(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.
