Source : Free On-Line Dictionary of Computing

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)