Vintage calculator dating from 1977. © Eugene Brennan
My first calculator from 1977 with a fluorescent display. Who can guess what the "D" button is for? The next one is a scientific calculator from 1984 when I started college and cost £5. Still my favourite, the Sharp EL-506P, although I use a calculator app now. This model had an immediate entry mode which I find more convenient than the more modern expression input.
Sharp scientific calculator model EL 506 with immediate mode data entry. © Eugene Brennan