Peer Network Using Graphing Calculators

These calculators are networked together, able to pass information and play games on a multi-screen playing field. All of this is thanks to [Christopher Mitchell’s] work on a package called CalcNet. This networking software takes advantage of [Christopher’s] shell and GUI for TI calculators called Doors CS. To demonstrate the high reliability and throughput of his network he wrote NetPong, a multi-calculator version of the popular game that you can watch in a clip after the break.

This is definitely an instance where asking ‘why?’ is the wrong question. We’re more interested in the how, a question you can answer for yourself by reading the whitepapers he provided in both of the links above. [Christopher] knows what he’s doing, he proved that with his face-recognizing augmented reality.


41 thoughts on “Peer Network Using Graphing Calculators

  1. i think its about time to make a new line of calculators. like a netbook crammed into a calculator. removable storage, wifi, color screen, maybe even a slide out keyboard, crammed into what appears to be a ti-84+ silver edition. that’s the last one i had, and it tempted me to learn BASIC, but idk where it is anymore, so i can’t really practice my BASIC anymore. back then, it was the best calculator that you could legally use on tests

  2. if it has a QWERTY keyboard, disqualified. or i would have gotten the TI-92. back then was Æons ago for me. i’ve been through like 20 cell phones since then, and back then, paid unbelievable prices for high capacity flash drives (1 or 2 gb for over $100, don’t really remember) that are long-gone, broke and lost before a year was up, have all my java programming work on them, and i could buy a 64gb flash drive for the same price today.

  3. @pRtkL xLr8r: Because it’s fun writing programs and making gadgets that have cutting-edge, useful applications, and it’s also fun trying to use my EE degrees to cram a robust networking stack into a few kilobytes of z80 assembly code. :) I think the answer to “why” is more or less “to show that I can.”

    @jeditalian: Texas Instruments has been pushing their TI-Nspire, but it is universally loathed by the TI calculator programming scene as being absolutely useless. It has almost no inbuilt programming capabilities, and although it has much more powerful hardware than any of their previous calculators, including a 200MHz ARM CPU instead of a 6MHz or 15MHZ z80, the only way to run homemade assembly/C programs is to essentially “jailbreak” it, which TI keeps patching and prevent in subsequent firmware revisions.

    @Bob: I’m sure it’s been done decades ago, but monochrome and 96×64?

    @Eirinn: I beg to differ, if you don’t mind; I wish I had the free time to be bored.

    @Mike: Thanks for featuring my project!

  4. Awesome! This network of calculators has almost as much processing power as a $150 iPod Nano! And it only cost 9 times as much!


    But I’ve done useless things before too, this is cool. :)

  5. Years ago I wrote a Chat/Msg program using Ti-Basic… paired with an extra long link cable I was communicating with my buddy during tests. Helped, and was a lot of fun (blew some peoples minds) but this is way, way cooler. Nowadays I guess its kind of useless but it still strikes me as completely awesome. Time to go read more in depth…

  6. Hrm, there were alternate OSes for HP’s 48-series calculators back in the mid-to-late ’90s. Heck, there’s a TCP/IP stack that runs on the circa-1992 HP 48 just fine, along with a web server! (Obviously, it connects via PPP since serial is the only interface.)

  7. @Kaboof: For non-cheating purposes, I’ve played around with wireless implementations, but nothing finalized yet.

    @CharonPDX: Someone once made a Telnet client for the TI-83, but it required a modem to be connected via a null modem cable, so it didn’t really do any serious communication processing on the calculator itself.

    @Nemo: ah, thanks, much appreciated. As you can tell by the version number, CALCnet2.2 is the culmination of the better part of a decade of having insufficient networking or z80 ASM knowledge to complete the project. :)

    @cpmike: And the teacher didn’t notice the link cable?

    @ScoutDavid: I highly disapprove of that usage of CALCnet.

  8. @cpmike

    On the final test for some math class, a friend asked if he could borrow my spare graphing calculator and I said sure. After the test, I checked the history and came to the conclusion that messages were typed and then calculators were swapped, much lower tech.

    I’ve been kicking around the idea of designing, building a wireless link and try to jam it inside the calculator so it looks like (aside from the calculators with translucent cases) perfectly normal. I smell an open source + group project :P . I suppose that could lead to a couple things: electronic warefare (snooping, jamming, counter-EW, etc.) and banning of personal graphing calculators for some tests. But think of all the fun MP games everyone could play during math class :P .

  9. @cornelius785
    I was just thinking wireless dongle. But an internal setup would be great although i dont know how much internal space there is to use. (great hacker i know i havent even taken my calculator apart yet :S) A dongle would be a good start for sure though. Maybe a small zigbee or 802.11 (add wifi to the calculator)

  10. @seanfalloy: Unfortunately, the processing power required by a WiFi module is prohibitive on current calculator models excluding the Nspire. Zigbee is an option, but it would be better to simply come up with a good way to encode the two-channel bidirectional wiring on some kind of standard RF link.

