<s>
The	O
IBM	B-Operating_System
3270	I-Operating_System
is	O
a	O
family	O
of	O
block	O
oriented	O
display	O
and	O
printer	O
computer	B-General_Concept
terminals	I-General_Concept
introduced	O
by	O
IBM	O
in	O
1971	O
and	O
normally	O
used	O
to	O
communicate	O
with	O
IBM	B-Device
mainframes	I-Device
.	O
</s>
<s>
The	O
3270	B-Operating_System
was	O
the	O
successor	O
to	O
the	O
IBM	B-Device
2260	I-Device
display	O
terminal	O
.	O
</s>
<s>
Due	O
to	O
the	O
text	O
color	O
on	O
the	O
original	O
models	O
,	O
these	O
terminals	O
are	O
informally	O
known	O
as	O
green	B-Device
screen	I-Device
terminals	O
.	O
</s>
<s>
Unlike	O
a	O
character-oriented	B-Application
terminal	I-Application
,	O
the	O
3270	B-Operating_System
minimizes	O
the	O
number	O
of	O
I/O	B-General_Concept
interrupts	B-Application
required	O
by	O
transferring	O
large	O
blocks	O
of	O
data	O
known	O
as	O
data	B-General_Concept
streams	I-General_Concept
,	O
and	O
uses	O
a	O
high	O
speed	O
proprietary	O
communications	O
interface	O
,	O
using	O
coaxial	O
cable	O
.	O
</s>
<s>
IBM	O
no	O
longer	O
manufactures	O
3270	B-Operating_System
terminals	I-Operating_System
,	O
but	O
the	O
IBM	B-Operating_System
3270	I-Operating_System
protocol	O
is	O
still	O
commonly	O
used	O
via	O
TN3270	O
clients	O
,	O
3270	B-Application
terminal	I-Application
emulation	I-Application
or	O
web	O
interfaces	O
to	O
access	O
mainframe-based	O
applications	O
,	O
which	O
are	O
sometimes	O
referred	O
to	O
as	O
green	B-Operating_System
screen	I-Operating_System
applications	I-Operating_System
.	O
</s>
<s>
The	O
3270	B-Operating_System
series	O
was	O
designed	O
to	O
connect	O
with	O
mainframe	O
computers	O
,	O
often	O
at	O
a	O
remote	O
location	O
,	O
using	O
the	O
technology	O
then	O
available	O
in	O
the	O
early	O
1970s	O
.	O
</s>
<s>
To	O
do	O
this	O
,	O
the	O
3270	B-Operating_System
was	O
designed	O
to	O
minimize	O
the	O
amount	O
of	O
data	O
transmitted	O
,	O
and	O
minimize	O
the	O
frequency	O
of	O
interrupts	B-Application
to	O
the	O
mainframe	O
.	O
</s>
<s>
By	O
ensuring	O
the	O
CPU	B-General_Concept
is	O
not	O
interrupted	O
at	O
every	O
keystroke	O
,	O
a	O
1970s-era	O
IBM	O
3033	O
mainframe	O
fitted	O
with	O
only	O
16MB	O
of	O
main	O
memory	O
was	O
able	O
to	O
support	O
up	O
to	O
17,500	O
3270	B-Operating_System
terminals	I-Operating_System
under	O
CICS	B-Application
.	O
</s>
<s>
Most	O
3270	B-Operating_System
devices	O
are	O
clustered	O
,	O
with	O
one	O
or	O
more	O
displays	O
or	O
printers	O
connected	O
to	O
a	O
control	O
unit	O
(	O
the	O
3275	O
and	O
3276	O
included	O
an	O
integrated	O
control	O
unit	O
)	O
.	O
</s>
<s>
Originally	O
devices	O
were	O
connected	O
to	O
the	O
control	O
unit	O
over	O
coaxial	O
cable	O
;	O
later	O
Token	B-Device
Ring	I-Device
,	O
twisted	O
pair	O
,	O
or	O
Ethernet	O
connections	O
were	O
available	O
.	O
</s>
<s>
A	O
local	O
control	O
unit	O
attaches	O
directly	O
to	O
the	O
channel	B-Device
of	O
a	O
nearby	O
mainframe	O
.	O
</s>
<s>
A	O
remote	O
control	O
unit	O
is	O
connected	O
to	O
a	O
communications	O
line	O
by	O
a	O
modem	B-Application
.	O
</s>
<s>
Remote	O
3270	B-Operating_System
controllers	O
are	O
frequently	O
multi-dropped	O
,	O
with	O
multiple	O
control	O
units	O
on	O
a	O
line	O
.	O
</s>
<s>
IBM	B-Operating_System
3270	I-Operating_System
devices	O
are	O
connected	O
to	O
a	O
3299	O
multiplexer	O
or	O
to	O
the	O
cluster	O
controller	O
,	O
e.g.	O
,	O
3271	O
,	O
3272	O
,	O
3274	O
,	O
3174	O
,	O
using	O
RG-62	O
,	O
93	O
ohm	O
,	O
coax	O
cables	O
in	O
a	O
point	O
to	O
point	O
configuration	O
with	O
one	O
dedicated	O
cable	O
per	O
terminal	O
.	O
</s>
<s>
Data	O
is	O
sent	O
with	O
a	O
bit	O
rate	O
of	O
2.3587	O
Mbit/s	O
using	O
a	O
slightly	O
modified	O
differential	B-Protocol
Manchester	I-Protocol
encoding	I-Protocol
.	O
</s>
<s>
Originally	O
devices	O
were	O
equipped	O
with	O
BNC	B-Protocol
connectors	I-Protocol
,	O
which	O
later	O
was	O
replaced	O
with	O
special	O
so-called	O
DPC	O
–	O
Dual	O
Purpose	O
Connectors	O
supporting	O
the	O
IBM	O
Shielded	O
twisted	O
pair	O
cabling	O
system	O
without	O
the	O
need	O
for	O
so-called	O
red	O
baluns	O
.	O
</s>
<s>
In	O
a	O
data	B-General_Concept
stream	I-General_Concept
,	O
both	O
text	O
and	O
control	O
(	O
or	O
formatting	O
functions	O
)	O
are	O
interspersed	O
allowing	O
an	O
entire	O
screen	O
to	O
be	O
painted	O
as	O
a	O
single	O
output	O
operation	O
.	O
</s>
<s>
The	O
concept	O
of	O
formatting	O
in	O
these	O
devices	O
allows	O
the	O
screen	O
to	O
be	O
divided	O
into	O
fields	O
(	O
clusters	O
of	O
contiguous	O
character	O
cells	O
)	O
for	O
which	O
numerous	O
field	O
attributes	O
,	O
e.g.	O
,	O
color	O
,	O
highlighting	O
,	O
character	O
set	O
,	O
protection	O
from	O
modification	O
,	O
can	O
be	O
set	O
.	O
</s>
<s>
This	O
technique	O
enhances	O
the	O
terminal	O
throughput	O
of	O
the	O
CPU	B-General_Concept
,	O
and	O
minimizes	O
the	O
data	O
transmitted	O
.	O
</s>
<s>
Some	O
users	O
familiar	O
with	O
character	O
interrupt-driven	O
terminal	O
interfaces	O
find	O
this	O
technique	O
unusual	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
read	O
buffer	O
capability	O
that	O
transfers	O
the	O
entire	O
content	O
of	O
the	O
3270-screen	O
buffer	O
including	O
field	O
attributes	O
.	O
</s>
<s>
Early	O
3270s	B-Operating_System
offered	O
three	O
types	O
of	O
keyboards	O
.	O
</s>
<s>
The	O
data	O
entry	O
keyboard	O
had	O
five	O
PF	B-Application
keys	I-Application
and	O
two	O
PA	B-Operating_System
keys	I-Operating_System
.	O
</s>
<s>
The	O
operator	O
console	O
keyboard	O
had	O
twelve	O
PF	B-Application
keys	I-Application
and	O
two	O
PA	B-Operating_System
keys	I-Operating_System
.	O
</s>
<s>
Later	O
3270s	B-Operating_System
had	O
an	O
Attention	O
key	O
,	O
a	O
Cursor	O
Select	O
key	O
,	O
a	O
System	O
Request	O
key	O
,	O
twenty-four	O
PF	B-Application
keys	I-Application
and	O
