[TUHS] Early Unix and Keyboard Skills
clemc at ccc.com
Fri Nov 4 02:18:22 AEST 2022
On Thu, Nov 3, 2022 at 11:19 AM Paul Winalski <paul.winalski at gmail.com>
> The LA36 DECwriter had a rather slow carriage return. It would buffer
> characters while a return was in progress and then print the buffered
> characters at 60 characters/second, slowing down to the normal 30 cps
> when caught up.
The key point here is that with the DEC Writer (LA36) DEC started to split
the print speed (*in cps*) from the line interface speed (*in baud* as it
was larger than an often character as it would have at least one start bit,
one or more stop bits, and maybe a parity bit too). Herein also lies
another problem, the mechanical interface, be it how fast the carriage
moved, or the head was positioned, etc, could be much longer than the
single character transfer time. As Paul mentioned on some
mechanical devices without any buffering, the print might be random as the
carriage moved the head.
Teletype made an amazing mechanical device that had a minimum amount of
electronics in it. By the time of the LA36, you start to see the
microprocessor revolution and the use of cheap transistors to replace
mechanical things to make faster/better devices with new features (like
buffering and being able to have different speeds for data transfer and
printing). But you also start to see the distinction between the
mechanics (the keyboard/printer) and things like the communications scheme
become even more obvious and terminology starts to be used to address the
specific part of the problem.
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