<s>
In	O
computing	O
,	O
time-sharing	B-General_Concept
is	O
the	O
sharing	O
of	O
a	O
computing	O
resource	O
among	O
many	O
users	O
at	O
the	O
same	O
time	O
by	O
means	O
of	O
multiprogramming	O
and	O
multi-tasking	B-Operating_System
.	O
</s>
<s>
Its	B-Application
emergence	O
as	O
the	O
prominent	O
model	O
of	O
computing	O
in	O
the	O
1970s	O
represented	O
a	O
major	O
technological	O
shift	O
in	O
the	O
history	O
of	O
computing	O
.	O
</s>
<s>
By	O
allowing	O
many	O
users	O
to	O
interact	O
concurrently	B-Architecture
with	O
a	O
single	O
computer	O
,	O
time-sharing	B-General_Concept
dramatically	O
lowered	O
the	O
cost	O
of	O
providing	O
computing	O
capability	O
,	O
made	O
it	O
possible	O
for	O
individuals	O
and	O
organizations	O
to	O
use	O
a	O
computer	O
without	O
owning	O
one	O
,	O
and	O
promoted	O
the	O
interactive	O
use	O
of	O
computers	O
and	O
the	O
development	O
of	O
new	O
interactive	O
applications	O
.	O
</s>
<s>
As	O
computers	O
grew	O
in	O
speed	O
,	O
run	B-Library
times	I-Library
dropped	O
,	O
and	O
soon	O
the	O
time	O
taken	O
to	O
start	O
up	O
the	O
next	O
program	O
became	O
a	O
concern	O
.	O
</s>
<s>
Newer	O
batch	B-General_Concept
processing	I-General_Concept
software	O
and	O
methodologies	O
,	O
including	O
batch	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
IBSYS	B-Operating_System
(	O
1960	O
)	O
,	O
decreased	O
these	O
"	O
dead	O
periods	O
"	O
by	O
queuing	O
up	O
programs	O
ready	O
to	O
run	O
.	O
</s>
<s>
Comparatively	O
inexpensive	O
card	B-Device
punch	I-Device
or	O
paper	O
tape	O
writers	O
were	O
used	O
by	O
programmers	O
to	O
write	O
their	O
programs	O
"	O
offline	O
"	O
.	O
</s>
<s>
The	O
concept	O
is	O
claimed	O
to	O
have	O
been	O
first	O
described	O
by	O
Robert	O
Dodds	O
in	O
a	O
letter	O
he	O
wrote	O
in	O
1949	O
although	O
he	O
did	O
not	O
use	O
the	O
term	O
time-sharing	B-General_Concept
.	O
</s>
<s>
Bob	O
Bemer	O
used	O
the	O
term	O
time-sharing	B-General_Concept
in	O
his	O
1957	O
article	O
"	O
How	O
to	O
consider	O
a	O
computer	O
"	O
in	O
Automatic	O
Control	O
Magazine	O
and	O
it	O
was	O
reported	O
the	O
same	O
year	O
he	O
used	O
the	O
term	O
time-sharing	B-General_Concept
in	O
a	O
presentation	O
.	O
</s>
<s>
In	O
a	O
paper	O
published	O
in	O
December	O
1958	O
by	O
W	O
.	O
F	O
.	O
Bauer	O
,	O
he	O
wrote	O
that	O
"	O
The	O
computers	O
would	O
handle	O
a	O
number	O
of	O
problems	O
concurrently	B-Architecture
.	O
</s>
<s>
Christopher	O
Strachey	O
,	O
who	O
became	O
Oxford	O
University	O
's	O
first	O
professor	O
of	O
computation	O
,	O
filed	O
a	O
patent	O
application	B-Application
for	O
"	O
time-sharing	B-General_Concept
"	O
in	O
February	O
1959	O
.	O
</s>
<s>
He	O
gave	O
a	O
paper	O