three	O
PA	B-Operating_System
keys	I-Operating_System
.	O
</s>
<s>
When	O
one	O
of	O
these	O
keys	O
is	O
pressed	O
,	O
it	O
will	O
cause	O
its	O
control	O
unit	O
to	O
generate	O
an	O
I/O	B-General_Concept
interrupt	B-Application
to	O
the	O
host	O
computer	O
and	O
present	O
an	O
Attention	O
ID	O
(	O
AID	O
)	O
identifying	O
which	O
key	O
was	O
pressed	O
.	O
</s>
<s>
A	O
downside	O
to	O
this	O
approach	O
was	O
that	O
vi-like	O
behavior	O
,	O
responding	O
to	O
individual	O
keystrokes	O
,	O
was	O
not	O
possible	O
.	O
</s>
<s>
For	O
the	O
same	O
reason	O
,	O
a	O
port	O
of	O
Lotus	B-Application
1-2-3	I-Application
to	O
mainframes	O
with	O
3279	O
screens	O
did	O
not	O
meet	O
with	O
success	O
because	O
its	O
programmers	O
were	O
not	O
able	O
to	O
properly	O
adapt	O
the	O
spreadsheet	O
's	O
user	O
interface	O
to	O
a	O
screen	O
at	O
a	O
time	O
rather	O
than	O
character	O
at	O
a	O
time	O
device	O
.	O
</s>
<s>
But	O
end-user	O
responsiveness	O
was	O
arguably	O
more	O
predictable	O
with	O
3270	B-Operating_System
,	O
something	O
users	O
appreciated	O
.	O
</s>
<s>
Following	O
its	O
introduction	O
the	O
3270	B-Operating_System
and	O
compatibles	O
were	O
by	O
far	O
the	O
most	O
commonly	O
used	O
terminals	O
on	O
IBM	B-Device
System/370	I-Device
and	O
successor	O
systems	O
.	O
</s>
<s>
IBM	O
and	O
third-party	O
software	O
that	O
included	O
an	O
interactive	O
component	O
took	O
for	O
granted	O
the	O
presence	O
of	O
3270	B-Operating_System
terminals	I-Operating_System
and	O
provided	O
a	O
set	O
of	O
ISPF	B-Operating_System
panels	O
and	O
supporting	O
programs	O
.	O
</s>
<s>
Conversational	B-Operating_System
Monitor	I-Operating_System
System	I-Operating_System
(	O
CMS	O
)	O
in	O
VM	B-Application
has	O
support	O
for	O
the	O
3270	B-Operating_System
continuing	O
to	O
z/VM	B-Application
.	O
</s>
<s>
Time	B-Application
Sharing	I-Application
Option	I-Application
(	O
TSO	O
)	O
in	O
OS/360	B-Application
and	I-Application
successors	I-Application
has	O
line	O
mode	O
command	O
line	O
support	O
and	O
also	O
has	O
facilities	O
for	O
full	O
screen	O
applications	O
,	O
e.g.	O
,	O
ISPF	B-Operating_System
.	O
</s>
<s>
Device	O
independent	O
Display	O
Operator	O
Console	O
Support	O
(	O
DIDOCS	O
)	O
in	O
Multiple	O
Console	O
Support	O
(	O
MCS	O
)	O
for	O
OS/360	B-Application
and	I-Application
successors	I-Application
supports	O
3270	B-Operating_System
devices	O
and	O
,	O
in	O
fact	O
,	O
MCS	O
in	O
current	O
versions	O
of	O
MVS	B-Application
no	O
longer	O
supports	O
line	O
mode	O
,	O
2250	O
and	O
2260	O
devices	O
.	O
</s>
<s>
The	O
SPF	O
and	O
Program	B-Operating_System
Development	I-Operating_System
Facility	I-Operating_System
(	O
ISPF/PDF	O
)	O
editors	B-Application
for	O
MVS	B-Application
and	O
VM/SP	B-Application
(	O
ISPF/PDF	O
was	O
available	O
for	O
VM	B-Application
,	O
but	O
little	O
used	O
)	O
and	O
the	O
XEDIT	B-Application
editors	B-Application
for	O
VM/SP	B-Application
through	O
z/VM	B-Application
make	O
extensive	O
use	O
of	O
3270	B-Operating_System
features	O
.	O
</s>
<s>
Customer	B-Application
Information	I-Application
Control	I-Application
System	I-Application
(	O
CICS	B-Application
)	O
has	O
support	O
for	O
3270	B-Operating_System
panels	O
.	O
</s>
<s>
Indeed	O
,	O
from	O
the	O
early	O
1970s	O
on	O
,	O
CICS	B-Application
applications	O
were	O
often	O
written	O
for	O
the	O
3270	B-Operating_System
.	O
</s>
<s>
Various	O
versions	O
of	O
Wylbur	B-Application
have	O
support	O
for	O
3270	B-Operating_System
,	O
including	O
support	O
for	O
full-screen	O
applications	O
.	O
</s>
<s>
The	O
modified	O
data	O
tag	O
is	O
well	O
suited	O
to	O
converting	O
formatted	O
,	O
structured	O
punched	O
card	O
input	O
onto	O
the	O
3270	B-Operating_System
display	O
device	O
.	O
</s>
<s>
With	O
the	O
appropriate	O
programming	O
,	O
any	O
batch	O
program	O
that	O
uses	O
formatted	O
,	O
structured	O
card	O
input	O
can	O
be	O
layered	O
onto	O
a	O
3270	B-Operating_System
terminal	I-Operating_System
.	O
</s>
<s>
IBM	O
's	O
OfficeVision	B-Application
office	O
productivity	O
software	O
enjoyed	O
great	O
success	O
with	O
3270	B-Operating_System
interaction	O
because	O
of	O
its	O
design	O
understanding	O
.	O
</s>
<s>
And	O
for	O
many	O
years	O
the	O
PROFS	B-Application
calendar	O
was	O
the	O
most	O
commonly	O
displayed	O
screen	O
on	O
office	O
terminals	O
around	O
the	O
world	O
.	O
</s>
<s>
A	O
version	O
of	O
the	O
WordPerfect	B-Application
word	B-General_Concept
processor	I-General_Concept
ported	O
to	O
System/370	B-Device
was	O
designed	O
for	O
the	O
3270	B-Operating_System
architecture	O
.	O
</s>
<s>
3270	B-Operating_System
devices	O
can	O
be	O
a	O
part	O
of	O
an	O
SNA	B-Architecture
–	I-Architecture
System	I-Architecture
Network	I-Architecture
Architecture	I-Architecture
network	O
or	O
non-SNA	O
network	O
.	O
</s>
<s>
If	O
the	O
controllers	O
are	O
SNA	B-Architecture
connected	O
,	O
they	O
appear	O
to	O
SNA	B-Architecture
as	O
PU	O
–	O
Physical	O
Unit	O
type	O
2.0	O
(	O
PU2.1	O
for	O
APPN	O
)	O
nodes	O
typically	O
with	O
LU	O
–	O
Logical	O
Unit	O
type	O
1	O
,	O
2	O
,	O
and	O
3	O
devices	O
connected	O
.	O
</s>
<s>
Local	O
,	O
channel	B-Device
attached	O
,	O
controllers	O
are	O
controlled	O
by	O
VTAM	B-Application
–	I-Application
Virtual	I-Application
Telecommunications	I-Application
Access	I-Application
Method	I-Application
.	O
</s>
<s>
Remote	O
controllers	O
are	O
controlled	O
by	O
the	O
NCP	O
–	O
Network	O
Control	O
Program	O
in	O
the	O
Front	B-General_Concept
End	I-General_Concept
Processor	I-General_Concept
i.e.	O
</s>
<s>
3705	B-Device
,	O
3720	B-Device
,	O
3725	B-Device
,	O
3745	B-Device
,	O
and	O
VTAM	B-Application
.	O
</s>
<s>
One	O
of	O
the	O
first	O
groups	O
to	O
write	O
and	O
provide	O
operating	O
system	O
support	O
for	O
the	O
3270	B-Operating_System
and	O
its	O
early	O
predecessors	O
was	O
the	O
