<s>
The	O
Tektronix	B-General_Concept
4010	I-General_Concept
series	O
was	O
a	O
family	O
of	O
text-and-graphics	O
computer	B-General_Concept
terminals	I-General_Concept
based	O
on	O
storage-tube	B-General_Concept
technology	O
created	O
by	O
Tektronix	O
.	O
</s>
<s>
Several	O
members	O
of	O
the	O
family	O
were	O
introduced	O
during	O
the	O
1970s	O
,	O
the	O
best	O
known	O
being	O
the	O
11-inch	O
4010	O
and	O
19-inch	O
4014	B-General_Concept
,	O
along	O
with	O
the	O
less	O
popular	O
25-inch	O
4016	O
.	O
</s>
<s>
They	O
were	O
widely	O
used	O
in	O
the	O
computer-aided	B-Application
design	I-Application
market	O
in	O
the	O
1970s	O
and	O
early	O
1980s	O
.	O
</s>
<s>
The	O
4000	O
series	O
were	O
much	O
less	O
expensive	O
than	O
earlier	O
graphics	O
terminals	O
,	O
such	O
as	O
the	O
IBM	B-Device
2250	I-Device
,	O
because	O
no	O
additional	O
electronics	O
were	O
needed	O
to	O
maintain	O
the	O
display	O
on	O
the	O
storage-tube	B-General_Concept
screen	O
;	O
images	O
drawn	O
to	O
the	O
screen	O
remained	O
there	O
until	O
deliberately	O
erased	O
.	O
</s>
<s>
This	O
eliminated	O
the	O
need	O
for	O
computer	B-General_Concept
memory	I-General_Concept
to	O
store	O
the	O
images	O
,	O
which	O
was	O
extremely	O
expensive	O
in	O
the	O
1970s	O
.	O
</s>
<s>
These	O
new	O
graphics	O
workstations	O
used	O
raster	B-Algorithm
displays	I-Algorithm
and	O
dedicated	O
screen	B-Algorithm
buffers	I-Algorithm
that	O
became	O
more	O
affordable	O
as	O
solid-state	B-Architecture
memory	I-Architecture
chips	O
became	O
markedly	O
cheaper	O
.	O
</s>
<s>
The	O
Tektronix	O
direct-view	O
bistable	O
storage	B-General_Concept
tube	I-General_Concept
was	O
first	O
used	O
in	O
the	O
Tektronix	O
564	O
oscilloscope	O
in	O
1963	O
,	O
and	O
was	O
first	O
used	O
for	O
non-oscilloscope	O
applications	O
in	O
the	O
601	O
monitor	O
in	O
1968	O
.	O
</s>
<s>
A	O
number	O
of	O
graphics	O
terminals	O
based	O
on	O
this	O
tube	O
and	O
others	O
from	O
the	O
600-series	O
were	O
developed	O
,	O
including	O
the	O
Advanced	O
Remote	O
Display	O
Station	O
from	O
MIT	O
's	O
Project	O
MAC	O
,	O
and	O
the	O
KV8I	B-General_Concept
(	O
later	O
,	O
KV8E	B-General_Concept
)	O
from	O
Digital	O
Equipment	O
Corporation	O
using	O
the	O
11-inch	O
diagonal	O
611	O
.	O
</s>
<s>
Tektronix	O
decided	O
to	O
enter	O
the	O
computer	B-General_Concept
terminal	I-General_Concept
market	O
themselves	O
,	O
introducing	O
the	O
4002	O
in	O
1969	O
,	O
and	O
the	O
updated	O
4002A	O
in	O
1971	O
.	O
</s>
<s>
These	O
were	O
similar	O
to	O
the	O
earlier	O
third-party	O
terminals	O
,	O
essentially	O
combining	O
one	O
of	O
their	O
storage	B-General_Concept
tubes	I-General_Concept
with	O
the	O
circuitry	O
needed	O
to	O
decode	O
