<s>
The	O
IBM	O
Time	B-General_Concept
Sharing	I-General_Concept
System	O
TSS/360	B-Application
is	O
a	O
discontinued	O
early	O
time-sharing	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
designed	O
exclusively	O
for	O
a	O
special	O
model	O
of	O
the	O
System/360	B-Application
line	O
of	O
mainframes	O
,	O
the	O
Model	B-Device
67	I-Device
.	O
</s>
<s>
TSS	B-Application
pioneered	O
a	O
number	O
of	O
novel	O
features	O
,	O
some	O
of	O
which	O
later	O
appeared	O
in	O
more	O
popular	O
systems	O
such	O
as	O
MVS	B-Application
.	O
</s>
<s>
TSS	B-Application
was	O
migrated	O
to	O
System/370	B-Device
and	I-Device
303x	I-Device
systems	I-Device
,	O
but	O
despite	O
its	O
many	O
advances	O
and	O
novel	O
capabilities	O
,	O
TSS	B-Application
failed	O
to	O
meet	O
expectations	O
and	O
was	O
eventually	O
canceled	O
.	O
</s>
<s>
TSS/370	B-Application
was	O
used	O
as	O
the	O
basis	O
for	O
a	O
port	O
of	O
UNIX	O
to	O
the	O
IBM	O
mainframe	O
.	O
</s>
<s>
TSS/360	B-Application
also	O
inspired	O
the	O
development	O
of	O
the	O
TSS/8	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
TSS/360	B-Application
was	O
one	O
of	O
the	O
first	O
implementations	O
of	O
tightly-coupled	O
symmetric	B-Operating_System
multiprocessing	I-Operating_System
.	O
</s>
<s>
A	O
pair	O
of	O
Model	B-Device
67	I-Device
mainframes	O
shared	O
a	O
common	O
physical	O
memory	O
space	O
,	O
and	O
ran	O
a	O
single	O
copy	O
of	O
the	O
kernel	O
(	O
and	O
application	O
)	O
code	O
.	O
</s>
<s>
An	O
I/O	B-General_Concept
operation	I-General_Concept
launched	O
by	O
one	O
processor	O
could	O
end	O
and	O
cause	O
an	O
interrupt	B-Application
in	O
the	O
other	O
.	O
</s>
<s>
The	O
Model	B-Device
67	I-Device
used	O
a	O
standard	O
360	O
instruction	O
called	O
Test	O
and	O
Set	O
to	O
implement	O
locks	O
on	O
code	O
critical	B-Operating_System
sections	I-Operating_System
.	O
</s>
<s>
It	O
also	O
implemented	O
virtual	B-Architecture
memory	I-Architecture
and	O
virtual	B-Architecture
machines	I-Architecture
using	O
position-independent	B-Operating_System
code	I-Operating_System
.	O
</s>
<s>
TSS/360	B-Application
included	O
an	O
early	O
implementation	O
of	O
a	O
"	O
Table	O
Driven	O
Scheduler	O
"	O
a	O
user-configured	O
table	O
whose	O
columns	O
were	O
parameters	O
such	O
as	O
current	O
priority	O
,	O
working	B-General_Concept
set	I-General_Concept
size	O
,	O
and	O
number	O
of	O
timeslices	O
used	O
to	O
date	O
.	O
</s>
<s>
The	O
kernel	O
would	O
refer	O
to	O
this	O
table	O
when	O
calculating	O
the	O
new	O
priority	O
of	O
a	O
thread	B-Operating_System
.	O
</s>
<s>
This	O
later	O
appeared	O
in	O
systems	O
as	O
diverse	O
as	O
Honeywell	B-Operating_System
CP-V	I-Operating_System
and	O
IBM	B-Application
z/OS	I-Application
.	O
</s>
<s>
As	O
was	O
standard	O
with	O
operating	B-General_Concept
system	I-General_Concept
software	O
at	O
the	O
time	O
,	O
TSS/360	B-Application
customers	O
(	O
such	O
as	O
General	B-Operating_System
Motors	I-Operating_System
Research	I-Operating_System
Laboratories	I-Operating_System
)	O
were	O
given	O
full	O
access	O
to	O
the	O
entire	O
source	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
code	O
and	O
development	O
tools	O
.	O
</s>
<s>
TSS	B-Application
provides	O
users	O
a	O
command-line	B-Application
interface	I-Application
.	O
</s>
<s>
Command	B-Application
lines	I-Application
can	O
be	O
continued	O
by	O
typing	O
a	O
hyphen	O
("-"	O
)	O
at	O
the	O
end	O
of	O
the	O
line	O
to	O
be	O
continued	O
and	O
typing	O
the	O
continuation	O
at	O
the	O
beginning	O
of	O
the	O
next	O
line	O
.	O
</s>
<s>
Comments	O
are	O
allowed	O
in	O
command	B-Application
lines	I-Application
,	O
separated	O
from	O
the	O
command	O
with	O
a	O
semicolon	O
and	O
included	O
in	O
single	O
quotes	O
("'"	O
)	O
.	O
</s>
<s>
Program	O
management	O
–	O
LOAD	O
,	O
DUMP	O
,	O
DISPLAY	O
,	O
TRAP	B-Application
,	O
etc	O
.	O
</s>