University	O
of	O
Michigan	O
,	O
who	O
created	O
the	O
Michigan	B-Application
Terminal	I-Application
System	I-Application
in	O
order	O
for	O
the	O
hardware	O
to	O
be	O
useful	O
outside	O
of	O
the	O
manufacturer	O
.	O
</s>
<s>
Many	O
manufacturers	O
,	O
such	O
as	O
GTE	O
,	O
Hewlett-Packard	O
,	O
Honeywell/Incoterm	O
Div	O
,	O
Memorex	O
,	O
ITT	O
Courier	O
,	O
McData	O
,	O
Harris	O
,	O
Alfaskop	O
and	O
Teletype/AT	O
&T	O
created	O
3270	B-Operating_System
compatible	O
terminals	O
,	O
or	O
adapted	O
ASCII	O
terminals	O
such	O
as	O
the	O
HP	B-General_Concept
2640	I-General_Concept
series	O
to	O
have	O
a	O
similar	O
block-mode	O
capability	O
that	O
would	O
transmit	O
a	O
screen	O
at	O
a	O
time	O
,	O
with	O
some	O
form	O
validation	O
capability	O
.	O
</s>
<s>
The	O
industry	O
distinguished	O
between	O
‘	O
System	O
compatible	O
controllers’	O
and	O
‘	O
Plug	O
compatibility	O
controllers’	O
,	O
where	O
‘	O
System	O
compatibility’	O
meant	O
that	O
the	O
3rd	O
party	O
system	O
was	O
compatible	O
with	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
terminated	O
in	O
the	O
unit	O
,	O
but	O
not	O
as	O
‘	O
Plug	O
compatibility’	O
equipment	O
,	O
also	O
were	O
compatible	O
at	O
the	O
coax	O
level	O
thereby	O
allowing	O
IBM	O
terminals	O
to	O
be	O
connected	O
to	O
a	O
3rd	O
party	O
controller	O
or	O
vice	O
versa	O
.	O
</s>
<s>
Modern	O
applications	O
are	O
sometimes	O
built	O
upon	O
legacy	O
3270	B-Operating_System
applications	O
,	O
using	O
software	O
utilities	O
to	O
capture	O
(	O
screen	O
scraping	O
)	O
screens	O
and	O
transfer	O
the	O
data	O
to	O
web	O
pages	O
or	O
GUI	O
interfaces	O
.	O
</s>
<s>
In	O
the	O
early	O
1990s	O
a	O
popular	O
solution	O
to	O
link	O
PCs	O
with	O
the	O
mainframes	O
was	O
the	O
Irma	B-Device
board	I-Device
,	O
an	O
expansion	B-Device
card	I-Device
that	O
plugged	O
into	O
a	O
PC	O
and	O
connected	O
to	O
the	O
controller	O
through	O
a	O
coaxial	O
cable	O
.	O
</s>
<s>
3270	B-Operating_System
simulators	O
for	O
IRMA	O
and	O
similar	O
adapters	O
typically	O
provide	O
file	O
transfers	O
between	O
the	O
PC	O
and	O
the	O
mainframe	O
using	O
the	O
same	O
protocol	O
as	O
the	O
IBM	B-Device
3270	I-Device
PC	I-Device
.	O
</s>
<s>
The	O
IBM	B-Operating_System
3270	I-Operating_System
display	O
terminal	O
subsystem	O
consists	O
of	O
displays	O
,	O
printers	O
and	O
controllers	O
.	O
</s>
<s>
Optional	O
features	O
for	O
the	O
3275	O
and	O
3277	O
are	O
the	O
selector-pen	O
,	O
ASCII	O
rather	O
than	O
EBCDIC	B-Language
character	O
set	O
,	O
an	O
audible	O
alarm	O
,	O
and	O
a	O
keylock	O
for	O
the	O
keyboard	O
.	O
</s>
<s>
Generally	O
,	O
3277	O
models	O
allow	O
only	O
upper-case	O
input	O
,	O
except	O
for	O
the	O
mixed	O
EBCDIC/APL	O
or	O
text	O
keyboards	O
,	O
which	O
have	O
lower	O
case	O
.	O
</s>
<s>
Lower-case	O
capability	O
and	O
dead	B-Device
keys	I-Device
were	O
available	O
as	O
an	O
RPQ	O
(	O
Request	O
Price	O
Quotation	O
)	O
;	B-Device
these	O
were	O
added	O
to	O
the	O
later	O
3278	B-Operating_System
&	O
3279	O
models	O
.	O
</s>
<s>
A	O
version	O
of	O
the	O
IBM	B-Device
PC	I-Device
called	O
the	O
3270	B-Device
PC	I-Device
,	O
released	O
in	O
October	O
1983	O
,	O
includes	O
3270	B-Application
terminal	I-Application
emulation	I-Application
.	O
</s>
<s>
Later	O
,	O
the	O
3270	B-Operating_System
PC/G	O
(	O
graphics	O
)	O
,	O
3270	B-Operating_System
PC/GX	O
(	O
extended	O
graphics	O
)	O
,	O
3270	B-Operating_System
Personal	O
Computer	O
AT	O
,	O
3270	B-Device
PC	I-Device
AT/G	O
(	O
graphics	O
)	O
and	O
3270	B-Device
PC	I-Device
AT/GX	O
(	O
extended	O
graphics	O
)	O
followed	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
3270	B-Operating_System
displays	O
in	O
respect	O
to	O
where	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
terminates	O
.	O
</s>
<s>
EBCDIC	B-Language
is	O
translated	O
by	O
the	O
controller	O
into	O
‘	O
3270	B-Operating_System
Character	O
Set’	O
,	O
and	O
keyboard	O
scan-codes	O
from	O
the	O
terminal	O
,	O
read	O
by	O
the	O
controller	O
through	O
a	O
poll	O
,	O
is	O
translated	O
by	O
the	O
controller	O
into	O
EBCDIC	B-Language
.	O
</s>
<s>
For	O
DFT	O
(	O
Distributed	O
Function	O
Terminal	O
)	O
type	O
displays	O
,	O
most	O
of	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
is	O
forwarded	O
to	O
the	O
display	O
by	O
the	O
controller	O
.	O
</s>
<s>
The	O
display	O
interprets	O
the	O
3270	B-Operating_System
protocol	O
itself	O
.	O
</s>
<s>
In	O
addition	O
to	O
passing	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
directly	O
to	O
the	O
terminal	O
,	O
allowing	O
for	O
features	O
like	O
EAB	O
-	O
Extended	O
Attributes	O
,	O
Graphics	O
,	O
etc.	O
,	O
DFT	O
also	O
enabled	O
multi	O
sessions	O
(	O
up	O
to	O
5	B-Application
simultaneous	O
)	O
,	O
featured	O
in	O
the	O
3290	O
and	O
3194	O
multisession	O
displays	O
.	O
</s>
<s>
This	O
feature	O
was	O
also	O
widely	O
used	O
in	O
2nd	O
generation	O
3270	B-Application
terminal	I-Application
emulation	I-Application
software	O
.	O
</s>
<s>
The	O
IBM	O
3279	O
was	O
IBM	O
's	O
first	O
color	O
terminal	O
.	O
</s>
<s>
The	O
3279	O
was	O
widely	O
used	O
as	O
an	O
IBM	B-Device
mainframe	I-Device
terminal	O
before	O
PCs	O
became	O
commonly	O
used	O
for	O
the	O
purpose	O
.	O
</s>
<s>
It	O
was	O
part	O
of	O
the	O
3270	B-Operating_System
series	O
,	O
using	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
.	O
</s>
<s>
Terminals	O
could	O
be	O
connected	O
to	O
a	O
3274	O
controller	O
,	O
either	O
channel	B-Device
connected	O
to	O
an	O
IBM	B-Device
mainframe	I-Device
or	O
linked	O
via	O
an	O
SDLC	B-Protocol
(	O
Synchronous	B-Protocol
Data	I-Protocol
Link	I-Protocol
Control	I-Protocol
)	O
link	O
.	O
</s>
<s>
In	O
the	O
Systems	B-Architecture
Network	I-Architecture
Architecture	I-Architecture
(	O
SNA	B-Architecture
)	O
protocol	O
these	O
terminals	O
were	O
logical	O
unit	O
type	O