instructions	O
from	O
the	O
host	O
and	O
turn	O
those	O
into	O
control	O
inputs	O
.	O
</s>
<s>
However	O
,	O
the	O
4002	O
had	O
the	O
unique	O
feature	O
that	O
only	O
a	O
portion	O
of	O
the	O
screen	O
was	O
a	O
storage	B-General_Concept
tube	I-General_Concept
,	O
with	O
a	O
small	O
section	O
set	O
aside	O
for	O
normal	O
refresh-based	O
drawing	O
.	O
</s>
<s>
Other	O
models	O
in	O
the	O
4010	O
series	O
included	O
the	O
4012	O
which	O
added	O
lower	O
case	O
characters	O
,	O
and	O
the	O
4013	O
with	O
an	O
APL	B-Language
character	O
set	O
.	O
</s>
<s>
The	O
4014	B-General_Concept
joined	O
the	O
line	O
at	O
,	O
introducing	O
a	O
larger	O
19-inch	O
screen	O
as	O
well	O
as	O
a	O
more	O
an	O
ergonomic	O
layout	O
.	O
</s>
<s>
It	O
had	O
a	O
wide	O
range	O
of	O
new	O
features	O
as	O
well	O
,	O
which	O
made	O
it	O
much	O
more	O
effective	O
in	O
many	O
contexts	O
and	O
became	O
especially	O
common	O
in	O
computer-aided	B-Application
design	I-Application
(	O
CAD	B-Application
)	O
use	O
.	O
</s>
<s>
The	O
upgraded	O
features	O
became	O
so	O
widely-used	O
that	O
the	O
4014	B-General_Concept
series	O
is	O
sometimes	O
considered	O
to	O
be	O
a	O
separate	O
line	O
from	O
the	O
4010	O
,	O
or	O
alternatively	O
the	O
canonical	B-Application
model	I-Application
for	O
the	O
entire	O
family	O
.	O
</s>
<s>
The	O
4015	O
was	O
a	O
4014	B-General_Concept
with	O
the	O
APL	B-Language
character	O
set	O
card	O
from	O
the	O
4013	O
.	O
</s>
<s>
A	O
properly	O
equipped	O
4014	B-General_Concept
could	O
also	O
drive	O
a	O
pen	O
plotter	O
through	O
an	O
expansion	O
card	O
,	O
including	O
the	O
GPIB-based	O
4662	O
Interactive	O
Digital	O
Plotter	O
and	O
4663	O
C-sized	O
version	O
.	O
</s>
<s>
Storage	O
options	O
included	O
the	O
4911	O
punch	O
tape	O
,	O
the	O
4912	O
using	O
cassette	O
tapes	O
based	O
on	O
a	O
Sykes	O
TT120	O
mechanism	O
,	O
and	O
later	O
added	O
the	O
4923	O
based	O
on	O
the	O
3M	O
DC300	B-Device
digital	O
tape	O
system	O
.	O
</s>
<s>
Other	O
devices	O
in	O
the	O
lineup	O
included	O
the	O
4901	O
and	O
4903	O
Interactive	O
Graphic	O
Unit	O
,	O
which	O
drew	O
crosshairs	O
on	O
the	O
4002	O
(	O
this	O
capability	O
was	O
built	O
into	O
the	O
later	O
models	O
)	O
,	O
and	O
the	O
4951	O
Joystick	B-Device
.	O
</s>
<s>
This	O
hardware	O
allowed	O
the	O
user	O
to	O
select	O
any	O
point	O
on	O
a	O
display	O
,	O
and	O
to	O
input	O
its	O
coordinates	O
to	O
a	O
computer	O
,	O
allowing	O
support	O
of	O
a	O
CAD	B-Application
system	O
.	O
</s>
<s>
The	O
4551	O
Light	B-Device
Pen	I-Device
,	O
originally	O
developed	O
for	O
the	O
611	O
,	O
could	O
also	O
be	O
used	O
to	O
input	O
graphical	O
data	O
points	O
.	O
</s>
<s>
The	O
Tektronix	O
4050	O
series	O
used	O
the	O
4010	O
