The Jargon File (version 4.4.7, 29 Dec 2003):
bit-paired keyboard
n.,obs.
(alt.: bit-shift keyboard) A non-standard keyboard layout that seems to
have originated with the Teletype ASR-33 and remained common for several
years on early computer equipment. The ASR-33 was a mechanical device (see
EOU), so the only way to generate the character codes from keystrokes was
by some physical linkage. The design of the ASR-33 assigned each character
key a basic pattern that could be modified by flipping bits if the SHIFT or
the CTRL key was pressed. In order to avoid making the thing even more of a
kluge than it already was, the design had to group characters that shared
the same basic bit pattern on one key.
Looking at the ASCII chart, we find:
high low bits
bits 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001
010 ! " # $ % & ' ( )
011 0 1 2 3 4 5 6 7 8 9
This is why the characters !"#$%&'() appear where they do on a Teletype
(thankfully, they didn't use shift-0 for space). The Teletype Model 33 was
actually designed before ASCII existed, and was originally intended to use
a code that contained these two rows:
low bits
high 0000 0010 0100 0110 1000 1010 1100 1110
bits 0001 0011 0101 0111 1001 1011 1101 1111
10 ) ! bel # $ % wru & * ( " : ? _ , .
11 0 1 2 3 4 5 6 7 8 9 ' ; / - esc del
The result would have been something closer to a normal keyboard. But as it
happened, Teletype had to use a lot of persuasion just to keep ASCII, and
the Model 33 keyboard, from looking like this instead:
! " ? $ ' & - ( ) ; : * / , .
0 1 2 3 4 5 6 7 8 9 + ~ < > ? |
Teletype's was not the weirdest variant of the QWERTY layout widely seen,
by the way; that prize should probably go to one of several (differing)
arrangements on IBM's even clunkier 026 and 029 card punches.
When electronic terminals became popular, in the early 1970s, there was no
agreement in the industry over how the keyboards should be laid out. Some
vendors opted to emulate the Teletype keyboard, while others used the
flexibility of electronic circuitry to make their product look like an
office typewriter. Either choice was supported by the ANSI computer
keyboard standard, X4.14-1971, which referred to the alternatives as ?
logical bit pairing? and ?typewriter pairing?. These alternatives became
known as bit-paired and typewriter-paired keyboards. To a hacker, the
bit-paired keyboard seemed far more logical ? and because most hackers in
those days had never learned to touch-type, there was little pressure from
the pioneering users to adapt keyboards to the typewriter standard.
The doom of the bit-paired keyboard was the large-scale introduction of the
computer terminal into the normal office environment, where out-and-out
technophobes were expected to use the equipment. The typewriter-paired
standard became universal, X4.14 was superseded by X4.23-1982, bit-paired
hardware was quickly junked or relegated to dusty corners, and both terms
passed into disuse.
However, in countries without a long history of touch typing, the argument
against the bit-paired keyboard layout was weak or nonexistent. As a
result, the standard Japanese keyboard, used on PCs, Unix boxen etc. still
has all of the !"#$%&'() characters above the numbers in the ASR-33 layout.
The Free On-line Dictionary of Computing (30 December 2018):
bit-paired keyboard
(Obsolete, or "bit-shift keyboard") A non-standard
keyboard layout that seems to have originated with the Teletype
ASR-33 and remained common for several years on early computer
equipment. The ASR-33 was a mechanical device (see EOU), so the
only way to generate the character codes from keystrokes was by
some physical linkage. The design of the ASR-33 assigned each
character key a basic pattern that could be modified by flipping
bits if the SHIFT or the CTRL key was pressed. In order to avoid
making the thing more of a Rube Goldberg kluge than it already
was, the design had to group characters that shared the same basic
bit pattern on one key.
Looking at the ASCII chart, we find:
high low bits
bits 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001
010 ! " # $ % & ' ( )
011 0 1 2 3 4 5 6 7 8 9
This is why the characters !"#$%&'() appear where they do on a
Teletype (thankfully, they didn't use shift-0 for space).
This was *not* the weirdest variant of the QWERTY layout
widely seen, by the way; that prize should probably go to one
of several (differing) arrangements on IBM's even clunkier
026 and 029 card punches.
When electronic terminals became popular, in the early
1970s, there was no agreement in the industry over how the
keyboards should be laid out. Some vendors opted to emulate
the Teletype keyboard, while others used the flexibility of
electronic circuitry to make their product look like an office
typewriter. These alternatives became known as "bit-paired"
and "typewriter-paired" keyboards. To a hacker, the
bit-paired keyboard seemed far more logical - and because most
hackers in those days had never learned to touch-type, there
was little pressure from the pioneering users to adapt
keyboards to the typewriter standard.
The doom of the bit-paired keyboard was the large-scale
introduction of the computer terminal into the normal office
environment, where out-and-out technophobes were expected to
use the equipment. The "typewriter-paired" standard became
universal, "bit-paired" hardware was quickly junked or
relegated to dusty corners, and both terms passed into disuse.
[Jargon File]
(1995-02-20)