<s>
The	O
VT220	O
is	O
a	O
computer	B-General_Concept
terminal	I-General_Concept
introduced	O
by	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
in	O
November	O
1983	O
.	O
</s>
<s>
The	O
VT240	B-Application
added	O
monochrome	O
ReGIS	B-Application
vector	O
graphics	O
support	O
to	O
the	O
base	O
model	O
,	O
while	O
the	O
VT241	O
did	O
the	O
same	O
in	O
color	O
.	O
</s>
<s>
The	O
200	O
series	O
replaced	O
the	O
successful	O
VT100	B-Device
series	O
,	O
providing	O
more	O
functionality	O
in	O
a	O
much	O
smaller	O
unit	O
with	O
a	O
much	O
smaller	O
and	O
lighter	O
keyboard	B-Device
.	O
</s>
<s>
Like	O
the	O
VT100	B-Device
,	O
the	O
VT200	O
series	O
implemented	O
a	O
large	O
subset	O
of	O
ANSI	O
X.364	O
.	O
</s>
<s>
Among	O
its	O
major	O
upgrades	O
was	O
a	O
number	O
of	O
international	B-General_Concept
character	I-General_Concept
sets	I-General_Concept
,	O
as	O
well	O
as	O
the	O
ability	O
to	O
define	O
new	O
character	B-General_Concept
sets	I-General_Concept
.	O
</s>
<s>
Released	O
at	O
$1	O
,	O
295	O
,	O
but	O
later	O
priced	O
at	O
$795	O
,	O
the	O
VT220	O
offered	O
features	O
,	O
packaging	O
and	O
price	O
that	O
no	O
other	O
serial	B-General_Concept
terminal	I-General_Concept
could	O
compete	O
with	O
at	O
the	O
time	O
.	O
</s>
<s>
Competitors	O
adapted	O
by	O
introducing	O
similar	O
models	O
at	O
lower	O
prices	O
,	O
leading	O
DEC	O
to	O
do	O
the	O
same	O
by	O
releasing	O
the	O
less-expensive	O
$545	O
VT300	B-Application
series	I-Application
in	O
1987	O
.	O
</s>
<s>
The	O
VT220	O
improved	O
on	O
the	O
earlier	O
VT100	B-Device
series	O
of	O
terminals	O
with	O
a	O
redesigned	O
keyboard	B-Device
,	O
much	O
smaller	O
physical	O
packaging	O
,	O
and	O
a	O
much	O
faster	O
microprocessor	O
.	O
</s>
<s>
The	O
VT100s	B-Device
,	O
like	O
the	O
VT50s	B-Application
before	O
them	O
,	O
had	O
been	O
packaged	O
in	O
relatively	O
large	O
cases	O
that	O
provided	O
room	O
for	O
expansion	O
systems	O
.	O
</s>
<s>
The	O
VT200s	O
abandoned	O
this	O
concept	O
,	O
and	O
wrapped	O
the	O
much	O
smaller	O
1980s-era	O
electronics	O
tightly	O
around	O
the	O
CRT	B-Device
.	O
</s>
<s>
The	O
result	O
was	O
a	O
truncated	O
pyramidal	O
case	O
with	O
the	O
apex	O
at	O
the	O
back	O
,	O
only	O
slightly	O
larger	O
than	O
the	O
CRT	B-Device
.	O
</s>
<s>
An	O
adjustable	O
stand	O
allowed	O
the	O
angle	O
of	O
the	O
CRT	B-Device
to	O
be	O
adjusted	O
up	O
and	O
down	O
.	O
</s>
<s>
The	O
LK201	B-Device
keyboard	B-Device
supplied	O
with	O
the	O
VT220	O
was	O
one	O
of	O
the	O
first	O
full-length	O
,	O
low-profile	O
keyboards	B-Device
available	O
;	O
it	O
was	O
developed	O
at	O
DEC	O
's	O
Roxbury	O
,	O
Massachusetts	O
facility	O
.	O
</s>
<s>
It	O
was	O
much	O
smaller	O
and	O
lighter	O
than	O
the	O
VT100s	B-Device
version	O
,	O
and	O
connected	O
to	O
the	O
terminal	O
using	O
a	O
lighter	O
and	O
more	O
flexible	O
coiled	O
cable	O
and	O
a	O
telephone	B-Protocol
jack	I-Protocol
connector	O
.	O
</s>
<s>
The	O
VT200s	O
were	O
the	O
last	O
DEC	O
terminals	O
to	O
provide	O
a	O
20mA	O
current	O
loop	O
serial	B-Protocol
interface	I-Protocol
,	O
an	O
older	O
standard	O
originally	O
developed	O
for	O
the	O
telegraph	O
system	O
but	O
became	O
popular	O
on	O
computers	O
due	O
to	O
the	O
early	O
use	O
of	O
Teletype	B-Application
Model	I-Application
33	I-Application
's	O
as	O
ad	O
