<s>
The	O
Dartmouth	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
(	O
DTSS	O
)	O
is	O
a	O
discontinued	O
operating	B-General_Concept
system	I-General_Concept
first	O
developed	O
at	O
Dartmouth	O
College	O
between	O
1963	O
and	O
1964	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
successful	O
large-scale	O
time-sharing	B-General_Concept
system	I-General_Concept
to	O
be	O
implemented	O
,	O
and	O
was	O
also	O
the	O
system	O
for	O
which	O
the	O
BASIC	O
language	O
was	O
developed	O
.	O
</s>
<s>
Mark	O
II	O
and	O
the	O
further	O
developed	O
Mark	O
III	O
was	O
widely	O
used	O
on	O
their	O
GE-600	B-Device
series	I-Device
mainframe	B-Architecture
computers	I-Architecture
and	O
formed	O
the	O
basis	O
for	O
their	O
online	O
services	O
.	O
</s>
<s>
These	O
were	O
the	O
largest	O
such	O
services	O
in	O
the	O
world	O
for	O
a	O
time	O
,	O
eventually	O
emerging	O
as	O
the	O
consumer-oriented	O
GEnie	B-Language
online	O
service	O
.	O
</s>
<s>
Professors	O
John	O
Kemeny	O
and	O
Thomas	O
Kurtz	O
at	O
Dartmouth	O
College	O
purchased	O
a	O
Royal	O
McBee	O
LGP-30	B-Device
computer	O
around	O
1959	O
,	O
which	O
was	O
programmed	O
by	O
undergraduates	O
in	O
assembly	O
language	O
.	O
</s>
<s>
Kurtz	O
and	O
four	O
students	O
programmed	O
the	O
Dartmouth	B-Language
ALGOL	I-Language
30	I-Language
compiler	O
,	O
an	O
implementation	O
of	O
the	O
ALGOL	B-Language
58	I-Language
programming	I-Language
language	I-Language
,	O
which	O
two	O
of	O
the	O
students	O
,	O
Stephen	O
Garland	O
and	O
Anthony	O
Knapp	O
then	O
evolved	O
into	O
the	O
SCALP	O
(	O
Self	O
Contained	O
ALgol	B-Language
Processor	O
)	O
language	O
between	O
1962-1964	O
.	O
</s>
<s>
Kemeny	O
and	O
freshman	O
Sidney	O
Marshall	O
collaborated	O
to	O
create	O
DOPE	B-Language
(	O
Dartmouth	O
Oversimplified	O
Programming	O
Experiment	O
)	O
,	O
which	O
was	O
used	O
in	O
large	O
freshman	O
courses	O
.	O
</s>
<s>
Kurtz	O
approached	O
Kemeny	O
in	O
either	O
1961	O
or	O
1962	O
,	O
with	O
the	O
following	O
proposal	O
:	O
all	O
Dartmouth	O
students	O
would	O
have	O
access	O
to	O
computing	O
,	O
it	O
should	O
be	O
free	O
and	O
open-access	O
,	O
and	O
this	O
could	O
be	O
accomplished	O
by	O
creating	O
a	O
time-sharing	B-General_Concept
system	I-General_Concept
(	O
which	O
Kurtz	O
had	O
learned	O
about	O
from	O
colleague	O
John	O
McCarthy	O
at	O
MIT	O
,	O
who	O
suggested	O
"	O
why	O
do	O
n't	O
you	O
guys	O
do	O
timesharing	B-General_Concept
?	O
"	O
)	O
.	O
</s>
<s>
Although	O
it	O
has	O
been	O
stated	O
that	O
DTSS	O
was	O
inspired	O
by	O
a	O
PDP-1-based	O
time-sharing	B-General_Concept
system	I-General_Concept
at	O
Bolt	O
,	O
Beranek	O
and	O
Newman	O
,	O
there	O
is	O
no	O
evidence	O
that	O
this	O
is	O
true	O
.	O
</s>
<s>
In	O
1962	O
,	O
Kemeny	O
and	O
Kurtz	O
submitted	O
a	O
proposal	O
for	O
the	O
development	O
of	O
a	O
new	O
time-sharing	B-General_Concept
system	I-General_Concept
to	O
NSF	O
