How to build an ASCII CRT terminal, circa 1967

[Paul Berger]

On 2016-08-31 12:15 PM, Al Kossow wrote:
> Magnetorestrictive delay lines and a charactron.
>
> http://bitsavers.org/pdf/rca/terminal/70_750/70-01-752-U_Model_70_752_Video_Data_Terminal_Maintenance_Manual_Oct73.pdf
>
> We got one (no keyboard) a couple days ago with the manual. I'm still cleaning it up. It had something nesting in it and
> the inside has sunflower seed husks in it. It was made with plastic DIP ICs, no idea of the logic family. The keyboard
> was made by IBM, don't know what character code it produces. Pretty funky if it encodes ASCII.
>
>
>
Nice a selectric keyboard... It looks like it has links that operates a 
microswitch for each of the bails.  The bails that would get pulled when 
the filter shaft comes around would depend on the tabs present on the 
key interposers, so the key interposers would determine the coding of 
the keyboard and it would be possible  to have it generate 7 bit ASCII 
code by using an appropriately "programmed" interposer under the keys.

Paul.