Casio CA-901 calculator game watch

Casio CA-901 calculator game watch

I can’t believe it’s taken me this long to write about the CA-901; it is (I think) my favourite Casio of all time.

It’s got everything…

  • time (12/24)
  • date (although you do have to fudge it from the year 2000 onward)
  • alarm (with 10 different buzzer pitch tones, amazing!)
  • stopwatch
  • dual-time
  • 8-digit calculator
  • GAME!

Totally feature-packed, consider it was 1980 and memory was expensive back then.

The game was obviously the best part – we had been introduced to it at school via the MG-880 calculator but to be able to carry it around on your wrist would have been the ultimate status symbol.

Unfortunately my parents (and, for that matter, all the parents of my friends) thought that NZ$100+ was way to much to spend on a watch for an 11-year-old; and they were probably right.

Didn’t stop me coveting that watch though – there were plenty of other models with the [134] module in them…the CA-90, CA-85, CA-851 and CA-86 but the CA-901 seemed to have the best combination of looks and style.

So fast-forward 20 years when I discovered eBay and all the missing watches of my childhood, and the CA-901 was one of the first I grabbed.

Since then many have come and gone but I always keep one in the collection, it’s the kind of watch you regret selling as soon as its gone and you immediately start looking for another one.

Casio seemed to get the balance right on this one too — it’s a big watch but doesn’t feel too large or clunky on your wrist. Using the calculator is simple with the fingertips (I curse people who use sharp pointy things on the keys as they invariably get scratched and spoil the look of the keypad).

The game is fun and even more of a challenge than on the full-size calculator, despite being able to use banks of keys rather than single keys to control the movement.

A true classic, and becoming more popular by the day; even beat-up examples sell for US$150+ and mint ones for much more than that. If you are going to have just one Casio calculator watch, the CA-901 should definitely be it!

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11 Responses to Casio CA-901 calculator game watch

      • Hi, I’ve just bought a CA-901 and cannot for the life of me work out how to even set the date??? I have set the time and also programmed the alarm which both work wonderfully! Heeeeeelllllp! 🙂

        • Press the set button (left hand side, recessed button) until the segments flash then use the calculator to input the date YYMMDD. It doesn’t go past 1999 so for 2019 use 91 as the year. E.g. November 4 2019 would be 911104 – then hit the set button again and it will be set.

  1. The way I did it, set date to 31 Dec 1999, at 23:59.
    Wait for it to click over midnight to 1 Jan 2000.
    Change date again to 31 Dec at 23:59 (year is retained at 2000)
    Click over to 2001, repeat… etc!!

  2. Greetings fellow watch enthusiasts!
    I bought this model at a flea market in South Africa for less than 5.00 USD!
    Granted it was not working and case was in pretty bad shape, so I ordered a new case and keypad plate for it.
    The module was looking good, but it did not work and I found battery acid had leaked onto circuit board. Having cleaned acid away, it did work but only thelight button.
    I then took apart entire module and cleaned every circuit trace, every inch and every part with alcohol and now working as good as new. LCD is crisp and light is extremely bright.
    What impresses me about it is that not a single drop of glue used anywhere in or around this watch.
    It is indeed a beautiful example of vintage Casio.

    • Hi Daud, we also found a beautiful CASIO CA-901 managed to get it working but had to clean everything as the battery acid also had some bad influence on it. We got the whole “Movement” out of the watch and now do have problems to get everything back into the case. Do you have any good advice to get things back where they have to be ;-))

      • An added note, Claudi, is to move all eight side pushers gently out of the way from inside the case and then also gently put movement back in from bottom to top. Everything should fit, but it is somewhat a battle to get all side pushers to match up with movement again. Just keep trying and caseback should “snap” on without too much hassle either.

  3. Hello, I get the idea to get the year past 1999, but I can’t get this to work as I have to input 6 digits to change the date, which cancels any previous date. How do you input just the day and month? I have been using my CA-851 as my alarm since 1983. When I change the batteries it has kept the date – until today when it reset. Thanks,

    • The date is only good on the CA-901 up to 1999. After that, set a year in the 1980-1999 as the current year (e.g. for 2019 you can choose 1985 or 1991 and it will set the correct day for the date). For today (Saturday, 28 September 2019) the six-digit combo is 910928 and it will set SA as the day.

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