Casio fx-510 scientific calculator (1980)


By the time of my secondary education the authorities had conceded that calculators were here to stay and were starting to encourage GCE Mathematics students to have a scientific calculator. From what I can remember, though, as far as O-level maths was concerned, we used them only for square roots, logarithms and trigonometry functions; everything else still had to be done manually!

I can recall three styles of calculator doing the rounds in the early 1980s. There were the first generation models, from the likes of Texas Instruments, which had a chunky plastic case, a red LED display and tacky, clicky keys. They weren’t sold as a kit of parts but that’s exactly what they became if dropped. Then came the stylish but battery-hungry vacuum fluorescent display (VFD) types, which included some manufactured by Casio and some identical (i.e. badge engineered!) models from Boots. The flat LCD design like this one, powered by a couple of button cells, was cutting edge at the time.

This was the top-line 10-digit model; the lower cost 8-digit fx-310 was also available. As can be seen, it comes with a PVC wallet; notice how this opens, rather inconveniently for the right-handed majority, with the unit on the left. This is actually a legacy of traditional Japanese writing which goes from top to bottom and right to left (think of Western text turned clockwise through 90 degrees) and so you read a book ‘backwards’. Somewhere along the line things got swapped over, since today’s smartphone wallets open the other way round. Also visible is the supplied card listing physical constants on one side and unit conversions on the other. Presumably, later scientific calculators can hold this data in non-volatile memory.

Construction-wise, I’m surprised just how ‘modern’ this unit is, or, put another way, ‘cheap’. The top and bottom case halves are joined by just two token screws and otherwise clip together, with the result that the unit can’t be opened without at least a tiny amount of damage. Inside is a single circuit board onto which the keys press via conductive rubber membranes and a single integrated circuit does all the work. Yet it cost, from memory, £28 – that’s the equivalent of well over £100 today. I needed to dismantle it in order to fix the dodgy on/off switch – this simply bridges tracks on the circuit board. A good clean-up got it working but the contact tracks are, however, badly worn.

Nowadays, a calculator, switchable between basic and scientific versions, is a standard-issue smartphone app, and standalone scientific calculators are capable of displaying graphics. It’s quite sobering to think that what was the early 1980s state-of-the-art – a single integrated circuit responsible for the complex mathematical functions of a scientific calculator – is now so primitive. Today, a similarly-sized component, with many more connection pins, is the ‘brain’ behind a smartphone.

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