<s>
A	O
bit-paired	B-Protocol
keyboard	I-Protocol
is	O
a	O
keyboard	B-Device
where	O
the	O
layout	O
of	O
shifted	B-Device
keys	I-Device
corresponds	O
to	O
columns	O
in	O
the	O
ASCII	B-Protocol
(	O
1963	O
)	O
table	O
,	O
archetypally	O
the	O
Teletype	B-Application
Model	I-Application
33	I-Application
(	O
1963	O
)	O
keyboard	B-Device
.	O
</s>
<s>
This	O
was	O
later	O
contrasted	O
with	O
a	O
typewriter-paired	B-Protocol
keyboard	I-Protocol
,	O
where	O
the	O
layout	O
of	O
shifted	B-Device
keys	I-Device
corresponds	O
to	O
electric	O
typewriter	O
layouts	O
,	O
notably	O
the	O
IBM	O
Selectric	O
(	O
1961	O
)	O
.	O
</s>
<s>
The	O
difference	O
is	O
most	O
visible	O
in	O
the	O
digits	O
row	O
(	O
top	O
row	O
)	O
:	O
compared	O
with	O
mechanical	O
typewriters	O
,	O
bit-paired	B-Protocol
keyboards	I-Protocol
remove	O
the	O
_	O
character	O
from	O
6	O
and	O
shift	O
the	O
remaining	O
*( 	O
)	O
from	O
7890	O
to	O
6789	O
,	O
while	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
replace	O
3	O
characters	O
:	O
from	O
"	O
to	O
@	O
from	O
_	O
to	O
^	O
and	O
from	O
'	O
to	O
*	O
.	O
</s>
<s>
An	O
important	O
subtlety	O
is	O
that	O
ASCII	B-Protocol
was	O
based	O
on	O
mechanical	O
typewriters	O
,	O
but	O
electric	O
typewriters	O
became	O
popular	O
during	O
the	O
same	O
period	O
that	O
ASCII	B-Protocol
was	O
adopted	O
,	O
and	O
made	O
their	O
own	O
changes	O
to	O
layout	O
.	O
</s>
<s>
Thus	O
differences	O
between	O
bit-paired	B-Protocol
and	O
(	O
electric	O
)	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
are	O
due	O
to	O
the	O
differences	O
of	O
both	O
of	O
these	O
from	O
earlier	O
mechanical	O
typewriters	O
.	O
</s>
<s>
Bit-paired	B-Protocol
keyboards	I-Protocol
were	O
common	O
in	O
the	O
United	O
States	O
in	O
the	O
1960s	O
and	O
1970s	O
,	O
due	O
to	O
ease	O
of	O
manufacture	O
,	O
but	O
died	O
out	O
in	O
the	O
late	O
1970s	O
with	O
office	B-Application
automation	I-Application
,	O
due	O
to	O
the	O
number	O
of	O
users	O
already	O
accustomed	O
to	O
(	O
electric	O
)	O
typewriter	O
layouts	O
.	O
</s>
<s>
Bit-paired	B-Protocol
keyboard	I-Protocol
layouts	O
survive	O
today	O
only	O
in	O
the	O
standard	O
Japanese	O
keyboard	B-Device
layout	O
,	O
which	O
has	O
all	O
shifted	O
values	O
of	O
digits	O
in	O
the	O
bit-paired	B-Protocol
layout	O
.	O
</s>
<s>
In	O
mechanical	O
typewriters	O
,	O
the	O
shift	B-Device
key	I-Device
functions	O
by	O
mechanically	O
shifting	O
some	O
component	O
so	O
an	O
alternate	O
row	O
of	O
characters	O
on	O
typebars	O
hits	O
the	O
paper	O
.	O
</s>
<s>
In	O
an	O
electronic	O
system	O
,	O
by	O
contrast	O
,	O
there	O
is	O
no	O
necessary	O
connection	O
between	O
the	O
code	O
points	O
of	O
unshifted	O
and	O
shifted	O
values	O
,	O
though	O
implementation	O
is	O
simpler	O
if	O
the	O
code	O
points	O
of	O
unshifted	O
and	O
shifted	B-Device
keys	I-Device
are	O
related	O
,	O
most	O
simply	O
by	O
a	O
single	O
bit	O
differing	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
among	O
others	O
(	O
such	O
as	O
ease	O
of	O
collation	O
)	O
,	O
the	O
ASCII	B-Protocol
standard	O
strove	O
to	O
organize	O
the	O
code	O
points	O
