<s>
The	O
AN/GYK	B-Device
-12	I-Device
is	O
an	O
obsolete	O
32-bit	O
minicomputer	B-Architecture
developed	O
by	O
Litton	O
Industries	O
for	O
the	O
United	O
States	O
Army	O
.	O
</s>
<s>
The	O
AN/GYK	B-Device
-12	I-Device
is	O
a	O
militarized	O
version	O
of	O
the	O
L-3050	O
computer	O
ruggedized	O
for	O
use	O
in	O
the	O
TACFIRE	B-Device
tactical	O
fire	O
direction	O
system	O
.	O
</s>
<s>
In	O
1980	O
,	O
the	O
Army	O
introduced	O
the	O
Nebula	O
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
(	O
MIL-STD-1862	O
)	O
,	O
intended	O
as	O
an	O
upgrade	O
to	O
the	O
AN/GYK	B-Device
-12	I-Device
.	O
</s>
<s>
Nebula	O
is	O
also	O
a	O
32-bit	O
architecture	O
with	O
32-bit	O
addressing	O
mode	O
and	O
instructions	O
optimized	O
for	O
running	O
programs	O
written	O
in	O
Ada	B-Language
.	O
</s>
<s>
The	O
basic	O
system	O
consists	O
of	O
three	O
rack-mounted	B-Application
modules	O
:	O
The	O
CPU	O
,	O
the	O
IOU	O
(	O
Input/Output	O
unit	O
)	O
,	O
and	O
the	O
MCMU	O
.	O
</s>
<s>
The	O
AN/GYK	B-Device
-12	I-Device
has	O
a	O
32-bit	O
instruction	O
format	O
and	O
operates	O
on	O
data	O
from	O
one	O
bit	O
to	O
a	O
doubleword	O
(	O
64bits	O
)	O
in	O
size	O
.	O
</s>
<s>
Logically	O
it	O
is	O
divided	O
into	O
pages	B-General_Concept
of	O
2KW	O
each	O
.	O
</s>
<s>
Access	O
to	O
pages	B-General_Concept
is	O
controlled	O
by	O
16	O
Page	O
Control	O
and	O
Address	O
Registers	O
per	O
program	O
level	O
,	O
allowing	O
an	O
individual	O
program	O
to	O
directly	O
address	O
128KB	O
at	O
one	O
time	O
.	O
</s>
