I have seen them only in books and have never worked with them. I bought something similar to that that I got at a yard sale back in the 1970's. It used a continous mylar loop with little dots you filled in with pencil for each phone number. You slid the pointer on the cover to the appropriate entry and pushed the start button. The sheet moved across a set of contacts which picked up the number of dots you filled in for each number creating rotary dial pulses. It actually worked, but it was a piece of junk! I guess it was technology from the 1960's or so.
