I had a Radio Shack scientific calculator about that same timeframe. It was stolen during a lab. I then bought a 32Sii. Just wanted to thank the thief, as I likely never would have been a lifelong RPN user.
But calculators were dropping quickly in price and a couple of years later I was able to pick up a discontinued HP-55 which I used for years until I picked up an HP-41CV with financial pac for going off to business school. (I probably had one of the horizontal format HP RPN calculators somewhere in there too.)