[GreenKeys] Printing Selectric

[Robert Nickels]

On 10/31/2018 4:42 PM, Jim Haynes wrote:
>
> There were some articles in the computer hobbyist magazines early on
> that told how to interface a Selectric I/O machine to your computer.
> I recall it was rather an intricate process to get maximum typing
> speed; if you did what was simplest to do the typing speed came out
> to be rather slow.

I'm sure that's what I based my parallel interface on, Jim.   I also had 
a buddy who had built a Tektronix 4051 graphics computer the "one piece 
at a time" method when he worked at Tek, and since it had an IEEE-488 
interface he built a 488 interface to his Selectric I/O.     That was 
about a foot square wirewrap board and I knew I definitely want 
something simpler.    The thing is, the Selectric I/O runs open loop, 
there is no feedback from the mechanism, all timing of the tilt, rotate, 
and shift solenoids had to be done by the driver software.   The 
mechanism was capable of 14.8 characters per second (don't ask me why 
that number was stuck in my brain all these years) - but as a practical 
matter I remember tweaking my delay loops to get 12 or 13 and calling it 
good.    After all the idea of a Selectric was to have letter quality 
output, not to win a print speed race ;-)

I found this little interface someone did back then using a 6802 - 
https://link.springer.com/content/pdf/10.3758/BF03202134.pdf

No software was provided as this was before open source - but it would 
be an easy job for an Arduino these days.   Who will be the first to put 
a Selectric on wi-fi?


73, Bob W9RAN