<s>
The	O
AN/UYK	B-Device
-20	I-Device
"	O
Data	O
Processing	O
Set	O
"	O
was	O
a	O
ruggedized	B-Device
small	O
computer	O
manufactured	O
by	O
Univac	O
and	O
used	O
by	O
the	O
United	O
States	O
Navy	O
for	O
small	O
and	O
medium-sized	O
shipboard	O
and	O
shore	O
systems	O
built	O
in	O
the	O
1970s	O
.	O
</s>
<s>
It	O
featured	O
non-volatile	B-General_Concept
magnetic	O
core	O
memory	O
and	O
was	O
housed	O
in	O
a	O
heavy-duty	O
metal	O
cube-shaped	O
box	O
which	O
was	O
designed	O
to	O
fit	O
through	O
a	O
25-inch	O
circular	O
hatch	O
.	O
</s>
<s>
In	O
March	O
1974	O
the	O
AN/UYK	B-Device
-20	I-Device
received	O
service	O
approval	O
and	O
by	O
late	O
1974	O
they	O
were	O
in	O
use	O
in	O
the	O
development	O
of	O
tactical	O
systems	O
.	O
</s>
<s>
The	O
AN/UYK	B-Device
-20	I-Device
is	O
still	O
currently	O
in	O
use	O
,	O
but	O
has	O
been	O
largely	O
supplanted	O
by	O
the	O
AN/UYK	B-Device
-44	I-Device
,	O
which	O
uses	O
a	O
'	O
superset	O
 '	O
of	O
the	O
UYK-20	O
instruction	O
set	O
,	O
meaning	O
the	O
UYK-44	O
will	O
execute	O
all	O
of	O
the	O
UYK-20	O
instructions	O
,	O
as	O
well	O
as	O
several	O
new	O
instructions	O
specific	O
to	O
the	O
UYK-44	O
.	O
</s>
