<s>
VPS/VM	B-Application
(	O
Virtual	B-Architecture
Processing	I-Architecture
System/Virtual	O
Machine	O
)	O
was	O
an	O
operating	B-General_Concept
system	I-General_Concept
that	O
ran	O
on	O
IBM	B-Device
System/370	I-Device
–	O
IBM	B-Device
3090	I-Device
computers	O
at	O
Boston	O
University	O
in	O
general	O
use	O
from	O
1977	O
to	O
around	O
1990	O
,	O
and	O
in	O
limited	O
use	O
until	O
at	O
least	O
1993	O
.	O
</s>
<s>
During	O
the	O
1980s	O
,	O
VPS/VM	B-Application
was	O
the	O
main	O
operating	B-General_Concept
system	I-General_Concept
of	O
Boston	O
University	O
and	O
often	O
ran	O
up	O
to	O
250	O
users	O
at	O
a	O
time	O
when	O
rival	O
VM/CMS	B-Application
computing	O
systems	O
could	O
only	O
run	O
120	O
or	O
so	O
users	O
.	O
</s>
<s>
Each	O
user	O
ran	O
in	O
a	O
Virtual	B-Architecture
Machine	I-Architecture
under	O
VM	B-Application
,	O
an	O
IBM	O
hypervisor	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
VM	B-Application
provided	O
the	O
virtual	O
IBM	B-Device
370	I-Device
machine	O
which	O
the	O
VPS	O
operating	B-General_Concept
system	I-General_Concept
ran	O
under	O
.	O
</s>
<s>
The	O
VM	B-Application
code	O
was	O
modified	O
to	O
allow	O
all	O
the	O
VPS	O
virtual	B-Architecture
machines	I-Architecture
to	O
share	O
pages	O
of	O
storage	O
with	O
read	O
and	O
write	O
access	O
.	O
</s>
<s>
VPS	O
utilized	O
a	O
shared	O
nucleus	O
,	O
as	O
well	O
as	O
pages	O
used	O
to	O
facilitate	O
passing	O
data	O
from	O
one	O
VPS	O
virtual	B-Architecture
machine	I-Architecture
to	O
another	O
.	O
</s>
<s>
This	O
organization	O
is	O
very	O
similar	O
to	O
that	O
of	O
MVS	B-Application
;	O
substituting	O
Address	O
Spaces	O
for	O
Virtual	B-Architecture
Machines	I-Architecture
.	O
</s>
<s>
An	O
IBM-based	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
quite	O
like	O
some	O
DOS/VSE	B-Application
time	B-Application
sharing	I-Application
options	I-Application
,	O
VPS/VM	B-Application
provided	O
the	O
user	O
an	O
IBM	B-Operating_System
3270	I-Operating_System
full	O
screen	O
terminal	O
(	O
a	O
green	O
screen	O
)	O
and	O
a	O
user	O
interface	O
that	O
was	O
like	O
VM/CMS	B-Application
.	O
</s>
<s>
Each	O
user	O
had	O
an	O
11	O
megabyte	O
virtual	B-Architecture
machine	I-Architecture
(	O
with	O
a	O
strange	O
3	O
megabyte	O
memory	O
gap	O
in	O
the	O
middle	O
)	O
and	O
,	O
from	O
1984	O
onwards	O
,	O
could	O
run	O
several	O
programs	O
at	O
a	O
time	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
was	O
sparsely	O
documented	O
but	O
was	O
written	O
first	O
by	O
Charles	O
Brown	O
,	O
a	O
BU	O
doctoral	O
student	O
,	O
and	O
John	O
H	O
.	O
Porter	O
,	O
a	O
physics	O
PHD	O
,	O
who	O
later	O
became	O
the	O
head	O
of	O
the	O
VPS	O
project	O
(	O
and	O
eventually	O
Boston	O
University	O
