**HP Memories Forum**

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**Good ol' 28C!**

*Posted by Matt J. McCullar on 25 June 2000, 2:31 p.m.*

When I advanced from the local junior college to the University of Texas at Arlington to study electrical engineering, I was fixing Apple IIe motherboards in Fort Worth. One of my coworkers was about to depart the U.S. to fulfill his missionary work overseas and was unloading a lot of his stuff. At the time, I was thinking about shopping for a good scientific calculator (upgrading from the old Radio Shack I'd bought in high school), but didn't quite know what to look for. I'd never used Reverse Polish Notation, but I'd heard that HP was good at this sort of thing.

Scott brought it to work and showed me the basics of using it. "Hooked" doesn't say it! I bought it immediately and he also provided all of the manuals (including tutorials). I wish I'd had this thing when I took calculus!

I quickly learned that engineering courses get considerably more complicated as the calculators get smarter. If you compare a statics or dynamics textbook against one from 40 years ago, you'll see that today's problems practically require a calculator or computer.

In showing the 28C to my dad, who earned his degree with a slide rule, he said, "I would have KILLED to have had something like that when I was in school."

I wasn't able to capitalize on the graphing functions (I had previously tried using a Casio graphing calculator, but I stupidly let a classmate borrow it, and of course I never got it back) with the HP, but to be honest it was too slow. The algebraic stuff was okay, too, but I could work it out myself faster than it could.

But the HP-28C really paid for itself when I took Circuit Analysis. The professor never said that a scientific calculator was REQUIRED, but he did say that he "strongly recommended" that we get one. We poor students quickly found out that you had better program your calc with the right formulas, because you would never finish the weekly 10-minute quiz without them. Changing resistor values from wye to delta (and vice-versa) is a breeze when you've got an HP, and murderously slow when you don't.

I took a class called "Engineering Economy," which was basically an economics course. This required a great deal of numerical interpolation, or trying to figure out what a particular number would be when you look at the numbers before and after it in a pattern. Programming the formulas for this into the calculator really sped things along, particularly during tests.

I still use my 28C today for troubleshooting digital circuits. It's great for decoding error codes. With the old equipment I work with, you never know if you're going to be working with binary, hex, decimal or even octal notation. We can nail down a flaky data bit immediately.

One thing I wish the 28C had was a function for working with fractions. My old Radio Shack calculator could add, subtract, multiply and divide fractions with ease. That's all I keep it for now. :)