or	O
4014	B-General_Concept
with	O
internal	O
processors	O
and	O
a	O
DC300	B-Device
tape	O
unit	O
to	O
produce	O
a	O
simple	O
desktop	O
unit	O
.	O
</s>
<s>
There	O
were	O
three	O
models	O
:	O
the	O
original	O
4010-based	O
4051	O
with	O
an	O
8-bit	O
processor	O
,	O
the	O
4052	O
with	O
a	O
16-bit	O
processor	O
,	O
and	O
the	O
4054	O
which	O
combined	O
the	O
4014	B-General_Concept
screen	O
with	O
the	O
4052	O
logic	O
.	O
</s>
<s>
The	O
4081	O
was	O
a	O
version	O
with	O
an	O
Interdata	O
7/16	O
minicomputer	B-Architecture
built	O
into	O
an	O
office	O
desk	O
,	O
which	O
saw	O
limited	O
use	O
.	O
</s>
<s>
Tektronix	O
continued	O
selling	O
the	O
basic	O
storage	B-General_Concept
tubes	I-General_Concept
to	O
OEMs	O
,	O
the	O
19-inch	O
version	O
as	O
the	O
GMA101	O
and	O
102	O
(	O
the	O
former	O
offering	O
roughly	O
twice	O
the	O
drawing	O
speed	O
)	O
and	O
the	O
25-inch	O
as	O
the	O
GMA125	O
.	O
</s>
<s>
Tektronix	O
also	O
sold	O
a	O
set	O
of	O
graphics	O
software	O
routines	O
in	O
FORTRAN	B-Application
known	O
as	O
PLOT10	O
that	O
converted	O
simple	O
inputs	O
like	O
lists	O
of	O
numbers	O
into	O
a	O
graphic	O
display	O
such	O
as	O
a	O
chart	O
.	O
</s>
<s>
This	O
de	O
facto	O
standard	O
for	O
encoding	O
graphical	O
information	O
was	O
later	O
ported	O
to	O
traditional	O
video	B-General_Concept
terminals	I-General_Concept
using	O
raster	O
scan	O
displays	O
,	O
although	O
these	O
generally	O
offered	O
lower	O
resolution	O
,	O
perhaps	O
half	O
that	O
of	O
the	O
4010	O
.	O
</s>
<s>
This	O
graphical	O
data	O
standard	O
continues	O
to	O
be	O
emulated	O
by	O
newer	O
terminals	O
to	O
this	O
day	O
;	O
NCSA	B-Protocol
Telnet	I-Protocol
and	O
xterm	B-Language
can	O
emulate	O
the	O
4014	B-General_Concept
(	O
xterm	B-Language
-t	O
)	O
.	O
</s>
<s>
A	O
modern	O
solution	O
is	O
to	O
use	O
additional	O
hardware	O
and	O
computer	B-General_Concept
memory	I-General_Concept
to	O
store	O
the	O
image	O
between	O
each	O
update	O
,	O
a	O
section	O
of	O
memory	O
known	O
as	O
a	O
framebuffer	B-Algorithm
.	O
</s>
<s>
In	O
the	O
1960s	O
,	O
memory	O
based	O
on	O
core	B-General_Concept
was	O
extremely	O
expensive	O
,	O
generally	O
priced	O
in	O
dollars	O
or	O
cents	O
per	O
bit	O
.	O
</s>
<s>
Solid-state	B-Architecture
memory	I-Architecture
was	O
even	O
more	O
expensive	O
,	O
and	O
could	O
only	O
be	O
used	O
for	O
a	O
handful	O
of	O
high-speed	O
working	O
storage	O
registers	O
in	O
data	O
processing	O
hardware	O
.	O
</s>
<s>
If	O
one	O
wanted	O
to	O
store	O
a	O
screen	O
of	O
text	O
at	O
80	O
columns	O
by	O
25	O
lines	O
and	O
using	O
7-bit	B-Protocol
ASCII	I-Protocol
,	O
one	O
would	O
require	O
8025	O
=	O
,	O
making	O
the	O
price	O
of	O
the	O
terminal	O
prohibitive	O