's	O
vice	O
president	O
for	O
information	O
systems	O
and	O
technology	O
)	O
.	O
</s>
<s>
Marian	O
Moore	O
wrote	O
much	O
of	O
the	O
later	O
VM	B-Application
code	O
necessary	O
to	O
run	O
the	O
VPS	O
system	O
.	O
</s>
<s>
Josie	O
Bondoc	O
wrote	O
some	O
of	O
the	O
later	O
VPS	O
additions	O
,	O
like	O
UNIX	B-Application
piping	O
.	O
</s>
<s>
Many	O
MVS/VM	O
programs	O
ran	O
on	O
VPS/VM	B-Application
,	O
such	O
as	O
XEDIT	B-Application
,	O
and	O
compilers	B-Language
for	O
Pascal	B-Application
,	O
PL/1	B-Language
,	O
C	B-Language
and	O
Cobol	B-Application
.	O
</s>
<s>
These	O
MVS/VM	O
programs	O
ran	O
under	O
an	O
OS	O
simulation	O
program	O
that	O
simulated	O
the	O
OS/VM	O
supervisor	O
calls	O
(	O
SVCs	O
)	O
.	O
</s>
<s>
Michael	O
Krugman	O
wrote	O
some	O
of	O
the	O
early	O
main	O
utilities	O
such	O
as	O
IFMSG	O
,	O
the	O
JCL	B-Application
language	O
for	O
VPS	O
,	O
and	O
also	O
MAIL	O
,	O
the	O
early	O
email	O
program	O
.	O
</s>
<s>
SENDMAIL	O
,	O
written	O
by	O
Francis	O
Costanzo	O
,	O
implemented	O
email	O
,	O
under	O
the	O
BITNET	B-General_Concept
system	O
.	O
</s>
<s>
Some	O
pre	O
SQL	O
databases	O
installed	O
on	O
VPS	O
were	O
FOCUS	O
and	O
NOMAD2	B-Application
.	O
</s>
<s>
The	O
graphics	O
department	O
,	O
under	O
Glenn	O
Bresnahan	O
,	O
essentially	O
,	O
ported	O
over	O
most	O
of	O
the	O
UNIX	B-Application
utilities	O
in	O
the	O
mid	O
1980s	O
.	O
</s>
<s>
William	O
Marshall	O
did	O
much	O
of	O
the	O
early	O
system	O
documentation	O
,	O
as	O
well	O
as	O
providing	O
PL/1	B-Language
support	O
.	O
</s>
<s>
VPS/VM	B-Application
was	O
a	O
working	O
pre-GUI	O
IBM	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
could	O
often	O
run	O
more	O
users	O
than	O
other	O
IBM	O
TSO-based	O
systems	O
.	O
</s>
<s>
When	O
most	O
University-based	O
systems	O
only	O
provided	O
editors	B-Application
and	O
compilers	B-Language
,	O
VPS	O
provided	O
these	O
services	O
to	O
a	O
10,000	O
BU	O
university	O
community	O
for	O
over	O
10	O
years	O
.	O
</s>
<s>
VPS/VM	B-Application
policy	O
was	O
for	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
main	O
utilities	O
to	O
be	O
written	O
in	O
IBM	B-Device
370	I-Device
assembler	B-Language
language	I-Language
.	O
</s>
<s>
This	O
decision	O
restricted	O
the	O
development	O
of	O
the	O
system	O
and	O
it	O
ultimately	O
could	O
not	O
compete	O
with	O
the	O
UNIX-based	O
systems	O
which	O
eventually	O
replaced	O
it	O
.	O
</s>
<s>
However	O
,	O
VPS	O
eventually	O
modeled	O
many	O
of	O
the	O
features	O
of	O
then-current	O
operating	B-General_Concept
systems	I-General_Concept
around	O
the	O
world	O
and	O
was	O
a	O
keen	O
trainer	O
for	O
many	O
companies	O
that	O
needed	O
IBM370	O
assembler	B-Language
programmers	O
in	O
the	O
1980s	O
.	O
</s>
