<s>
The	O
BBN	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
was	O
an	O
early	O
time-sharing	B-General_Concept
system	I-General_Concept
created	O
at	O
Bolt	O
,	O
Beranek	O
and	O
Newman	O
(	O
BBN	O
)	O
for	O
the	O
PDP-1	B-Device
computer	O
.	O
</s>
<s>
He	O
learned	O
about	O
time-sharing	B-General_Concept
from	O
Christopher	O
Strachey	O
at	O
a	O
UNESCO-sponsored	O
conference	O
on	O
Information	O
Processing	O
in	O
Paris	O
in	O
June	O
1959	O
.	O
</s>
<s>
Digital	O
Equipment	O
Corporation	O
's	O
prototype	O
PDP-1	B-Device
was	O
ready	O
in	O
November	O
,	O
1959	O
,	O
and	O
the	O
machine	O
was	O
featured	O
in	O
the	O
November/December	O
issue	O
of	O
Datamation	O
magazine	O
.	O
</s>
<s>
Given	O
BBN	O
's	O
interest	O
,	O
DEC	O
's	O
founder	O
and	O
President	O
Ken	O
Olsen	O
visited	O
and	O
explained	O
that	O
DEC	O
had	O
just	O
completed	O
construction	O
of	O
a	O
prototype	O
PDP-1	B-Device
,	O
and	O
that	O
they	O
needed	O
a	O
test	O
site	O
for	O
a	O
month	O
.	O
</s>
<s>
BBN	O
agreed	O
to	O
be	O
the	O
test	O
site	O
,	O
at	O
its	O
regular	O
hourly	O
rates	O
,	O
and	O
then	O
in	O
early	O
1960	O
obtained	O
the	O
prototype	O
PDP-1	B-Device
.	O
</s>
<s>
The	O
first	O
production	O
PDP-1	B-Device
arrived	O
in	O
November	O
1960	O
,	O
and	O
was	O
formally	O
accepted	O
in	O
April	O
1961	O
.	O
</s>
<s>
With	O
the	O
PDP-1	B-Device
installed	O
at	O
BBN	O
,	O
in	O
1960	O
Licklider	O
took	O
on	O
MIT	O
's	O
John	O
McCarthy	O
and	O
Marvin	O
Minsky	O
as	O
consultants	O
.	O
</s>
<s>
McCarthy	O
had	O
been	O
advocating	O
for	O
the	O
concept	O
of	O
time-sharing	B-General_Concept
computers	O
since	O
the	O
same	O
year	O
,	O
but	O
had	O
found	O
slow	O
progress	O
at	O
MIT	O
.	O
</s>
<s>
In	O
particular	O
,	O
Fredkin	O
insisted	O
that	O
"	O
timesharing	B-General_Concept
could	O
be	O
done	O
on	O
a	O
small	O
computer	O
,	O
namely	O
,	O
a	O
PDP-1.	O
"	O
</s>
<s>
John	O
’s	O
invention	O
of	O
time-sharing	B-General_Concept
and	O
his	O
telling	O
me	O
about	O
his	O
ideas	O
all	O
occurred	O
before	O
the	O
PDP-1	B-Device
existed	O
.	O
</s>
<s>
When	O
I	O
first	O
saw	O
the	O
PDP-1	B-Device
at	O
the	O
Eastern	O
Joint	O
Computer	O
Conference	O
,	O
I	O
realized	O
that	O
it	O
was	O
the	O
perfect	O
low-cost	O
vehicle	O
for	O
implementing	O
John	O
's	O
ideas	O
.	O
</s>
<s>
That	O
is	O
why	O
I	O
specified	O
that	O
several	O
of	O
the	O
modifications	O
for	O
time	B-General_Concept
sharing	I-General_Concept
be	O
part	O
of	O
the	O
PDP-1b	O
.	O
</s>
<s>
Accordingly	O
,	O
a	O
BBN	O
team	O
,	O
largely	O
led	O
by	O
Sheldon	O
Boilen	O
,	O
built	O
custom	O
hardware	O
add-ons	O
to	O
the	O
company	O
's	O
second	O
PDP-1	B-Device
to	O
provide	O
an	O
external	O
interrupt	O
system	O
and	O
a	O
magnetic	O
drum	O
for	O
swapping	O
storage	O
.	O
</s>
<s>
To	O
this	O
end	O
,	O
BBN	O
acquired	O
the	O
first	O
UNIVAC	B-Device
FASTRAND	I-Device
rotating	O
drum	O
,	O
with	O
a	O
45-Mbyte	O
storage	O
capacity	O
and	O
an	O
access	O
time	O
of	O
about	O
0.1	O
second	O
.	O
</s>
<s>
In	O
Fall	O
1962	O
,	O
BBN	O
conducted	O
a	O
public	O
demonstration	O
of	O
the	O
BBN	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
,	O
with	O
one	O
operator	O
in	O
Washington	O
,	O
D.C.	O
,	O
and	O
two	O
in	O
Cambridge	O
.	O
</s>
<s>
As	O
described	O
in	O
McCarthy	O
et	O
al.	O
,	O
the	O
computer	O
's	O
hardware	O
was	O
as	O
follows	O
:	O
"	O
The	O
PDP-1	B-Device
is	O
a	O
single	O
address	O
binary	O
computer	O
with	O
an	O
18	O
bit	O
word	O
and	O
five	O
microsecond	O
memory	O
cycle	O
;	O
most	O
instructions	O
require	O
ten	O
microseconds	O
to	O
execute	O
.	O
</s>
<s>
The	O
machine	O
we	O
used	O
has	O
8192	O
words	O
,	O
4096	O
of	O
which	O
are	O
reserved	O
for	O
the	O
time-sharing	B-General_Concept
system	I-General_Concept
.	O
</s>