.	O
</s>
<s>
The	O
IBM	B-Device
2250	I-Device
graphics	O
terminal	O
used	O
this	O
solution	O
,	O
and	O
sold	O
for	O
.	O
</s>
<s>
Tektronix	O
had	O
originally	O
developed	O
their	O
storage	B-General_Concept
tubes	I-General_Concept
in	O
the	O
late	O
1950s	O
as	O
a	O
way	O
to	O
store	O
images	O
on	O
oscilloscope	O
displays	O
for	O
study	O
,	O
although	O
the	O
same	O
system	O
had	O
already	O
been	O
used	O
in	O
radar	B-Application
displays	O
.	O
</s>
<s>
The	O
storage	B-General_Concept
tube	I-General_Concept
technology	O
was	O
vulnerable	O
to	O
screen	B-General_Concept
burn-in	I-General_Concept
,	O
as	O
the	O
continuous	O
flow	O
of	O
electrons	O
illuminating	O
a	O
stored	O
image	O
gradually	O
degraded	O
the	O
light-emitting	O
phosphors	O
over	O
a	O
long	O
period	O
of	O
time	O
.	O
</s>
<s>
Software	O
screensaver	B-General_Concept
programs	O
were	O
not	O
useful	O
in	O
protecting	O
storage	B-General_Concept
tube	I-General_Concept
display	O
screens	O
from	O
burn-in	O
of	O
images	O
.	O
</s>
<s>
Early	O
CAD	B-Application
systems	O
made	O
by	O
companies	O
such	O
as	O
Computervision	O
took	O
full	O
advantage	O
of	O
the	O
graphic	O
storage	O
capability	O
,	O
and	O
were	O
able	O
to	O
display	O
arbitrarily	O
complex	O
designs	O
without	O
annoying	O
flicker	O
.	O
</s>
<s>
The	O
main	O
disadvantage	O
of	O
storage	B-General_Concept
tubes	I-General_Concept
was	O
that	O
once	O
an	O
image	O
was	O
stored	O
,	O
it	O
could	O
only	O
be	O
removed	O
by	O
erasing	O
the	O
entire	O
image	O
.	O
</s>
<s>
Some	O
early	O
CAD	B-Application
workstations	I-Application
employed	O
both	O
a	O
video	B-General_Concept
terminal	I-General_Concept
to	O
display	O
frequently	O
changing	O
text	O
,	O
and	O
a	O
Tektronix	O
display	O
showing	O
complex	O
graphics	O
images	O
.	O
</s>
<s>
The	O
401x	O
series	O
physically	O
consisted	O
of	O
a	O
large	O
CRT	B-Device
display	I-Device
sitting	O
on	O
top	O
of	O
a	O
wheeled	O
cart	O
.	O
</s>
<s>
The	O
4014	B-General_Concept
terminal	O
was	O
normally	O
shipped	O
with	O
the	O
standard	O
Communications	O
Interface	O
installed	O
,	O
offering	O
an	O
RS-232	O
connection	O
,	O
although	O
only	O
the	O
most	O
important	O
connector	O
pins	O
were	O
supported	O
.	O
</s>
<s>
As	O
an	O
alternative	O
to	O
the	O
Communications	O
Interface	O
,	O
the	O
TTY	O
Interface	O
allowed	O
the	O
terminal	O
to	O
be	O
connected	O
to	O
a	O
20-mA	O
current-loop	O
teletype	O
interface	O
,	O
which	O
was	O
still	O
widely	O
used	O
by	O
mainframe	B-Architecture
computers	I-Architecture
of	O
that	O
era	O
.	O
</s>
<s>
Direct	O
interfaces	O
using	O
proprietary	O
serial	O
or	O
parallel	O
connections	O
were	O
also	O
available	O
for	O
most	O
mainframe	B-Architecture
systems	O
.	O
