HP 28S: 21 years of calculating and still going

I was crunching some numbers with my calculator when it suddenly dawned on me that I’ve been using this calculator for 21 years now. 21 years! I know people who weren’t even born when I bought it!
My HP 28S, purchased sometime around 1988 when I was just a lowly undergrad student in my first year of school (could have been 1989, which would make it only 20 years old and me in my second year of school) .
HP 28S Front
I think it was actually the first purchase I ever made with my very first credit card. I remember one of my engineer friends had one, and after playing with his for a bit, I decided I needed one too. It turned out to be probably the best $280Cdn that I ended up spending during my school years.
HP 28S open
These days it doesn’t get used nearly as much as it used to and the calculations it does get used for aren’t nearly as complex. It’s still pretty reliable though and does everything I ask it to.
HP 28S Back
HP 28S circa 1988 serial number 2933A03136. I even have the manuals for it too.
No, you can’t have it.

5 Replies to “HP 28S: 21 years of calculating and still going”

  1. Hello,
    i just change the 3 N2 batteries to my HP 28s and I can’t remember how to reduce the contrast on the display. Do you have the combination for that?
    I do appreciate your help.

  2. Changing the contrast is easy. With the calculator on, hold down the ON button and press either the – or +. – reduces the screen contrast, + increases the screen contrast.

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