Tom Scott did a great video showing the last one in operation. They use totally unique keyboards with what is essentially a stenography system: https://www.you

Tom Scott did a great video showing the last one in operation. They use totally unique keyboards with what is essentially a stenography system: https://www.youtube.com/watch?v=XxCha4Kez9c https://www.youtube.com/watch?v=XxCha4Kez9c