_System
jiffy	I-Operating_System
was	O
originally	O
the	O
time	O
between	O
two	O
ticks	O
of	O
the	O
system	O
timer	O
interrupt	B-Application
.	O
</s>
<s>
It	O
is	O
not	O
an	O
absolute	O
time	O
interval	O
unit	O
,	O
since	O
its	O
duration	O
depends	O
on	O
the	O
clock	O
interrupt	B-Application
frequency	O
of	O
the	O
particular	O
hardware	O
platform	O
.	O
</s>
<s>
Many	O
older	O
game	O
consoles	O
(	O
which	O
use	O
televisions	O
as	O
a	O
display	O
device	O
)	O
commonly	O
synchronize	O
the	O
system	O
interrupt	B-Application
timer	O
with	O
the	O
vertical	O
frequency	O
of	O
the	O
local	O
television	O
standard	O
,	O
either	O
59.94Hz	O
with	O
NTSC	O
systems	O
,	O
or	O
50.0Hz	O
(	O
20	O
ms	O
)	O
with	O
most	O
PAL	B-Language
systems	O
.	O
</s>
<s>
1980s	O
8-bit	O
Commodore	O
computers	O
,	O
such	O
as	O
the	O
C64	O
and	O
C128	B-Device
,	O
had	O
a	B-Operating_System
jiffy	I-Operating_System
of	O
1/60	O
second	O
,	O
which	O
was	O
not	O
dependent	O
on	O
the	O
mains	O
AC	O
or	O
video	O
vertical	O
refresh	O
rate	O
.	O
</s>
<s>
A	O
timer	O
in	O
the	O
computer	O
creates	O
the	O
60	O
Hz	O
rate	O
,	O
causing	O
an	O
interrupt	B-Application
service	O
routine	O
to	O
execute	O
every	O
1/60	O
second	O
,	O
which	O
increments	O
a	O
24-bit	O
jiffy	B-Operating_System
counter	O
,	O
scans	O
the	O
keyboard	O
,	O
and	O
some	O
other	O
housekeeping	O
too	O
.	O
</s>
<s>
Jiffy	B-Operating_System
values	O
for	O
various	O
Linux	B-Application
versions	O
and	O
platforms	O
have	O
typically	O
varied	O
between	O
about	O
1ms	O
and	O
10ms	O
,	O
with	O
10ms	O
(	O
1/100	O
s	O
)	O
reported	O
as	O
an	O
increasingly	O
common	O
standard	O
in	O
the	O
Jargon	O
File	O
.	O
</s>
<s>
Stratus	B-General_Concept
VOS	I-General_Concept
(	O
Virtual	O
Operating	O
System	O
)	O
uses	O
a	B-Operating_System
jiffy	I-Operating_System
of	O
1/65	O
,	O
536	O
second	O
to	O
express	O
date	O
and	O
time	O
(	O
number	O
of	O
jiffies	B-Operating_System
elapsed	O
since	O
.	O
</s>
<s>
Stratus	B-General_Concept
also	O
defines	O
the	O
microJiffy	O
,	O
being	O
1/65	O
,	O
536	O
of	O
a	O
regular	O
Jiffy	B-Operating_System
.	O
</s>
<s>
The	O
term	O
"	O
jiffy	B-Operating_System
"	O
is	O
sometimes	O
used	O
in	O
computer	O
animation	O
as	O
a	O
method	O
of	O
defining	O
playback	O
rate	O
,	O
with	O
the	O
delay	O
interval	O
between	O
individual	O
frames	O
specified	O
in	O
1/100	O
of	O
a	O
second	O
(	O
10ms	O
)	O
jiffies	B-Operating_System
,	O
particularly	O
in	O
Autodesk	B-Application
Animator	I-Application
.FLI	B-Application
sequences	O
(	O
one	O
global	O
frame	O
frequency	O
setting	O
)	O
and	O
animated	O
Compuserve	O
.GIF	O
images	O
(	O
each	O
frame	O
having	O
an	O
individually	O
defined	O
display	O
time	O
measured	O
in	O
1/100s	O
)	O
.	O
</s>
<s>
The	O
speed	O
of	O
light	O
in	O
a	O
vacuum	O
provides	O
a	O
convenient	O
universal	O
relationship	O
between	O
distance	O
and	O
time	O
,	O
so	O
in	O
physics	O
(	O
particularly	O
in	O
quantum	O
physics	O
)	O
and	O
often	O
in	O
chemistry	O
,	O
a	B-Operating_System
jiffy	I-Operating_System
is	O
defined	O
as	O
the	O
time	O
taken	O
for	O
light	O
to	O
travel	O
some	O
specified	O
distance	O
.	O
</s>
<s>
In	O
astrophysics	O
and	O
quantum	O
physics	O
a	B-Operating_System
jiffy	I-Operating_System
is	O
,	O
as	O
defined	O
by	O
Edward	O
R	O
.	O
Harrison	O
,	O
the	O
time	O
it	O
takes	O
for	O
light	O
to	O
travel	O
one	O
fermi	O
,	O
which	O
is	O
approximately	O
the	O
size	O
of	O
a	O
nucleon	O
.	O
</s>
<s>
One	O
fermi	O
is	O
10−15m	O
,	O
so	O
a	B-Operating_System
jiffy	I-Operating_System
is	O
about	O
3×10−24seconds	O
.	O
</s>
