<s>
ESCON	B-Device
(	O
Enterprise	B-Device
Systems	I-Device
Connection	I-Device
)	O
is	O
a	O
data	O
connection	O
created	O
by	O
IBM	O
,	O
and	O
is	O
commonly	O
used	O
to	O
connect	O
their	O
mainframe	B-Architecture
computers	I-Architecture
to	O
peripheral	O
devices	O
such	O
as	O
disk	B-Device
storage	I-Device
,	O
tape	O
drives	O
and	O
IBM	B-Operating_System
3270	I-Operating_System
display	O
controllers	O
.	O
</s>
<s>
ESCON	B-Device
is	O
an	O
optical	B-Architecture
fiber	I-Architecture
,	O
half-duplex	O
,	O
serial	B-Protocol
interface	O
.	O
</s>
<s>
IBM	O
introduced	O
ESCON	B-Device
in	O
September	O
1990	O
as	O
part	O
of	O
its	O
System/390	O
announcement	O
.	O
</s>
<s>
It	O
replaced	O
the	O
older	O
,	O
slower	O
(	O
4.5MB/s	O
)	O
,	O
copper-based	O
,	O
parallel	O
,	O
IBM	B-Application
System/360	I-Application
Bus	B-Device
and	I-Device
Tag	I-Device
channels	I-Device
technology	O
of	O
1960-1990	O
era	O
mainframes	B-Architecture
.	O
</s>
<s>
Optical	B-Architecture
fiber	I-Architecture
is	O
smaller	O
in	O
diameter	O
and	O
weight	O
,	O
and	O
hence	O
could	O
save	O
installation	O
costs	O
.	O
</s>
<s>
Space	O
and	O
labor	O
could	O
also	O
be	O
reduced	O
when	O
fewer	O
physical	O
links	O
were	O
required	O
-	O
due	O
to	O
ESCON	B-Device
's	O
switching	O
features	O
.	O
</s>
<s>
ESCON	B-Device
is	O
being	O
supplanted	O
by	O
the	O
substantially	O
faster	O
FICON	B-Architecture
,	O
which	O
runs	O
over	O
Fibre	B-Architecture
Channel	I-Architecture
.	O
</s>
<s>
ESCON	B-Device
allows	O
the	O
establishment	O
and	O
reconfiguration	O
of	O
channel	O
connections	O
dynamically	O
,	O
without	O
having	O
to	O
take	O
equipment	O
off-line	O
and	O
manually	O
move	O
the	O
cables	O
.	O
</s>
<s>
ESCON	B-Device
supports	O
channel	O
connections	O
using	O
serial	B-Protocol
transmission	I-Protocol
over	O
a	O
pair	O
of	O
fibers	O
.	O
</s>
<s>
The	O
ESCON	B-Device
Director	I-Device
supports	O
dynamic	O
switching	O
(	O
which	O
could	O
be	O
achieved	O
prior	O
to	O
ESCON	B-Device
,	O
but	O
not	O
with	O
IBM-only	O
products	O
)	O
.	O
</s>
<s>
ESCON	B-Device
switching	O
has	O
advantages	O
over	O
a	O
collection	O
of	O
point-to-point	O
links	O
.	O
</s>
<s>
A	O
peripheral	O
previously	O
capable	O
of	O
accessing	O
a	O
single	O
mainframe	B-Architecture
can	O
now	O
be	O
connected	O
simultaneously	O
to	O
up	O
to	O
eight	O
mainframes	B-Architecture
,	O
providing	O
peripheral	O
sharing	O
.	O
</s>
<s>
The	O
ESCON	B-Device
interface	O
specifications	O
were	O
adopted	O
in	O
1996	O
by	O
ANSI	O
X3T1	O
committee	O
as	O
the	O
SBCON	B-Device
standard	O
,	O
which	O
is	O
now	O
managed	O
by	O
X3T11	B-Architecture
.	O
</s>
