Casio CFX-400c scientific calculator watch - Page 1
Forum section: electronics / general

author: Johnboy
author_rank: Regular Contributor
timestamp: March 19, 2018, 05:06:17 am
content: While I'm not exactly surewhereto put this... I've always wanted one of these. It came as a complete shock to me tonight to realize that the guy who started this site is the designer of the uWatch. I couldn't understand why manufacturers don't seem to be interested in developing a new scientific calculator watch. I know, I know... there are a few of them available, but they're high end. What I loved about Dave's methodology in presenting his design was the concept of "you want something like this that badly? Alright. Build it yourself." I really wanted one of those kits and even sent him an email about them (this is quite a long time ago, of course, when he was presumably less busy), and he told me that he'd moved on from it. Obviously, he has.My question to you is this: How many of you would use (were it readily available) a wristbound calculator with all the functions you'd expect from your scientific pocket calculator, or your phone app moonlighting as one? Am I alone in imagining that there's a hole that needs to be filled here, and not just the one in my mouth for my shoe to fit into?

author: EEVblog
author_rank: Unknown
timestamp: March 19, 2018, 05:09:17 am
content: AFAIK Casio still make an almost identical case for a databank calc watch. It would take them much to redo the CFX-400 surely?I've always want to try a re-purposing project for this.Maybe start a petition to send the Casio?Would they make it if say 50,000 people were interested?EDIT: Now searching Linkedin for a suitable contact...

author: EEVblog
author_rank: Unknown
timestamp: March 19, 2018, 05:18:54 am
content: Quote from: Johnboy on March 19, 2018, 05:06:17 amNo, you are not alone, I think there would be a huge market for it if implemented correctly. It anything just for an anti-smart watch appeal.

author: EEVblog
author_rank: Unknown
timestamp: March 19, 2018, 05:23:04 am
content: These dudes look approachablehttps://www.linkedin.com/in/joseph-gillio-7789275/https://www.linkedin.com/in/robert-prunk-9429882/

author: Johnboy
author_rank: Regular Contributor
timestamp: March 19, 2018, 05:27:50 am
content: I am thrilled to hear that you are supportive of a "petition" of sorts, Dave. Surely I can't be the only kid who ever wrote a letter to Casio and asked "what gives"?I think you're right about the backlash regarding the "smartwatch phenomenon". My first question upon seeing one wasn't whether I could give it voice commands to start my car, but whether it had a pi key.

author: Ampera
author_rank: Super Contributor
timestamp: March 19, 2018, 03:14:17 pm
content: I'd buy one if it had an RPN option.

author: floobydust
author_rank: Super Contributor
timestamp: March 19, 2018, 03:19:03 pm
content: 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.I lost a job interview because I was wearing it.Interviewing manager said "I noticed your watch, you must be very detail-oriented and calculating"

author: rsjsouza
author_rank: Super Contributor
timestamp: March 19, 2018, 04:04:01 pm
content: I absolutely love these old watches, but I just don't see a use for a full scientific calculator on the wrist... I could buy one if the price is right (which is what obviously matters to Casio).

author: 2N3055
author_rank: Super Contributor
timestamp: March 19, 2018, 04:56:33 pm
content: If we could pressure Casio to restart production of something old, I would vote for old calculator fx-61FI don't know what I'm going to do if mine dies..

author: Johnboy
author_rank: Regular Contributor
timestamp: March 19, 2018, 10:08:55 pm
content: Quote from: floobydust on March 19, 2018, 03:19:03 pmOf course. That's the kind of manager I'd want running my company when I wasn't around. I'd rather have sloppy, vapid employees any day. Sigh.Quote from: 2N3055 on March 19, 2018, 04:56:33 pmI might recommend the TI-36X Pro. The only fault I've found with it is that it's too large to mount on my wrist.Quote from: rsjsouza on March 19, 2018, 04:04:01 pmI foresee any number of AP high school and college students who might forget to bring their calculator to a test, but would be much less likely to forget their watch (taking into consideration that cellular phones often aren't allowed). It would certainly make a good gift as a backup from those parents and grandparents who used their watches, not their phones, to tell the time.Quote from: rsjsouza on March 19, 2018, 04:04:01 pmMy point exactly. Certainly this thing could be more cheaply manufactured now. That's why I don't understand why no one has jumped into this niche.I'd like to respectfully ask the moderators, considering my regrettable lack of foresight in the matter and relative novelty around here as a posting member of this forum, to consider moving this thread to a different section where we might get a larger sampling of views from forum members (for example, "Products" or even "General Chat"). I ask this because A) I'm not at all certain that a discussion of a discontinued calculator watch (or, especially, petitioning for a future model!) necessarily belongs in the "Vintage Computers" section, and B) because I feel strongly enough about this topic that I'd like more people to notice the option to weigh in with their opinions and information.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 19, 2018, 11:22:17 pm
content: Quote from: Johnboy on March 19, 2018, 10:08:55 pmPerhaps you may be right, although I suspect younger audiences simply don't use wristwatches as much as folks of our generation...Quote from: Johnboy on March 19, 2018, 10:08:55 pmMy impression is that he electronics are not the costly thing anymore, but instead the machining and the assembly to put all this into the form factor of the wristwatch.

author: Muttley Snickers
author_rank: Unknown
timestamp: March 19, 2018, 11:53:09 pm
content: Quote from: Johnboy on March 19, 2018, 10:08:55 pmYou as the original author of this thread have the ability to relocate it to almost any part of the forum you see fit, have a read of the thread linked below for guidance and instructions.Moving Topics.https://www.eevblog.com/forum/blog/what's-this-move-topic-icon-all-about/

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 09:42:21 am
content: Quote from: floobydust on March 19, 2018, 03:19:03 pmWhere did you get a new one? That would fetch probably $1000 on ebay!

