Citizen 9410 - Francis WEB

Back in the 1970's, calculators were just starting to evolve, changing from LED display to LCD. Watches were doing the same, and with the advantage of LCD (small size, small power required), the creator of the watch could add more functions into the CPU. However, most of the watches at that time were square-ish, with a keypad below the display (or touch screen):


CITIZEN came up with a different idea, and kept the traditional round look of the watch, by placing the buttons around the screen:

This was their first try, and had only a minimum number of functions. They released the next model, 9315 with additional features in 1977
Here is a picture of the model I own:

This model (9315) came out in 1977, for a price of $250. As you can see, the watch offers not only the basic 4 operations, but also memory, square root and percent.
With this disposition of the buttons, you can really use the watch with only your fingernail, no stylus required. Just press the SW button, to go in Calculator mode, and start your operations.

But Citizen had greater ideas, and the next year, in 1978, they came out with one of the most complex calculator watch I have ever seen: The model 9410

Incredibly, the size of the watch is identical to the previous model, but you can see the number of functions available is huge. Not only the buttons on the left have the regular scientific functions (sin, cos, tan, etc.), by pressing the key with the arrow on top, the button has a second function : Sin-1, Cos-1, etc.
There is a cube root function
The ones on the bottom of the screen are statistical functions.

It is really a true wonder in the watch world, thinking that it came out in 1978. Imagine yourself wearing this, while driving your 1978 corvette


However the watch had a price, and a good one: $800.
In 1978 money, $800 was a lot. Just think that the average income was around $10,000 (a year).

Below is a short video showing the 2 models I own,, 9315 and 9410. Still looking for the basic model..