(	O
which	O
was	O
ultimately	O
funded	O
in	O
1964	O
)	O
.	O
</s>
<s>
In	O
particular	O
,	O
they	O
evaluated	O
candidate	O
computers	O
from	O
Bendix	O
,	O
GE	O
,	O
and	O
IBM	O
,	O
and	O
settled	O
upon	O
the	O
GE-225	B-Device
system	O
paired	O
with	O
a	O
DATANET-30	B-Device
communications	O
processor	O
.	O
</s>
<s>
In	O
essence	O
,	O
the	O
DATANET-30	B-Device
provided	O
the	O
user-interface	O
and	O
scheduler	O
,	O
while	O
user	O
programs	O
ran	O
in	O
the	O
GE-225	B-Device
.	O
</s>
<s>
The	O
GE-225	B-Device
and	O
DATANET-30	B-Device
computers	O
arrived	O
in	O
February	O
1964	O
.	O
</s>
<s>
Two	O
students	O
,	O
John	O
McGeachie	O
and	O
Michael	O
Busch	O
,	O
wrote	O
the	O
operating	B-General_Concept
systems	I-General_Concept
for	O
the	O
DATANET-30	B-Device
and	O
GE-225	B-Device
;	O
Kemeny	O
contributed	O
the	O
BASIC	O
compiler	O
.	O
</s>
<s>
In	O
autumn	O
of	O
1964	O
,	O
hundreds	O
of	O
freshman	O
students	O
began	O
to	O
use	O
the	O
system	O
via	O
20	O
teletypes	O
,	O
with	O
access	O
at	O
Hanover	O
High	O
School	O
via	O
one	O
additional	O
teletype	O
;	O
later	O
that	O
autumn	O
the	O
GE-225	B-Device
computer	O
was	O
replaced	O
with	O
a	O
faster	O
GE-235	B-Device
computer	O
with	O
minimal	O
issues	O
.	O
</s>
<s>
The	O
program	O
in	O
the	O
Datanet-30	B-Device
is	O
divided	O
into	O
two	O
parts	O
,	O
a	O
real-time	O
part	O
and	O
a	O
spare-time	O
part	O
.	O
</s>
<s>
In	O
the	O
GE-235	B-Device
part	O
there	O
is	O
resident	O
compiler	O
system	O
that	O
acts	O
as	O
a	O
translator	O
,	O
and	O
a	O
resident	O
executive	O
routine	O
to	O
manage	O
the	O
disc	O
input-output	O
operations	O
and	O
to	O
perform	O
other	O
functions	O
.	O
</s>
<s>
The	O
executive	O
system	O
permits	O
simultaneous	O
use	O
of	O
the	O
card	O
equipment	O
,	O
the	O
tape	O
drives	O
,	O
and	O
the	O
high-speed	O
printer	O
during	O
time-sharing	B-General_Concept
through	O
interrupt	O
processing	O
.	O
</s>
<s>
Two	O
algebraic	O
languages	O
,	O
BASIC	O
and	O
ALGOL	B-Language
,	O
are	O
available	O
,	O
with	O
FORTRAN	B-Application
planned	O
for	O
September	O
1965	O
.	O
</s>
<s>
It	O
implemented	O
the	O
world	O
's	O
first	O
Integrated	B-Application
Design	I-Application
Environment	I-Application
(	O
IDE	O
)	O
.	O
</s>
<s>
This	O
method	O
of	O
editing	O
provided	O
a	O
simple	O
and	O
easy	O
to	O
use	O
service	O
that	O
allowed	O
large	O
numbers	O
of	O
teleprinters	O
as	O
the	O
terminal	O
units	O
for	O
the	O
Dartmouth	B-Operating_System
Timesharing	I-Operating_System
system	I-Operating_System
.	O
</s>
<s>
These	O
commands	O
were	O
often	O
believed	O
to	O
be	O
part	O
of	O
the	O
BASIC	O
language	O
by	O
users	O
,	O
but	O
in	O
fact	O
they	O
were	O
part	O
of	O
the	O
time	B-General_Concept
sharing	I-General_Concept
system	O
and	O
were	O
also	O
used	O
when	O
preparing	O
ALGOL	B-Language
or	O
FORTRAN	B-Application
programs	O
via	O
the	O
DTSS	O
terminals	O
.	O
</s>
<s>
That	O
said	O
,	O
