[GreenKeys] [External] Carriage return questions

[Jones, Douglas W]

From: Mike Dodd [mike at mdodd.com] -- Friday, May 15, 2020 9:08 AM

> Can someone refresh my memory about how the carriage in older TTYs and
> the type box in newer machines was moved to the start of a new line upon
> receipt of a CR character?

On the Model 33, a long coil spring slams the print mechanism sharply to the left, with a dashpot at the end of travel to bring it to a stop.  The carriage is driven to the right using a ratchet advance mechanism, pulling the spring tighter as each character is printed.  So, motor power tightens the spring as the line is printed, and then the stored energy is released with a bang when the carriage return character comes in.

           Doug Jones
           jones at cs.uiowa.edu