For your consideration, here is a f/22 Darkroom Computer Sliding Calculator, with Case and Instructions, dated 1980. There are two instruction sheets as well as instructions printed on the computer.

It is in nice shape with very little wear on the computer. The plastic case has a little wear on it. It will be mailed in a bubble mailer with foam core sttiffeners. Item pictured is the actual item up for sale and comes from a non-smoking household. (140.830x-.5ob)