so	O
that	O
shifting	O
could	O
be	O
implemented	O
by	O
simply	O
toggling	O
a	O
bit	O
.	O
</s>
<s>
This	O
is	O
also	O
present	O
,	O
but	O
less	O
precisely	O
,	O
in	O
the	O
organization	O
of	O
digits	O
and	O
symbols	O
in	O
columns	O
2	O
(	O
010	O
)	O
and	O
3	O
(	O
011	O
)	O
–	O
this	O
discrepancy	O
is	O
the	O
source	O
of	O
bit-paired	B-Protocol
layouts	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
implementing	O
an	O
electromechanical	O
keyboard	B-Device
that	O
produced	O
an	O
ASCII	B-Protocol
encoding	O
but	O
had	O
conventional	O
typewriter	O
key	O
mappings	O
would	O
require	O
significant	O
complexity	O
due	O
to	O
key-specific	O
shift	O
mechanisms	O
for	O
digits	O
and	O
symbol	O
keys	O
.	O
</s>
<s>
This	O
could	O
be	O
avoided	O
by	O
changing	O
the	O
key	O
mappings	O
to	O
correspond	O
to	O
the	O
ASCII	B-Protocol
table	O
,	O
which	O
was	O
notably	O
done	O
in	O
the	O
Teletype	B-Application
Model	I-Application
33	I-Application
(	O
1963	O
)	O
.	O
</s>
<s>
Later	O
keyboards	B-Device
continued	O
to	O
use	O
this	O
mapping	O
,	O
which	O
was	O
formalized	O
in	O
the	O
American	O
Standards	O
Association	O
X4.14-1971	O
standard	O
and	O
the	O
European	O
Computer	O
Manufacturers	O
 '	O
Association	O
ECMA-23	O
standard	O
,	O
where	O
it	O
is	O
referred	O
to	O
as	O
logical	O
bit	O
pairing	O
,	O
and	O
contrasted	O
with	O
typewriter	O
pairing	O
.	O
</s>
<s>
In	O
everyday	O
usage	O
these	O
were	O
referred	O
to	O
as	O
bit-paired	B-Protocol
and	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
.	O
</s>
<s>
The	O
most	O
conspicuous	O
feature	O
of	O
a	O
bit-paired	B-Protocol
keyboard	I-Protocol
are	O
the	O
shifted	O
values	O
of	O
the	O
digits	O
,	O
which	O
are	O
(	O
only	O
9	O
values	O
,	O
0	O
being	O
unpaired	O
)	O
:	O
</s>
<s>
…	O
instead	O
of	O
the	O
conventional	O
mechanical	O
typewriter-paired	B-Protocol
values	O
of	O
:	O
</s>
<s>
…	O
and	O
the	O
electric	O
typewriter-paired	B-Protocol
values	O
of	O
:	O
</s>
<s>
The	O
shifted	O
values	O
of	O
digits	O
in	O
a	O
bit-paired	B-Protocol
keyboard	I-Protocol
thus	O
differ	O
from	O
mechanical	O
typewriters	O
only	O
in	O
omitting	O
_	O
and	O
shifting	O
the	O
remaining	O
characters	O
left	O
.	O
</s>
<s>
Overall	O
this	O
results	O
in	O
the	O
following	O
comparison	O
between	O
bit-paired	B-Protocol
keyboards	I-Protocol
and	O
(	O
electric	O
)	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
:	O
they	O
agree	O
in	O
1	O
,	O
3	O
,	O
4	O
,	O
5	O
,	O
and	O
differ	O
in	O
2	O
,	O
6	O
,	O
7	O
,	O
8	O
,	O
9	O
,	O
0	O
:	O
bit-pairing	O
replaces	O
@	O
with	O
"	O
(	O
position	O
2	O
)	O
,	O
removes	O
^	O
(	O
position	O
6	O
,	O
shifting	O
later	O
characters	O
left	O
)	O
,	O
and	O
replaces	O
*	O
with	O
'	O
(	O
position	O
8/7	O
)	O
;	O
there	O
is	O
also	O
no	O
shifted	O
value	O
for	O
0	O
,	O
as	O
this	O
corresponds	O
to	O
space	O
,	O
which	O
is	O
covered	O
by	O
the	O
space	O
bar	O
.	O
</s>
<s>
This	O
corresponds	O
in	O
the	O
ASCII	B-Protocol
table	O
to	O
the	O
following	O
columns	O
(	O
displayed	O
as	O
rows	O
here	O
)	O
:	O
</s>
<s>
There	O
are	O
also	O
less	O
conspicuous	O
differences	O
in	O
the	O
