21 January 2019

Review: TI-55

I had this review planned for the day after Christmas, but due to my hiatus, it has been delayed until today. But hey, Christmas starts earlier every year, so why not start in January?

When I ask people about calculators they remember fondly, almost every one of them begin with the letters "TI". Texas Instruments has been designing and refining calculators since 1973, and even in their early days they were absolutely killing it. Vintage TI devices have become collectibles for people like myself while newer devices still reign supreme in various markets.

The TI-55 was released in 1977, back when it was still cool to use LEDs. Later variants of the TI-55 used boring LCD displays. This was probably to preserve battery life, but I'll take a gorgeous display over longevity any day.

Speaking of batteries, the TI-55 had its own rechargeable battery pack. This might seem great until you remember this was way back in the 70s, before lithium ion batteries were a thing. Because of this, no stock TI-55 currently works today. Thankfully, this battery pack is fairly easy to remove and can be replaced with a standard 9 volt battery. The video review goes into a bit more detail about this, and there are guides online that explain why this works. It's just awesome that this calculator can be made to work these days.

Aside from the outstanding display, the TI-55 has a great color scheme and overall design. Sitting at a desk and looking down at it, you can see that this was designed to be viewed from an angle. This makes it ideal for school work, especially since it's fairly weighty and has rubber feet to keep it still on a flat surface. However, when viewed from directly above, the display is blocked. This may have been to prevent onlookers from seeing operations. Great care was taken in this calculator's design.
Slightly different angle shows display obscured.
Of course, this is The Calculator Review, so you know I'm going to talk about the button feel. Considering this device could technically be considered a pocket calculator, I am blown away by how amazing these buttons feel. They're clicky and responsive, and perfectly debounced to prevent accidental double-presses. I have no idea why Texas Instruments didn't choose to stick with this button design with later models because it's incredible.

It's a shame, really, that the LCD has become so ubiquitous in pocket calculators. From a technical perspective, it makes perfect sense, as it paved the way for solar and dual powered devices. But from an aesthetic perspective, it's disappointing. The TI-55 is a marvel of engineering and design. It looks beautiful in my collection.

Back of calculator.
Original battery compartment disassembled. 
Each button was taken out to be cleaned. This was a huge pain to put back together.
Calculator completely disassembled.
Foam removed. It crumbled at the slightest touch, so it couldn't be reinstalled.
Duct tape used in place of the foam. Slightly alters the feel of the buttons, but still works just fine.
Red goes to black and black goes to red. It's annoying, but that's how this calculator does it.
New 9 volt battery adapter installed.
Electrical tape used to hold things in place.
Testing the new battery setup to make sure everything's working just fine.
The battery is loose without the cover, but with the cover it's held comfortably in place.
Complete calculator with its leather case.


  1. This was the calculator of my youth....got me through Trigonometry, Calculus, Chemistry and Physics in high school and then through various technical schools....I used it from 1979 until at least 1996. The recharge function was long dead but at the time I had a battery adapter that you could plug in that still worked. It is a terrific calculator and your review brought back great memories!

  2. I had one. Was my calculator for my engineering studies. Confortable, reliable, useful. I gladly remember it.

  3. My TI-55 still works as well as the day I bought it new back in 1977

  4. I could only afford a picture of a calculator in the 70s but I had a slide rule!!!

  5. I used one of these in my manufacturing engineering functions, especially in the programming of CNC machines. It was awesome!

  6. The TI-55 was my transition scientific calculator from my TI-30 in junior high school (1977-1979). Used it and the upgrade to the LCD version TI-55 II with much longer battery life throughout high school. Went on to college to study electrical engineering where I upgraded further to the HP 15C.

    I still have my TI's tucked away. I do bring them out every now and then. For some reason, I feel smarter when I do! ;0)