Project idea: Open-source graphing calculator? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: November 27, 2020, 12:04:21 pm
content: This is inspired bythis threadand the suggestion that an open source graphing calculator might be possible. So here is some ideas:Allwinner F1C200s (the memory-doubled drop-in replacement of F1C100s) has an ARM926 core, 64MB built-in SDRAM and can directly drive a full-color RGB LCD in RGB888 mode.Obviously the F1C200s has to boot from internal storage - SPI flahs or eMMC - after it is set up, but a microSD card slot would be useful for development and firmware upgrades.That USB OTG connection would definitely be used to implement a combined charge and data port. Going with USB-C can save a GPIO pin as the CC controller chip puts the OTG ID pin's functionality onto the main I2C bus. Also it allows fast charging if so desired.F1C200s won't have much I/O left after the storage devices, LCD display and maybe a Wi-Fi/Bluetooth module, so the keypad has to be dealt with, either using an I2C keypad scanning chip, or a second microcontroller.And we need some kind of CAS software running on top of a lightweight Linux distribution.

author: daqq
author_rank: Super Contributor
timestamp: November 27, 2020, 12:13:44 pm
content: So... a feature limited smartphone? Not really sure what would be the advantage.

author: technix
author_rank: Super Contributor
timestamp: November 27, 2020, 01:40:38 pm
content: Quote from: daqq on November 27, 2020, 12:13:44 pmOpenness for openness's sake maybe? RMS's gist really.

author: cgroen
author_rank: Unknown
timestamp: November 27, 2020, 01:54:00 pm
content: That's one of the few projects I don't see any use for, but that's probably only meTo me a calculator is a tool like a hammer (or a scope or...), I have 3 27 inch monitors at my workstation and a mobile. If I need a graphing calculator, I start one up on one of the many screens here....If I need to take it with me, I have my phone.I just don't get it ?

author: HB9EVI
author_rank: Frequent Contributor
timestamp: November 27, 2020, 03:18:49 pm
content: I'd say it could be a nice diy project, but then with advanced math features like integration/diffentiation, solver a.s.o. to learn how to do it, it's not such a bad idea

author: ejeffrey
author_rank: Super Contributor
timestamp: November 27, 2020, 03:33:43 pm
content: Quote from: cgroen on November 27, 2020, 01:54:00 pmMaybe for people who like physical buttons?I'd much rather use an old school scientific calculator than a smartphone app. I just need it rarely enough that it isnt worth having a dedicated device for a niche application.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 27, 2020, 03:40:46 pm
content: The project might make sense as a learning exercise.As for having it as a tool, there are already plenty of open source graphing tools out there:Geogebra - live interaction, animations, 3D, geometry, etc. can work either online (as a webpage) or offline (as a local installed program). Very eye candy, here's an example:https://www.geogebra.org/m/ehkwndmaOctave (Matlab compatible, but free and open source)https://www.gnu.org/software/octave/indexMatplotlib in Python (or in other programming language)https://matplotlib.org/These are the first 3 tools that came to mind, there are many others: QUCS Spice or LTspice for electronics, LabVIEW as a generic tool for scientific instruments control and display, any spreadsheet chart, and so on.

author: cgroen
author_rank: Unknown
timestamp: November 27, 2020, 03:42:18 pm
content: Quote from: ejeffrey on November 27, 2020, 03:33:43 pmSure, that's why I tend to use my workstation for this kind of stuff (with full PC keyboard....)And in the few circumstances I need to take my "graphing calculator" with me, I can handle the fact that its a touch screen on a phone I need to use.I have enough devices in my lab so I don't need yet another dedicated device that can only handle one specific job.(and no, I'm not a young(er) guy that grew up with touch screens, 53 years old and into this embedded stuff for the last 35+ years)

author: dkonigs
author_rank: Regular Contributor
timestamp: November 27, 2020, 03:43:36 pm
content: Believe it or not, I still wind up taking out my 25+ year old TI-85 whenever I want to do some sort of quick calculation. Most utility-style desktop calculator apps kinda suck (they're all chasing the featureset of a lower-end non-graphing calculator), and I've never found a smartphone app for this that I like either. Though I probably blame certain "necessary" UI quirks of a smartphone for this. (The need to constantly be shutting off the display, always wanting to lock the UI, and having too many choices with no clear winner to run to.)There is a market for this, if you note how SwissMicros builds modern recreations of HP calculators. Unfortunately for me, I've never felt "fluent" at the HP style (as the TI style is a far better fit for how I actually want to do a calculation). However, the Sharp Memory LCDs they use are really nice.Seriously, if there was a modernized equivalent to those old TI calculators, I'd buy it in a heartbeat. Unfortunately, I have yet to stumble upon one.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 27, 2020, 04:47:30 pm
content: I suppose you already know this project?https://www.numworks.com/(If not, have a look.)Then, why not, but I for one am not convinced dedicated handheld calculators are that useful anymore. I made a whole thread about it before, so let's not do it all over again, but just my thought. Keep in mind it's just personal opinion here - but then I'm not sure all the effort would be justified.Technically, given your specs, it's probably going to draw significant power. So battery life will be limited. Again personal opinion, but if I'm gonna use an handheld calculator, at least I don't want to have to recharge it every day or every other day...