"	O
Time	B-General_Concept
Sharing	I-General_Concept
in	O
Large	O
Fast	O
Computers	O
"	O
at	O
the	O
first	O
UNESCO	O
Information	O
Processing	O
Conference	O
in	O
Paris	O
in	O
June	O
that	O
year	O
,	O
where	O
he	O
passed	O
the	O
concept	O
on	O
to	O
J	O
.	O
C	O
.	O
R	O
.	O
Licklider	O
.	O
</s>
<s>
The	O
meaning	O
of	O
the	O
term	O
time-sharing	B-General_Concept
has	O
shifted	O
from	O
its	B-Application
original	O
usage	O
.	O
</s>
<s>
From	O
1949-1960	O
,	O
time-sharing	B-General_Concept
was	O
used	O
to	O
refer	O
to	O
multiprogramming	O
without	O
multiple-interactive	O
user	O
sessions	O
.	O
</s>
<s>
In	O
1984	O
Christopher	O
Strachey	O
wrote	O
he	O
considered	O
the	O
change	O
in	O
the	O
meaning	O
of	O
the	O
term	O
time-sharing	B-General_Concept
a	O
source	O
of	O
confusion	O
and	O
not	O
what	O
he	O
meant	O
when	O
he	O
wrote	O
his	O
paper	O
in	O
1960	O
.	O
</s>
<s>
These	O
include	O
SAGE	B-Device
(	O
1958	O
)	O
,	O
SABRE	B-Application
(	O
1960	O
)	O
and	O
PLATO	B-Operating_System
II	I-Operating_System
,	O
created	O
by	O
Donald	O
Bitzer	O
at	O
a	O
public	O
demonstration	O
at	O
Robert	O
Allerton	O
Park	O
near	O
the	O
University	O
of	O
Illinois	O
in	O
early	O
1961	O
.	O
</s>
<s>
Bitzer	O
has	O
long	O
said	O
that	O
the	O
PLATO	B-Operating_System
project	O
would	O
have	O
gotten	O
the	O
patent	O
on	O
time-sharing	B-General_Concept
if	O
only	O
the	O
University	O
of	O
Illinois	O
had	O
not	O
lost	O
the	O
patent	O
for	O
two	O
years	O
.	O
</s>
<s>
The	O
first	O
interactive	O
,	O
general-purpose	O
time-sharing	B-General_Concept
system	I-General_Concept
usable	O
for	O
software	O
development	O
,	O
Compatible	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
,	O
was	O
initiated	O
by	O
John	O
McCarthy	O
at	O
MIT	O
writing	O
a	O
memo	O
in	O
1959	O
and	O
then	O
Fernando	O
J	O
.	O
Corbató	O
spearheading	O
the	O
actual	O
development	O
of	O
the	O
system	O
.	O
</s>
<s>
Philip	O
M	B-Language
.	O
Morse	O
arranged	O
for	O
IBM	O
to	O
provide	O
a	O
series	O
of	O
their	O
mainframe	B-Architecture
computers	I-Architecture
starting	O
with	O
the	O
IBM	B-Device
704	I-Device
and	O
then	O
the	O
IBM	B-Device
709	I-Device
product	O
line	O
IBM	B-Device
7090	I-Device
and	O
IBM	B-Device
7094	I-Device
.	O
</s>
<s>
IBM	O
loaned	O
those	O
mainframes	B-Architecture
at	O
no	O
cost	O
to	O
MIT	O
along	O
with	O
the	O
staff	O
to	O
operate	O
them	O
and	O
also	O
provided	O
hardware	O
modifications	O
mostly	O
in	O
the	O
form	O
of	O
RPQs	O
as	O
prior	O
customers	O
had	O
already	O
commissioned	O
the	O
modifications	O
.	O
</s>
<s>
MIT	O
could	O
not	O
charge	O
for	O
use	O
of	O
CTSS	B-Operating_System
.	O
</s>
<s>
In	O
1963	O
a	O
second	O
deployment	O
of	O
