That does not compute

From: Eric Smith <eric_at_brouhaha.com>
Date: Thu Dec 31 22:28:06 1998

Sam wrote:
> Interestingly though, Woz squeezed the '_at_' symbol
> on to the original Apple ][ keyboard above the P key (shift-P = _at_). Who
> knows why. The _at_ wasn't used for anything inherent in the Apple.

This wasn't so much a matter of how Woz wanted it, but how the standard
keyboard encoder chips of the time (GI AY-5-2376, AY-5-3600) were
programmed.

It's called a 'bit-paired' keyboard layout, and you can blame it on the
ASR-33 Teletype. It was much easier to build a mechanical keyboard encoder
such that unshifted and shifted characters from the same key differed by only
one bit. So 'P' (0x50) is a natural character to pair with '_at_' (0x40).
Similarly, the double-quote character (0x22) is the shift of the digit
'2' (0x32), and the single-quote (0x27) is the shift of the digit '7' (0x37),
rather than having both quotes on the key to the right of the semicolon.

The square brackets and backslash are shift-K through shift-M for the same
reason.

By the time of the MOS keyboard encoder chips, the bit patterns could be
set arbitrarily in the ROM, but the standard versions were deliberately
programmed to match the Teletype. Had Apple wanted to spend the money,
they certainly could have gotten a different keyboard layout, but in late
'76 or early '77 they probably couldn't justify the expense. And back
then people considered themselves lucky to get a keyboard at all.

Eric
Received on Thu Dec 31 1998 - 22:28:06 GMT