author: Ian.M
author_rank: Super Contributor
timestamp: November 27, 2020, 04:51:43 pm
content: IMHO the O.P's concept is a waste of time/effort. The continued survival of dedicated 'scientific' calculators is largely an artifact of the western world higher education system, which for scientific and technical subjects almost invariably requires a calculating device with no network access that can be put into an easy to verify, locked down 'examination' mode that purges stored data and notes, and disables any solvers. An open-source calculator wouldn't be acceptable as any 'examination' mode would be too easy to 'backdoor'.For those of us not involved with academia, a dedicated calculator is only preferable to an app on a smartphone or tablet if it offers a much better physical user interface and extended battery life, *AND* if you either routinely work without a computer or smartphone/tablet/PDA, or if it can readily exchange data with your PC/smartphone/tablet/PDA via a shared clipboard and CSV file import/export.Why not go for the low-hanging fruit?It might be worth investigating adding a full function calculator keyboard in a clamshell case to a hackable eInk ebook reader. Many such devices have a logic level serial port that functions as a Linux serial (debug) console, and it would be reasonably simple to add a low power MCU to manage a calculator keyboard, disabled when it receives Linux bootup messages, and enabled by a particular 'magic' string sent by a calculator app. If the eReader doesn't have external access to its UART and power/battery connections, the case would replace the back of the eReader, to permit such access. It would be advantagous to include a hinge sensor, to put the eReader to sleep when closed, and disable the added keyboard when the clamshell is hinged right back, to allow normal use as an eReader. The electronics and additional MCU firmware are reasonably trivial. Most of the effort would be application development on the eReader, and designing a high quality clamshell case constructed with 3D printed buttons and smaller case parts, and laser cut flat panels for greater strength and a superior surface finish.Also, the SwissMicro range of open source RPN calculators has already been mentioned. As they are open source, adding a TI-like conventional calculator mode to them would only require software development, and possibly a keyboard overlay.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: November 27, 2020, 04:58:34 pm
content: Sounds fun.I still use my Casio FX7300 (it's even older than me) but for something very complex I don't feel like using maxima or octave from a handheld device.

author: rstofer
author_rank: Super Contributor
timestamp: November 27, 2020, 05:12:51 pm
content: We have a workstation in the living room, I'm using it now. There is an HP48GX on the table.In the back room, where the real work happens, there is an HP35S on the desk. I have another HP 48GX but I thought the 35 was pretty handy.I have several variations of graphing calculators (HP & TI) and I don't find any of them preferable to something like MATLAB or wxMaxima. I'm just getting into graphing with Python.I have an HP41 emulator on my cell phone and it's pretty sweet but I don't carry my phone, ever, so it isn't all that handy.Just build a dedicated front end to Raspberry Pi. Boot straight to a calculator, I suppose.

author: bson
author_rank: Unknown
timestamp: November 27, 2020, 07:44:25 pm
content: I use calculators for all sorts of quick numerical needs, or python if I'm at a computer, but a calculator is much quicker than opening a laptop.I use Mathematica for algebra and plotting/visualization. This is the really tedious stuff where a computer is a huge time saver. Unfortunately sympy isn't good enough and has problems even solving simple sets of equations that I can trivially solve myself, I'd say maybe 50% of the time it can't solve them. Mathematica on the other hand sucks for numerical stuff, where numpy and scipy are vastly superior. Sympy also isn't well integrated, and when it does come up with a solution there's no easy way to e.g. find a polynomial fit. You invariably end up retyping a bunch of stuff, sometimes a LOT of stuff. Meh.The HP-48 is pretty good and handles a lot of algebra fine, but it can be very slow. (Not surprising given its saturn processor with a 4-bit bus, and the entire algebra system implemented in a symbolic, stack-based threaded language, RPL. Given those circumstances it's very fast.)

author: Bud
author_rank: Super Contributor
timestamp: November 27, 2020, 09:05:22 pm
content: Smartphones cant compete with handheld calculators on instant readiness. It only takes one push of the power switch to get a handheld ready. By the time i get a calc app ready on the smartphone i forget what i wanted to calculate. I only use phone app when not at home, otherwise it is one of the old good dedicated calculators.

author: james_s
author_rank: Super Contributor
timestamp: November 27, 2020, 09:44:53 pm
content: It could be an interesting project, but IMO most of the value in an off the shelf calculator is the form factor. You get a nice housing with printed buttons, a power source and often a protective cover to store it in. If you build something yourself it's going to be very difficult to replicate anything near as nice as a custom injection molded housing. You could use a touchscreen (yuck) but then you've got something that is pretty much just a smartphone except it's invariably going to be more bulky and clunky than an off the shelf phone. If you wanted the instant on of a calculator in the smartphone form factor then a cheap Android phone or small tablet with custom firmware is probably the easiest.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 27, 2020, 11:35:36 pm
content: Quote from: james_s on November 27, 2020, 09:44:53 pmWay easier nowadays with 3D printing.

