Author Topic: Casio CFX-400c scientific calculator watch  (Read 1164 times)

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Offline EEVblog

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Re: Casio CFX-400c scientific calculator watch
« Reply #25 on: March 21, 2018, 12:56:34 am »
That’s not really an issue for every day calcs. It makes a difference which way round you write it on paper as well.

You clearly weren't there this morning when I tried to use a VPAM in the lab, and the screams of frustration. Ask David2.

On paper I simply write 2m
 

Online bd139

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Re: Casio CFX-400c scientific calculator watch
« Reply #26 on: March 21, 2018, 01:11:31 am »
That’s not really an issue for every day calcs. It makes a difference which way round you write it on paper as well.

You clearly weren't there this morning when I tried to use a VPAM in the lab, and the screams of frustration. Ask David2.

On paper I simply write 2m

You write 2m on the 991EX too.

The old method is broken because if you enter say 10 E 3 (-) and realise you screwed up the 10, you have to C then entire entry buffer to get back to it. The original method was because the processing power and complexity was limited by technology of the day. Same with RPN to some extent.

Now say I want to solve a real problem. These are way beyond VPAM/SVPAM. Want to pick an inductor to resonate a 100pF at 7MHz. Stuff the formula in, solve for X. X= 5.1uH. Pick a spectrum 5u3L, tune it in circuit. Job done.



Perhaps 99% of my problems are solved in this fashion, with the engineering units persisted.
« Last Edit: March 21, 2018, 01:15:21 am by bd139 »
 

Offline Johnboy

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Re: Casio CFX-400c scientific calculator watch
« Reply #27 on: March 25, 2018, 04:38:54 am »
Forgive my ignorance regarding dedicated engineering calculators. My earlier reference to the Texas Instruments model had to do with the prevailing need for educational testing calculators that don't allow a lot of programming and can be "cleared". The model I cited is a commonly-approved tool for engineering school usage in the States, but would not be as useful for actual work as the other models in this thread.

Again, I believe that there is a niche market for the return of a product along the lines of the CFX-400. The open-source model Dave Jones offered should have been a wake-up call to companies like Casio, and I wish his efforts had become better known to the public at large during the time in which he was actively pursuing them. I recently saw a Kickstarter campaign for a "slide rule watch", which incorporates a circular slide rule for arithmetical calculation (as opposed to the flight calculation orientation typically seen in watch bezels). As I see it, if there's a genuine market for a slide rule watch, there should certainly be one for a scientific calculator watch! More functions, less novelty. The Citizen 9140A is another example of a scientific watch design that I think is fascinating, if maybe a little heavy-handed. I don't think these things should be merely resigned to the shelves of rarity collectors!



(That said, I love mechanical slide rules and wouldn't be opposed to owning a watch that also incorporated one into the design. Even in the absence of battery power, such a watch would still be intrinsically useful to some people, albeit a much smaller demographic.)
 

Offline Zad

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Re: Casio CFX-400c scientific calculator watch
« Reply #28 on: March 25, 2018, 02:01:40 pm »
I always preferred the CFX-200. Hence the profile photo :D

An RPN watch with something like the firmware from the WP-34s / HP-30b would be a bit of a holy grail.

Offline Johnboy

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Re: Casio CFX-400c scientific calculator watch
« Reply #29 on: March 25, 2018, 04:48:16 pm »
I always preferred the CFX-200. Hence the profile photo :D

An RPN watch with something like the firmware from the WP-34s / HP-30b would be a bit of a holy grail.

Thank you for your response. From what I've read, the 200 model was more reliable over time. There was apparently an issue with the 400 model involving the keypad. I've looked at the Databank series and I don't understand why they persisted in manufacture, and with stronger external construction than either the cfx200 or the cfx400. Surely one could put a proffered business card into their wallet? What was the allure of the Databank besides the backlight? Industrial espionage? Hiding love affairs from the wife? A diary on your wrist? I don't get it. And yet I'm pretty sure they're still available. Why not the CFX series?
 

Offline moonunit

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Re: Casio CFX-400c scientific calculator watch
« Reply #30 on: April 07, 2018, 10:06:35 pm »
Casio (Asia Zone) do in fact still make the Databank DBC-611-1 with what appears to be the same case as the CFX-400.

https://www.casio-intl.com/asia/en/wat/e_data/

I had a stainless (it's actually chromed plastic) CFX-400 for many years - bought it for $29 from Kmart in the 80's. The keypad perished, and I'm not sure if I threw it out. I'm still kicking myself and would dearly love for Casio to produce the CFX-400 again. Given the model's fan status it would have to be more popular than the databank version they sell at present. It would also serve as a great promotion for Casio's full size Scientific Calculators.

Computer science and engineering was pretty niche in the 80's, given the resurgence of STEM, and geek culture I'm sure it would be a worthy product to reprise as a special run today. I agree , the databank is superseded by the smartphone and iwatch, a scientific calculator is a much more useful thing to have on the wrist for anyone in a technical profession.


 

Offline floobydust

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Re: Casio CFX-400c scientific calculator watch
« Reply #31 on: April 08, 2018, 02:51:00 am »
Dear God, I have the original bought in 1993 and a few years ago purchased another (new) one to replace it.
Casio was still making them, although slightly different LCD and internals.

Where did you get a new one? That would fetch probably $1000 on ebay!

I bought the second Casio calculator watch DBC-611-1 from Amazon, they still sell them there.
 


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