  11. @cornelius785: just math class? back in school i was on my calculator in EVERY class. that was even before i knew how to text… i sound much older than i actually am :P

    @seanfalloy: it’s been a while since i cracked open my 86 (i can’t even find it now…) but i think things are fairly packed, though not by today’s standards. if you swapped out the batteries for a flat lithium polymer battery or something, there might be room for a little board there…

    @Christopher Mitchell: i’m kindof sad that technology rushed through IR communication (or maybe i just missed it). i feel like there’s a novelty to pointing two devices together for a slow, tenuous short-range connection. with that in mind, could one just breakout the existing IO port with an LED and phototransitor? that sounds like it must have been done before

  12. @ConcernedEE: during class she didn’t care about it, but during said test she found it eventually and wore it around her neck for the rest of the session. as a joke, I pulled out my spare cable ;)

    @cornelius785: always dreamed of a wireless version! back then that was a little out of my reach… I feel like it would be MUCH easier today, though its a shame that I rarely use it anymore, considering how much time I had spent programming that thing.

    a little UART Bluetooth module may be small enough to squeeze in there, and throwing some SPP back and forth shouldnt be too hard.

  13. For wireless wouldn’t a lowpower transmitter be better suited? Like the one used in the article form a couple of days ago.
    The downside is you’ll have to add a µC to convert the data from the calculator to something the ic understands. But the µC wouldn’t have to be that big, any with SPI will do

  14. @cpmike UART BT Module was what came first to my mind too (well.. there is one lying on my desk so it was also the nearest to my mind..) and as the TIs aren’t “tiny” or “small” I could imagine there is a spare place to put one in :D

  15. We actually build a wireless transceiver module for the Voyage 200 , one of TIs m68k based calculators. Never got around to finish the calculator part for it, but the hardware is working and the module firmware is complete, too. And it fits completely in the case of the calculator! We put a SD card on the module, too so you can extend the memory of your calculator to 4Gb. Have a look at it at Everything is open source.

  16. I remember when I was in high school ten years ago Texas Instruments had networking hubs in our calculus class… one per table, and each hub cascaded into a computer at the front of the class, or another calculator. You could either control all of the calculators from the master calculator, or push apps, or whatever you want. I still remember writing client/server apps on that network.

  17. i don’t mean to be obtuse here, but..

    what’s the deal with all of the ti-83 / 84 / old bs love?

    you spent some serious time with that platform. why not ti-89 instead? much better screen res at the very least.

    is the 83 firmware/os less restrictive or something?

    or is it just that you’ve been toying with the 83 you’ve had forever and ever, and you don’t care to abandon your experience with it in favor of something else?

    idk, i use my 89-titanium all the time. i find doing work on the 83/84 to be painful. even if you’re not doing much with its CAS, the enhanced screen resolution and vastly superior interface [scrolling around through command history, pretty type and formatting, etc] to be a night-and-day difference. i was a little disappointed when i read that it’s for the 83 platform ;[

    the nspire sounds cool, but from what i’ve been able to gather, the software sucks. the 89 is currently more functional if you’re looking for, you know, a good calculator / portable CAS tool. i’m also a little surprised that the ti-89 and hp50g, which seem to be the leaders in this product category, are only this good. they could be better. all of this college board / SAT / ACT certification stuff irks me, too. i guess that’s what a lot of the things i’m bitching about stem from. in the end, they seem to be intended for kids. the fact that these things come pre-loaded with SAT study card / US presidents quiz / stupid bs like that illustrates this. they’re classroom tools. anyone know of a big boy calculator? there are a lot of little [and big] things that could be fixed or added, but it seems like improvements and new features are not necessary for the target consumers. sure, there’s mathematica / matlab / whatever, but it’s nice to have something with very high durability, battery life, and portability. i guess i’m not a very big market segment. ;[

  18. Why go with BT?
    Maxim makes really impressive system on a chip modules that require minimal amounts of power. Add a QFN micro to do the communication and you could fit the entire thing into the calculator and power it off the batteries without any adverse effect.. Or make a little plugin module.

  19. How about using a small cheap wireless module and arduino + the calc to group-cheat-chat in scool :P

    NoClue has joined the channel.
    Cheater has joinned the channel.

    NoClue: Do you know the solution of number six? LOL

    Cheater: I think it’s a number, ROFL!
    NoClue: A number? U sure? I mean, in a math test? L-O-L
    Cheater: XD
    NoClue: EggsDee

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