<s>
Diode	B-General_Concept
logic	I-General_Concept
(	O
or	O
diode-resistor	B-General_Concept
logic	I-General_Concept
)	O
constructs	O
AND	O
and	O
OR	O
logic	O
gates	O
with	O
diodes	O
and	O
resistors	O
.	O
</s>
<s>
An	O
active	O
device	O
(	O
vacuum	O
tubes	O
in	O
early	B-Architecture
computers	I-Architecture
,	O
then	O
transistors	B-Application
in	O
diode	B-General_Concept
–	I-General_Concept
transistor	I-General_Concept
logic	I-General_Concept
)	O
is	O
additionally	O
required	O
to	O
provide	O
logical	O
inversion	O
(	O
NOT	O
)	O
for	O
functional	O
completeness	O
and	O
amplification	O
for	O
voltage	O
level	O
restoration	O
,	O
which	O
diode	B-General_Concept
logic	I-General_Concept
alone	O
ca	O
n't	O
provide	O
.	O
</s>
<s>
Since	O
voltage	O
levels	O
weaken	O
with	O
each	O
diode	B-General_Concept
logic	I-General_Concept
stage	O
,	O
multiple	O
stages	O
ca	O
n't	O
easily	O
be	O
cascaded	O
,	O
limiting	O
diode	B-General_Concept
logic	I-General_Concept
's	O
usefulness	O
.	O
</s>
<s>
However	O
,	O
diode	B-General_Concept
logic	I-General_Concept
has	O
the	O
advantage	O
of	O
utilizing	O
only	O
cheap	O
passive	O
components	O
.	O
</s>
<s>
Diode	B-General_Concept
logic	I-General_Concept
can	O
only	O
implement	O
OR	O
and	O
AND	O
,	O
because	O
inverters	O
(	O
NOT	O
gates	O
)	O
require	O
an	O
active	O
device	O
.	O
</s>
<s>
The	O
following	O
diode	B-General_Concept
logic	I-General_Concept
gates	O
work	O
in	O
both	O
active-high	O
or	O
active-low	O
logic	O
,	O
however	O
the	O
logical	O
function	O
they	O
implement	O
is	O
different	O
depending	O
on	O
what	O
voltage	O
level	O
is	O
considered	O
active	O
.	O
</s>
<s>
Forward-biased	O
diodes	O
have	O
low	O
impedance	O
approximating	O
a	O
short	B-Application
circuit	I-Application
with	O
a	O
small	O
voltage	O
drop	O
,	O
while	O
reverse-biased	O
diodes	O
have	O
a	O
very	O
high	O
impedance	O
approximating	O
an	O
open	O
circuit	O
.	O
</s>
<s>
Each	O
input	O
of	O
a	O
diode	B-General_Concept
logic	I-General_Concept
gate	O
connects	O
through	O
a	O
diode	O
connected	O
to	O
a	O
shared	O
wired	O
logic	O
output	O
.	O
</s>
<s>
Designers	O
must	O
rely	O
on	O
a	O
diode	O
's	O
specification	B-Application
sheet	O
,	O
which	O
primarily	O
provides	O
a	O
maximum	O
forward	O
voltage	O
drop	O
at	O
one	O
or	O
more	O
forward	O
currents	O
,	O
a	O
reverse	O
leakage	O
current	O
(	O
or	O
saturation	O
current	O
)	O
,	O
and	O
a	O
maximum	O
reverse	O
voltage	O
limited	O
by	O
Zener	O
or	O
avalanche	O
breakdown	O
.	O
</s>
<s>
Effects	O
of	O
temperature	O
and	O
process	B-Algorithm
variation	I-Algorithm
are	O
usually	O
included	O
.	O
</s>
<s>
If	O
a	O
diode	B-General_Concept
–	I-General_Concept
transistor	I-General_Concept
logic	I-General_Concept
gate	O
drives	O
a	O
transistor	B-Application
inverter	O
of	O
similar	O
construction	O
,	O
the	O
transistor	B-Application
will	O
have	O
a	O
similar	O
base-collector	O
capacitance	O
that	O
is	O
amplified	O
by	O
the	O
transistor	B-Application
gain	O
,	O
so	O
that	O
it	O
will	O
be	O
too	O
slow	O
to	O
pass	O
the	O
glitch	O
.	O
</s>
<s>
But	O
when	O
the	O
diode	O
is	O
much	O
slower	O
,	O
recovery	O
will	O
become	O
a	O
concern:In	O
one	O
unusual	O
design	O
,	O
small	O
selenium	B-Library
diode	O
discs	O
were	O
used	O
with	O
germanium	O
transistors	B-Application
.	O
</s>
<s>
The	O
recovery	O
time	O
of	O
the	O
very	O
slow	O
selenium	B-Library
diodes	O
caused	O
a	O
glitch	O
on	O
the	O
inverter	O
output	O
.	O
</s>
<s>
It	O
was	O
fixed	O
by	O
placing	O
a	O
selenium	B-Library
diode	O
across	O
the	O
base-emitter	O
junction	O
of	O
the	O
transistor	B-Application
making	O
it	O
think	O
it	O
was	O
a	O
selenium	B-Library
transistor	B-Application
(	O
if	O
there	O
could	O
ever	O
be	O
one	O
)	O
.	O
</s>
<s>
High	O
5V	O
level	O
is	O
reduced	O
twice.Bigelow	O
,	O
Ken	O
(	O
2015	O
)	O
,	O
Diode	B-General_Concept
logic	I-General_Concept
,	O
archived	O
from	O
the	O
original	O
7	O
May	O
2021	O
.	O
</s>
<s>
