<s>
VNET	B-General_Concept
is	O
an	O
international	O
computer	B-Architecture
networking	I-Architecture
system	I-Architecture
deployed	O
in	O
the	O
mid-1970s	O
and	O
still	O
in	O
current	O
,	O
but	O
highly	O
diminished	O
use	O
.	O
</s>
<s>
VNET	B-General_Concept
was	O
first	O
deployed	O
as	O
a	O
private	O
host	O
to	O
host	O
network	O
among	O
CP/67	O
and	O
VM/370	B-Application
mainframes	O
beginning	O
before	O
1975	O
.	O
</s>
<s>
It	O
was	O
based	O
on	O
RSCS	B-Application
,	O
a	O
virtual	B-Architecture
machine	I-Architecture
–	O
based	O
communications	O
program	O
and	O
an	O
inter	O
machine	O
protocol	O
developed	O
in	O
IBM	O
's	O
Advanced	O
Systems	O
Development	O
Division	O
's	O
Remote	O
Service	O
System	O
(	O
RSS	O
)	O
prototype	O
which	O
produced	O
some	O
of	O
the	O
technology	O
in	O
the	O
IBM	O
Tivoli	O
product	O
.	O
</s>
<s>
RSCS	B-Application
used	O
the	O
Binary	B-Protocol
Synchronous	I-Protocol
Communications	I-Protocol
(	O
BSC	O
)	O
protocol	O
,	O
not	O
SNA/SDLC	O
,	O
to	O
support	O
file	O
to	O
file	O
transfer	O
among	O
virtual	B-Architecture
machine	I-Architecture
users	O
.	O
</s>
<s>
RSCS-compatible	O
communications	O
code	O
was	O
subsequently	O
developed	O
for	O
MVT/HASP	O
,	O
MVT/ASP	O
and	O
MVS	B-Application
mainframe	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Unlike	O
the	O
Internet	O
,	O
VNET	B-General_Concept
switched	O
files	O
among	O
mainframes	O
using	O
a	O
store	O
and	O
forward	O
technique	O
.	O
</s>
<s>
The	O
first	O
widely	O
disruptive	O
computer	O
worm	O
,	O
"	O
Christmas	O
Tree	O
EXEC	O
"	O
in	O
December	O
1987	O
,	O
originated	O
on	O
BITNET	B-General_Concept
and	O
spread	O
to	O
this	O
network	O
.	O
</s>