CTSS	B-Operating_System
was	O
installed	O
on	O
an	O
IBM	B-Device
7094	I-Device
that	O
MIT	O
has	O
purchased	O
using	O
ARPA	O
money	O
.	O
</s>
<s>
This	O
was	O
used	O
to	O
support	O
Multics	B-Application
development	O
at	O
Project	O
MAC	O
.	O
</s>
<s>
JOSS	B-Language
began	O
time-sharing	B-General_Concept
service	O
in	O
January	O
1964	O
.	O
</s>
<s>
Dartmouth	B-Operating_System
Time	I-Operating_System
Sharing	I-Operating_System
System	I-Operating_System
(	O
DTSS	O
)	O
began	O
service	O
in	O
March	O
1964	O
.	O
</s>
<s>
Throughout	O
the	O
late	O
1960s	O
and	O
the	O
1970s	O
,	O
computer	B-General_Concept
terminals	I-General_Concept
were	O
multiplexed	O
onto	O
large	O
institutional	O
mainframe	B-Architecture
computers	I-Architecture
(	O
centralized	B-General_Concept
computing	I-General_Concept
systems	O
)	O
,	O
which	O
in	O
many	O
implementations	O
sequentially	O
polled	O
the	O
terminals	O
to	O
see	O
whether	O
any	O
additional	O
data	O
was	O
available	O
or	O
action	O
was	O
requested	O
by	O
the	O
computer	O
user	O
.	O
</s>
<s>
Later	O
technology	O
in	O
interconnections	O
were	O
interrupt	B-Application
driven	O
,	O
and	O
some	O
of	O
these	O
used	O
parallel	O
data	O
transfer	O
technologies	O
such	O
as	O
the	O
IEEE	O
488	O
standard	O
.	O
</s>
<s>
Generally	O
,	O
computer	B-General_Concept
terminals	I-General_Concept
were	O
utilized	O
on	O
college	O
properties	O
in	O
much	O
the	O
same	O
places	O
as	O
desktop	B-Device
computers	I-Device
or	O
personal	B-Device
computers	I-Device
are	O
found	O
today	O
.	O
</s>
<s>
In	O
the	O
earliest	O
days	O
of	O
personal	B-Device
computers	I-Device
,	O
many	O
were	O
in	O
fact	O
used	O
as	O
particularly	O
smart	O
terminals	O
for	O
time-sharing	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Conversely	O
,	O
timesharing	B-General_Concept
users	O
thought	O
that	O
their	O
terminal	O
was	O
the	O
computer	O
.	O
</s>
<s>
A	O
football	O
simulation	O
,	O
among	O
early	B-Application
mainframe	I-Application
games	I-Application
written	O
for	O
DTSS	O
,	O
used	O
less	O
than	O
two	O
seconds	O
of	O
computer	O
time	O
during	O
the	O
15	O
minutes	O
of	O
real	O
time	O
for	O
playing	O
the	O
game	O
.	O
</s>
<s>
With	O
the	O
rise	O
of	O
microcomputing	O
in	O
the	O
early	O
1980s	O
,	O
time-sharing	B-General_Concept
became	O
less	O
significant	O
,	O
because	O
individual	O
microprocessors	O
were	O
sufficiently	O
inexpensive	O
that	O
a	O
single	O
person	O
could	O
have	O
all	O
the	O
CPU	O
time	O
dedicated	O
solely	O
to	O
their	O
needs	O
,	O
even	O
when	O
idle	O
.	O
</s>
<s>
However	O
,	O
the	O
Internet	O
brought	O
the	O
general	O
concept	O
of	O
time-sharing	B-General_Concept
back	O
into	O
popularity	O
.	O
</s>
<s>
