<s>
Synchronous	B-Protocol
transmit-receive	I-Protocol
(	O
STR	O
)	O
was	O
an	O
early	O
IBM	O
character-oriented	O
communications	O
protocol	O
which	O
preceded	O
Bisync	B-Protocol
.	O
</s>
<s>
The	O
IBM	B-Protocol
1009	I-Protocol
Data	O
Transmission	O
Unit	O
,	O
the	O
IBM	B-Device
1130	I-Device
Synchronous	O
Communications	O
Adapter	O
,	O
the	O
IBM	B-Application
System/360	I-Application
model	O
20	O
Communications	O
Adapter	O
,	O
and	O
the	O
IBM	B-Device
2701	I-Device
Data	O
Transmission	O
Unit	O
provided	O
host	O
computer	O
support	O
for	O
STR	O
.	O
</s>
<s>
The	O
IBM	B-Device
7701	I-Device
,	O
the	O
IBM	B-Device
7702	I-Device
Magnetic	O
Tape	O
Transmission	O
Terminal	O
,	O
the	O
IBM	B-Device
1013	I-Device
Card	O
Transmission	O
Terminal	O
,	O
and	O
the	O
IBM	O
7710	O
and	O
IBM	O
7711	O
Data	O
Communication	O
Units	O
were	O
among	O
the	O
remote	O
devices	O
supported	O
by	O
STR	O
.	O
</s>
<s>
Like	O
other	O
kinds	O
of	O
6b/8b	B-Protocol
encoding	I-Protocol
,	O
exactly	O
four	O
bits	O
of	O
each	O
character	O
were	O
one	O
bits	O
there	O
are	O
70	O
such	O
possible	O
bit	O
combinations	O
.	O
</s>
<s>
The	O
second	O
column	O
of	O
graphics	O
is	O
for	O
the	O
1130	O
SCA	O
,	O
graphics	O
are	O
shown	O
only	O
if	O
different	O
from	O
the	O
7701	O
,	O
mostly	O
characters	O
from	O
the	O
EBCDIC	B-Language
character	O
set	O
which	O
were	O
not	O
present	O
in	O
BCD	O
.	O
</s>
<s>
These	O
are	O
the	O
synchronous	B-Protocol
transmit-receive	I-Protocol
control	O
codes	O
.	O
</s>