author: dkonigs
author_rank: Regular Contributor
timestamp: November 28, 2020, 01:24:39 am
content: Quote from: NiHaoMike on November 27, 2020, 11:35:36 pmEasier to prototype, but not easier to actually get made to the same standard. You're simply not going to get the same quality of the enclosure and buttons out of an FDM 3D printer (the more common type). You'll probably need an SLA one to even attempt nice buttons. And, assuming you pull this off, it still doesn't solve the problem of printing the necessary labels onto those buttons.3D printers are an incredibly useful tool, and enable a lot of things that weren't previously possible, but they're not the magic solution to everything that people often think they are.

author: james_s
author_rank: Super Contributor
timestamp: November 28, 2020, 02:54:34 am
content: Several of my friends have 3D printers, they're cool and the idea shows a lot of promise but IMHO we're not really "there" yet. Everyone I know who has one spends more time tinkering with it and getting the process dialed in than actually printing useful parts. They've all made a bunch of toys and trinkets for their kids but I struggle to think of many truly useful finished parts any of them have made. I'm really not a fan of the 3D printed look, filament printers don't even come close to the quality of injection molding and it's very, very slow. Designing and printing a complete set of parts for something like a calculator with dozens of buttons would probably take many tens of hours. They seem really handy for making mechanical prototypes if you're into 3D CAD but I haven't seen anything to entice me into buying one for myself.

author: technix
author_rank: Super Contributor
timestamp: November 28, 2020, 03:01:46 am
content: Well I can just hijack an existing graphing calculator, for example gut an old and electronically broken TI-83 or damaged-by-kids TI-84 Plus and put the DIY solution in that case, keeping its original form factor and make just a small case modification to the link port so it can be USB-C instead of whatever TI uses.

author: james_s
author_rank: Super Contributor
timestamp: November 28, 2020, 03:03:30 am
content: If you only want to build one of them then that's viable. I'd be curious to see the result when you finish.

author: wizard69
author_rank: Super Contributor
timestamp: November 28, 2020, 05:38:50 am
content: Quote from: technix on November 27, 2020, 12:04:21 pmThere are plenty of open source calculators out there. So you can either start with something half done or go your own route, I don't see software as a big deal either way.QuoteIn List order:The trick with such a calculator is to not go overboard. I can't say if the F1C200 is going overboard, never herd of it until now, but in my mind a calculator has t operate for a very long time on batteries or a super cap and solar cells to b useful beyond my cell phone that is always with me. To put it another way extremely low power is a must.This line leads me to believe you are off on the wrong foot already. Fast charging assumes that you have a fast depleting battery, that is not good at all. Ideally the unit would be solar powered or at the very least battery powered for months at a time.It really sounds like you are trying to recreate a PDA here. Instead of trimming the device down to what is required to get the job done you are finding more and more things to throw in the sink. In this case we are talkign a power sink.Linux? Are you serious? The era of the PDA was passed decades ago now, I don't see a reason to bring them back when smart phones are a reality.QuoteIn industry we still have uses for calculators but even here that usage is declining. Often they are stuck on a tools, with Velcro of all things, to solve a repetitive calculation problem for the operator. Even here as plant control technology increases that sort of thing isn't as needed as in the past. For the most part the more traditional uses in engineering have been replaced by laptops (often running a spreadsheet) or cellphones. In fact I'd go far as to say a portable calculator that can run a spreadsheet has more applicability in the modern world with Python not far behind. Graphs have their place but producing them is hardly the bulk of the daily calculations done in the world.Then you have to consider where computing itself is going. I just picked up an Apple M1 based Mac Book Air and have to say this machine is game changing. I can open it up be on line in fractions of a second running any number of apps. It is literally as fast as whipping out a traditional calculator. More so I have my choice of apps from utilities like calculators, to compilers, to interpreters to spreadsheets. Basically it can handle any calculation chore from a quick addition to complex analysis off arbitrary data. All of this and it hardly gets to the point where the chip heats up at all. In some cases it is actually cooler than handheld calculators of the past.So if you ask me the real market would be in a Linux laptop with similar qualities. Extreme low power, instant on, a stable GUI and all the tools (custom apps/programs) that I can throw at the unit. Why the world has resisted building a decent ARM based laptop, with Linux as its OS, is beyond me. The world just needs to say screw Intel & MS and move to something far more efficient and with delicious battery life. It is really frustrating that it takes Apple to make this move especially when Linux has a large portion of its entire software base already there.So I ramble a big here because your project is basically 80% of the way there ot a Linux based laptop. Why not got the next few steps and make it an actual laptop?

author: BravoV
author_rank: Super Contributor
timestamp: November 28, 2020, 07:42:05 am
content: Trust me, as regular and I know the OP, this is all just talk and I bet with my Fluke 287, this will never materialize.Here, an excellent example on do it 1st mentality, discuss later ->A High-Performance Open Source Oscilloscope: development log & future ideasClearly above example is not just another boring ... "I have an idea, can anyone do it for me ?" thread that just wasting lots of energy, pointlessdiscussionchit chat and ends up with nothing.

author: technix
author_rank: Super Contributor
timestamp: December 07, 2020, 05:45:03 pm
content: Quote from: BravoV on November 28, 2020, 07:42:05 amSo I just can not have a scrapbook of ideas and bounce them off people then? Do you have one?

