<s>
The	O
ERA	B-Device
1101	I-Device
,	O
later	O
renamed	O
UNIVAC	B-Device
1101	I-Device
,	O
was	O
a	O
computer	O
system	O
designed	O
and	O
built	O
by	O
Engineering	O
Research	O
Associates	O
(	O
ERA	O
)	O
in	O
the	O
early	O
1950s	O
and	O
continued	O
to	O
be	O
sold	O
by	O
the	O
Remington	O
Rand	O
corporation	O
after	O
that	O
company	O
later	O
purchased	O
ERA	O
.	O
</s>
<s>
The	O
team	O
had	O
built	O
a	O
number	O
of	O
code-breaking	O
machines	O
,	O
similar	O
to	O
the	O
more	O
famous	O
Colossus	B-Device
computer	I-Device
in	O
England	O
,	O
but	O
designed	O
to	O
attack	O
Japanese	O
codes	O
.	O
</s>
<s>
The	O
resulting	O
machines	O
,	O
known	O
as	O
"	O
Atlas	O
"	O
,	O
used	O
drum	B-General_Concept
memory	I-General_Concept
for	O
main	O
memory	O
and	O
featured	O
a	O
simple	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
built	O
for	O
integer	O
math	O
.	O
</s>
<s>
A	O
faster	O
version	O
using	O
Williams	B-General_Concept
tubes	I-General_Concept
and	O
drums	O
was	O
delivered	O
to	O
the	O
NSA	O
in	O
1953	O
.	O
</s>
<s>
The	O
ERA	B-Device
1101	I-Device
was	O
publicly	O
announced	O
in	O
December	O
1951	O
.	O
</s>
<s>
Atlas	O
II	O
,	O
slightly	O
modified	O
became	O
the	O
ERA	B-Device
1103	I-Device
,	O
while	O
a	O
more	O
heavily	O
modified	O
version	O
with	O
core	B-General_Concept
memory	I-General_Concept
and	O
floating	B-Algorithm
point	I-Algorithm
math	I-Algorithm
support	O
became	O
the	B-Operating_System
UNIVAC	I-Operating_System
1103A	O
.	O
</s>
<s>
Remington	O
Rand	O
had	O
recently	O
purchased	O
Eckert	O
–	O
Mauchly	O
Computer	O
Corporation	O
,	O
builders	O
of	O
the	O
famed	O
UNIVAC	B-Operating_System
I	I-Operating_System
,	O
the	O
first	O
commercial	O
computer	O
in	O
the	O
US	O
.	O
</s>
<s>
Although	O
ERA	O
and	O
UNIVAC	O
were	O
run	O
separately	O
within	O
the	O
company	O
,	O
looking	O
to	O
cash	O
in	O
on	O
the	B-Operating_System
UNIVAC	I-Operating_System
's	O
well	O
known	O
name	O
,	O
they	O
renamed	O
the	O
machine	O
to	O
become	O
the	O
"	O
UNIVAC	B-Device
1101	I-Device
"	O
.	O
</s>
<s>
Its	O
drum	B-General_Concept
memory	I-General_Concept
was	O
in	O
diameter	O
,	O
rotated	O
at	O
3500	O
rpm	O
,	O
had	O
200	O
read-write	O
heads	O
,	O
and	O
held	O
16,384	O
24-bit	O
words	O
(	O
a	O
memory	O
size	O
equivalent	O
to	O
48	O
kB	O
)	O
with	O
access	O
time	O
between	O
32	O
microseconds	O
and	O
17	O
milliseconds	O
.	O
</s>
<s>
Instructions	B-General_Concept
were	O
24	O
bits	O
long	O
,	O
with	O
six	O
bits	O
for	O
the	O
opcode	B-Language
,	O
four	O
bits	O
for	O
the	O
"	O
skip	O
"	O
value	O
(	O
telling	O
how	O
many	O
memory	O
locations	O
to	O
skip	O
to	O
get	O
to	O
the	O
next	O
instruction	O
in	O
program	O
sequence	O
)	O
,	O
and	O
14	O
bits	O
for	O
the	O
memory	O
address	O
.	O
</s>
<s>
The	O
single	O
48-bit	O
accumulator	B-General_Concept
was	O
fundamentally	O
subtractive	O
,	O
addition	O
being	O
carried	O
out	O
by	O
subtracting	O
the	O
ones	O
 '	O
complement	O
of	O
the	O
number	O
to	O
be	O
added	O
.	O
</s>
<s>
The	O
machine	O
had	O
38	O
instructions	B-General_Concept
.	O
</s>