2	O
(	O
LU2	O
)	O
.	O
</s>
<s>
The	O
IBM	O
3279	O
with	O
its	O
graphics	O
software	O
support	O
,	O
Graphical	B-Device
Data	I-Device
Display	I-Device
Manager	I-Device
(	O
GDDM	B-Device
)	O
,	O
was	O
designed	O
at	O
IBM	O
's	O
Hursley	O
Development	O
Laboratory	O
,	O
near	O
Winchester	O
,	O
England	O
.	O
</s>
<s>
The	O
3290	O
Information	O
Panel	O
a	O
17	O
"	O
,	O
amber	O
monochrome	O
plasma	O
display	O
unit	O
announced	O
March	O
8	O
,	O
1983	O
,	O
capable	O
of	O
displaying	O
in	O
various	O
modes	O
,	O
including	O
four	O
independent	O
3278	B-Operating_System
model	O
2	O
terminals	O
,	O
or	O
a	O
single	O
160×62	O
terminal	O
;	O
it	O
also	O
supports	O
partitioning	O
.	O
</s>
<s>
The	O
3180	O
was	O
a	O
monochrome	B-Device
display	I-Device
,	O
introduced	O
on	O
March	O
20	O
,	O
1984	O
,	O
that	O
the	O
user	O
could	O
configure	O
for	O
several	O
different	O
basic	O
and	O
extended	O
display	O
modes	O
;	O
all	O
of	O
the	O
basic	O
modes	O
have	O
a	O
primary	O
screen	O
size	O
of	O
24x80	O
.	O
</s>
<s>
Modes	O
2	O
and	O
2+	O
have	O
a	O
secondary	O
size	O
of	O
24x80	O
,	O
3	O
and	O
3+	O
have	O
a	O
secondary	O
size	O
of	O
32x80	O
,	O
4	O
and	O
4+	O
have	O
a	O
secondary	O
size	O
of	O
43x80	O
and	O
5	B-Application
and	O
5+	O
have	O
a	O
secondary	O
size	O
of	O
27x132	O
.	O
</s>
<s>
The	O
IBM	O
3191	O
Display	O
Station	O
is	O
an	O
economical	O
monochrome	B-Device
CRT	I-Device
.	O
</s>
<s>
Models	O
A	O
and	O
B	B-Language
are	O
1920	O
characters	O
12-inch	O
CRTs	O
.	O
</s>
<s>
Models	O
D	B-Application
,	O
E	B-Language
and	O
L	O
are	O
1920	O
or	O
2560	O
character	O
14-inch	O
CRTs	O
.	O
</s>
<s>
The	O
IBM	O
3194	O
is	O
a	O
Display	O
Station	O
that	O
features	O
a	O
1.44MB	O
3.5	O
"	O
floppy	O
drive	O
and	O
IND$FILE	B-Application
transfer	O
.	O
</s>
<s>
Several	O
third-party	O
manufacturers	O
produced	O
3270	B-Operating_System
displays	O
besides	O
IBM	O
.	O
</s>
<s>
GTE	O
manufactured	O
the	O
IS/7800	O
Video	O
Display	O
System	O
,	O
nominally	O
compatible	O
with	O
IBM	B-Operating_System
3277	I-Operating_System
displays	O
attached	O
to	O
a	O
3271	O
or	O
3272	O
.	O
</s>
<s>
An	O
incompatibility	O
with	O
the	O
RA	O
buffer	O
order	O
broke	O
the	O
logon	O
screen	O
in	O
VM/SE	O
(	O
SEPP	O
)	O
.	O
</s>
<s>
Harris	O
manufactured	O
the	O
8000	O
Series	O
Terminal	O
Systems	O
,	O
compatible	O
with	O
IBM	B-Operating_System
3277	I-Operating_System
displays	O
attached	O
to	O
a	O
3271	O
or	O
3272	O
.	O
</s>
<s>
Informer	O
Computer	B-General_Concept
Terminals	I-General_Concept
manufactured	O
a	O
special	O
version	O
of	O
their	O
model	O
270	O
terminal	O
that	O
was	O
compatible	O
with	O
IBM	B-Operating_System
3270	I-Operating_System
and	O
its	O
associated	O
coax	O
port	O
to	O
connect	O
to	O
a	O
3x74	O
.	O
</s>
<s>
AT&T	O
introduced	O
the	O
Dataspeed	O
40	O
terminal/controller	O
,	O
compatible	O
with	O
the	O
IBM	O
3275	O
,	O
in	O
1980	O
.	O
</s>
<s>
The	O
first	O
was	O
implemented	O
in	O
the	O
optional	O
Programmed	O
Symbol	O
Sets	O
(	O
PSS	O
)	O
of	O
the	O
3278	B-Operating_System
,	O
3279	O
and	O
3287	O
,	O
which	O
became	O
a	O
standard	O
feature	O
on	O
the	O
later	O
3279-S3G	O
,	O
a.k.a.	O
</s>
<s>
The	O
second	O
later	O
implementation	O
provided	O
All	O
Points	O
Addressable	O
(	O
APA	O
)	O
graphics	O
,	O
a.k.a.	O
</s>
<s>
Both	O
implementations	O
are	O
supported	O
by	O
IBM	B-Device
GDDM	I-Device
-	O
Graphical	B-Device
Data	I-Device
Display	I-Device
Manager	I-Device
first	O
released	O
in	O
1979	O
,	O
and	O
by	O
SAS	B-Language
with	O
their	O
SAS/GRAPH	O
software	O
.	O
</s>
<s>
IBM	O
3279-S3G	O
,	O
a.k.a.	O
</s>
<s>
3279G	O
,	O
terminal	O
,	O
announced	O
in	O
1979	O
,	O
was	O
IBM	O
's	O
graphics	O
replacement	O
for	O
the	O
3279-3B	O
with	O
PSS	O
.	O
</s>
<s>
The	O
terminal	O
supported	O
7	O
colors	O
and	O
the	O
graphics	O
were	O
made	O
up	O
of	O
Programmable	O
Symbol	O
sets	O
loaded	O
to	O
the	O
terminal	O
by	O
the	O
graphical	O
application	O
GDDM	B-Device
-	I-Device
Graphical	I-Device
Data	I-Device
Display	I-Device
Manager	I-Device
using	O
Write	O
Structured	O
Field	O
command	O
.	O
</s>
<s>
The	O
IBM	O
3179G	O
announced	O
June	O
18	O
,	O
1985	O
,	O
is	O
an	O
IBM	B-Device
mainframe	I-Device
computer	B-General_Concept
terminal	I-General_Concept
providing	O
80×24	O
or	O
80×32	O
characters	O
,	O
16	O
colors	O
,	O
plus	O
graphics	O
and	O
is	O
the	O
first	O
terminal	O
to	O
support	O
the	O
APA	O
graphics	O
apart	O
from	O
the	O
3270	O
PC/G	O
,	O
3270	O
PC/GX	O
,	O
PC	O
AT/G	O
and	O
PC	O
AT/GX	O
.	O
</s>
<s>
3179-G	O
terminals	O
combine	O
text	O
and	O
graphics	O
as	O
separate	O
layers	O
on	O
the	O
screen	O
.	O
</s>
<s>
The	O
text	O
layer	O
contains	O
the	O
usual	O
3270-style	O
cells	O
which	O
display	O
characters	O
(	O
letters	O
,	O
numbers	O
,	O
symbols	O
,	O
or	O
invisible	O
control	O
characters	O
)	O
.	O
</s>
<s>
As	O
well	O
as	O
being	O
separate	O
layers	O
on	O
the	O
screen	O
,	O
the	O
text	O
and	O
graphics	O
layers	O
are	O
sent	O
to	O
the	O
display	O
in	O
separate	O
data	B-General_Concept
streams	I-General_Concept
,	O
making	O
them	O
completely	O
independent	O
.	O
</s>
<s>
The	O
application	O
i.e.	O
</s>
<s>
GDDM	B-Device
sends	O
the	O
vector	O
definitions	O
to	O
the	O
3179-G	O
,	O
and	O
the	O
work	O
of	O
activating	O
the	O
pixels	O
that	O
represent	O
the	O
picture	O
(	O
the	O
vector-to-raster	O
conversion	O
)	O
is	O
done	O
in	O
the	O
terminal	O
itself	O
.	O
</s>
<s>
Arcs	O
are	O
split	O
into	O
short	O
vectors	O
,	O
that	O
are	O
sent	O
to	O
the	O
3179-G	O
to	O
be	O
drawn	O
.	O
</s>
<s>
The	O
3179-G	O
does	O
not	O
store	O
graphic	O
data	O
,	O
and	O
so	O
cannot	O
offload	O
any	O
manipulation	O
function	O
from	O
GDDM	B-Device
.	O
</s>
<s>
The	O
3179G	O
is	O
a	O
distributed	O
function	O
terminal	O
(	O
DFT	O
)	O
and	O
requires	O
a	O
downstream	O
load	O
(	O
DSL	O
)	O
to	O
load	O
its	O
microcode	O
from	O