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 08, 2020, 04:20:23 am
content: Quote from: wizard69 on November 28, 2020, 05:38:50 amPDAs haven't disappeared, if anything they're a lot more popular than they were in the past. They either have merged with cell phones to make smartphones or became bigger to become tablets. Arguably, you could say that some have became smaller to become smartwatches.I see a significant advantage of a device similar to the PDAs of 20 years ago over the modernized version: less connectivity is a plus for very high security. I suppose there's not much point making a specialized device for that when you can find a cheap smartphone that has a decent open ROM like LineageOS and hack it to disable unwanted wireless interfaces.That said, for a calculator, something like a STM32 should be plenty for at least 99% of the things people use calculators for and a provision to connect a smartphone or PC to use as additional compute power and a bigger display would cover almost all of the remainder. It would address the main problem of software calculators - the lack of a tactile user interface.Perhaps if you used an eink display it could create a new kind of calculator that is "always on" displaying the last calculation you did.

author: technix
author_rank: Super Contributor
timestamp: December 08, 2020, 09:04:20 am
content: Quote from: NiHaoMike on December 08, 2020, 04:20:23 amThis would be a good idea, as I have worked with touch-sensitive e-ink display before, which seem to me like a good starting point.Speaking of PDA’s, IMO the closest thing to the PDA of the old would be iPod touch.

author: DiTBho
author_rank: Super Contributor
timestamp: December 08, 2020, 11:30:02 am
content: The point here is:*** the software! ***CASIO, TI, and HP have spent a lot of financial resources, time, and human power to design the software that runs inside their calculator, and this *IS* the value you get when you purchase a product like a graphing calculator from them!I have seen a lot of very long discussions on the internet where it's easy for everyone to open a topic just to claim "hey? I have a great idea, why not to develop my own calculator?" which usually means that you can put a Linux little SoC inside a plastic box attached to an LCD or something and get it running some opensource math program on it.Does it sound cool, easy, and doable for hobby, ain't it?Yes, there is Matheamtica for the Linux/RPI, and you get get it for free (no money), yes this software is designed like a big kernel that does waits for serial input, does all the calculations, and serially returns all the output to the display-module,input-modules ----> kernel ----> output-modulesbut as you get it out of the box its interfaces are all designed for a large computer screen and it sucks when you try to embed it into a pocket calculator because you have no way to "click", and you would have to redesign the whole "input-modules" as well as the whole "output-module": has anyone already thought about doing it? Not yetyes there is "Numpy" and a lot of other great stuff for python and other stuff, as well as "Gnuplot" and Octave, and other stuff, but they all suck when you do not have the proper interface to type and visualize things: has anyone already thought about doing it? Not yetPeople love to recreate things from scratch, so again let's design a Linux graphing calculator from hardware up: for me it doesn't make really sense since instead of rethinking about the hardware,first you would have to think about the software, which is what is really missing.Here you have two choices:if you really want to run something on Linux/BSD, you have to improve what actually exists, and thinking about running it on a Laptop/Workstation. All the opensource programs I have tested ... well suck a lot about their interfaces, so here you can think about giving a hand to their authors, and this will be for sure more useful than starting your own fork. So there is a lot to do hereor you can think about the purchase of a "NumWorks graphing calculator" (seehere, it costs 90 euro + S/H) as "eval hardware" where to upload new firmware through a USB cable. So you can study their current firmware, see what needs more work and improve it, or change it entirely. There is a lot to do here alsoA friend of mine bought months ago a NumWorks graphing calculator and lent it to me for a couple of weeks to hear what I think about it, and ... well, in short ... it's an interesting product, but the current firmware islight years inferiorto what you can get from my new CASIO FX-9860GIII and even from my old CASIO FX-7500.And if you compare these products with TI's products ... well, the TI89, TI92 are something that no-opensource project can beat!In fact people still support and run TI89/92 emulator (20 years old products!!!), and I have read that some folk were/still are thinking about making a PDA-Linux box with some buttons which looks like a calculator and which only executes those emulators.Does it make sense? Well, this way they think they have solved the "firmware" problem

author: DiTBho
author_rank: Super Contributor
timestamp: December 08, 2020, 11:40:11 am
content: I have seenthisTI-Emu-software running on Linux/RPI attached to a little LCD coupled with a touchscreen to emulate the keyboard on the screen.You just need to dump the "ROM" from an original TI's product, which is supposed you own in order to run the emulator. You can find a lot of old TI89 calculators on eBay so you can fix this "legal" point, and just download a ROM from the internet.These files are the only thing "not opensource" of the whole project, and if you own a physical product, then using the ROM is not illegal.

