<s>
The	O
AN/USQ	B-Device
-17	I-Device
or	O
Naval	B-Device
Tactical	I-Device
Data	I-Device
System	I-Device
(	O
NTDS	O
)	O
computer	O
referred	O
to	O
in	O
Sperry	O
Rand	O
documents	O
as	O
the	O
Univac	B-Device
M-460	I-Device
,	O
was	O
Seymour	O
Cray	O
's	O
last	O
design	O
for	O
UNIVAC	O
.	O
</s>
<s>
UNIVAC	O
later	O
released	O
a	O
commercial	O
version	O
,	O
the	O
UNIVAC	B-Device
490	I-Device
.	O
</s>
<s>
When	O
the	O
Navy	O
awarded	O
Sperry	O
Rand	O
a	O
US$50	O
million	O
contract	O
to	O
build	O
the	O
AN/USQ	B-Device
-17	I-Device
,	O
Univac	O
engineers	O
redesigned	O
the	O
entire	O
machine	O
from	O
scratch	O
using	O
silicon	O
transistors	O
.	O
</s>
<s>
They	O
retained	O
the	O
instruction	B-General_Concept
set	I-General_Concept
,	O
so	O
that	O
programs	O
developed	O
for	O
the	O
original	O
machine	O
would	O
still	O
run	O
on	O
the	O
new	O
one	O
.	O
</s>
<s>
This	O
new	O
design	O
was	O
designated	O
the	O
AN/USQ	B-Device
-20	I-Device
.	O
</s>
<s>
The	O
main	O
memory	O
was	O
32,768	O
=	O
32K	O
words	O
of	O
core	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
The	O
available	O
processor	B-General_Concept
registers	I-General_Concept
were	O
:	O
</s>
<s>
One	O
30-bit	O
accumulator	B-General_Concept
(	O
A	O
)	O
.	O
</s>
<s>
Seven	O
15-bit	O
index	B-General_Concept
registers	I-General_Concept
(	O
B1B7	O
)	O
.	O
</s>
<s>
The	O
instruction	O
format	O
defined	O
for	O
the	O
AN/USQ	B-Device
-17	I-Device
marked	O
the	O
beginning	O
of	O
an	O
instruction	B-General_Concept
set	I-General_Concept
which	O
would	O
be	O
carried	O
on	O
,	O
with	O
many	O
changes	O
along	O
the	O
way	O
,	O
into	O
later	O
UNIVAC	O
computers	O
including	O
the	O
UNIVAC	B-Device
1100/2200	I-Device
series	I-Device
,	O
which	O
is	O
still	O
in	O
use	O
.	O
</s>