GE	O
and	O
Dartmouth	O
promoted	O
the	O
operational	O
Dartmouth	B-Operating_System
Time	I-Operating_System
Sharing	I-Operating_System
System	I-Operating_System
in	O
October	O
1964	O
at	O
the	O
Fall	O
Joint	O
Computer	O
Conference	O
in	O
San	O
Francisco	O
,	O
with	O
three	O
teletypes	O
connected	O
to	O
the	O
Dartmouth	O
system	O
in	O
Hanover	O
.	O
</s>
<s>
In	O
early	O
1965	O
,	O
GE	O
began	O
to	O
advertise	O
timesharing	B-General_Concept
services	O
on	O
its	O
GE-265	O
system	O
(	O
GE	O
235	O
+	O
DATANET	O
30	O
)	O
,	O
including	O
BASIC	O
and	O
Dartmouth	O
Algol	B-Language
,	O
later	O
renaming	O
it	O
the	O
GE	O
Mark	O
I	O
time-sharing	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
In	O
1965	O
,	O
Warner	O
Sinback	O
recommended	O
that	O
they	O
begin	O
to	O
sell	O
time-sharing	B-General_Concept
services	O
using	O
the	O
time-sharing	B-General_Concept
system	I-General_Concept
(	O
Mark	O
1	O
)	O
developed	O
at	O
Dartmouth	O
on	O
a	O
General	O
Electric	O
265	O
computer	O
.	O
</s>
<s>
The	O
service	O
was	O
an	O
instant	O
success	O
and	O
by	O
1968	O
,	O
GEIS	O
had	O
40%	O
of	O
the	O
$	O
70	O
million	O
time-sharing	B-General_Concept
market	O
.	O
</s>
<s>
The	O
service	O
continued	O
to	O
grow	O
,	O
and	O
over	O
time	O
migrated	O
to	O
the	O
GE	O
developed	O
Mark	O
II	O
and	O
Mark	O
III	O
operating	B-General_Concept
systems	I-General_Concept
running	O
on	O
large	O
mainframe	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
From	O
1966-1968	O
,	O
DTSS	O
was	O
reimplemented	O
on	O
the	O
GE	B-Device
635	I-Device
,	O
still	O
using	O
the	O
DATANET-30	B-Device
for	O
terminal	O
control	O
.	O
</s>
<s>
The	O
GE	B-Device
635	I-Device
system	O
was	O
delivered	O
in	O
November	O
1966	O
.	O
</s>
<s>
Phase	O
II	O
of	O
the	O
Dartmouth	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
replaced	O
Phase	O
I	O
on	O
April	O
1	O
,	O
1969	O
,	O
at	O
Dartmouth	O
.	O
</s>
<s>
The	O
published	O
concepts	O
of	O
the	O
Multics	B-Application
system	O
.	O
</s>
<s>
The	O
635	O
version	O
provided	O
interactive	O
time-sharing	B-General_Concept
to	O
up	O
to	O
nearly	O
300	O
simultaneous	O
users	O
in	O
the	O
1970s	O
,	O
a	O
very	O
large	O
number	O
at	O
the	O
time	O
,	O
and	O
operated	O
at	O
eleven	O
commercial	O
and	O
academic	O
sites	O
in	O
the	O
U.S.A.	O
,	O
Canada	O
and	O
Europe	O
.	O
</s>
<s>
As	O
it	O
evolved	O
in	O
the	O
1970s	O
,	O
later	O
versions	O
moved	O
to	O
Honeywell	B-Device
6000	I-Device
series	I-Device
mainframes	B-Architecture
(	O
1973	O
)	O
and	O
Honeywell	B-Device
716	I-Device
communication	O
processors	O
(	O
1974	O
)	O
.	O
</s>
<s>
In	O
1976	O
the	O
GE-635	B-Device
system	O
was	O
replaced	O
by	O
a	O
Honeywell	O
66/40A	O
computer	O
.	O
</s>
<s>
DTSS	O
,	O
version	O
2	O
,	O
included	O
a	O
novel	O
form	O
of	O
inter-process	B-Operating_System
communication	I-Operating_System
called	O
"	O
communication	O
files	O
"	O
.	O
</s>
<s>
They	O
