A lifetime of calculating devices. The Hemmi bamboo slide rule dates from about 1970. The Sharp PC-1802 was a gift in 1974 for reaching sixth form in high school, and its original cost was just over a whopping $100. The huge semi-programmable Sharp PC-1001 belonged to my friend Neil and dates from 1973. Sadly the PC-1001 developed a wiring fault and was sold in 2011 on eBay for $7.

My first "modern" calculator since high-school was the Sharp EL-5030 which worked well for a few years until it died in 2001 when the key contacts started to fail. The Sharp EL-5120 which replaced the EL-5030 worked wonderfully from 2002 to 2012 when it died due to partial display failure. The Sharp EL-506W was purchased in March 2012 to replace the EL-5120, but I accidentally purchased the ordinary EL-506W instead of the EL-W506 which has "WriteView" realistic displays. The anagram of the names caused me to enter the wrong value in the web order form.

Six years later, on a whim while wandering around Officeworks in July 2018 I purchased a quite cheap HP 300s+ to either replace or work alongside the EL-506W. The keys and labelling on the HP are clearer and the display is crisper with more contrast, and most importantly, it can display simple mathematical notation. Unfortunately, the 300s+ is so cryptic and inefficient to use that it's been placed in a drawer and never used. Maybe its 'modes' can be changed to make it feel familar, but I can't be bothered spending hours reading the manual and experimenting, so I'll write it off as a bad investment.

It is rather odd to be buying and using pocket calculators this far into the 21st century, because I can quickly run Windows Calculator for simple calculations or even fire-up Mathematica for arbitrarily complex work. However, there is a human-machine usability issue which occasionally makes it quicker and easier to grab the calculator off the desk, punch a few keys and get an instant result.

Links: The Old Calculator Museum | Sharp Scientific Calculators | HP Calculators