When I was in high school, (early 1990s,) there was a giant one mounted above the blackboard. It was clearly used for instruction in the past, but it looked so

When I was in high school, (early 1990s,) there was a giant one mounted above the blackboard. It was clearly used for instruction in the past, but it looked so cool that no one wanted to remove it. Every once in awhile a teacher would spend about 10-15 minutes showing how to use it. Everyone would "oooh" and "awww" and then we would all laugh about how we didn't need to use them now that we all had calculators in our pocket that were more powerful than the computers that put people on the moon. It's always nice to learn about the past so we can appreciate what we have now.