symbol	O
keys	O
:	O
bit-paired	B-Protocol
and	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
agree	O
on	O
(	O
rows	O
12	O
,	O
14	O
,	O
and	O
15	O
)	O
but	O
bit-paired	B-Protocol
keyboards	I-Protocol
have	O
(	O
rows	O
10	O
,	O
11	O
,	O
and	O
13	O
)	O
instead	O
of	O
and	O
are	O
missing	O
the	O
key	O
,	O
as	O
these	O
are	O
shifted	O
values	O
of	O
digits	O
.	O
</s>
<s>
This	O
is	O
the	O
complete	O
set	O
of	O
symbols	O
on	O
the	O
Model	O
33	O
;	O
it	O
is	O
notably	O
missing	O
though	O
these	O
are	O
present	O
on	O
other	O
bit-paired	B-Protocol
keyboards	I-Protocol
.	O
</s>
<s>
On	O
both	O
bit-paired	B-Protocol
and	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
,	O
are	O
paired	O
(	O
rows	O
11	O
,	O
12	O
,	O
and	O
13	O
)	O
,	O
but	O
on	O
bit-paired	B-Protocol
keyboards	I-Protocol
are	O
paired	O
and	O
is	O
an	O
unpaired	O
key	O
,	O
while	O
on	O
typewriter-paired	B-Protocol
keyboards	I-Protocol
and	O
are	O
shifted	O
digits	O
,	O
while	O
are	O
paired	O
and	O
is	O
paired	O
with	O
.	O
</s>
<s>
In	O
the	O
US	O
,	O
bit-paired	B-Protocol
keyboards	I-Protocol
continued	O
to	O
be	O
used	O
into	O
the	O
1970s	O
,	O
including	O
on	O
electronic	O
keyboards	B-Device
like	O
the	O
HP	B-General_Concept
2640	I-General_Concept
terminal	O
(	O
1975	O
)	O
and	O
the	O
first	O
model	O
Apple	B-Device
II	I-Device
computer	O
(	O
1977	O
)	O
.	O
</s>
<s>
A	O
typewriter-paired	B-Protocol
layout	O
similar	O
to	O
the	O
IBM	O
Selectric	O
's	O
was	O
used	O
in	O
the	O
DEC	O
VT52	B-Application
(	O
1975	O
)	O
,	O
the	O
IBM	B-Device
PC	I-Device
(	O
1981	O
)	O
,	O
and	O
the	O
Model	B-Device
M	I-Device
keyboard	I-Device
(	O
1984	O
)	O
.	O
</s>
<s>
Other	O
personal	B-Device
computers	I-Device
imitated	O
it	O
,	O
resulting	O
in	O
the	O
typewriter-paired	B-Protocol
layout	O
becoming	O
standard	O
in	O
the	O
US	O
,	O
and	O
to	O
a	O
lesser	O
extent	O
globally	O
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
bit-paired	B-Protocol
keyboards	I-Protocol
were	O
used	O
on	O
most	O
8-bit	O
computers	O
such	O
as	O
the	O
Acorn	O
BBC	O
computers	O
and	O
the	O
earlier	O
Atom	O
and	O
Systems	O
,	O
the	O
Amstrad	O
CPC	O
series	O
,	O
and	O
(	O
to	O
an	O
extent	O
)	O
the	O
ZX	O
Spectrum	O
.	O
</s>
<s>
In	O
Europe	O
,	O
keyboards	B-Device
of	O
computers	O
for	O
text	O
processing	O
underwent	O
the	O
transition	O
to	O
national	O
typewriter	O
layouts	O
in	O
the	O
late	O
1970s	O
,	O
but	O
otherwise	O
the	O
international	O
bit-paired	B-Protocol
layout	O
of	O
ISO	O
2530	O
(	O
1975	O
)	O
remained	O
in	O
use	O
until	O
general-purpose	O
PC	B-Device
keyboards	I-Device
replaced	O
the	O
device-specific	O
ones	O
in	O
the	O
late	O
1980s	O
.	O
</s>
<s>
It	O
was	O
found	O
in	O
the	O
Japanese	O
keyboard	B-Device
layout	O
,	O
the	O
Turkish	O
F-keyboard	O
,	O
and	O
the	O
Russian	O
JCUKEN	O
(	O
Latin	O
)	O
layout	O
.	O
</s>
<s>
Of	O
these	O
,	O
only	O
the	O
Japanese	O
remains	O
in	O
use	O
;	O
the	O
Turkish	O
layout	O
was	O
replaced	O
by	O
QWERTY	O
with	O
typewriter-paired	B-Protocol
keys	O
,	O
while	O
the	O
JCUKEN	O
(	O
Latin	O
)	O
was	O
replaced	O
by	O
Cyrillic	O
layouts	O
.	O
</s>