author: tooki
author_rank: Super Contributor
timestamp: December 08, 2020, 12:32:17 pm
content: I own the lovely HP Prime calculator, whose software is based on this open source package:https://en.wikipedia.org/wiki/XcasThis would undoubtedly take care of the software issue DiTBho identified.Quote from: Ian.M on November 27, 2020, 04:51:43 pmI couldn’t disagree more. Sure, smartphones have displaced the pocket calculators people used to carry around for occasional arithmetic. And sure, spreadsheets and things like Mathematica have taken other areas. But calculators aren’t going anywhere. Touchscreen phones are horrible to type on. I don’t want to open an app to do a calculation. I want a totally reliable little doodad with a great keypad. (TI: you really need to up your game in that regard!)I’ve actually considered taking a TI calculator and hacking a new case for it, with proper tactile buttons instead of mushy membrane BS. The HP Prime has nice keys, which is why I bought it!

author: Ian.M
author_rank: Super Contributor
timestamp: December 08, 2020, 12:56:17 pm
content: Ahem . . . .Quote from: Ian.M on November 27, 2020, 04:51:43 pmQuote from: tooki on December 08, 2020, 12:32:17 pmYou've actually just agreed with me on one of the key issues I raised!Also your HP Prime has USB connectivity, so we probably aren't too far apart on that issue either.

author: voltsandjolts
author_rank: Unknown
timestamp: December 08, 2020, 02:22:40 pm
content: Quote from: technix on November 27, 2020, 12:04:21 pmhttps://symbolibre.org/

author: technix
author_rank: Super Contributor
timestamp: December 22, 2020, 03:07:47 pm
content: Quote from: DiTBho on December 08, 2020, 11:30:02 amOh ho ho ho... TI-92. I still own a TI Voyage 200 (the large form TI-89 Titanium, similar to TI-92 Plus being the large form of original TI-89.) and I know how excellent that line still is - the newer Nspire CX CAS has no chance against that.Should an open source graphing calculator be implemented, it have to have feature parity with that line and then some, which is a huge undertaking on the software side. The main undertaking would be linking the hardware to the user interface, and implementing said user interface, while the CAS core can be offloaded to NumPy or the like. AFAIK TI's 68k CAS firmware is bought from elsewhere, based on a CAS known as Derive.

author: wizard69
author_rank: Super Contributor
timestamp: December 25, 2020, 11:35:33 pm
content: Quote from: NiHaoMike on December 08, 2020, 04:20:23 amSo they disappeared replaced by cell phones? The point here is that the market is already saturated and getting enough volume to be cost competitive will not be easy. And then you have to consider how many people would bother to buy such a device when they already have a cell phone in their pocket.By the way as calculators go, they are still real nice to have, that physical keyboard makes a big difference if you need to use them a lot. But even here it is far easier to replace much of what was once done on a calculator with Python or one of the up and coming languages like Julia or Swift.QuoteThere will always be demand for specialized hardware. I just don't see PDA's as being in demand anytime in the near future.QuoteI actually agree here that a keyboard can make a big difference, especially when you consider how calculators where used in the past. These days we have spreadsheets, graphing programs, programming languages (far easier to use than most calculators), Math apps like Matlab, maxima, R and others easily obtainable. As such there really isn't a demand for traditional calculators like the old HP's/QuoteI will not try to stop somebody trying something new, I just think it is fair to point out where they will have difficulty succeeding.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 26, 2020, 12:46:13 am
content: Quote from: wizard69 on December 25, 2020, 11:35:33 pmIf you consider a tablet as just a big PDA (that's literally what it is), they hardly disappeared. It's just that technology has improved to the point where it is no longer necessary to restrict the screen size to the 3-5" of "classic" PDAs to keep the device affordable with reasonable battery life. I remember that when the classic PDA was coming to an end, a few manufacturers came out with PDAs with 7" displays and hardware keyboards, similar to the "netbooks" that came just a few years later but even smaller.As for a calculator, a good direction to go is features that few or no smartphones have - eink display and hardware keypad. Also it would be good to have solar charging so that it will rarely or never need charging using USB just like the cheap "basic" calculators that are commonly available.Or we can go in the other direction and make a keypad that plugs into a smartphone to address the main problem with using a smartphone as a calculator - the lack of a tactile user interface. It would be pretty simple hardware wise - just a bunch of buttons wired to a USB microcontroller.

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 10:23:57 am
content: Quote from: technix on December 22, 2020, 03:07:47 pmNever tried any HP calculator before, but I have just found that the newHP Prime G2has a superior CAS-engine and it's full of powerful featuresUmm, as ergonomics nothing can beat theCasio FX9860GIII(with ucPython), and there is nothing similar to the "Casio FIX/SCI/ENG display" (love it); the new Prime G2 is bigger, less "pocket" and also very expensive (200-250 euro), but it's really an awesome super-calculator! And it's also very very fast!You can try its firmware on a full-but-free simulator written by HP itself, which runs on Windows, Linux, and Mac.

author: Ian.M
author_rank: Super Contributor
timestamp: December 27, 2020, 10:49:41 am
content: Quote from: NiHaoMike on December 26, 2020, 12:46:13 amAs I said way up-thread, developing a calculator keyboard accessory for a hackable eBook reader with nice tactile feedback keys is probably the way to go unless you've got a vast budget. OTOH if you put a flashy enough crowd-funding proposal together, you could milk the development of a standalone device for long enough to keep yourself and a few of your mates supplied with fast cars and fast 'ladies' for a few years!I don't think solar power would be practical in an accessory, as the host device probably isn't sufficiently power optimized to be capable of running from a reasonable panel area at indoor light levels. A wireless charging coil might be an alternative.However, if you are a native Cantonese speaker and well tied into the 'shanzhai' community, you may well be able to develop a standalone eInk calculator on a reasonable budget, starting from an eInk tablet or eBook reader reference design.

