# Did You Ever Use A Slide Rule ?

A group of engineers were discussing old ways of calculating things and the slide rule came up. Engineers used slide rules to multiply, divide and calculate roots of numbers. Slide rules used logarithmic scales. Bob Hannon of JHU/APL put together a good presentation on the history of slide rulers. H-P introduced the HP-35 calculator in […]

A group of engineers were discussing old ways of calculating things and the slide rule came up. Engineers used slide rules to multiply, divide and calculate roots of numbers. Slide rules used logarithmic scales. Bob Hannon of JHU/APL put together a good presentation on the history of slide rulers.
H-P introduced the HP-35 calculator in Feb 1972. Slide rules rapidly become obsolete. The electronic calculate then laid the groundwork for the personal computer. The first complete personal computer was the Commodore PET introduced in January 1977. It was soon followed by the popular Apple II and then the IBM personal computer (PC).
Slide rule information
www.sliderulemuseum.com has an excellent tutorial on how to use a slide rule, with an on-screen slide-rule simulator if you don’t have your own slide rule.

I learned how to use a slide rule when I entered college in 1968 and majored in physics. The catchphrase at the time when solving problems was “slide rule accuracy,” which really was pretty good if you were careful. While in graduate school in 1972 or 1973 I even taught a class on using the slide rule at the local community college in Louisville.

As I recall the HP-35 was about $400 when introduced so only the Physcis Department could afford one, certainly not an poor, underpaid Graduate Teaching Assistant. I did have a few students who paid $100 for a four-function calculator! In 1974, my first employer paid half the cost of a scientific calculator. My how times have changed!

I still have my slide rule, but I’m not sure where it is right now. (And, no, I never walked around with my slide rule clipped to my belt.)