the	O
cluster	O
controller	O
's	O
floppy	O
disk	O
or	O
hard	O
drive	O
.	O
</s>
<s>
The	O
G10	O
model	O
is	O
a	O
standard	O
122-key	O
typewriter	O
keyboard	O
,	O
while	O
the	O
G20	O
model	O
offers	O
APL	B-Language
on	O
the	O
same	O
layout	O
.	O
</s>
<s>
Compatible	O
with	O
IBM	B-Device
System/370	I-Device
,	O
IBM	B-Device
4300	I-Device
series	I-Device
,	O
303x	B-Device
,	O
308x	O
,	O
IBM	B-Device
3090	I-Device
,	O
and	O
IBM	B-Device
9370	I-Device
.	O
</s>
<s>
It	O
featured	O
16	O
colors	O
,	O
and	O
support	O
for	O
printers	O
(	O
i.e.	O
,	O
IBM	O
Proprinter	O
)	O
for	O
local	O
hardcopy	O
with	O
graphical	O
support	O
,	O
or	O
system	O
printer	O
,	O
text	O
only	O
,	O
implemented	O
as	O
an	O
additional	O
LU	O
.	O
</s>
<s>
Unlike	O
the	O
3192-G	O
,	O
it	O
needed	O
no	O
expansion	O
unit	O
to	O
attach	O
a	O
mouse	O
or	O
color	O
plotter	O
,	O
and	O
it	O
needed	O
no	O
expansion	O
unit	O
to	O
attach	O
a	O
mouse	O
or	O
color	O
plotter	O
and	O
it	O
could	O
also	O
attach	O
a	O
tablet	O
device	O
for	O
digitised	O
input	O
and	O
a	O
bar	O
code	O
reader	O
.	O
</s>
<s>
Most	O
IBM	O
terminals	O
,	O
starting	O
with	O
the	O
3277	O
,	O
could	O
be	O
delivered	O
with	O
an	O
APL	B-Language
keyboard	O
,	O
allowing	O
the	O
operator/programmer	O
to	O
enter	O
APL	B-Language
symbolic	O
instructions	O
directly	O
into	O
the	O
editor	O
.	O
</s>
<s>
In	O
order	O
to	O
display	O
APL	B-Language
symbols	O
on	O
the	O
terminal	O
,	O
it	O
had	O
to	O
be	O
equipped	O
with	O
an	O
APL	B-Language
character	O
set	O
in	O
addition	O
to	O
the	O
normal	O
3270-character	O
set	O
.	O
</s>
<s>
The	O
APL	B-Language
character	O
set	O
is	O
addressed	O
with	O
a	O
preceding	O
Graphic	O
Escape	O
X'08'	O
instruction	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
graphic	O
terminal	O
3179G	O
,	O
the	O
APL	B-Language
character	O
set	O
was	O
expandable	O
to	O
138	O
characters	O
,	O
called	O
APL2	O
.	O
</s>
<s>
Later	O
APL2	O
symbols	O
were	O
supported	O
by	O
3191	O
Models	O
D	B-Application
,	O
E	B-Language
,	O
L	O
,	O
the	O
CUT	O
version	O
of	O
3192	O
,	O
and	O
3472	O
.	O
</s>
<s>
Please	O
note	O
that	O
IBM	O
's	O
version	O
's	O
of	O
APL	B-Language
also	O
is	O
called	O
APL2	O
.	O
</s>
<s>
The	O
3276	O
could	O
connect	O
to	O
a	O
non-SNA	O
or	O
SNA	B-Architecture
host	O
using	O
BSC	B-Protocol
or	O
SDLC	B-Protocol
with	O
line	O
speed	O
of	O
up	O
to	O
9,600	O
bit/s	O
.	O
</s>
<s>
The	O
3276	O
looked	O
very	O
much	O
like	O
the	O
3278	B-Operating_System
terminal	O
,	O
and	O
the	O
terminal	O
feature	O
of	O
the	O
3276	O
itself	O
,	O
was	O
more	O
or	O
less	O
identical	O
to	O
those	O
of	O
the	O
3278	B-Operating_System
.	O
</s>
<s>
In	O
1984	O
announced	O
IPDS	B-Application
–	I-Application
Intelligent	I-Application
Printer	I-Application
Data	I-Application
Stream	I-Application
for	O
online	O
printing	O
of	O
AFP	B-Application
-	I-Application
Advanced	I-Application
Function	I-Application
Presentation	I-Application
documents	O
,	O
using	O
bidirectional	O
communications	O
between	O
the	O
application	O
and	O
the	O
printer	O
.	O
</s>
<s>
With	O
the	O
emergence	O
of	O
printers	O
,	O
including	O
laser	O
printers	O
,	O
from	O
HP	O
,	O
Canon	O
,	O
and	O
others	O
,	O
targeted	O
the	O
PC	O
market	O
,	O
3270	B-Operating_System
customers	O
got	O
an	O
alternative	O
to	O
IBM	B-Operating_System
3270	I-Operating_System
printers	O
by	O
connecting	O
this	O
type	O
of	O
printers	O
through	O
printer	O
protocol	O
converters	O
from	O
manufactures	O
like	O
I-data	O
,	O
MPI	O
Tech	O
,	O
Adacom	O
,	O
and	O
others	O
.	O
</s>
<s>
In	O
the	O
later	O
versions	O
of	O
3174	O
the	O
Asynchronous	O
Emulation	O
Adapter	O
(	O
AEA	O
)	O
,	O
supporting	O
async	O
RS-232	O
character-based	O
type	O
terminals	O
,	O
was	O
enhanced	O
to	O
support	O
printers	O
equipped	O
with	O
a	O
serial	O
interface	O
.	O
</s>
<s>
By	O
1994	O
the	O
3174	O
Establishment	O
Controller	O
supported	O
features	O
such	O
as	O
attachment	O
to	O
multiple	O
hosts	O
via	O
Token	B-Device
Ring	I-Device
,	O
Ethernet	O
,	O
or	O
X.25	B-Protocol
in	O
addition	O
to	O
the	O
standard	O
channel	B-Device
attach	O
or	O
SDLC	B-Protocol
;	O
terminal	O
attachment	O
via	O
twisted	O
pair	O
,	O
Token	B-Device
Ring	I-Device
or	O
Ethernet	O
in	O
addition	O
to	O
co-ax	O
;	O
and	O
TN3270	O
.	O
</s>
<s>
They	O
also	O
support	O
attachment	O
of	O
asynchronous	O
ASCII	O
terminals	O
,	O
printers	O
,	O
and	O
plotters	O
alongside	O
3270	B-Operating_System
devices	O
.	O
</s>
<s>
Where	O
the	O
features	O
of	O
the	O
3271	O
–	O
2	O
was	O
hardcoded	O
,	O
the	O
3274	O
was	O
controlled	O
by	O
its	O
microcode	O
that	O
was	O
read	O
from	O
the	O
3274	O
's	O
built-in	O
8	O
”	O
floppy	O
drive	O
.	O
</s>
<s>
3274	O
models	O
included	O
8	O
,	O
12	O
,	O
16	O
,	O
and	O
32	O
port	O
remote	O
controllers	O
and	O
32-port	O
local	O
channel	B-Device
attached	O
units	O
.	O
</s>
<s>
The	O
3274-1A	O
was	O
an	O
SNA	B-Architecture
physical	O
Unit	O
type	O
2.0	O
(	O
PU2.0	O
)	O
,	O
required	O
only	O
a	O
single	O
address	O
on	O
the	O
channel	B-Device
for	O
all	O
32	O
devices	O
and	O
was	O
not	O
compatible	O
with	O
the	O
3272	O
.	O
</s>
<s>
The	O
3274-1B	O
and	O
3274-1D	O
were	O
compatible	O
with	O
the	O
3272	O
and	O
were	O
referred	O
to	O
as	O
local	O
non-SNA	O
models	O
.	O
</s>
<s>
The	O
3274	O
controllers	O
introduced	O
a	O
new	O
generation	O
of	O
the	O
coax	O
protocol	O
,	O
named	O
Category	O
A	O
,	O
to	O
differentiate	O
them	O
from	O
the	O
Category	O
B	B-Language
coax	O
devices	O
,	O
such	O
as	O
the	O
3277	O
terminal	O
and	O
the	O
3284	O
printer	O
.	O
</s>
<s>
The	O
first	O
Category	O
A	O
coax	O
devices	O
were	O
the	O
3278	B-Operating_System
and	O
the	O
first	O
color	O
terminal	O
,	O
the	O
IBM	O
3279	O
Color	O
Display	O
Station	O
.	O
</s>
<s>
Enabling	O
backward	O
compatibility	O
,	O
it	O
was	O
possible	O
to	O
install	O
coax	O
boards	O
,	O