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 10:56:56 am
content: QuoteYup! We need wifi/usb math-keyboards for math-apps running on smartphones!

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 01:09:08 pm
content: Quote from: voltsandjolts on December 08, 2020, 02:22:40 pmIt looks cool, but in my opinon it has strong dependencies, such as qcustomplot, qtermwidget, and ginac.Ginac is something I wouldn't like to have.

author: Bicurico
author_rank: Super Contributor
timestamp: December 27, 2020, 03:42:44 pm
content: The problem regarding commercial calculators is that they are regulated by education ministries. This why they have a stupid alpha layout and other kind of limitations.Also, the market is dominated by TI with some competition from Casio. The HP Prime tried to enter this market but I guess with little success despite being hands down the best calculator around.The monopoly of TI is due to the fact that they cleverly subsidized the teachers by providing them free calculators and ready made courses. How many teachers are going to deal with students that have other brands?This said, these modern calculators are made for textbook exercises and little more.The best calculators for me (personal opinion) were the HP48GX and HP50, as well as, the Casio pocket computers like FX850P/880P or PB2000C.The HP Prime is borderline between nice calculator and over engineered calculator.I don't see any reason for a DIY calculator as suggested by OP. I just run my old HP48GX which is broken by now as an emulator on my phone. It is almost the same feeling.Another fact is that once you are out of University you don't need a calculator often. Mostly I open an Excel sheet - almost as a brain storming math tool.Regards,Vitor

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 03:54:36 pm
content: Quote from: Bicurico on December 27, 2020, 03:42:44 pmThis applies only to calculators that needs to be admitted to examinations.For instance, the CASIO FX-CP* is different from Casio FX-9*The CASIO FX-CP400 doesn't need to be regulated by any education ministries because it's not admitted to any examinations.The CASIO FX-9860GII and GIII do need to be regulated by education ministries because they need to be admitted to examinations.Quote from: Bicurico on December 27, 2020, 03:42:44 pmStupid Alpha layout? Other kind of limitations?

author: Bicurico
author_rank: Super Contributor
timestamp: December 27, 2020, 05:36:44 pm
content: Alpha-Layout: I meant that keys with letters are ordered ABC... instead of using any QWERTY convention. Exceptions where pocket calculators (Sharp, Casio, ...) and the TI 92 Plus/Ti Voyage 200. Nowadays you cannot buy ANY new calculator with QUERTY keyboard, despite the fact that for instance the TI92 was available with detachable/exchangable keyboard (they could have provided one with QUERTY layout, but didn't).Other limitations: CAS missing (except on TI 92 CAS and HP Prime, both can be locked by teacher in "exam mode"), limited programming capabilities, to name a couple.But what I tried to say is this: while in the 70ies and 80ies, engineers relied on scientific calculators to do their work, they now use computers with much more powerful software (CAD/CAM/CAE, Matlab, Excel, etc.).This has reduced the marked of scientific calculators basically to education.If a student asks me what scientific calculator he should purchase for his engineering course, I tell him to buy the cheapest one admited to exams (like any 20 Euro CASIO) and save the money for a laptop.Regards,Vitor

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 05:58:21 pm
content: Quote from: Bicurico on December 27, 2020, 05:36:44 pmThat's not a problem with CASIO-basic since you don't have to "type" but rather to select the language keywords by pressing one single button.This may be a problem with uPython, where you have to write keyword char by char, but hey? are you seriously going to program in python on a screen that is less than 320x240 pixel? Of course no, you program on your PC, and you download the code to the calculator, which is exactly what CASIO tells people to do in the manual.The TI89 has the same problem, and for $50-$90 USD TI sells an external big QWERTY keyboard. It works with two batteries, and it talks to the calculator serially via the TI-link cable. It's a sort of "i2c" keyboard.Quote from: Bicurico on December 27, 2020, 05:36:44 pmYes, but also the price is different. The HP Prime G2 costs 2 times the CASIO GX8960GIII, and note: not all the CAS calculators are admitted to examinations, whereas all the non-CAS graphical calculators are usually admitted to examinations.I am no more a student, so I only partially care, I mean I can understand certain company decisions by CASIO, TI, HP, et all.Personally I like the CASIO GX8960GIII for for it's SCI/FIX/ENG display mode, this is *THE* reason why I bought it, followed by its capability to manage matrix operations with the complex numbers, as well as the simplicity of its 2D graphical engine that accepts both y=f(x) (implicit), r=f(o) (polar), even parametric functions (a bit limited, but very useful) and it's able to produce a table of numbers, which you can even trace dynamically on the screen.I use this stuff daily for projects.I also like the statistical engine, which is very useful when you to make some banking plans, but you are not at home, and you need to take a decision in mobility.This stuff requires the capability to numerically calculate defined integrals. CASIO isn't great with that, but not too bad.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 27, 2020, 06:02:50 pm
content: Quote from: Ian.M on December 27, 2020, 10:49:41 amWhile it will obviously depend on how often it's used, a small eink display driven by a STM32 uses very little power.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 27, 2020, 06:22:47 pm
content: Why not just get a wireless calculator-style keypad?

