<s>
NCSA	B-Protocol
Telnet	I-Protocol
is	O
an	O
implementation	O
of	O
the	O
Telnet	B-Protocol
protocol	O
developed	O
at	O
the	O
National	B-General_Concept
Center	I-General_Concept
for	I-General_Concept
Supercomputing	I-General_Concept
Applications	I-General_Concept
of	O
the	O
University	O
of	O
Illinois	O
at	O
Urbana-Champaign	O
,	O
first	O
released	O
in	O
1986	O
and	O
continuously	O
developed	O
until	O
1995	O
.	O
</s>
<s>
The	O
initial	O
implementation	O
ran	O
under	O
Mac	B-Application
OS	I-Application
and	O
Microsoft	B-Application
MS-DOS	I-Application
,	O
and	O
provided	O
basic	O
DEC	B-Device
VT102	I-Device
terminal	O
emulation	O
with	O
support	O
for	O
multiple	O
simultaneous	O
connections	O
and	O
an	O
internal	O
FTP	B-Protocol
server	O
.	O
</s>
<s>
NCSA	B-Protocol
Telnet	I-Protocol
was	O
the	O
first	O
implementation	O
of	O
telnet	B-Protocol
for	O
the	O
Macintosh	B-Device
or	O
PC	O
that	O
provided	O
the	O
ability	O
to	O
connect	O
to	O
multiple	O
hosts	O
simultaneously	O
.	O
</s>
<s>
Support	O
for	O
Tektronix	O
4010/4014	O
vector	O
terminal	O
emulation	O
and	O
a	O
protocol	O
for	O
downloading	O
and	O
viewing	O
raster	O
images	O
were	O
added	O
.	O
</s>
<s>
In	O
1987	O
,	O
a	O
short-lived	O
version	O
for	O
Sun	O
Microsystems	O
SunOS	B-Operating_System
was	O
released	O
.	O
</s>
<s>
Although	O
the	O
MS-DOS	B-Application
version	O
of	O
NCSA	B-Protocol
Telnet	I-Protocol
lost	O
popularity	O
after	O
Microsoft	O
Windows	O
became	O
widespread	O
,	O
the	O
Macintosh	B-Device
version	O
remained	O
in	O
use	O
throughout	O
the	O
1990s	O
as	O
a	O
basic	O
connectivity	O
tool	O
in	O
academic	O
and	O
commercial	O
installations	O
.	O
</s>
<s>
NCSA	B-Protocol
Telnet	I-Protocol
originally	O
used	O
a	O
built-in	O
TCP/IP	B-Protocol
protocol	I-Protocol
stack	I-Protocol
to	O
communicate	O
over	O
the	O
network	O
.	O
</s>
<s>
As	O
standard	O
APIs	B-Application
became	O
available	O
for	O
network	O
communication	O
,	O
the	O
program	O
was	O
adapted	O
to	O
use	O
them	O
,	O
most	O
notably	O
Apple	O
's	O
MacTCP	B-Operating_System
.	O
</s>
<s>
However	O
,	O
the	O
built-in	O
stack	O
,	O
one	O
of	O
the	O
few	O
completely	O
independently	O
developed	O
TCP/IP	B-Protocol
stacks	I-Protocol
in	O
use	O
at	O
the	O
time	O
,	O
continued	O
to	O
ship	O
in	O
the	O
software	O
for	O
years	O
.	O
</s>