so-called	O
‘	O
panels’	O
,	O
in	O
groups	O
of	O
4	O
or	O
8	O
supporting	O
the	O
now	O
older	O
Category	O
B	B-Language
coax	O
devices	O
.	O
</s>
<s>
A	O
maximum	O
of	O
16	O
Category	O
B	B-Language
terminals	O
could	O
be	O
supported	O
,	O
and	O
only	O
8	O
if	O
the	O
controller	O
were	O
fully	O
loaded	O
with	O
a	O
maximum	O
of	O
4	O
panels	O
each	O
supporting	O
8	O
Category	O
A	O
devices	O
.	O
</s>
<s>
The	O
3174	O
was	O
designed	O
to	O
enhance	O
the	O
3270	B-Operating_System
product	O
line	O
with	O
many	O
new	O
connectivity	O
options	O
and	O
features	O
.	O
</s>
<s>
Like	O
the	O
3274	O
,	O
it	O
was	O
customizable	O
,	O
the	O
main	O
difference	O
was	O
that	O
it	O
used	O
smaller	O
(	O
5.25-inch	O
)	O
diskettes	O
than	O
the	O
3274	O
(	O
8-inch	O
diskettes	O
)	O
,	O
and	O
that	O
the	O
larger	O
floor	O
models	O
had	O
10	O
slots	O
for	O
adapters	O
,	O
some	O
of	O
them	O
were	O
per	O
default	O
occupied	O
by	O
channel	B-Device
adapter/serial	O
interface	O
,	O
coax	O
adapter	O
,	O
etc	O
.	O
</s>
<s>
Unlike	O
the	O
3274	O
,	O
any	O
local	O
models	O
could	O
be	O
configured	O
as	O
either	O
local	O
SNA	B-Architecture
or	O
local	O
non-SNA	O
,	O
including	O
PU2.1	O
(	O
APPN	O
)	O
.	O
</s>
<s>
The	O
01L	O
were	O
local	O
channel	B-Device
attached	O
,	O
the	O
R	B-Language
models	O
remotely	O
connected	O
,	O
and	O
the	O
x3R	O
Token	B-Device
Ring	I-Device
(	O
upstream	O
)	O
connected	O
.	O
</s>
<s>
The	O
0xL/R	O
models	O
were	O
floor	O
units	O
supporting	O
up	O
to	O
32	O
coax	O
devices	O
through	O
the	O
use	O
of	O
internal	O
or	O
external	O
multiplexers	O
(	O
TMA/3299	O
)	O
.	O
</s>
<s>
The	O
5xR	O
,	O
models	O
were	O
shelf	O
units	O
with	O
9	B-Application
coax	O
ports	O
,	O
expandable	O
to	O
16	O
,	O
by	O
the	O
connection	O
of	O
a	O
3299	O
multiplexer	O
.	O
</s>
<s>
In	O
the	O
3174	O
controller	O
line	O
IBM	O
also	O
slightly	O
altered	O
the	O
classical	O
BNC	B-Protocol
coax	O
connector	O
by	O
changing	O
the	O
BNC	B-Protocol
connector	I-Protocol
to	O
DPC	O
–	O
Dual	O
Purpose	O
Connector	O
.	O
</s>
<s>
The	O
DPC	O
female	O
connector	O
was	O
a	O
few	O
millimeters	O
longer	O
and	O
with	O
a	O
built-in	O
switch	O
that	O
detected	O
if	O
a	O
normal	O
BNC	B-Protocol
connector	I-Protocol
were	O
connected	O
or	O
a	O
newer	O
DPC	O
connector	O
was	O
connected	O
,	O
thereby	O
changing	O
the	O
physical	O
layer	O
from	O
93	O
ohm	O
unbalanced	O
coax	O
,	O
to	O
150	O
ohm	O
balanced	O
twisted-pair	O
,	O
thereby	O
directly	O
supporting	O
the	O
IBM	O
Cabling	O
system	O
without	O
the	O
need	O
for	O
a	O
so-called	O
red	O
balun	O
.	O
</s>
<s>
It	O
supported	O
all	O
the	O
hardware	O
modules	O
present	O
at	O
the	O
time	O
,	O
almost	O
all	O
the	O
microcode	O
features	O
found	O
in	O
3274	O
and	O
introduced	O
a	O
number	O
of	O
new	O
features	O
including	O
:	O
Intelligent	O
Printer	O
Data	B-General_Concept
Stream	I-General_Concept
(	O
IPDS	O
)	O
,	O
Multiple	O
Logical	O
Terminals	O
,	O
Country	O
Extended	O
Code	O
Page	O
(	O
CECP	O
)	O
,	O
Response	O
Time	O
Monitor	O
,	O
and	O
Token	B-Device
Ring	I-Device
configured	O
as	O
host	O
interface	O
.	O
</s>
<s>
Configuration	O
Support	O
S	B-Language
,	O
strangely	O
following	O
release	O
A	O
,	O
introduced	O
that	O
a	O
local	O
or	O
remote	O
controller	O
could	O
act	O
as	O
3270	B-Operating_System
Token-Ring	B-Device
DSPU	O
Gateway	O
,	O
supporting	O
up	O
to	O
80	O
Downstream	O
PU	O
's	O
.	O
</s>
<s>
The	O
new	O
line	O
of	O
controllers	O
came	O
with	O
Configuration	O
Support	O
B	B-Language
release	O
1	O
,	O
increased	O
the	O
number	O
of	O
supported	O
DSPU	O
on	O
the	O
Token-Ring	B-Device
gateway	O
to	O
250	O
units	O
,	O
and	O
introduced	O
at	O
the	O
same	O
time	O
‘	O
Group	O
Polling’	O
that	O
offloaded	O
the	O
mainframe/VTAM	O
polling	O
requirement	O
on	O
the	O
channel	B-Device
.	O
</s>
<s>
Configuration	O
Support	O
B	B-Language
release	O
2	O
to	O
5	B-Application
,	O
enabled	O
features	O
like	O
:	O
Local	O
Format	O
Storage	O
(	O
CICS	B-Application
Screen	B-Algorithm
Buffer	I-Algorithm
)	O
,	O
Type	O
Ahead	O
,	O
Null/Space	O
Processing	O
,	O
ESCON	O
channel	B-Device
support	O
.	O
</s>
<s>
The	O
12L	O
offered	O
ESCON	O
fibreoptic	O
channel	B-Device
attachment	O
.	O
</s>
<s>
The	O
90R	O
was	O
not	O
intended	O
as	O
a	O
coax	O
controller	O
,	O
it	O
was	O
positioned	O
as	O
a	O
Token	B-Device
Ring	I-Device
3270	B-Operating_System
DSPU	O
gateway	O
.	O
</s>
<s>
The	O
line	O
of	O
controllers	O
came	O
with	O
Configuration	O
Support	O
C	B-Language
to	O
support	O
ISDN	O
,	O
APPN	O
and	O
Peer	O
Communication	O
.	O
</s>
<s>
The	O
ISDN	O
feature	O
allowed	O
downstream	O
devices	O
,	O
typically	O
PC	O
's	O
,	O
to	O
connect	O
to	O
the	O
3174	O
via	O
the	O
ISDN	O
network	O
.	O
</s>
<s>
The	O
APPN	O
support	O
enabled	O
the	O
3174	O
to	O
be	O
a	O
part	O
of	O
an	O
APPN	O
network	O
,	O
and	O
the	O
Peer	O
Communication	O
allowed	O
coax	O
attached	O
PC	O
's	O
with	O
‘	O
Peer	O
Communication	O
Support’	O
to	O
access	O
resources	O
on	O
the	O
Token-Ring	B-Device
network	I-Device
attached	O
to	O
the	O
3174	O
.	O
</s>
<s>
The	O
subsequent	O
releases	O
2	O
to	O
6	O
of	O
Configuration	O
Support	O
C	B-Language
enables	O
support	O
for	O
:	O
Split	O
screen	O
,	O
Copy	O
from	O
session	O
to	O
session	O
,	O
Calculator	O
function	O
,	O
Access	O
to	O
AS/400	B-Device
host	O
and	O
5250	O
keyboard	O
emulation	O
,	O
Numerous	O
APPN	O
enhancements	O
,	O
TCP/IP	B-Protocol
Telnet	B-Protocol
support	O
that	O
allowed	O
3270	B-Operating_System
CUT	O
terminals	O
to	O
communicate	O
with	O
TCP/IP	B-Protocol
servers	O
using	O
Telnet	B-Protocol
,	O
and	O
at	O
the	O
same	O
time	O
in	O
another	O
screen	O
to	O
communicate	O
with	O
the	O
mainframe	O
using	O
native	O
3270	B-Operating_System
.	O
</s>
<s>
TN3270	O
support	O
where	O
the	O
3174	O
could	O
connect	O
to	O
a	O
TN3270	O
host/gateway	O
,	O
eliminating	O
SNA	B-Architecture