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 27, 2020, 06:24:22 pm
content: Power consumption of eInk displays is not necessarily as favorable as it may seem though.Whereas they can use as little as ZERO power while displaying a static image (you can just shut them down), they use quite a significant amount of power for refreshing their content (often significantly more than a typical LCD display), and refresh times can be quite significant. So they are worth it only if the display changes infrequently - a scenario here which entirely depends on how you use the calculator. A scenario where you launch any calculation/graph/whatever that would take a while to read (so you'd need the display to remain ON for a longish time while being static) would be favorable, but otherwise that may not be that interesting. For many other scenarios, you could just save power by automatically shutting down the display after a configurable time-out, and powering on again on the press of a key, or touch of the screen or whatever. You can also use (as Swissmicros did with their latest calc) a memory LCD display which draws extremely little power (to the point of being able to leave it on while the calc is off, with a static image, while drawing insignificant power from the battery...)Also, an annoying point IMO is the refresh time (and artifacts) that is still pretty annoying, even with the partial refresh modes that some of them offer. I'd personally find a calculator with eInk display pretty annoying.As to global system power, a low-power STM32 MCU is nothing like what you suggested first as your main CPU, and whether it could comfortably run the kind of software you had in mind is also to be questioned.Just a couple random thoughts.

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 07:06:02 pm
content: Quote from: Alex Eisenhut on December 27, 2020, 06:22:47 pmGreat idea! For example there is a NumWorks App for iOS, but not yet a math-keyboard

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 27, 2020, 07:22:47 pm
content: https://www.ebay.ca/itm/Targus-wireless-Stow-N-Go-Calculator-keypad-USB-desktop-accessory-BNIB-SEALED/283734693288?hash=item420fe7d5a8:g:0GAAAOSwVb5eFCgTSeem pretty cheap. There's your physical keys, and your calculator is now 100% software.

author: Ian.M
author_rank: Super Contributor
timestamp: December 27, 2020, 08:17:11 pm
content: So its been done, but for accountants, (and idiots who don't understand you don't have to add up the numbers in Excel by hand,) not engineers/scientists. User guide. The host computer apparently cant write to the keypad display in keypad mode.Also note that Targus have discontinued it

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 27, 2020, 08:46:54 pm
content: Quote from: SiliconWizard on December 27, 2020, 06:24:22 pmDoesn't Sharp have their own version of "eink" that refreshes somewhat faster?QuoteThe classic TI calculators have CPUs far slower than a STM32. Maybe RISC-V would be a better choice for something to be truly open source.Of course you could put in some GHz class ARM CPUs but that's overkill for what calculators are typically used for.

author: DiTBho
author_rank: Super Contributor
timestamp: December 27, 2020, 08:49:07 pm
content: Themath-keyboardI was talking about is not a simplenumeric-padbut rather something that has all the symbols you need to operate with trigonometric functions (and their inverse), logarithms, exponential, teta, pi, etc, etc.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 27, 2020, 09:59:07 pm
content: Quote from: NiHaoMike on December 27, 2020, 08:46:54 pmI think that is exactly what I refered to above as "memory LCD".https://www.sharpsma.com/products?sharpCategory=Memory%20LCD(I'm not aware of any other kind of similar displays from Sharp, maybe there is though.)As I said, Swissmicros used one in their latest products:https://www.swissmicros.com/products(DM42, DM41X)I also used one in a project (some kind of weather station). They look great and draw very little power. They are nothing like eInk actually, and are much closer to conventional LCDs. They have fast refresh, but at the same time can hold static content (so between changes) with only minimal current.

author: tooki
author_rank: Super Contributor
timestamp: December 28, 2020, 05:25:03 pm
content: Quote from: DiTBho on December 27, 2020, 10:23:57 amI have it and it’s a great calculator.Quote from: DiTBho on December 27, 2020, 10:23:57 amUnless the Casio also has tactile keys, then its ergonomics are inferior to the HP Prime.Quote from: DiTBho on December 27, 2020, 10:23:57 amWhat’s so special about that? The HP Prime has all of those display modes and several more.Quote from: DiTBho on December 27, 2020, 10:23:57 amThe HP Prime is smaller in every dimension than the FX9860GIII. And I don’t know where you pulled out that price number: it costs around 135 euros.It is fast though!Quote from: DiTBho on December 27, 2020, 05:58:21 pmLocal vendor here in CH:HP Prime: 135 CHFFX8960GIII: 119 CHFAmazon.de:HP Prime: €149FX8960GIII: ~€110 including caseAmazon.co.uk:HP Prime: £132FX8960GIII: £99Yes, the HP Prime is more expensive, but not by the absurd amount you claim.

