<s>
270x	B-Device
is	O
a	O
generic	O
name	O
for	O
a	O
family	O
of	O
IBM	O
non-programmable	O
communications	B-General_Concept
controllers	I-General_Concept
used	O
with	O
System/360	B-Application
and	O
System/370	B-Device
computers	O
.	O
</s>
<s>
The	O
2701	O
and	O
2702	O
were	O
announced	O
simultaneously	O
with	O
System/360	B-Application
in	O
1964	O
,	O
the	O
2703	O
was	O
announced	O
a	O
year	O
later	O
.	O
</s>
<s>
The	O
270x	B-Device
series	O
was	O
superseded	O
by	O
the	O
IBM	B-Device
3704	I-Device
and	I-Device
3705	I-Device
communications	I-Device
controllers	I-Device
in	O
1972	O
.	O
</s>
<s>
It	O
had	O
two	O
multiplexor	O
channel	B-Device
interfaces	I-Device
for	O
connection	O
to	O
one	O
or	O
two	O
host	O
computers	O
.	O
</s>
<s>
The	O
synchronous	O
adapter	O
originally	O
supported	O
the	O
Synchronous	O
Transmit-Receive	O
(	O
STR	O
)	O
protocol	O
,	O
and	O
later	O
Binary	B-Protocol
Synchronous	I-Protocol
Communications	I-Protocol
(	O
BISYNC	B-Protocol
)	O
when	O
it	O
was	O
introduced	O
in	O
1967	O
,	O
in	O
half	O
duplex	O
mode	O
at	O
speeds	O
of	O
up	O
to	O
40,800	O
bitspersecond( 	O
bit/s	O
)	O
.	O
</s>
<s>
Later	O
the	O
IBM	O
2740	O
and	O
IBM	O
2741	O
Communication	O
Terminals	O
,	O
and	O
the	O
IBM	B-Device
2260/2848	I-Device
were	O
added	O
.	O
</s>
<s>
The	O
System/360	B-Application
Configurator	O
indicates	O
that	O
in	O
the	O
2702	O
supported	O
start-stop	O
lines	O
only	O
.	O
</s>
<s>
The	O
2703	O
supported	O
up	O
to	O
176	O
half-duplex	O
start-stop	O
or	O
Binary	B-Protocol
Synchronous	I-Protocol
communication	O
lines	O
.	O
</s>
<s>
Many	O
companies	O
produced	O
clones	O
of	O
270x	B-Device
controllers	O
,	O
such	O
as	O
the	O
Memorex	O
1270	O
,	O
introduced	O
in	O
1970	O
,	O
and	O
devices	O
from	O
NCR-Comten	O
.	O
</s>
