<s>
MUSIC/SP	B-Application
(	O
Multi-User	B-Application
System	I-Application
for	I-Application
Interactive	I-Application
Computing/System	I-Application
Product	I-Application
;	O
originally	O
"	O
McGill	O
University	O
System	O
for	O
Interactive	O
Computing	O
"	O
)	O
was	O
developed	O
at	O
McGill	O
University	O
in	O
the	O
1970s	O
from	O
an	O
early	O
IBM	O
time-sharing	B-General_Concept
system	I-General_Concept
called	O
RAX	B-Application
(	O
Remote	B-Application
Access	I-Application
Computing	I-Application
System	I-Application
)	O
.	O
</s>
<s>
The	O
system	O
ran	O
on	O
IBM	B-Application
S/360	I-Application
,	O
S/370	B-Device
,	O
and	O
4300-series	B-Device
mainframe	B-Device
hardware	O
,	O
and	O
offered	O
then-novel	O
features	O
such	O
as	O
file	B-Application
access	I-Application
control	O
and	O
data	B-General_Concept
compression	I-General_Concept
.	O
</s>
<s>
It	O
was	O
designed	O
to	O
allow	O
academics	O
and	O
students	O
to	O
create	O
and	O
run	O
their	O
programs	O
interactively	O
on	O
terminals	B-General_Concept
,	O
in	O
an	O
era	O
when	O
most	O
mainframe	B-Device
computing	O
was	O
still	O
being	O
done	O
from	O
punched	B-Architecture
cards	I-Architecture
.	O
</s>
<s>
MUSIC	O
was	O
originally	O
designed	O
as	O
a	O
stand-alone	O
operating	O
system	O
but	O
with	O
the	O
advent	O
of	O
IBM	O
's	O
virtual	O
machine	O
facility	O
,	O
VM/370	B-Application
,	O
it	O
became	O
more	O
common	O
to	O
deploy	O
MUSIC	O
as	O
a	O
guest	O
operating	O
system	O
running	O
under	O
VM/370	B-Application
.	O
</s>
<s>
1966	O
–	O
IBM	B-Application
Remote	I-Application
Access	I-Application
Computing	I-Application
System	O
(	O
RAX	B-Application
)	O
released	O
.	O
</s>
<s>
1972	O
–	O
McGill	O
's	O
RAX	B-Application
modifications	O
accepted	O
by	O
IBM	O
for	O
distribution	O
as	O
"	O
Installed	O
User	O
Program	O
"	O
under	O
the	O
name	O
of	O
"	O
McGill	O
University	O
System	O
for	O
Interactive	O
Computing	O
"	O
(	O
MUSIC	O
)	O
.	O
</s>
<s>
1978	O
–	O
MUSIC	O
4.0	O
Major	O
change	O
to	O
file	B-Application
system	I-Application
providing	O
longer	O
file	O
names	O
and	O
advanced	O
access	O
control	O
.	O
</s>
<s>
1981	O
–	O
MUSIC	O
5.0	O
Support	O
for	O
IBM	B-Device
4300	I-Device
series	I-Device
CPUs	O
and	O
FBA	B-Device
disks	O
.	O
</s>
<s>
1985	O
–	O
MUSIC/SP	B-Application
1.0	O
Adopted	O
by	O
IBM	O
as	O
"	O
System	O
Product	O
"	O
.	O
</s>
<s>
Support	O
for	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
1990	O
–	O
MUSIC/SP	B-Application
2.2	O
,	O
described	O
by	O
IBM	O
as	O
having	O
"	O
significant	O
enhancements.	O
"	O
</s>
<s>
1991	O
–	O
MUSIC/SP	B-Application
2.3	O
Internet	O
support	O
and	O
tree-structured	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Over	O
the	O
years	O
the	O
following	O
people	O
contributed	O
to	O
the	O
MUSIC	O
and	O
MUSIC/SP	B-Application
systems	O
.	O
</s>
<s>
The	O
MUSIC/SP	B-Application
file	B-Application
system	I-Application
was	O
unique	O
in	O
a	O
