<s>
The	O
Rice	B-Device
Institute	I-Device
Computer	I-Device
,	O
also	O
known	O
as	O
the	O
Rice	B-Device
Computer	I-Device
or	O
R1	O
,	O
was	O
a	O
54-bit	O
tagged	B-Architecture
architecture	I-Architecture
digital	O
computer	O
built	O
during	O
1958	O
–	O
1961	O
(	O
partially	O
operational	O
beginning	O
in	O
1959	O
)	O
on	O
the	O
campus	O
of	O
Rice	O
University	O
,	O
Houston	O
,	O
Texas	O
,	O
United	O
States	O
.	O
</s>
<s>
Operating	O
as	O
Rice	O
's	O
primary	O
computer	O
until	O
the	O
middle	O
1960s	O
,	O
the	O
Rice	B-Device
Institute	I-Device
Computer	I-Device
was	O
decommissioned	O
in	O
1971	O
.	O
</s>
<s>
The	O
system	O
initially	O
used	O
vacuum	O
tubes	O
and	O
semiconductor	O
diodes	O
for	O
its	O
logic	O
circuits	O
;	O
some	O
later	O
peripherals	O
were	O
built	O
in	O
solid-state	O
emitter-coupled	B-General_Concept
logic	I-General_Concept
.	O
</s>
<s>
Originally	O
a	O
cathode	B-Device
ray	I-Device
tube	I-Device
or	O
"	O
Williams	B-General_Concept
tube	I-General_Concept
"	O
array	O
,	O
RCA	O
core	B-General_Concept
memory	I-General_Concept
was	O
introduced	O
in	O
1966	O
,	O
followed	O
by	O
Ampex	O
core	B-General_Concept
memory	I-General_Concept
in	O
1967	O
.	O
</s>
<s>
Following	O
those	O
two	O
upgrades	B-General_Concept
,	O
the	O
R1	O
had	O
reached	O
its	O
full	O
32k	O
word	O
capacity	O
,	O
although	O
the	O
original	O
electrostatic	O
memory	O
was	O
soon	O
decommissioned	O
due	O
to	O
falling	O
reliability	O
in	O
its	O
old	O
age	O
.	O
</s>
<s>
The	O
R1	O
had	O
seven	O
memory-mapped	O
general-purpose	O
processor	B-General_Concept
registers	I-General_Concept
,	O
each	O
54bits	O
in	O
size	O
,	O
in	O
addition	O
to	O
a	O
constant	O
zero	O
register	O
.	O
</s>
