Today, I was frantically searching my closet for something I bought 2 years ago and "put away" in a safe place. I didn't find what I was looking for, but I did find my old TI calculators. I remember when they came out because I was competing in University Interscholastic League's slide rule competition that year. We have come a long way.
Here is my first calculator, the Texas Instrument SR 10:
Info on the TI SR 10 from vintagecalculators.com
Here are the SR 51A and the SR 51II:
Now, I need to find that slide rule . . .