,	O
but	O
preserving	O
the	O
3270	B-Operating_System
data	I-Operating_System
stream	I-Operating_System
.	O
</s>
<s>
IP	O
forwarding	O
allowing	O
bridging	O
of	O
LAN	O
(	O
Token-Ring	B-Device
or	O
Ethernet	O
)	O
connected	O
devices	O
downstream	O
to	O
the	O
3174	O
to	O
route	O
IP	O
traffic	O
onto	O
the	O
Frame	O
Relay	O
WAN	O
interface	O
.	O
</s>
<s>
This	O
was	O
also	O
IBM	O
's	O
final	O
hardware	O
announcement	O
of	O
3174	O
.	O
</s>
<s>
The	O
floor	O
models	O
,	O
and	O
the	O
rack-mountable	O
units	O
,	O
could	O
be	O
expanded	O
with	O
a	O
range	O
of	O
special	O
3174	O
adapters	O
,	O
that	O
by	O
1993	O
included	O
:	O
Channel	B-Device
adapter	O
,	O
ESCON	O
adapter	O
,	O
Serial	O
(	O
V.24/V.35	O
)	O
adapter	O
,	O
Concurrent	O
Communication	O
Adapter	O
,	O
Coax	O
adapter	O
,	O
Fiber	O
optic	O
“	O
coax	O
”	O
adapter	O
,	O
Async	O
adapter	O
,	O
ISDN	O
adapter	O
,	O
Token-Ring	B-Device
adapter	O
,	O
Ethernet	O
adapter	O
,	O
and	O
line	O
encryption	O
adapter	O
.	O
</s>
<s>
In	O
1994	O
,	O
IBM	O
incorporated	O
the	O
functions	O
of	O
RPQ	O
8Q0935	O
into	O
Configuration	O
Support-C	O
release	O
3	O
,	O
including	O
the	O
TN3270	O
client	O
.	O
</s>
<s>
It	O
's	O
a	O
combination	O
of	O
an	O
Arduino	O
shield	O
with	O
a	O
BNC	B-Protocol
connector	I-Protocol
and	O
a	O
Python	B-Language
program	I-Language
that	O
runs	O
on	O
a	O
POSIX	O
system	O
.	O
</s>
<s>
OEC	O
allows	O
to	O
connect	O
a	O
3270	B-Operating_System
display	O
to	O
IBM	B-Device
mainframes	I-Device
via	O
TN3270	O
or	O
to	O
other	O
systems	O
via	O
VT100	B-Device
.	O
</s>
<s>
A	O
number	O
of	O
vendors	O
manufactured	O
3270	B-Operating_System
multiplexers	O
before	O
and	O
alongside	O
IBM	O
including	O
Fibronics	O
and	O
Adacom	O
offering	O
multiplexers	O
that	O
supported	O
TTP	O
–	O
Telephone	O
Twisted	O
Pair	O
as	O
an	O
alternative	O
to	O
coax	O
,	O
and	O
fiber-optic	O
links	O
between	O
the	O
multiplexers	O
.	O
</s>
<s>
The	O
IBM	B-Operating_System
3270	I-Operating_System
display	O
terminal	O
subsystem	O
was	O
designed	O
and	O
developed	O
by	O
IBM	O
's	O
Kingston	O
,	O
New	O
York	O
,	O
laboratory	O
(	O
which	O
later	O
closed	O
during	O
IBM	O
's	O
difficult	O
time	O
in	O
the	O
mid-1990s	O
)	O
.	O
</s>
<s>
The	O
subsystem	O
products	O
were	O
manufactured	O
in	O
Kingston	O
(	O
displays	O
and	O
controllers	O
)	O
,	O
Endicott	O
(	O
printers	O
)	O
,	O
and	O
Greenock	O
,	O
Scotland	O
,	O
UK	O
,	O
(	O
most	O
products	O
)	O
and	O
shipped	O
to	O
users	O
in	O
U.S.	O
and	O
worldwide	O
.	O
</s>
<s>
3278	B-Operating_System
terminals	O
continued	O
to	O
be	O
manufactured	O
in	O
Hortolândia	O
,	O
near	O
Campinas	O
,	O
Brazil	O
as	O
far	O
as	O
late	O
1980s	O
,	O
having	O
its	O
internals	O
redesigned	O
by	O
a	O
local	O
engineering	O
team	O
using	O
modern	O
CMOS	O
technology	O
,	O
while	O
retaining	O
its	O
external	O
look	O
and	O
feel	O
.	O
</s>
<s>
Telnet	B-Protocol
3270	B-Operating_System
,	O
or	O
tn3270	O
describes	O
both	O
the	O
process	O
of	O
sending	O
and	O
receiving	O
3270	B-Operating_System
data	I-Operating_System
streams	I-Operating_System
using	O
the	O
telnet	B-Protocol
protocol	O
and	O
the	O
software	O
that	O
emulates	O
a	O
3270	B-Operating_System
class	O
terminal	O
that	O
communicates	O
using	O
that	O
process	O
.	O
</s>
<s>
tn3270	O
allows	O
a	O
3270	B-Operating_System
terminal	I-Operating_System
emulator	O
to	O
communicate	O
over	O
a	O
TCP/IP	B-Protocol
network	I-Protocol
instead	O
of	O
an	O
SNA	B-Architecture
network	O
.	O
</s>
<s>
Telnet	B-Protocol
3270	B-Operating_System
can	O
be	O
used	O
for	O
either	O
terminal	O
or	O
print	O
connections	O
.	O
</s>
<s>
Standard	O
telnet	B-Protocol
clients	O
cannot	O
be	O
used	O
as	O
a	O
substitute	O
for	O
tn3270	O
clients	O
,	O
as	O
they	O
use	O
fundamentally	O
different	O
techniques	O
for	O
exchanging	O
data	O
.	O
</s>
<s>
The	O
3270	B-Operating_System
displays	O
are	O
available	O
with	O
a	O
variety	O
of	O
keyboards	O
and	O
character	O
sets	O
.	O
</s>
<s>
The	O
following	O
table	O
shows	O
the	O
3275/3277/3284	O
–	O
3286	O
character	O
set	O
for	O
US	O
English	O
EBCDIC	B-Language
(	O
optional	O
characters	O
were	O
available	O
for	O
US	O
ASCII	O
,	O
and	O
UK	O
,	O
French	O
,	O
German	O
,	O
and	O
Italian	O
EBCDIC	B-Language
)	O
.	O
</s>
<s>
NL	O
,	O
EM	O
,	O
DUP	O
,	O
and	O
FM	O
control	O
characters	O
display	O
and	O
print	O
as	O
5	B-Application
,	O
9	B-Application
,	O
*	B-Language
,	O
and	O
;	B-Device
characters	O
,	O
respectively	O
,	O
except	O
by	O
the	O
printer	O
when	O
WCC	O
or	O
CCC	O
bits	O
2	O
and	O
3	O
=	O
'	O
00'b	O
,	O
in	O
which	O
case	O
NL	O
and	O
EM	O
serve	O
their	O
control	O
function	O
and	O
do	O
not	O
print	O
.	O
</s>
<s>
Data	O
sent	O
to	O
the	O
3270	B-Operating_System
consist	O
of	O
commands	O
,	O
a	O
Copy	O
Control	O
Character	O
(	O
CCC	O
)	O
or	O
Write	O
Control	O
Character	O
(	O
WCC	O
)	O
if	O
appropriate	O
,	O
a	O
device	O
address	O
for	O
copy	O
,	O
orders	O
,	O
character	O
data	O
and	O
structured	O
fields	O
.	O
</s>
<s>
Commands	O
instruct	O
the	O
3270	B-Operating_System
control	O
unit	O
to	O
perform	O
some	O
action	O
on	O
a	O
specified	O
device	O
,	O
such	O
as	O
a	O
read	O
or	O
write	O
.	O
</s>
<s>
Orders	O
are	O
sent	O
as	O
part	O
of	O
the	O
data	B-General_Concept
stream	I-General_Concept
to	O
control	O
the	O
format	O
of	O
the	O
device	O
buffer	O
.	O
</s>
<s>
On	O
a	O
local	O
non-SNA	O
controller	O
,	O
the	O
command	O
is	O
a	O
CCW	O
opcode	O
rather	O
than	O
the	O
first	O
byte	O
of	O
the	O
outbound	O
display	O
stream	O
;	O
on	O
all	O
other	O
controllers	O
,	O
the	O
command	O
is	O
the	O
first	O
byte	O
of	O
the	O
display	O
stream	O
,	O
exclusive	O
of	O
protocol	O
headers	O
.	O
</s>
<s>
The	O
following	O
table	O
includes	O
datastream	O
commands	O
and	O
CCW	O
opcodes	O
for	O
local	O
non-SNA	O
controllers	O
;	O
it	O
does	O
not	O
include	O
CCW	O
opcodes	O
for	O
