Retro Calculators

When you say “retro” to most people think of things that were cool in the time and still maintain the same appeal as it used to do. Being the age I am… I don’t consider myself to be “old” more like “retro” as in cool and trendy 😛 I recently read an article about Smartphones and how they have begun making other devices redundant. Which isn’t really all that much of a surprise when you consider that the phone you are holding in your hand has at least 1000x the processing power of the computer that was used to land men on the moon.

If you saw someone in a white coat with a slide rule you “knew” he could do math!

In the past you would use/own an array of devices which were engineered for a specific function e.g. compass, remote control, watch & camera etc., whereas these days a smartphone serves more as a convergence device in that it can perform the majority of these functions in the same device. Now a smartphone camera such as the one on Nokia’s Lumia 1020 with its 41 Megapixel sensor can give a compact a run for its money but doesn’t offer the same experience that using a Leica would (but then again it is a phone first!).

I recently saw a sample GCSE maths paper which came in 2 parts and amazingly allowed the use of a calculator in one of the papers! All this got me thinking about the humble calculator and how we got through our exams from school to university.

When I was doing maths at school in those way back days you had several methods of getting the answers you needed. First was the long hand method where you had to show all your workings, using log tables

(no… not those!) which you used when you started doing basic trigonometry and lastly the daddy of then all the slide rule. I used to own a WH Smiths Slide Rule back in the day.

WH Smith Slide Rule

Slide rules were the essential piece of equipment in any sci-fi drama of the period! If you saw someone in a white coat with a slide rule you “knew” he could do math!


Having an interest in electronics back in the late 70’s I saw the emergence of “pocket” calculators, which could carry out all of the functions of their desktop brethren in a compact size. The technology was quite expensive in its day. However, with the advances in integrated circuits the prices started to fall and became an affordable alternative for the masses.

Hewlett-Packard’s offerings were akin to high class hookers, you know the kind you could never afford but would drool over even though they were out of your league.

Here’s a list of the calculators I had owned in my school/college days:

Radio Shack EC-375


If memory serves this was the 2nd calculator I had. I believe that the first one was a RPN calculator that didn’t work so we got this one as a replacement. It was a big chunky calculator with a gorgeous vacuum green display with just the basics. My brother used this for his business for many years afterwards.

Commodore SR4190


This was my first serious calculator, it was a beast, I had never seen a calculator with so many buttons on it. I remember staring at the window of what may have been the Dixons shop in Sale late one night after the shop had closed trying to make note of how many functions it had. I’m pretty sure I still have it somewhere in the loft (shame on me I know…).

Casio FX 570


Moving on to college LCD calculators had now become more commonplace and the brand nearly everyone went for was Casio and for good reason. Casio’s combined the latest technologies and features with an emphasis on value for money. The FX-570 was a solid calculator for an Electronics Engineering student.

Casio FX450


I decided to upgrade to the FX450 as it had additional button functions in the flap that was attached to the calculator. As with my previous Casio it proved to be a good calculator, at least until the buttons became intermittent on the flap, so much for flexible connectors.

Texas Instruments TI57


About this time I was looking at getting a programmable calculator. Prior to this they were few and far between with sky high price tags to go with them. My buying decision was based on fact that the TI57 was programmable and was not majorly expensive. Sadly this calculator despite having a great feature set was a piece of crap. Yes that’s right I was not impressed with Texas Instruments, I thought they were meant to be good but this particular model tainted their reputation in my eyes. The thing that really bugged me was the fact that the keys suffered from “switch bounce” which meant that you could easily enter something twice. Not good if you’re entering a long program sequence.

Casio FX115s


This calculator was acquired during my time working at MMU in a open access lab. Some silly student had left this calculator and never came to collect it so I claimed it as my own. It was a dual power model, using a mixture of conventional button cell and solar panel to power it. I haven’t had much cause to use it much though so can’t comment on the algebraic “enhancements” Casio added to the device.

The thing about all of the above calculators was that they were for the main part at the mid to low end of the market. There were still some iconic calculators that were truly ground breaking and for anyone interested in collecting them these are worth keeping an eye out for…

Sinclair Scientific


HP 11C & 15C


HP 35


HP 67


Rockwell 44RD


Texas Instruments SR-51A


Of these I’d say that the HP models are what “calculator porn” is all about. While Sinclair’s brought the pocket calculator within the grasps of executives on the move, Hewlett-Packard’s offerings were akin to high class hookers, you know the kind you could never afford but would drool over even though they were out of your league.

Most people would now look to their PC or Smartphone to use a calculator in this day and age. Thankfully the HP 11C and HP 48 are available as emulators for both the PC and Android & iOS.

HP 48 on Android courtesy of Google Play Store

HP 48 emu

HP 15C on PC courtesy of HP Calculator Emulator program

HP 15C Emu

So the next time you need to work something out don’t just click on your calculator shortcut but try a “real” calculator for a change, it’s as easy as 22/7!