</s>
<s>
The	O
terminal	O
was	O
"	O
dumb	O
"	O
by	O
standards	O
of	O
the	O
day	O
,	O
lacking	O
various	O
smart	O
terminal	O
features	O
like	O
addressable	O
cursor	B-Application
positioning	O
.	O
</s>
<s>
Switching	O
between	O
the	O
columns	O
was	O
accomplished	O
by	O
moving	O
to	O
the	O
very	O
last	O
line	O
in	O
any	O
given	O
column	O
and	O
pressing	O
line	O
feed	O
on	O
the	O
keyboard	B-Device
.	O
</s>
<s>
The	O
cursor	B-Application
would	O
then	O
reappear	O
at	O
the	O
top	O
of	O
the	O
next	O
column	O
.	O
</s>
<s>
The	O
terminals	O
also	O
optionally	O
supported	O
a	O
second	O
character	O
set	O
via	O
plug-in	O
circuit	O
boards	O
,	O
selecting	O
between	O
them	O
with	O
the	O
ASCII	B-Protocol
and	O
characters	O
.	O
</s>
<s>
This	O
was	O
required	O
for	O
the	O
APL	B-Language
language	I-Language
,	O
which	O
used	O
a	O
large	O
number	O
of	O
special	O
characters	O
.	O
</s>
<s>
These	O
values	O
were	O
encoded	O
in	O
ASCII	B-Protocol
,	O
using	O
5	O
bits	O
per	O
character	O
,	O
and	O
thus	O
requiring	O
two	O
characters	O
per	O
value	O
,	O
or	O
4	O
characters	O
for	O
a	O
complete	O
X	O
,	O
Y	O
coordinate	O
.	O
</s>
<s>
The	O
encoding	O
scheme	O
was	O
designed	O
to	O
make	O
the	O
coordinate	O
characters	O
safely	O
sent	O
over	O
serial	O
links	O
by	O
assigning	O
each	O
value	O
from	O
the	O
set	O
of	O
ASCII	B-Protocol
printable	O
characters	O
.	O
</s>
<s>
To	O
convert	O
location	O
to	O
an	O
ASCII	B-Protocol
character	I-Protocol
code	O
,	O
one	O
added	O
64	O
to	O
the	O
X	O
value	O
,	O
and	O
96	O
to	O
the	O
Y	O
value	O
.	O
</s>
<s>
Adding	O
23	O
to	O
64	O
gives	O
87	O
,	O
which	O
is	O
ASCII	B-Protocol
character	I-Protocol
,	O
and	O
since	O
no	O
shift	O
is	O
required	O
the	O
"	O
shift	O
character	O
"	O
is	O
.	O
</s>
<s>
Graphics	O
are	O
drawn	O
by	O
entering	O
graph	O
mode	O
by	O
sending	O
the	O
ASCII	B-Protocol
Group	O
Separator	O
(	O
GS	O
)	O
character	O
(	O
)	O
.	O
</s>
<s>
The	O
first	O
four	O
following	O
the	O
GS	O
position	O
the	O
graphic	O
cursor	B-Application
,	O
every	O
point	O
after	O
that	O
draws	O
a	O
vector	O
on	O
the	O
display	O
.	O
</s>
<s>
For	O
graphics	O
input	O
,	O
the	O
terminal	O
used	O
a	O
pair	O
of	O
thumb	O
wheels	O
on	O
the	O
keyboard	B-Device
to	O
control	O
the	O
position	O
of	O
a	O
cursor	B-Application
.	O
</s>
<s>
The	O
cursor	B-Application
was	O
displayed	O
using	O
a	O
lower	O
intensity	O
of	O
the	O
electron	O
beam	O
that	O
had	O
insufficient	O
energy	O
to	O
cause	O
the	O
storage	O
system	O
to	O
trigger	O
.	O
</s>
<s>
The	O
cursor	B-Application
was	O
dynamically	O
refreshed	O
by	O
the	O
electronics	O
of	O
the	O
terminal	O
.	O
</s>
<s>
The	O
cursor	B-Application
was	O
turned	O
on	O
with	O
(	O
)	O
(	O
which	O
also	O
