<s>
Basic	B-Application
Telecommunications	I-Application
Access	I-Application
Method	I-Application
(	O
BTAM	B-Application
)	O
is	O
a	O
low-level	O
programming	O
interface	O
specified	O
by	O
IBM	O
for	O
use	O
on	O
the	O
IBM	B-Application
System/360	I-Application
for	O
start-stop	O
and	O
binary	B-Protocol
synchronous	I-Protocol
telecommunications	O
terminals	O
.	O
</s>
<s>
Later	O
,	O
IBM	O
specified	O
higher-level	O
interfaces	O
QTAM	B-Application
and	O
TCAM	B-Application
.	O
</s>
<s>
BTAM	B-Application
was	O
superseded	O
by	O
VTAM	B-Application
for	O
Systems	B-Architecture
Network	I-Architecture
Architecture	I-Architecture
(	O
SNA	O
)	O
devices	O
.	O
</s>
<s>
BTAM	B-Application
continued	O
to	O
be	O
supported	O
in	O
later	O
iterations	O
of	O
the	O
system	O
architecture	O
,	O
and	O
IBM	O
finally	O
withdrew	O
support	O
in	O
2000	O
.	O
</s>
<s>
BTAM	B-Application
requires	O
the	O
application	O
program	O
or	O
transaction	B-Application
processing	I-Application
system	I-Application
to	O
handle	O
almost	O
every	O
detail	O
of	O
the	O
protocol	O
.	O
</s>
<s>
BTAM	B-Application
is	O
an	O
access	O
method	O
for	O
interactively	O
communicating	O
with	O
remote	O
terminals	O
,	O
usually	O
connected	O
through	O
a	O
front	B-General_Concept
end	I-General_Concept
processor	I-General_Concept
such	O
as	O
a	O
270x	B-Device
communications	I-Device
controller	I-Device
,	O
although	O
support	O
for	O
local	O
channel-attached	O
3270	B-Operating_System
terminals	I-Operating_System
is	O
included	O
.	O
</s>
<s>
BTAM	B-Application
dynamically	O
builds	O
Channel	O
command	O
words	O
(	O
CCWs	O
)	O
for	O
reading	O
,	O
writing	O
and	O
"	B-General_Concept
polling	I-General_Concept
"	I-General_Concept
terminals	O
and	O
deals	O
with	O
specific	O
responses	O
from	O
those	O
terminals	O
,	O
according	O
to	O
the	O
success	O
or	O
failure	O
of	O
the	O
communication	O
channel	O
.	O
</s>
<s>
BTAM	B-Application
was	O
a	O
key	O
component	O
in	O
IBM	O
's	O
early	O
transaction	B-Application
processing	I-Application
systems	I-Application
such	O
as	O
MTCS	B-Application
,	O
CICS	B-Application
and	O
IMS	B-Application
and	O
underpinned	O
the	O
rise	O
of	O
online	O
transaction	B-General_Concept
processing	I-General_Concept
for	O
many	O
large	O
commercial	O
banks	O
and	O
insurance	O
companies	O
.	O
</s>
<s>
It	O
was	O
not	O
unusual	O
for	O
BTAM	B-Application
and	O
later	O
developed	O
access	O
methods	O
(	O
such	O
as	O
VTAM	B-Application
)	O
to	O
co-exist	O
,	O
supporting	O
different	O
devices	O
simultaneously	O
under	O
the	O
same	O
transaction	B-Application
processing	I-Application
system	I-Application
.	O
</s>
<s>
Material	O
in	O
this	O
section	O
taken	O
from	O
IBM	B-Application
System/360	I-Application
Operating	O
System	O
Basic	B-Application
Telecommunications	I-Application
Access	I-Application
Method	I-Application
;	O
GC30-2004-6	O
.	O
</s>
<s>
BTAM	B-Application
programming	O
requires	O
detailed	O
knowledge	O
of	O
the	O
characteristics	O
of	O
the	O
specific	O
terminals	O
to	O
be	O
used	O
.	O
</s>
<s>
DEVD	O
=	O
BS	O
can	O
be	O
coded	O
to	O
specify	O
a	O
Binary	B-Protocol
Synchronous	I-Protocol
(	O
Bisync	B-Protocol
)	O
line	O
.	O
</s>
<s>
This	O
macro	O
specifies	O
the	O
line	O
characteristicsstart-stop	O
,	O
bisync	B-Protocol
,	O
point-to-point	O
,	O
multipoint	O
,	O
leased	O
line	O
or	O
dial	O
and	O
the	O
type	O
of	O
polling	B-General_Concept
required	O
wrap	O
around	O
or	O
open	O
.	O
</s>
<s>
The	O
polling	B-General_Concept
characters	O
or	O
telephone	O
number	O
used	O
to	O
identify	O
each	O
specific	O
remote	O
device	O
on	O
the	O
line	O
are	O
coded	O
.	O
</s>
<s>
A	O
wrap-around	O
polling	B-General_Concept
list	O
will	O
cause	O
each	O
device	O
in	O
the	O
list	O
to	O
be	O
polled	O
sequentially	O
by	O
the	O
channel	O
until	O
a	O
response	O
was	O
received	O
,	O
This	O
reduces	O
the	O
load	O
on	O
the	O
CPU	O
for	O
continuous	O
polling	B-General_Concept
.	O
</s>
<s>
BTAM	B-Application
can	O
construct	O
the	O
pool	O
automatically	O
or	O
the	O
programmer	O
can	O
construct	O
the	O
pool	O
in	O
various	O
ways	O
.	O
</s>
<s>
For	O
read	O
operations	O
BTAM	B-Application
will	O
automatically	O
obtain	O
one	O
or	O
more	O
buffers	O
from	O
the	O
pool	O
and	O
store	O
the	O
received	O
message	O
.	O
</s>
<s>
Tha	O
ASMTRTAB	O
and	O
TRNSLATE	O
include	O
translation	O
tables	O
and	O
translate	O
to	O
and	O
from	O
non	O
EBCDIC	B-Language
character	O
codes	O
.	O
</s>
<s>
The	O
standard	O
OS/360	O
OPEN	O
and	O
CLOSE	O
macros	O
are	O
used	O
to	O
initiate	O
and	O
terminate	O
processing	O
of	O
a	O
BTAM	B-Application
line	O
.	O
</s>
<s>
BTAM	B-Application
provides	O
a	O
large	O
number	O
of	O
options	O
for	O
the	O
READ	O
and	O
WRITE	O
macros	O
,	O
depending	O
on	O
the	O
line	O
and	O
terminal	O
types	O
and	O
the	O
current	O
status	O
.	O
</s>
<s>
The	O
RESETPL	O
macro	O
cancels	O
an	O
outstanding	O
read	O
and/or	O
stops	O
polling	B-General_Concept
on	O
a	O
line	O
.	O
</s>
<s>
Amongst	O
many	O
other	O
devices	O
supported	O
,	O
BTAM	B-Application
handles	O
:	O
</s>