As	O
with	O
the	O
early	O
serial	B-General_Concept
terminals	I-General_Concept
,	O
web	O
sites	O
operate	O
primarily	O
in	O
bursts	O
of	O
activity	O
followed	O
by	O
periods	O
of	O
idle	O
time	O
.	O
</s>
<s>
In	O
the	O
1960s	O
,	O
several	O
companies	O
started	O
providing	O
time-sharing	B-General_Concept
services	O
as	O
service	O
bureaus	O
.	O
</s>
<s>
Early	O
systems	O
used	O
Teletype	B-Application
Model	I-Application
33	I-Application
KSR	O
or	O
ASR	O
or	O
Teletype	O
Model	O
35	O
KSR	O
or	O
ASR	O
machines	O
in	O
ASCII	B-Protocol
environments	O
,	O
and	O
IBM	O
Selectric	O
typewriter-based	O
terminals	O
(	O
especially	O
the	O
IBM	O
2741	O
)	O
with	O
two	O
different	O
seven-bit	O
codes	O
.	O
</s>
<s>
They	O
would	O
connect	O
to	O
the	O
central	B-General_Concept
computer	I-General_Concept
by	O
dial-up	O
Bell	O
103A	O
modem	B-Application
or	O
acoustically	B-Device
coupled	I-Device
modems	I-Device
operating	O
at	O
1015	O
characters	O
per	O
second	O
.	O
</s>
<s>
Later	O
terminals	O
and	O
modems	B-Application
supported	O
30120	O
characters	O
per	O
second	O
.	O
</s>
<s>
The	O
time-sharing	B-General_Concept
system	I-General_Concept
would	O
provide	O
a	O
complete	O
operating	O
environment	O
,	O
including	O
a	O
variety	O
of	O
programming	O
language	O
processors	O
,	O
various	O
software	O
packages	O
,	O
file	O
storage	O
,	O
bulk	O
printing	O
,	O
and	O
off-line	O
storage	O
.	O
</s>
<s>
Common	O
systems	O
used	O
for	O
time-sharing	B-General_Concept
included	O
the	O
SDS	B-Device
940	I-Device
,	O
the	O
PDP-10	B-Device
,	O
the	O
IBM	B-Application
360	I-Application
,	O
and	O
the	O
GE-600	B-Device
series	I-Device
.	O
</s>
<s>
Companies	O
providing	O
this	O
service	O
included	O
GE	O
's	O
GEISCO	O
,	O
the	O
IBM	O
subsidiary	O
The	O
Service	O
Bureau	O
Corporation	O
,	O
Tymshare	B-Application
(	O
founded	O
in	O
1966	O
)	O
,	O
National	O
CSS	O
(	O
founded	O
in	O
1967	O
and	O
bought	O
by	O
Dun	O
&	O
Bradstreet	O
in	O
1979	O
)	O
,	O
Dial	B-Application
Data	I-Application
(	O
bought	O
by	O
Tymshare	B-Application
in	O
1968	O
)	O
,	O
Bolt	O
,	O
Beranek	O
,	O
and	O
Newman	O
(	O
BBN	O
)	O
and	O
Time	B-Language
Sharing	I-Language
Ltd	I-Language
.	I-Language
in	O
the	O
UK	O
.	O
</s>
<s>
The	O
Auerbach	O
Guide	O
to	O
Timesharing	B-General_Concept
(	O
1973	O
)	O
lists	O
125	O
different	O
timesharing	B-General_Concept
services	O
using	O
equipment	O
from	O
Burroughs	O
,	O
CDC	O
,	O
DEC	O
,	O
HP	O
,	O
Honeywell	O
,	O
IBM	O
,	O
RCA	O
,	O
Univac	O
,	O
and	O
XDS	O
.	O
</s>
<s>
In	O
1975	O
,	O
acting	O
president	O
of	O
Prime	O
Computer	O
Ben	O
F	O
.	O
Robelen	O
told	O
stockholders	O
that	O
"	O
The	O
biggest	O
end-user	O
market	O
currently	O
is	O