turned	O
off	O
graphic	O
mode	O
if	O
it	O
was	O
on	O
)	O
,	O
and	O
then	O
(	O
)	O
.	O
</s>
<s>
This	O
could	O
be	O
done	O
interactively	O
by	O
sending	O
the	O
and	O
then	O
pressing	O
a	O
key	O
on	O
the	O
keyboard	B-Device
,	O
or	O
immediately	O
by	O
the	O
host	O
sending	O
.	O
</s>
<s>
The	O
4014	B-General_Concept
series	O
had	O
a	O
number	O
of	O
minor	O
changes	O
and	O
some	O
more	O
major	O
improvements	O
.	O
</s>
<s>
In	O
the	O
4010	O
,	O
the	O
cursor	B-Application
and	O
graphic	O
crosshairs	O
were	O
interactive	O
and	O
used	O
dark	O
mode	O
to	O
move	O
about	O
the	O
screen	O
without	O
writing	O
to	O
memory	O
.	O
</s>
<s>
The	O
4014	B-General_Concept
added	O
escape	O
codes	O
to	O
allow	O
the	O
user	O
to	O
select	O
this	O
mode	O
deliberately	O
by	O
sending	O
any	O
of	O
the	O
sequences	O
from	O
through	O
.	O
</s>
<s>
It	O
could	O
also	O
be	O
used	O
to	O
move	O
the	O
graphics	O
cursor	B-Application
to	O
a	O
new	O
location	O
without	O
having	O
to	O
exit	O
and	O
re-enter	O
graphics	O
mode	O
,	O
which	O
previously	O
was	O
the	O
only	O
way	O
to	O
accomplish	O
this	O
.	O
</s>
<s>
The	O
4014	B-General_Concept
made	O
a	O
change	O
to	O
the	O
way	O
graphics	O
points	O
were	O
entered	O
by	O
adding	O
an	O
execution	O
character	O
which	O
denoted	O
that	O
a	O
particular	O
coordinate	O
was	O
complete	O
.	O
</s>
<s>
On	O
a	O
4010	O
series	O
terminal	O
or	O
4014	B-General_Concept
without	O
the	O
Enhanced	O
Graphic	O
Module	O
,	O
this	O
extra	O
byte	O
would	O
then	O
immediately	O
be	O
overwritten	O
by	O
the	O
actual	O
low-order	O
address	O
that	O
arrived	O
as	O
the	O
next	O
character	O
,	O
and	O
thus	O
have	O
no	O
effect	O
.	O
</s>
<s>
These	O
were	O
selected	O
using	O
the	O
same	O
escape	O
characters	O
as	O
the	O
drawing	O
mode	O
selection	O
of	O
the	O
normal	O
4014	B-General_Concept
,	O
the	O
range	O
through	O
.	O
</s>
<s>
Incremental	O
plot	O
,	O
entered	O
with	O
the	O
ASCII	B-Protocol
Record	O
Separator	O
(	O
RS	O
)	O
character	O
,	O
replaced	O
the	O
normal	O
coordinates	O
with	O
single-character	O
directions	O
.	O
</s>
<s>
Entering	O
the	O
normal	O
point	O
plot	O
mode	O
with	O
the	O
ASCII	B-Protocol
File	I-Protocol
Separator	O
(	O
FS	O
)	O
,	O
instead	O
of	O
RS	O
for	O
graph	O
mode	O
,	O
plotted	O
only	O
the	O
points	O
at	O
the	O
coordinates	O
being	O
sent	O
,	O
not	O
the	O
vectors	O
between	O
them	O
.	O
</s>
<s>
The	O
overall	O
build	O
quality	O
of	O
the	O
Tektronix	B-General_Concept
4010	I-General_Concept
was	O
excellent	O
,	O
with	O
gold-plated	O
boards	O
of	O
high-quality	O
epoxy	O
fiberglass	O
material	O
.	O
</s>
<s>
Construction	O
Pedestal	O
with	O
keyboard	B-Device
Display	O
74	O
×	O
35	O
characters	O
or	O
1024	O
×	O
780	O
pixels	O
.	O
</s>
