Not the N600 but I did use the 160 back in the day...1987. In high school my father said I had to learn how to use a slide rule before he would buy me a calculator. I've been looking for the N600 as a collector for my collection but they are pricy. You might enjoy this link to the Gemini and Apollo flown N600s
Wow...Beautiful example!!! Lovely color on the dial and hands. My dial looks similar, a shade lighter, but unfortunately along the way the hands were replaced, but they are tritium.