time-sharing.	O
"	O
</s>
<s>
For	O
DEC	O
,	O
for	O
a	O
while	O
the	O
second	O
largest	O
computer	O
company	O
(	O
after	O
IBM	O
)	O
,	O
this	O
was	O
also	O
true	O
:	O
Their	O
PDP-10	B-Device
and	O
IBM	O
's	O
360/67	B-Device
were	O
widely	O
used	O
by	O
commercial	O
timesharing	B-General_Concept
services	O
such	O
as	O
CompuServe	O
,	O
On-Line	O
Systems	O
,	O
Inc	O
.	O
(	O
OLS	O
)	O
,	O
Rapidata	O
and	O
Time	B-Language
Sharing	I-Language
Ltd	I-Language
.	I-Language
</s>
<s>
The	O
advent	O
of	O
the	O
personal	B-Device
computer	I-Device
marked	O
the	O
beginning	O
of	O
the	O
decline	O
of	O
time-sharing	B-General_Concept
.	O
</s>
<s>
Although	O
many	O
time-sharing	B-General_Concept
services	O
simply	O
closed	O
,	O
Rapidata	O
held	O
on	O
,	O
and	O
became	O
part	O
of	O
National	O
Data	O
Corporation	O
.	O
</s>
<s>
It	O
was	O
still	O
of	O
sufficient	O
interest	O
in	O
1982	O
to	O
be	O
the	O
focus	O
of	O
"	O
A	O
User	O
's	O
Guide	O
to	O
Statistics	O
Programs	O
:	O
The	O
Rapidata	O
Timesharing	B-General_Concept
System	O
"	O
.	O
</s>
<s>
Even	O
as	O
revenue	O
fell	O
by	O
66%	O
and	O
National	O
Data	O
subsequently	O
developed	O
its	B-Application
own	O
problems	O
,	O
attempts	O
were	O
made	O
to	O
keep	O
this	O
timesharing	B-General_Concept
business	O
going	O
.	O
</s>
<s>
Time	B-General_Concept
Sharing	I-General_Concept
Limited	O
(	O
TSL	O
,	O
1969-1974	O
)	O
-	O
launched	O
using	O
DEC	O
systems	O
.	O
</s>
<s>
PERT	O
was	O
one	O
of	O
its	B-Application
popular	O
offerings	O
.	O
</s>
<s>
Beginning	O
in	O
1964	O
,	O
the	O
Multics	B-Application
operating	I-Application
system	I-Application
was	O
designed	O
as	O
a	O
computing	B-Operating_System
utility	I-Operating_System
,	O
modeled	O
on	O
the	O
electrical	O
or	O
telephone	O
utilities	O
.	O
</s>
<s>
In	O
the	O
1970s	O
,	O
Ted	O
Nelson	O
's	O
original	O
"	O
Xanadu	B-Protocol
"	O
hypertext	O
repository	O
was	O
envisioned	O
as	O
such	O
a	O
service	O
.	O
</s>
<s>
Time-sharing	B-General_Concept
was	O
the	O
first	O
time	O
that	O
multiple	O
processes	B-Operating_System
,	O
owned	O
by	O
different	O
users	O
,	O
were	O
running	O
on	O
a	O
single	O
machine	O
,	O
and	O
these	O
processes	B-Operating_System
could	O
interfere	O
with	O
one	O
another	O
.	O
</s>
<s>
For	O
example	O
,	O
one	O
process	O
might	O
alter	O
shared	B-General_Concept
resources	I-General_Concept
which	O
another	O
process	O
relied	O
on	O
,	O
such	O
as	O
a	O
variable	O
stored	O
in	O
memory	O
.	O
</s>
<s>
To	O
prevent	O
this	O
from	O
happening	O
,	O
an	O
operating	B-General_Concept
system	I-General_Concept
needed	O
to	O
enforce	O
a	O
set	O
of	O
policies	O
that	O
determined	O
which	O
privileges	O
each	O
process	O