author: tooki
author_rank: Super Contributor
timestamp: December 28, 2020, 05:40:33 pm
content: Quote from: DiTBho on December 27, 2020, 03:54:36 pmA-Z rather than QWERTY.Makes text entry annoyingly slow for anyone who knows how to type.Quote from: DiTBho on December 27, 2020, 03:54:36 pmLittle or no communication features, often specific calculations left out, etc. (That's why TI has so many nearly-identical models. For example, many have a "plus" and "pro" version that differ only in the "plus" version lacking a few functions that are banned at a particular school level.)

author: DiTBho
author_rank: Super Contributor
timestamp: December 28, 2020, 08:08:35 pm
content: Quote from: tooki on December 28, 2020, 05:25:03 pmThis is what ePrice lists for the calculator.I didn't check Amazon.

author: DiTBho
author_rank: Super Contributor
timestamp: December 28, 2020, 08:28:40 pm
content: Quote from: tooki on December 28, 2020, 05:25:03 pmCASIO is inferior for a lot of reasons, but the ENG display feature is something I have never seen in any TI and Sharp calculators that I have ever owned or tried. For instance I owned a TI89, liked it when I was a student for its CAS that helped me a lot studying math and physics, but for recent daily stuff I seriously love how my CASIO represents numbers when I need then in the ENG format.ENG means if you type 1.000.000, the calculator represents it as "1M"That's so beautiful when you deal with electronic stuff. Pico? Fempto? Nano? Milli? In a matrix of number to evaluate something? That's it, you have a comfortable menu with all the ENG-symbols, so you type them in ENG-format, the engine elaborates its stuff, and boom, you get the solution in vector form and displayed in ENG mode.Fantastic!Quote from: DiTBho on December 27, 2020, 10:23:57 amCalcuso sells protective-cases for calculators, according to themThe HP Prime v2 should be something like 14x86x182 mmThe CASIO FX9860GIII should be something like 19x84x176 mmUmm, not so bigger, as a matter of fact.

author: DiTBho
author_rank: Super Contributor
timestamp: December 28, 2020, 08:36:51 pm
content: Quote from: tooki on December 28, 2020, 05:40:33 pmyeah, then you want a keyboard like this

author: ttx450
author_rank: Regular Contributor
timestamp: December 28, 2020, 09:33:17 pm
content: did not read the whole thread. This is my graph cal.. Ti-92 it is older.Not sure what you are wanting to do, but maybe rooting one of these might work if you are trying to install your own OS. I rooted phones, not sure about this. This was expensive back in the day and have no reason to screw with it as it works fine. they might be cheap now.

author: tooki
author_rank: Super Contributor
timestamp: December 28, 2020, 09:46:09 pm
content: Quote from: DiTBho on December 28, 2020, 08:28:40 pmOK, I see. While I'd love to have that mode, "engineering notation" is generally understood to mean x.xxxxEn(i.e. x.xxx*10^n), with n being a multiple of 3.Quote from: DiTBho on December 28, 2020, 08:28:40 pmYou're right, the website I was looking at has the size of the Casio wrong. With that said, it's only a small difference in footprint, and the HP is 25% thinner, so extremely similar volume.

author: tooki
author_rank: Super Contributor
timestamp: December 28, 2020, 09:55:57 pm
content: Quote from: DiTBho on December 28, 2020, 08:36:51 pmIn a way, yes! (Though given TI's general lack of ambition in keypad design, I don't expect it'd be a particularly good keyboard… :/)Interestingly, it looks like modern TI calcs support USB keyboards!I'll have to dig out a USB OTG adapter and see if the HP supports one...

author: DiTBho
author_rank: Super Contributor
timestamp: December 29, 2020, 11:46:38 am
content: Quote from: tooki on December 28, 2020, 09:55:57 pmI happen to own one of these keyboard, found on eBay for 20 bucks shipped, practically a bargain you can't let go. It looks and "sounds" of the same quality as a cheap membrane keyboard. Nothing special, but not too bad.

author: ttx450
author_rank: Regular Contributor
timestamp: December 30, 2020, 12:37:26 am
content: Quote from: cgroen on November 27, 2020, 01:54:00 pmthere use to be a ton of online cal tools.. sure mnay more now.. very nice tools. my 92 is for fun and makes me feel smartthen again I am into old computers

author: DiTBho
author_rank: Super Contributor
timestamp: December 30, 2020, 10:48:15 am
content: Quote from: 3roomlab on December 29, 2020, 07:36:27 amis there any opensource like these?

author: technix
author_rank: Super Contributor
timestamp: January 13, 2021, 05:26:19 am
content: Quote from: ttx450 on December 28, 2020, 09:33:17 pmI have a similar unit - TI Voyage 200, which is basically the TI-89 Platinum to TI-92 and original TI-89. You can module upgrade it to a TI-92 Plus, which opens up a bunch of new features.