<s>
Viewdata	B-Application
is	O
a	O
Videotex	B-Operating_System
implementation	O
.	O
</s>
<s>
It	O
is	O
a	O
type	O
of	O
information	B-Library
retrieval	I-Library
service	O
in	O
which	O
a	O
subscriber	O
can	O
access	O
a	O
remote	O
database	O
via	O
a	O
common	O
carrier	O
channel	O
,	O
request	O
data	O
and	O
receive	O
requested	O
data	O
on	O
a	O
video	O
display	O
over	O
a	O
separate	O
channel	O
.	O
</s>
<s>
Samuel	O
Fedida	O
,	O
who	O
had	O
the	O
idea	O
for	O
Viewdata	B-Application
in	O
1968	O
,	O
was	O
credited	O
as	O
inventor	O
of	O
the	O
system	O
which	O
was	O
developed	O
while	O
working	O
for	O
the	O
British	O
Post	O
Office	O
which	O
was	O
the	O
operator	O
of	O
the	O
national	O
telephone	O
system	O
.	O
</s>
<s>
Viewdata	B-Application
offered	O
a	O
display	O
of	O
40×24	O
characters	O
,	O
based	O
on	O
ISO	O
646	O
(	O
IRV	O
IA5	O
)	O
–	O
7	O
bits	O
with	O
no	O
accented	O
characters	O
.	O
</s>
<s>
Originally	O
Viewdata	B-Application
was	O
accessed	O
with	O
a	O
special	O
purpose	O
terminal	B-General_Concept
(	O
or	O
emulation	B-Application
software	I-Application
)	O
and	O
a	O
modem	B-Application
running	O
at	O
ITU-T	O
V.23	O
speed	O
(	O
1,200	O
bit/s	O
down	O
,	O
75	O
bit/s	O
up	O
)	O
.	O
</s>
<s>
By	O
2004	O
it	O
was	O
normally	O
accessed	O
over	O
TCP/IP	B-Protocol
using	O
Viewdata	B-Application
client	B-Protocol
software	I-Protocol
on	O
a	O
personal	B-Device
computer	I-Device
running	O
Microsoft	B-Application
Windows	I-Application
,	O
or	O
using	O
a	O
Web-based	O
emulator	B-Application
.	O
</s>
<s>
As	O
of	O
2015	O
,	O
Viewdata	B-Application
was	O
still	O
in	O
use	O
in	O
the	O
United	O
Kingdom	O
,	O
mainly	O
by	O
the	O
travel	O
industry	O
.	O
</s>
<s>
Viewdata	B-Application
is	O
regarded	O
within	O
the	O
industry	O
as	O
low-cost	O
and	O
reliable	O
,	O
travel	O
consultants	O
have	O
been	O
trained	O
to	O
use	O
Viewdata	B-Application
and	O
would	O
need	O
training	O
to	O
book	O
holidays	O
on	O
the	O
Internet	O
,	O
and	O
tour	O
operators	O
cannot	O
agree	O
on	O
a	O
Web-based	O
standard	O
.	O
</s>
<s>
A	O
number	O
of	O
Viewdata	B-Application
bulletin	B-Application
board	I-Application
systems	I-Application
existed	O
in	O
the	O
1980s	O
,	O
predominantly	O
in	O
the	O
UK	O
due	O
to	O
the	O
proliferation	O
of	O
the	O
BBC	B-Device
Micro	I-Device
,	O
and	O
a	O
short-lived	O
Viewdata	B-Application
Revival	O
appeared	O
in	O
the	O
late	O
1990s	O
fuelled	O
by	O
the	O
retrocomputing	O
vogue	O
.	O
</s>
<s>
Some	O
Viewdata	B-Application
boards	O
still	O
exist	O
,	O
with	O
accessibility	O
in	O
the	O
form	O
of	O
Java	B-Device
Telnet	B-Protocol
clients	O
.	O
</s>
<s>
Viewdata	B-Application
uses	O
special	O
symbols	O
already	O
widely	O
available	O
on	O
telephone	O
keypads	O
:	O
the	O
"	O
star	O
"	O
key	O
and	O
the	O
"	O
square	O
"	O
key	O
,	O
as	O
formally	O
standardised	O
by	O
the	O
International	O
Telecommunication	O
Union	O
.	O
</s>
<s>
These	O
are	O
often	O
treated	O
as	O
approximately	O
corresponding	O
to	O
the	O
ASCII	O
asterisk	B-Language
( *	O
)	O
and	O
number	O
sign	O
( #	O
)	O
,	O
which	O
do	O
not	O
necessarily	O
conform	O
to	O
the	O
ITU	O
specifications	O
for	O
the	O
keypad	O
symbols	O
;	O
the	O
asterisk	B-Language
is	O
also	O
usually	O
displayed	O
smaller	O
and	O
raised	O
.	O
</s>
<s>
These	O
symbols	O
appear	O
as	O
'	O
Sextile	O
 '	O
and	O
'	O
Viewdata	B-Application
square	O
 '	O
in	O
the	O
Miscellaneous	O
Symbols	O
and	O
Miscellaneous	O
Technical	O
Unicode	O
blocks	O
,	O
respectively	O
.	O
</s>
