<s>
The	O
UNIVAC	B-Device
LARC	I-Device
,	O
short	O
for	O
the	O
Livermore	B-Device
Advanced	I-Device
Research	I-Device
Computer	I-Device
,	O
is	O
a	O
mainframe	B-Architecture
computer	I-Architecture
designed	O
to	O
a	O
requirement	O
published	O
by	O
Edward	O
Teller	O
in	O
order	O
to	O
run	O
hydrodynamic	O
simulations	O
for	O
nuclear	O
weapon	O
design	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
earliest	O
supercomputers	B-Architecture
.	O
</s>
<s>
LARC	O
supported	O
multiprocessing	B-Operating_System
with	O
two	O
CPUs	B-General_Concept
(	O
called	O
Computers	O
)	O
and	O
an	O
input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
Processor	O
(	O
called	O
the	O
Processor	O
)	O
.	O
</s>
<s>
Both	O
examples	O
had	O
only	O
one	O
Computer	O
,	O
so	O
no	O
multiprocessor	B-Operating_System
LARCs	O
were	O
ever	O
built	O
.	O
</s>
<s>
The	O
LARC	O
CPUs	B-General_Concept
were	O
able	O
to	O
perform	O
addition	O
in	O
about	O
4microseconds	O
,	O
corresponding	O
to	O
about	O
250	O
kIPS	O
speed	O
.	O
</s>
<s>
This	O
made	O
it	O
the	O
fastest	O
computer	O
in	O
the	O
world	O
until	O
1962	O
when	O
the	O
IBM	B-Device
7030	I-Device
took	O
the	O
title	O
.	O
</s>
<s>
The	O
LARC	O
was	O
a	O
decimal	O
mainframe	B-Architecture
computer	I-Architecture
with	O
48	O
bits	O
per	O
word	O
.	O
</s>
<s>
It	O
used	O
bi-quinary	B-Algorithm
coded	I-Algorithm
decimal	I-Algorithm
arithmetic	O
with	O
four	O
bits	O
per	O
digit	O
,	O
allowing	O
for	O
11-digit	O
signed	B-Algorithm
numbers	I-Algorithm
.	O
</s>
<s>
Instructions	B-General_Concept
were	O
48	O
bits	O
long	O
,	O
one	O
per	O
word	O
.	O
</s>
<s>
Every	O
digit	O
in	O
the	O
machine	O
had	O
one	O
parity	B-Error_Name
bit	I-Error_Name
for	O
error	B-Error_Name
checking	I-Error_Name
,	O
meaning	O
every	O
word	O
occupied	O
60	O
bits	O
(	O
48	O
bits	O
for	O
data	O
with	O
12	O
bits	O
for	O
parity	B-Error_Name
check	I-Error_Name
)	O
.	O
</s>
<s>
The	O
basic	O
configuration	O
had	O
26	O
general-purpose	O
registers	B-General_Concept
,	O
which	O
could	O
be	O
expanded	O
to	O
99	O
.	O
</s>
<s>
The	O
general-purpose	O
registers	B-General_Concept
had	O
an	O
access	O
time	O
of	O
one	O
microsecond	O
.	O
</s>
<s>
The	O
basic	O
configuration	O
had	O
one	O
Computer	O
and	O
LARC	O
could	O
be	O
expanded	O
to	O
a	O
multiprocessor	B-Operating_System
with	O
a	O
second	O
Computer	O
.	O
</s>
<s>
The	O
Processor	O
is	O
an	O
independent	O
CPU	O
(	O
with	O
a	O
different	O
instruction	B-General_Concept
set	I-General_Concept
from	O
the	O
Computers	O
)	O
and	O
provides	O
control	O
for	O
12	O
to	O
24	O
magnetic	B-General_Concept
drum	I-General_Concept
storage	O
units	O
,	O
four	O
to	O
forty	O
UNISERVO	O
II	O
tape	O
drives	O
,	O
two	O
electronic	O
page	O
recorders	O
(	O
a	O
35mm	O
film	O
camera	O
facing	O
a	O
cathode-ray	O
tube	O
)	O
,	O
one	O
or	O
two	O
high-speed	O
printers	O
,	O
and	O
a	O
high-speed	O
punched	O
card	O
reader	O
.	O
</s>
<s>
The	O
core	O
memory	O
had	O
one	O
parity	B-Error_Name
bit	I-Error_Name
on	O
each	O
digit	O
for	O
error	B-Error_Name
checking	I-Error_Name
,	O
resulting	O
in	O
60	O
bits	O
per	O
memory	O
word	O
.	O
</s>
<s>
The	O
core	O
memory	O
system	O
enforces	O
a	O
system	O
of	O
interlocks	O
and	O
priorities	O
to	O
avoid	O
simultaneous	O
access	O
of	O
the	O
same	O
memory	O
bank	O
by	O
multiple	O
sections	O
of	O
the	O
system	O
(	O
the	O
Computers	O
,	O
Processor	O
,	O
and	O
I/O	B-General_Concept
DMA	O
Synchronizers	O
)	O
without	O
conflicts	O
or	O
deadlocks	B-Operating_System
.	O
</s>
<s>
To	O
prevent	O
deadlocks	B-Operating_System
and	O
timeouts	O
in	O
the	O
I/O	B-General_Concept
system	O
the	O
following	O
priorities	O
are	O
enforced	O
:	O
</s>
<s>
It	O
was	O
the	O
fastest	O
computer	O
in	O
196061	O
,	O
until	O
the	O
IBM	B-Device
7030	I-Device
took	O
the	O
title	O
.	O
</s>