number	O
of	O
respects	O
.	O
</s>
<s>
The	O
owner	O
's	O
userid	B-Application
and	O
the	O
file	O
name	O
were	O
hashed	O
to	O
locate	O
the	O
file	O
in	O
this	O
index	O
,	O
so	O
any	O
file	O
on	O
the	O
system	O
could	O
be	O
located	O
with	O
a	O
single	O
I/O	O
operation	O
.	O
</s>
<s>
However	O
,	O
this	O
presented	O
a	O
flat	O
file	B-Application
system	I-Application
to	O
the	O
user	O
.	O
</s>
<s>
It	O
lacked	O
the	O
directory	O
structure	O
commonly	O
offered	O
by	O
DOS	B-Device
,	O
Microsoft	B-Application
Windows	I-Application
and	O
Unix	B-Application
systems	I-Application
.	O
</s>
<s>
In	O
1990	O
a	O
"	O
tree-structured	O
"	O
directory	O
view	O
of	O
the	O
file	B-Application
system	I-Application
was	O
overlaid	O
on	O
this	O
,	O
bringing	O
the	O
system	O
more	O
in	O
line	O
with	O
the	O
file	B-Application
systems	I-Application
that	O
were	O
then	O
available	O
.	O
</s>
<s>
The	O
file	B-Application
system	I-Application
had	O
a	O
fairly	O
sophisticated	O
access	O
control	O
scheme	O
allowing	O
the	O
owner	O
to	O
control	O
who	O
could	O
read	O
,	O
write	O
,	O
append	O
to	O
and	O
execute	O
the	O
file	O
.	O
</s>
<s>
The	O
initial	O
versions	O
of	O
the	O
system	O
provided	O
no	O
support	O
for	O
virtual	B-Architecture
memory	I-Architecture
and	O
address	O
translation	O
.	O
</s>
<s>
Virtual	B-Architecture
memory	I-Architecture
support	O
was	O
introduced	O
in	O
1985	O
.	O
</s>
<s>
System	O
performance	O
was	O
also	O
improved	O
by	O
pre-loading	O
commonly	O
used	O
modules	O
into	O
virtual	B-Architecture
memory	I-Architecture
at	O
startup	O
time	O
where	O
they	O
could	O
be	O
available	O
to	O
all	O
users	O
simultaneously	O
.	O
</s>
<s>
The	O
system	O
nucleus	B-Operating_System
was	O
written	O
in	O
IBM/370	B-Device
assembler	O
but	O
most	O
of	O
the	O
native	O
applications	O
were	O
written	O
in	O
FORTRAN	B-Application
.	O
</s>
<s>
The	O
system	O
supported	O
the	O
Waterloo	O
WATFIV	B-Language
and	O
WATBOL	B-Application
compilers	O
and	O
also	O
provided	O
compilers	O
for	O
Pascal	B-Application
,	O
C	O
,	O
PL/I	B-Language
,	O
BASIC	O
,	O
APL	B-Language
,	O
ALGOL	B-Language
,	O
RPG	B-Language
,	O
and	O
GPSS	B-Language
.	O
</s>
<s>
The	O
system	O
was	O
missing	O
a	O
command	O
scripting	O
language	O
until	O
REXX	B-Language
was	O
ported	O
from	O
CMS	O
in	O
1984	O
.	O
</s>
<s>
Later	O
,	O
in	O
1986	O
,	O
a	O
complete	O
user	O
interface	O
was	O
written	O
entirely	O
in	O
REXX	B-Language
.	O
</s>
<s>
E-mail	O
was	O
one	O
of	O
the	O
major	O
applications	O
on	O
MUSIC/SP	B-Application
.	O
</s>
<s>
As	O
the	O
networks	O
developed	O
,	O
this	O
was	O
expanded	O
to	O
provide	O
access	O
to	O
BITNET	B-General_Concept
and	O
Internet	O
based	O
e-mail	O
.	O
</s>
<s>
MUSIC/SP	B-Application
did	O
not	O
have	O
direct	O
access	O
to	O
the	O
Internet	O
until	O
1990	O
,	O
when	O
the	O
University	O
of	O
Wisconsin	O
WiscNet	O
TCP/IP	B-Protocol
code	O
was	O
ported	O
to	O
the	O
system	O
,	O
allowing	O
the	O