hoc	O
terminals	O
.	O
</s>
<s>
Later	O
DEC	O
terminals	O
would	O
replace	O
both	O
of	O
these	O
with	O
their	O
proprietary	O
Modified	B-Device
Modular	I-Device
Jack	I-Device
(	O
MMJ	O
)	O
connectors	O
.	O
</s>
<s>
The	O
VT220	O
was	O
designed	O
to	O
be	O
compatible	O
with	O
the	O
VT100	B-Device
,	O
but	O
added	O
features	O
to	O
make	O
it	O
more	O
suitable	O
for	O
an	O
international	O
market	O
.	O
</s>
<s>
This	O
was	O
accomplished	O
by	O
including	O
a	O
number	O
of	O
different	O
character	B-General_Concept
sets	I-General_Concept
that	O
could	O
be	O
selected	O
among	O
using	O
a	O
series	O
of	O
ANSI	O
commands	O
.	O
</s>
<s>
The	O
terminal	O
shipped	O
with	O
a	O
total	O
of	O
288	O
characters	O
in	O
its	O
ROM	B-Device
,	O
each	O
one	O
formed	O
from	O
an	O
8	O
by	O
10	O
pixel	O
glyph	O
.	O
</s>
<s>
The	O
VT200s	O
included	O
the	O
ability	O
to	O
make	O
minor	O
changes	O
to	O
the	O
character	B-General_Concept
set	I-General_Concept
using	O
the	O
National	O
Replacement	O
Character	B-General_Concept
Set	I-General_Concept
(	O
NRCS	O
)	O
concept	O
.	O
</s>
<s>
When	O
operating	O
on	O
an	O
8-bit	O
clean	O
link	O
up	O
to	O
256	O
character	B-General_Concept
codes	I-General_Concept
were	O
available	O
,	O
which	O
included	O
a	O
full	O
set	O
of	O
European	O
characters	O
.	O
</s>
<s>
Most	O
terminals	O
solved	O
this	O
by	O
shipping	O
multiple	O
complete	O
character	B-General_Concept
sets	I-General_Concept
in	O
ROM	B-Device
,	O
but	O
there	O
was	O
a	O
cost	O
in	O
doing	O
so	O
.	O
</s>
<s>
This	O
eliminated	O
the	O
need	O
to	O
ship	O
14	O
versions	O
of	O
the	O
terminal	O
,	O
or	O
to	O
include	O
14	O
different	O
7-bit	O
character	B-General_Concept
sets	I-General_Concept
in	O
ROM	B-Device
.	O
</s>
<s>
Additionally	O
,	O
the	O
VT200s	O
allowed	O
for	O
another	O
96	O
characters	O
in	O
the	O
Dynamically	B-Device
Redefined	I-Device
Character	I-Device
Set	I-Device
(	O
DRCS	O
)	O
,	O
which	O
could	O
be	O
downloaded	O
from	O
the	O
host	O
computer	O
.	O
</s>
<s>
Data	O
for	O
the	O
glyphs	O
was	O
sent	O
by	O
encoding	O
a	O
set	O
of	O
six	O
vertical	O
pixels	O
into	O
a	O
single	O
character	B-General_Concept
code	I-General_Concept
,	O
and	O
then	O
sending	O
many	O
of	O
these	O
Sixels	O
to	O
the	O
terminal	O
,	O
which	O
decoded	O
them	O
into	O
the	O
character	B-General_Concept
set	I-General_Concept
memory	O
.	O
</s>
<s>
In	O
later	O
models	O
,	O
the	O
same	O
sixel	O
concept	O
would	O
be	O
used	O
to	O
send	O
bitmapped	B-Algorithm
graphics	I-Algorithm
as	O
well	O
.	O
</s>
<s>
Prior	O
to	O
the	O
VT220	O
,	O
if	O
an	O
Escape	B-Device
key	I-Device
was	O
present	O
,	O
it	O
was	O
positioned	O
in	O
the	O
upper	O
left	O
corner	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
For	O
users	O
of	O
the	O
TECO	B-Application
editor	O
,	O
in	O
which	O
it	O
is	O
heavily	O
used	O
,	O
this	O
was	O
inconvenient	O
.	O
</s>
<s>
In	O
1983-1984	O
,	O
during	O
the	O
design	O
phase	O
of	O
the	O
Model	O
M	O
keyboard	B-Device
,	O
the	O
VT220	O
was	O
a	O
new	O
and	O
very	O
popular	O
product	O
.	O
</s>
<s>
IBM	O
's	O
design	O
team	O
chose	O
to	O
emulate	O
its	O
LK201	B-Device
keyboard	B-Device
layout	O
.	O
</s>
<s>
Through	O
those	O
standards	O
,	O
minor	O
variations	O
of	O
the	O
VT220	O
's	O
keyboard	B-Device
layout	O
have	O
dominated	O
keyboard	B-Device
design	O
ever	O
since	O
.	O
</s>