significantly	O
antedated	O
Unix	B-Operating_System
pipes	I-Operating_System
,	O
as	O
design	O
documents	O
put	O
their	O
conceptual	O
origin	O
sometime	O
in	O
1967	O
,	O
and	O
were	O
described	O
briefly	O
in	O
a	O
1969	O
conference	O
:	O
</s>
<s>
As	O
Douglas	O
McIlroy	O
notes	O
:	O
"	O
In	O
this	O
,	O
[	O
communication	O
files	O
were ]	O
more	O
akin	O
to	O
Plan	B-Operating_System
9	I-Operating_System
's	O
9P	B-Operating_System
protocol	I-Operating_System
than	O
to	O
familiar	O
IO.	O
"	O
</s>
<s>
They	O
arranged	O
for	O
the	O
second	O
trimester	O
of	O
the	O
freshman	O
mathematics	O
class	O
to	O
include	O
a	O
requirement	O
for	O
writing	O
and	O
debugging	O
four	O
Dartmouth	B-Language
BASIC	I-Language
programs	O
.	O
</s>
<s>
By	O
that	O
year	O
university	O
administration	O
used	O
28%	O
of	O
timesharing	B-General_Concept
resources	O
to	O
students	O
 '	O
20%	O
,	O
with	O
the	O
registrar	O
and	O
housing	O
office	O
among	O
users	O
.	O
</s>
<s>
The	O
library	O
of	O
hundreds	O
of	O
programs	O
included	O
,	O
Kemeny	O
and	O
Kurtz	O
reported	O
,	O
"	O
many	B-Application
games	I-Application
"	O
.	O
</s>
<s>
Kemeny	O
—	O
by	O
then	O
the	O
university	O
president	O
—	O
wrote	O
in	O
a	O
1971	O
brochure	O
describing	O
the	O
system	O
that	O
just	O
as	O
a	O
student	O
could	O
enter	O
Baker	O
Memorial	O
Library	O
and	O
borrow	O
a	O
book	O
without	O
asking	O
permission	O
or	O
explaining	O
his	O
purpose	O
,	O
"	O
any	O
student	O
may	O
walk	O
into	O
Kiewit	O
Computation	O
Center	O
,	O
sit	O
down	O
at	O
a	O
console	O
,	O
and	O
use	O
the	O
time-sharing	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
off-campus	O
Dartmouth	O
Educational	O
Time-Sharing	B-General_Concept
Network	O
included	O
users	O
with	O
79	O
terminals	O
at	O
30	O
high	O
schools	O
and	O
20	O
universities	O
,	O
including	O
Middlebury	O
College	O
,	O
Phillips	O
Andover	O
,	O
Mount	O
Holyoke	O
College	O
,	O
Goddard	O
College	O
,	O
the	O
United	O
States	O
Merchant	O
Marine	O
Academy	O
,	O
the	O
United	O
States	O
Naval	O
Academy	O
,	O
Bates	O
College	O
,	O
the	O
Dartmouth	O
Club	O
of	O
New	O
York	O
,	O
and	O
a	O
Dartmouth	O
affiliate	O
in	O
Jersey	O
City	O
,	O
New	O
Jersey	O
,	O
sharing	O
DTSS	O
with	O
Dartmouth	O
people	O
.	O
</s>
<s>
The	O
system	O
allowed	O
email-type	O
messages	O
to	O
be	O
passed	O
between	O
users	O
and	O
real-time	O
chat	O
via	O
a	O
precursor	O
to	O
the	O
Unix	B-Device
talk	I-Device
program	O
.	O
</s>
<s>
While	O
several	O
languages	O
were	O
available	O
on	O
DTSS	O
,	O
98%	O
of	O
programs	O
were	O
written	O
in	O
Dartmouth	B-Language
BASIC	I-Language
.	O
</s>
<s>
In	O
2000	O
,	O
a	O
project	O
to	O
recreate	O
the	O
DTSS	O
system	O
on	O
a	O
simulator	O
was	O
undertaken	O
and	O
as	O
a	O
result	O
DTSS	O
is	O
now	O
available	O
for	O
Microsoft	B-Application
Windows	I-Application
systems	O
and	O
for	O
the	O
Apple	B-Device
Macintosh	I-Device
computer	I-Device
.	O
</s>