<s>
Program	O
product	O
language	O
interface	O
–	O
ASM	O
(	O
Assembler	O
(	O
F	O
)	O
)	O
,	O
COBOL	B-Application
,	O
HASM	O
(	O
Assembler	O
(	O
H	O
)	O
)	O
,	O
PLI	O
(	O
PL/I	O
(	O
F	O
)	O
)	O
,	O
PLIOPT	O
(	O
PL/I	O
Optimizing	O
Compiler	O
)	O
,	O
FTNH	O
(	O
FORTRAN	O
(	O
H	O
)	O
)	O
,	O
etc	O
.	O
</s>
<s>
TSS	B-Application
provided	O
an	O
early	O
implementation	O
of	O
position-independent	B-Operating_System
code	I-Operating_System
,	O
the	O
ability	O
to	O
have	O
different	O
processes	O
run	O
a	O
single	O
copy	O
of	O
an	O
executable	O
possibly	O
mapped	O
to	O
a	O
different	O
virtual	O
addresses	O
in	O
each	O
process	B-Operating_System
.	O
</s>
<s>
Address	B-Language
constants	I-Language
of	O
external	O
procedures	O
and	O
entry	O
points	O
must	O
be	O
located	O
in	O
the	O
PSECT	O
,	O
since	O
the	O
dynamic	O
loader	O
will	O
not	O
place	O
a	O
routine	O
at	O
the	O
same	O
virtual	B-Architecture
address	I-Architecture
in	O
every	O
process	B-Operating_System
.	O
</s>
<s>
When	O
the	O
dynamic	O
loader	O
loads	O
a	O
program	O
,	O
it	O
makes	O
a	O
copy	O
of	O
the	O
PSECT	O
and	O
relocates	O
the	O
adcons	O
to	O
reflect	O
the	O
virtual	O
addresses	O
assigned	O
within	O
the	O
current	O
process	B-Operating_System
,	O
therefore	O
each	O
user	O
of	O
the	O
program	O
has	O
a	O
unique	O
copy	O
of	O
the	O
PSECT	O
.	O
</s>
<s>
The	O
Dynamic	O
Loader	O
does	O
not	O
load	O
program	O
pages	O
or	O
resolve	O
address	B-Language
constants	I-Language
until	O
the	O
first	O
page	O
fault	O
.	O
</s>
<s>
TSS/360	B-Application
suffered	O
from	O
performance	O
and	O
reliability	O
problems	O
and	O
lack	O
of	O
compatibility	O
with	O
OS/360	B-Application
,	O
although	O
those	O
issues	O
were	O
eventually	O
addressed	O
.	O
</s>
<s>
IBM	O
attempted	O
to	O
develop	O
TSS	B-Application
on	O
a	O
very	O
aggressive	O
schedule	O
with	O
a	O
large	O
staff	O
of	O
programmers	O
to	O
compete	O
with	O
Multics	B-Application
.	O
</s>
<s>
By	O
1967	O
,	O
it	O
had	O
become	O
evident	O
that	O
TSS/360	B-Application
was	O
suffering	O
from	O
the	O
same	O
kinds	O
of	O
delays	O
as	O
OS/360	B-Application
.	O
</s>
<s>
In	O
February	O
1968	O
,	O
at	O
the	O
time	O
of	O
SHARE	O
30	O
,	O
there	O
were	O
eighteen	O
S/360	B-Device
-67	I-Device
sites	O
attempting	O
to	O
run	O
TSS	B-Application
.	O
</s>
<s>
During	O
the	O
conference	O
,	O
IBM	O
announced	O
via	O
"	O
blue	O
letter	O
"	O
that	O
TSS/360	B-Application
was	O
being	O
decommitted	O
a	O
great	O
blow	O
to	O
the	O
time-sharing	B-General_Concept
community	O
.	O
</s>
<s>
This	O
decision	O
was	O
temporarily	O
reversed	O
,	O
and	O
TSS/360	B-Application
was	O
not	O
officially	O
canceled	O
until	O
1971	O
.	O
</s>
<s>
However	O
,	O
TSS/360	B-Application
continued	O
to	O
be	O
quietly	O
available	O
for	O
a	O
time	O
to	O
existing	O
TSS/360	B-Application
customers	O
,	O
as	O
an	O
interim	O
measure	O
.	O
</s>
<s>
After	O
TSS/360	B-Application
was	O
canceled	O
,	O
IBM	O
put	O
its	O
primary	O
efforts	O
into	O
the	O
Time	B-Application
Sharing	I-Application
Option	I-Application
(	O
TSO	O
)	O
,	O
a	O
time-sharing	B-General_Concept
monitor	O
for	O
OS/360	B-Application
.	O
</s>
<s>
Several	O
other	O
groups	O
developed	O
less	O
ambitious	O
,	O
more	O
successful	O
time	B-General_Concept
sharing	I-General_Concept
systems	O
for	O
the	O
S/360	B-Device
-67	I-Device
,	O
notably	O
CP-67	B-Application
at	O
IBM	O
's	O
Cambridge	O
Scientific	O
Center	O
,	O
an	O
early	O
virtual	B-Architecture
machine	I-Architecture
monitor	O
which	O
evolved	O
into	O
VM/370	B-Application
,	O
MTS	B-Application
at	O
the	O
University	O
of	O
Michigan	O
,	O
and	O
ORVYL	B-Application
at	O
Stanford	O
University	O
.	O
</s>
<s>
IBM	O
also	O
provided	O
the	O
TSS/370	B-Application
PRPQ	O
as	O
a	O
migration	O
path	O
for	O
existing	O
TSS/360	B-Application
customers	O
,	O
which	O
went	O
through	O
multiple	O
releases	O
.	O
</s>