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 09:43:59 am
content: Quote from: 2N3055 on March 19, 2018, 04:56:33 pmI'd love to do an EEVblog branded version of the FX-61F!

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 09:54:28 am
content: Quote from: EEVblog on March 19, 2018, 05:23:04 amI have his direct email

author: 2N3055
author_rank: Super Contributor
timestamp: March 20, 2018, 10:36:51 am
content: Quote from: EEVblog on March 20, 2018, 09:43:59 amIf you do I would like serial number 00001 :-)I would actually buy two, one for me (backup to the one I have) and one for my son...People that don't have it, don't understand the genius of built in impedance mode....And a parallel operator...So yes you have my vote!!Regards,Sinisa

author: bd139
author_rank: Super Contributor
timestamp: March 20, 2018, 10:41:48 am
content: Sign me up for one watch and one FX-61FThere is the possibility of repurposing HP's calculator line as it's just an ARM7:https://en.wikipedia.org/wiki/HP_30bEdit: the new FX-991 EX is pretty good. You can turn off all the shitty entry functions and use it as an engineering calculator. has solver, engineering units, conversions, constants, base-N and the display isn't shit. If they do a programmable one I'm going to be all over it like a seagull on chips.Edit again: For ref, the OEM for most of the calcuators from Casio, Sharp, HP, TI etc these days is Kinpo:http://www.kinpo.com.tw/English/

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 11:58:08 am
content: Quote from: bd139 on March 20, 2018, 10:41:48 amIt still has that VPAM entry rubbish

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 12:02:45 pm
content: Quote from: bd139 on March 20, 2018, 10:41:48 amIIRC one of the guys who wrote that firmware also re-wrote my uWatch code to play chess and do other stuff.

author: bd139
author_rank: Super Contributor
timestamp: March 20, 2018, 12:31:04 pm
content: Quote from: EEVblog on March 20, 2018, 11:58:08 amYou need that for solver expression entry. Compromise really.

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 12:33:53 pm
content: Quote from: bd139 on March 20, 2018, 12:31:04 pmSure it's great for that, but otherwise a PITA for everyday calcs. It can't even figure out that 2 EXP 3 (-) means 2 milli, you have to use the correct order of 2 EXP (-) 3The original Casio's are smart enough to work both ways.

author: Ampera
author_rank: Super Contributor
timestamp: March 20, 2018, 12:38:10 pm
content: The HP Prime has some of the best data entry I've seen on a calculator. It's actually better in some ways than a proper PC CAS, considering you have dedicated functions for everything, and the 400mhz puts it above anything that Ti has to offer.

author: bd139
author_rank: Super Contributor
timestamp: March 20, 2018, 12:44:09 pm
content: Quote from: EEVblog on March 20, 2018, 12:33:53 pmThat’s not really an issue for every day calcs. It makes a difference which way round you write it on paper as well.

author: 2N3055
author_rank: Super Contributor
timestamp: March 20, 2018, 12:51:08 pm
content: Quote from: bd139 on March 20, 2018, 10:41:48 amSlightly off topic but.. it just occurred to me, that if we had member with name LM723 , three of us would make fine PSU :-)) LOLBeauty of the fx-61F is it's impedance mode and dedicated capacitor, inductor, parallel buttons, together withunit suffixes. I type into it directly from schematic..... It is very quick...

author: bd139
author_rank: Super Contributor
timestamp: March 20, 2018, 12:59:46 pm
content: HahahaI had an HP50g for a while. I programmed those buttons with RPL as soft buttons on F1-F6. Problem solved. Really barely used it past that so the Casio got the job in the end because I can remember how to use it every time I pick it up. Excel is pretty good at crunching numbers otherwise which mainly amounts to tweaking for me.

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2018, 01:56:34 pm
content: Quote from: bd139 on March 20, 2018, 12:44:09 pmYou 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

author: bd139
author_rank: Super Contributor
timestamp: March 20, 2018, 02:11:31 pm
content: Quote from: EEVblog on March 20, 2018, 01:56:34 pmYou 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.

author: Johnboy
author_rank: Regular Contributor
timestamp: March 24, 2018, 05:38:54 pm
content: 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.)

author: Zad
author_rank: Super Contributor
timestamp: March 25, 2018, 03:01:40 am
content: I always preferred the CFX-200. Hence the profile photoAn RPN watch with something like the firmware from the WP-34s / HP-30b would be a bit of a holy grail.

author: Johnboy
author_rank: Regular Contributor
timestamp: March 25, 2018, 05:48:16 am
content: Quote from: Zad on March 25, 2018, 03:01:40 amThank 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?

author: moonunit
author_rank: Newbie
timestamp: April 07, 2018, 12:06:35 pm
content: 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.

author: floobydust
author_rank: Super Contributor
timestamp: April 07, 2018, 04:51:00 pm
content: Quote from: EEVblog on March 20, 2018, 09:42:21 amI bought the second Casio calculator watch DBC-611-1 from Amazon, they still sell them there.