CASIO 50QS-17 released by Casio in 1979.
There are three buttons on the front, but the middle button is slightly to the left of the center, giving it the appearance of a design inspired by the SEIKO 06LC, the world's first six-digit digital wristwatch.
The appeal of this model is that it has some very unique features that are not found in other digital watches.
I would like to introduce some of the unique features of this model one by one.

Feature 1: Stopwatch with 4-digit display
This model has a 4-digit display of "hours, hours: minutes, minutes" when displaying the time, but when in stopwatch mode, it displays 4-digits of "minutes: seconds".
What about sub-second measurements?→ There is no such function.
I introduced it before SEIKO A129 had a stopwatch function that measured 1/10 seconds, but this model is a stopwatch that measures in units of 1 second.
Some of you may be wondering, "Isn't it just a seconds display, not a stopwatch?", but this model's seconds display is CASIOTRON 03-502 Similarly, the gauge above the time display flashes and advances one frame every 10 seconds, and you can only see the passage of seconds in real time in stopwatch mode.

In addition, the "+" display at the right end (below the "SA" position) serves both as a stopwatch mode and as a "PM" indicator.
By the way, "12:00 PM" is displayed as "12:00", so you can distinguish it from the stopwatch mode shown in the photo above.
(Also, the day of the week indicator lights up when the time is displayed)

Feature 2: Unique operation method (time setting method)
First, please take a look at the document below (Easy Guide to Digital Watch Operation '80).

This model requires you to press and hold the left and right buttons at the same time for up to 18 seconds to enter time setting mode.
Have you ever held down multiple buttons on a digital watch at the same time for 18 seconds?
Without the instruction manual or the book mentioned above, I think it would be almost impossible to figure out how to operate this on your own.
I was reminded of a certain famous Famicom game where you had to "leave the controller for an hour without doing anything" in order to proceed.
We sincerely hope that as many people as possible who obtained this model without the instruction manual can find this page.

[Additional note] At the bottom of this page, we have summarized models other than this model that require the same operation method (time adjustment method).

Feature #3: Attention to mysterious design
This model's button placement is not only inspired by the SEIKO 06LC, but there are also some design issues here and there, such as a black plastic part sandwiched between the main body and the back cover, and the middle button (light) being slightly shorter than the buttons on either side.Functionally?You can see the commitment.
I'm sure Casio's development team put a lot of effort into making it, so calling it a "mysterious obsession" might get people angry.

This model may have been positioned as an experimental model, at a time when the standard "design" and "operation etiquette" for digital watches had not yet been established, allowing the watch to actively try new things.
In any case, this model is one of my favorites as it shows the momentum of Casio's early digital watches.

【postscript】
Similar to this model, we have compiled a list of models that require you to hold down two buttons for a long time to set the time.
We hope that by looking at this page, you will be able to use as many old Casio as possible.
・27CGL series (27CGL-11, 27CGL-14, 27CGL-16)
・27CL series (27CL-10, 27CL-11, etc.)
・29CS-11
・31 series (31CGR-14, 31CGS-10, 31CS-10, 31QR-11, 31QS-12, etc.)
・35QR-23
・53 series (53CS-18, 53CGS-18, etc.)