However	O
,	O
passive	O
diode	B-General_Concept
logic	I-General_Concept
gates	O
accumulate	O
the	O
following	O
voltage	O
losses	O
when	O
gates	O
are	O
cascaded	O
:	O
</s>
<s>
Historically	O
,	O
diode	B-General_Concept
logic	I-General_Concept
was	O
used	O
extensively	O
in	O
the	O
construction	O
of	O
early	B-Architecture
computers	I-Architecture
,	O
since	O
semiconductor	O
diodes	O
could	O
replace	O
bulky	O
and	O
costly	O
active	O
vacuum	O
tubes	O
.	O
</s>
<s>
The	O
invention	O
of	O
the	O
transistor	B-Application
allowed	O
transistors	B-Application
to	O
replace	O
tubes	O
as	O
the	O
active	O
element	O
in	O
diode	B-General_Concept
–	I-General_Concept
transistor	I-General_Concept
logic	I-General_Concept
.	O
</s>
<s>
Since	O
early	O
transistors	B-Application
were	O
not	O
reliable	O
,	O
the	O
D-17B	B-Device
missile	O
guidance	O
computer	O
,	O
for	O
instance	O
,	O
primarily	O
used	O
diode	B-General_Concept
logic	I-General_Concept
and	O
only	O
used	O
transistors	B-Application
when	O
necessary	O
.	O
</s>
<s>
Transistors	B-Application
quickly	O
advanced	O
to	O
replace	O
diode	B-General_Concept
logic	I-General_Concept
almost	O
entirely	O
.	O
</s>
<s>
However	O
,	O
diode	B-General_Concept
logic	I-General_Concept
still	O
finds	O
some	O
modern	O
uses	O
.	O
</s>
<s>
Low-impedance	O
push	O
–	O
pull	O
outputs	O
of	O
conventional	O
ICs	O
should	O
n't	O
directly	O
be	O
connected	O
to	O
external	O
circuitry	O
,	O
as	O
they	O
may	O
create	O
a	O
short	B-Application
circuit	I-Application
between	O
power	O
and	O
ground	O
.	O
</s>
<s>
Such	O
outputs	O
,	O
however	O
,	O
may	O
be	O
used	O
as	O
inputs	O
to	O
passive	O
AND	O
or	O
OR	O
diode	B-General_Concept
logic	I-General_Concept
gates	O
.	O
</s>
<s>
However	O
,	O
diode	B-General_Concept
logic	I-General_Concept
will	O
degrade	O
voltage	O
levels	O
and	O
result	O
in	O
poor	O
noise	O
rejection	O
,	O
so	O
designers	O
should	O
be	O
aware	O
of	O
the	O
interfaced	O
logic	O
family	O
's	O
voltage	O
ranges	O
and	O
limitations	O
,	O
to	O
prevent	O
failures	O
.	O
</s>
<s>
The	O
humorously-named	O
"	O
Micky	O
Mouse	O
Logic	O
"	O
described	O
in	O
Don	O
Lancaster	O
's	O
CMOS	B-Device
Cookbook	O
suggests	O
using	O
diodes	O
as	O
a	O
multi-tool	O
for	O
augmenting	O
the	O
limited	O
capabilities	O
of	O
regular	O
CMOS	B-Device
4000-series	O
ICs	O
,	O
for	O
instance	O
by	O
using	O
a	O
diode	O
OR	O
gate	O
to	O
add	O
extra	O
inputs	O
on	O
a	O
flip-flop	B-General_Concept
,	O
or	O
a	O
diode	O
AND	O
gate	O
to	O
configure	O
a	O
divide-by-N	O
counter	O
.	O
</s>
<s>
An	O
active-low	O
OR	O
diode	B-General_Concept
logic	I-General_Concept
gate	O
is	O
formed	O
by	O
a	O
keypad	B-Device
containing	O
diodes	O
at	O
each	O
switch	O
,	O
all	O
connected	O
to	O
a	O
shared	O
pull-up	O
resistor	O
.	O
</s>
<s>
Then	O
a	O
microcontroller	B-Architecture
can	O
wake	O
from	O
power-saving	O
standby	O
and	O
scan	O
the	O
key	O
matrix	O
to	O
determine	O
which	O
key	O
specifically	O
was	O
pressed	O
.	O
</s>
<s>
When	O
compared	O
to	O
transistor	B-Application
logic	O
gates	O
of	O
the	O
time	O
,	O
the	O
tunnel	O
diode	O
offered	O
much	O
higher	O
speeds	O
.	O
</s>
<s>
The	O
operating	O
principles	O
of	O
a	O
tunnel	O
diode	B-General_Concept
logic	I-General_Concept
rely	O
on	O
biasing	O
of	O
the	O
tunnel	O
diode	O
and	O
supply	O
of	O
current	O
from	O
inputs	O
over	O
a	O
threshold	O
current	O
,	O
to	O
switch	O
the	O
diode	O
between	O
two	O
states	O
.	O
</s>
<s>
Consequently	O
,	O
tunnel	O
diode	B-General_Concept
logic	I-General_Concept
circuits	O
required	O
a	O
means	O
to	O
reset	O
the	O
diode	O
after	O
each	O
logical	O
operation	O
.	O
</s>
<s>
Advances	O
in	O
discrete	O
and	O
integrated	O
circuit	O
transistor	B-Application
speed	O
and	O
the	O
more	O
nearly	O
unilateral	O
nature	O
of	O
transistor	B-Application
amplifiers	O
overtook	O
the	O
tunnel	O
diode	O
gate	O
,	O
resulting	O
in	O
it	O
no	O
longer	O
being	O
used	O
in	O
modern	O
computers	O
.	O
</s>