system	O
to	O
provide	O
access	O
to	O
all	O
Internet	B-Protocol
services	I-Protocol
.	O
</s>
<s>
A	O
major	O
feature	O
of	O
the	O
system	O
was	O
its	O
ability	O
to	O
run	O
programs	O
that	O
were	O
designed	O
to	O
run	O
on	O
IBM	O
's	O
mainstream	O
operating	O
system	O
(	O
MVS	B-Application
)	O
.	O
</s>
<s>
This	O
was	O
accomplished	O
using	O
an	O
MVS	B-Application
emulator	O
that	O
intercepted	O
system	O
calls	O
at	O
the	O
Supervisor	B-Operating_System
Call	I-Operating_System
instruction	I-Operating_System
(	O
SVC	O
)	O
level	O
.	O
</s>
<s>
Rather	O
than	O
write	O
their	O
own	O
version	O
of	O
an	O
application	O
,	O
the	O
MUSIC/SP	B-Application
developers	O
would	O
usually	O
start	O
from	O
the	O
MVS	B-Application
version	O
and	O
rebuild	O
it	O
to	O
run	O
in	O
MVS	B-Application
emulation	O
mode	O
.	O
</s>
<s>
Since	O
the	O
MVS	B-Application
emulation	O
was	O
a	O
small	O
subset	O
of	O
the	O
real	O
thing	O
,	O
the	O
applications	O
generally	O
ran	O
more	O
efficiently	O
on	O
MUSIC/SP	B-Application
.	O
</s>
<s>
One	O
major	O
advantage	O
the	O
system	O
had	O
in	O
educational	O
environments	O
was	O
that	O
through	O
the	O
use	O
of	O
special	O
lines	O
called	O
"	O
control	O
cards	O
"	O
at	O
the	O
top	O
of	O
a	O
file	O
,	O
source	O
files	O
for	O
any	O
supported	O
language	O
could	O
be	O
automatically	O
directed	O
to	O
the	O
appropriate	O
compiler	O
(	O
Fortran	B-Application
being	O
the	O
default	O
)	O
,	O
compiled	O
,	O
linked	O
,	O
and	O
executed	O
,	O
(	O
with	O
compilation	O
,	O
linkage	O
,	O
and	O
execution	O
options	O
also	O
specified	O
in	O
control	O
cards	O
)	O
simply	O
by	O
entering	O
the	O
filename	O
on	O
a	O
command	O
line	O
.	O
</s>
<s>
A	O
wide	O
variety	O
of	O
terminals	B-General_Concept
were	O
supported	O
as	O
of	O
1980	O
,	O
including	O
both	O
EBCDIC-based	O
units	O
using	O
IBM-proprietary	O
protocols	O
,	O
and	O
asynchronous	O
ASCII-based	O
units	O
.	O
</s>
<s>
Since	O
terminals	B-General_Concept
were	O
connected	O
through	O
various	O
types	O
of	O
front-end	B-General_Concept
processors	I-General_Concept
(	O
as	O
per	O
common	O
IBM	O
timesharing	B-General_Concept
practice	O
both	O
then	O
and	O
now	O
)	O
,	O
and	O
could	O
therefore	O
function	O
without	O
CPU	O
attention	O
for	O
a	O
considerable	O
amount	O
of	O
time	O
,	O
MUSIC	O
used	O
variable-length	O
time	O
slices	O
,	O
which	O
could	O
,	O
on	O
compute-bound	O
processing	O
,	O
reach	O
a	O
maximum	O
of	O
several	O
seconds	O
per	O
time	O
slice	O
;	O
conversely	O
,	O
if	O
a	O
user	O
filled	O
the	O
output	O
buffer	O
or	O
reached	O
a	O
conversational	O
read	O
,	O
the	O
timeslice	O
would	O
end	O
immediately	O
.	O
</s>
<s>
The	O
Sim390	O
emulator	O
contains	O
a	O
demonstration	O
system	O
of	O
MUSIC/SP	B-Application
.	O
</s>
<s>
It	O
is	O
freely	O
available	O
and	O
runs	O
on	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
demonstration	O
system	O
will	O
also	O
run	O
under	O
Hercules	B-Application
.	O
</s>