had	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
might	O
deny	O
access	O
to	O
a	O
certain	O
variable	O
by	O
a	O
certain	O
process	O
.	O
</s>
<s>
The	O
first	O
international	O
conference	O
on	O
computer	O
security	O
in	O
London	O
in	O
1971	O
was	O
primarily	O
driven	O
by	O
the	O
time-sharing	B-General_Concept
industry	O
and	O
its	B-Application
customers	O
.	O
</s>
<s>
Time-sharing	B-General_Concept
in	O
the	O
form	O
of	O
shell	O
accounts	O
has	O
been	O
considered	O
a	O
risk	O
.	O
</s>
<s>
Significant	O
early	O
timesharing	B-General_Concept
systems	O
:	O
</s>
<s>
Cambridge	O
Multiple	O
Access	O
System	O
was	O
developed	O
for	O
the	O
Titan	B-Device
,	O
the	O
prototype	O
Atlas	B-Device
2	O
computer	O
built	O
by	O
Ferranti	O
for	O
the	O
University	O
of	O
Cambridge	O
.	O
</s>
<s>
This	O
was	O
the	O
first	O
time-sharing	B-General_Concept
system	I-General_Concept
developed	O
outside	O
the	O
United	O
States	O
,	O
and	O
which	O
influenced	O
the	O
later	O
development	O
of	O
UNIX	B-Application
.	O
</s>
<s>
International	O
Timesharing	B-General_Concept
Corporation	O
on	O
dual	O
CDC	B-Device
3300	I-Device
systems	O
.	O
</s>
<s>
Michigan	B-Application
Terminal	I-Application
System	I-Application
,	O
on	O
the	O
IBM	B-Device
S/360	I-Device
-67	I-Device
,	O
S/370	B-Device
,	O
and	O
successors	O
.	O
</s>
<s>
National	O
CSS	O
VP/CSS	B-Application
,	O
on	O
IBM	B-Application
360	I-Application
series	O
;	O
originally	O
based	O
on	O
IBM	O
's	O
CP/CMS	B-Application
.	O
</s>
<s>
Oregon	O
State	O
University	O
OS-3	O
,	O
on	O
CDC	B-Device
3000	I-Device
series	I-Device
.	O
</s>
<s>
Service	O
in	O
Informatics	O
and	O
Analysis	O
(	O
SIA	O
)	O
,	O
on	O
CDC	B-Device
6600	I-Device
Kronos	B-Operating_System
.	O
</s>
<s>
System	O
Development	O
Corporation	O
Time-sharing	B-General_Concept
System	I-General_Concept
,	O
on	O
the	O
AN/FSQ	B-Architecture
-32	I-Architecture
.	O
</s>
<s>
Stanford	O
ORVYL	B-Application
and	I-Application
WYLBUR	I-Application
,	O
on	O
IBM	B-Device
S/360	I-Device
-67	I-Device
.	O
</s>
<s>
Time	B-Language
Sharing	I-Language
Ltd	I-Language
.	I-Language
(	O
TSL	O
)	O
on	O
DEC	B-Device
PDP-10	I-Device
systems	O
→	O
Automatic	O
Data	O
Processing	O
(	O
ADP	O
)	O
,	O
first	O
commercial	O
time-sharing	B-General_Concept
system	I-General_Concept
in	O
Europe	O
and	O
first	O
dual	O
(	O
fault	O
tolerant	O
)	O
time-sharing	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Tone	O
(	O
TSO-like	O
,	O
for	O
VS1	B-Application
)	O
,	O
a	O
non-IBM	O
Time-sharing	B-General_Concept
product	O
,	O
marketed	O
by	O
Tone	O
Software	O
Co	O
;	O
TSO	B-Application
required	O
VS2	O
.	O
</s>
<s>
UC	O
Berkeley	O
CAL-TSS	O
,	O
on	O
CDC	B-Device
6400	I-Device
.	O
</s>
