<s>
3+Share	B-General_Concept
,	O
also	O
known	O
simply	O
as	O
3+	O
or	O
3	O
Plus	O
,	O
was	O
a	O
pioneering	O
file	B-Application
and	O
print	B-Application
sharing	I-Application
product	O
from	O
3Com	O
.	O
</s>
<s>
Introduced	O
in	O
the	O
early	O
1980s	O
,	O
3+Share	B-General_Concept
was	O
competitive	O
with	O
Novell	O
's	O
NetWare	B-Operating_System
in	O
the	O
network	B-Application
server	I-Application
business	O
throughout	O
the	O
1980s	O
.	O
</s>
<s>
It	O
was	O
replaced	O
by	O
the	O
joint	O
Microsoft-3Com	O
LAN	B-Algorithm
Manager	I-Algorithm
in	O
1990	O
,	O
but	O
3Com	O
exited	O
the	O
server	O
market	O
in	O
1991	O
.	O
</s>
<s>
In	O
1984	O
,	O
Microsoft	O
announced	O
MS-Net	B-Application
,	O
a	O
framework	O
for	O
building	O
multitasking	B-Operating_System
network	B-Application
servers	I-Application
that	O
ran	O
on	O
top	O
of	O
single-tasking	O
MS-DOS	B-Application
.	O
</s>
<s>
MS-Net	B-Application
implemented	O
only	O
the	O
basic	O
services	O
for	O
file	B-Application
and	O
print	B-Application
sharing	I-Application
,	O
and	O
left	O
out	O
the	O
actual	O
networking	O
protocol	B-Protocol
stack	I-Protocol
in	O
favor	O
of	O
a	O
virtual	O
system	O
in	O
the	O
form	O
of	O
IBM	O
's	O
NetBIOS	B-Protocol
.	O
</s>
<s>
Vendors	O
,	O
like	O
3Com	O
,	O
licensed	O
the	O
MS-Net	B-Application
system	O
and	O
then	O
added	O
device	B-Application
drivers	I-Application
and	O
other	O
parts	O
of	O
the	O
protocol	B-Protocol
stack	I-Protocol
to	O
implement	O
a	O
complete	O
server	O
system	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
3+Share	B-General_Concept
,	O
3Com	O
based	O
their	O
networking	O
solution	O
on	O
the	O
seminal	O
Xerox	B-Protocol
Network	I-Protocol
Systems	I-Protocol
(	O
XNS	B-Protocol
)	O
,	O
which	O
3Com	O
's	O
CEO	O
Robert	O
Metcalfe	O
had	O
helped	O
design	O
.	O
</s>
<s>
XNS	B-Protocol
provided	O
the	O
networking	O
protocol	O
as	O
well	O
as	O
connections	O
to	O
the	O
underlying	O
Ethernet	O
hardware	O
it	O
ran	O
on	O
,	O
which	O
Metcalf	O
had	O
also	O
helped	O
design	O
.	O
</s>
<s>
They	O
also	O
modified	O
MS-Net	B-Application
'	O
s	O
servers	O
to	O
produce	O
what	O
they	O
called	O
EtherShare	O
and	O
EtherPrint	O
protocols	O
,	O
which	O
could	O
be	O
accessed	O
with	O
any	O
MS-DOS	B-Application
computer	O
that	O
had	O
the	O
MS-Net	B-Application
client	O
software	O
installed	O
.	O
</s>
<s>
Internally	O
,	O
3+Share	B-General_Concept
had	O
a	O
network	B-Protocol
stack	I-Protocol
,	O
file	B-Application
and	O
print	B-Application
server	I-Application
modules	O
,	O
disk	O
caching	O
,	O
user	O
handling	O
and	O
more	O
,	O
all	O
running	O
simultaneously	O
inside	O
the	O
DOS	O
memory	O
space	O
.	O
</s>
<s>
Because	O
they	O
were	O
not	O
limited	O
by	O
the	O
PC	O
memory	O
map	O
,	O
3+Share	B-General_Concept
could	O
support	O
a	O
megabyte	O
or	O
so	O
of	O
flat	O
memory	O
,	O
breaking	O
the	O
x86	B-Operating_System
PC	I-Operating_System
's	I-Operating_System
640	B-Device
kByte	I-Device
barrier	I-Device
.	O
</s>
<s>
This	O
was	O
a	O
large	O
amount	O
of	O
RAM	B-Architecture
for	O
the	O
time	O
.	O
</s>
<s>
They	O
later	O
added	O
the	O
XNS	B-Protocol
Name	O
Service	O
,	O
which	O
mapped	O
network	O
addresses	O
to	O
human-readable	O
names	O
and	O
allowed	O
users	O
to	O
look	O
up	O
devices	O
by	O
looking	O
for	O
strings	O
like	O
"	O
3rd	O
floor	O
printer	O
"	O
.	O
</s>
<s>
Name	O
services	O
were	O
part	O
of	O
the	O
IBM-created	O
NetBIOS	B-Protocol
in	O
MS-Net	B-Application
,	O
but	O
Microsoft	O
had	O
left	O
those	O
commands	O
out	O
of	O
the	O
server	O
,	O
and	O
it	O
was	O
common	O
for	O
3rd	O
party	O
implementations	O
like	O
3+	O
to	O
add	O
these	O
sorts	O
of	O
services	O
back	O
in	O
.	O
</s>
<s>
3Com	O
soon	O
partnered	O
3+Share	B-General_Concept
with	O
dedicated	O
server	O
hardware	O
called	O
the	O
3Server	B-Application
,	O
a	O
combination	O
which	O
can	O
be	O
seen	O
to	O
be	O
the	O
first	O
network-attached	B-Application
storage	I-Application
system	O
.	O
</s>
<s>
3Com	O
and	O
Microsoft	O
jointly	O
developed	O
LAN	B-Algorithm
Manager	I-Algorithm
2.0	I-Algorithm
as	O
a	O
successor	O
to	O
3+Share	B-General_Concept
,	O
a	O
product	O
which	O
was	O
introduced	O
in	O
1990	O
.	O
</s>
<s>
3Com	O
soon	O
lost	O
interest	O
in	O
the	O
network	O
software	O
market	O
,	O
handing	O
over	O
its	O
LAN	B-Algorithm
Manager	I-Algorithm
product	O
(	O
now	O
called	O
3+Open	B-General_Concept
)	O
as	O
well	O
as	O
its	O
intellectual	O
property	O
to	O
Microsoft	O
in	O
1991	O
.	O
</s>
<s>
This	O
work	O
was	O
absorbed	O
into	O
Microsoft	O
and	O
IBM	O
's	O
Server	B-Operating_System
Message	I-Operating_System
Block	I-Operating_System
protocol	O
,	O
which	O
is	O
still	O
used	O
today	O
.	O
</s>
<s>
3+Share	B-General_Concept
client	O
drivers	O
uses	O
less	O
memory	O
than	O
corresponding	O
ones	O
for	O
LAN	B-Algorithm
Manager	I-Algorithm
.	O
</s>
<s>
3+Share	B-General_Concept
uses	O
a	O
primitive	O
security	O
mechanism	O
in	O
which	O
the	O
client	O
's	O
security	O
level	O
access	O
is	O
stored	O
in	O
the	O
client	O
's	O
RAM	B-Architecture
.	O
</s>