local	O
SNA	B-Architecture
controllers	O
.	O
</s>
<s>
+3270	O
commands	O
Command	O
HexadecimalGraphic	O
Function	O
localnon-SNA	O
EBCDIC	B-Language
ASCII	O
Copy	O
F7	O
37	O
7	O
Copy	O
from	O
one	O
device	O
buffer	O
to	O
another	O
,	O
e.g.	O
,	O
from	O
a	O
display	O
to	O
a	O
printer	O
Erase	O
All	O
Unprotected	O
0F	O
6F	O
3F	O
?	B-Device
</s>
<s>
Erase	O
all	O
unprotected	O
fields	O
and	O
reset	O
modified	O
data	O
tags	O
Erase/Write	O
05	O
F5	O
35	O
5	B-Application
Erase	O
device	O
buffer	O
,	O
then	O
write	O
WCC	O
folloed	O
by	O
orders	O
and	O
data	O
Erase/Write	O
Alternate	O
0D	O
7E	O
3D	O
=	O
Erase	O
device	O
buffer	O
,	O
set	O
alternate	O
size	O
,	O
then	O
write	O
WCC	O
folloed	O
by	O
orders	O
and	O
data	O
No	O
Operation	O
03	O
May	O
be	O
used	O
to	O
retrieve	O
pending	O
status	O
Read	O
Buffer	O
02	O
F2	O
22	O
2	O
Read	O
entire	O
device	O
buffer	O
,	O
including	O
attributes	O
Read	O
Modified	O
06	O
F6	O
36	O
6	O
Read	O
AID	O
,	O
cursor	O
and	O
,	O
except	O
for	O
short	O
read	O
,	O
modified	O
fields	O
from	O
device	O
Read	O
Modified	O
All	O
6E	O
3E	O
:	O
Read	O
AID	O
,	O
cursor	O
and	O
modified	O
fields	O
from	O
device	O
;	O
no	O
short	O
read	O
Select	O
0B	O
Transfer	O
data	O
from	O
device	O
to	O
control	O
unit	O
with	O
channel	B-Device
disconnected	O
Select	O
RB	O
1B	O
Select	O
Read	O
Buffer	O
;	O
may	O
only	O
be	O
chained	O
to	O
Read	O
Buffer	O
Select	O
RBP	O
3B	O
Select	O
Read	O
Buffer	O
from	O
Position	O
;	O
may	O
only	O
be	O
chained	O
to	O
Read	O
Buffer	O
Select	O
RM	O
DB	O
Select	O
Read	O
Modified	O
Select	O
RMP	O
2B	O
Select	O
Read	O
Modified	O
from	O
Position	O
Select	O
WRT	O
4B	O
Select	O
WRT	O
CommandMay	O
only	O
be	O
chained	O
to	O
a	O
Write	O
or	O
Write	O
Structured	O
Field	O
Sense	O
04	O
Retrieve	O
error	O
information	O
after	O
unit	O
check	O
Sense	O
ID	O
E4	O
Retrieve	O
control	O
unit	O
identification	O
Write	O
01	O
F1	O
31	O
1	O
Write	O
WCC	O
followed	O
by	O
orders	O
and	O
data	O
Write	O
Structured	O
Field	O
11	O
F3	O
3	O
Write	O
Structured	O
Field	O
For	O
remote	O
3270s	B-Operating_System
non-significant	O
bits	O
are	O
set	O
so	O
that	O
the	O
command	O
forms	O
a	O
valid	O
EBCDIC	B-Language
(	O
or	O
ASCII	O
)	O
character	O
.	O
</s>
<s>
The	O
3270	B-Operating_System
has	O
three	O
kinds	O
of	O
attributes	O
:	O
</s>
<s>
Bits	O
0	O
and	O
1	O
are	O
set	O
so	O
that	O
the	O
attribute	O
will	O
always	O
be	O
a	O
valid	O
EBCDIC	B-Language
(	O
or	O
ASCII	O
)	O
character	O
.	O
</s>
<s>
Bit	O
4	O
and	O
5	B-Application
operate	O
in	O
tandem	O
:	O
</s>
<s>
'	O
00'B	O
indicate	O
that	O
the	O
field	O
is	O
displayed	O
on	O
the	O
screen	O
and	O
is	O
not	O
selector-pen	O
detectable	O
.	O
</s>
<s>
'	O
01'B	O
indicates	O
that	O
the	O
field	O
is	O
displayable	O
and	O
selector-pen	O
detectable	O
.	O
</s>
<s>
'	O
10'B	O
indicates	O
that	O
the	O
field	O
is	O
intensified	O
(	O
bright	O
)	O
,	O
displayable	O
,	O
and	O
selector-pen	O
detectable	O
.	O
</s>
<s>
'	O
11'B	O
indicates	O
that	O
the	O
field	O
is	O
non-display	O
,	O
non-printable	O
,	O
and	O
not	O
pen	O
detectable	O
.	O
</s>
<s>
Later	O
models	O
include	O
base	O
color	O
:	O
"	O
Base	O
color	O
(	O
four	O
colors	O
)	O
can	O
be	O
produced	O
on	O
color	O
displays	O
and	O
color	O
printers	O
from	O
current	O
3270	B-Operating_System
application	O
programs	O
by	O
use	O
of	O
combinations	O
of	O
the	O
field	O
intensify	O
and	O
field	O
protection	O
attribute	O
bits	O
.	O
</s>
<s>
For	O
more	O
information	O
on	O
color	O
,	O
refer	O
to	O
IBM	B-Operating_System
3270	I-Operating_System
Information	O
System	O
:	O
Color	O
and	O
Programmed	O
Symbols	O
,	O
GA33-3056.	O
"	O
</s>
<s>
The	O
3278	B-Operating_System
and	O
3279	O
and	O
later	O
models	O
used	O
extended	O
attributes	O
to	O
add	O
support	O
for	O
seven	O
colors	O
,	O
blinking	O
,	O
reverse	O
video	O
,	O
underscoring	O
,	O
field	O
outlining	O
,	O
field	O
validation	O
,	O
and	O
programmed	O
symbols	O
.	O
</s>
<s>
The	O
3278	B-Operating_System
and	O
3279	O
and	O
later	O
models	O
allowed	O
attributes	O
on	O
individual	O
characters	O
in	O
a	O
field	O
to	O
override	O
the	O
corresponding	O
field	O
attributes	O
.	O
</s>
<s>
3270	B-Operating_System
displays	O
and	O
printers	O
have	O
a	O
buffer	O
containing	O
one	O
byte	O
for	O
every	O
screen	O
position	O
.	O
</s>
<s>
Later	O
3270s	B-Operating_System
with	O
larger	O
screen	O
sizes	O
use	O
fourteen	O
or	O
sixteen	O
bits	O
.	O
</s>
<s>
For	O
twelve	O
bit	O
addresses	O
the	O
high	O
order	O
two	O
bits	O
of	O
each	O
byte	O
are	O
set	O
to	O
form	O
valid	O
EBCDIC	B-Language
(	O
or	O
ASCII	O
)	O
characters	O
.	O
</s>
<s>
For	O
example	O
,	O
address	O
0	O
is	O
coded	O
as	O
X'4040'	O
,	O
or	O
space-space	O
,	O
address	O
1919	O
is	O
coded	O
as	O
X'5D7F'	O
,	O
or	O
''	O
.	O
</s>
<s>
Programmers	O
hand-coding	O
panels	O
usually	O
keep	O
the	O
table	O
of	O
addresses	O
from	O
the	O
3270	B-Operating_System
Component	O
Description	O
or	O
the	O
3270	B-Operating_System
Reference	O
Card	O
handy	O
.	O
</s>
<s>
The	O
following	O
data	B-General_Concept
stream	I-General_Concept
writes	O
an	O
attribute	O
in	O
row	O
24	O
,	O
column	O
1	O
,	O
writes	O
the	O
(	O
protected	O
)	O
characters	O
'	B-Language
>	O
'	B-Language
in	O
row	O
24	O
,	O
columns	O
2	O
and	O
3	O
,	O
and	O
creates	O
an	O
unprotected	O
field	O
on	O
row	O
24	O
from	O
columns	O
5-79	O
.	O
</s>
<s>
This	O
data	B-General_Concept
stream	I-General_Concept
would	O
normally	O
be	O
written	O
using	O
an	O
Erase/Write	O
command	O
which	O
would	O
set	O
undefined	O
positions	O
on	O
the	O
screen	O
to	O
'	O
00'x	O
.	O
</s>
<s>
Most	O
3270	B-Operating_System
terminals	I-Operating_System
newer	O
than	O
the	O
3275	O
,	O
3277	O
,	O
3284	O
and	O
3286	O
support	O
an	O
extended	O
data	B-General_Concept
stream	I-General_Concept
(	O
EDS	O
)	O
that	O
allows	O
many	O
new	O
capabilities	O
,	O
including	O
:	O
</s>
