LOL! My Calculator Crashed! - Page 1
Forum section: electronics / general

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 03:13:04 pm
content: CASIO Algebra FX2. Bought in 2005.Unbelievable, I took 15 years to crash it, and I don't actually know what I did, but yesterday it happenedSo, even a pocket calculator can crash.

author: BravoV
author_rank: Super Contributor
timestamp: December 31, 2020, 03:16:21 pm
content: Buy a lottery ... quick, before your luck running out of steam while in 2020 !!!

author: george.b
author_rank: Frequent Contributor
timestamp: December 31, 2020, 03:19:54 pm
content: Interesting - those calculators use a NEC V30 processor, says Wikipedia. 8088-compatible. Cool!

author: rsjsouza
author_rank: Super Contributor
timestamp: December 31, 2020, 03:42:20 pm
content: Quote from: george.b on December 31, 2020, 03:19:54 pmWow... That is cool indeed, although I wonder if battery life sucks. The NEC V30 was not famous for low power...

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: December 31, 2020, 04:01:30 pm
content: Wonder if it runs Doom.

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 04:03:03 pm
content: Quote from: rsjsouza on December 31, 2020, 03:42:20 pmI don't know which CPU is used in the old Algebra 2, but battery life is great! Batteries last up to three years with an average of daily 1 hour usage

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 04:04:06 pm
content: Quote from: Ed.Kloonk on December 31, 2020, 04:01:30 pmNo, it doesn't. It's not hackable, there is no SDK, and it only has 64Kbyte of ram

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 04:20:40 pm
content: Quote from: BravoV on December 31, 2020, 03:16:21 pmAfter you wrote that, I had a second tab on my Chrome browser, so I went to eBay, and got a message "you are the millionth user", blablabla, I didn't read the rest because it looked click-bait!Because? what?I don't believe in "luck", even if I did, what the day of today would represent? the D-day when I can crash a calculator, perhaps meet Marisha Ray in person and win the lottery or something? Do you want the truth? I clicked on "I am not interested in any premium as millionth user", and then eBay showed my I have to pay the final bill for the 2020.My last 212 euro for the 2020But hey? I am happy because I have recently already bought a new CASIO calculator, which will (hopefully) take years to show a crash.it also has uPython as new entry feature, and it's so polished and nice that it seems to wish "long life and prosper" to itself and to his owner

author: Twoflower
author_rank: Frequent Contributor
timestamp: December 31, 2020, 04:52:12 pm
content: Quote from: DiTBho on December 31, 2020, 04:04:06 pmThat doesn't stop people. At least on a TI-83 (32kB RAM) runs a reduced version of Doom:https://www.youtube.com/watch?v=nduMTX86Zl0Or evenpregnancy testscan run doom nowadays

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 31, 2020, 07:47:06 pm
content: Quote from: DiTBho on December 31, 2020, 04:04:06 pmAre you sure for the RAM? According to Wikipedia (and a couple other sources I found), it looks like the FX 2.0 had 146 KB of RAM. There is a 2.0 Plus model, but from what I gathered, the main differences are in the software and the hardware is essentially the same?

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 31, 2020, 07:51:25 pm
content: Quote from: rsjsouza on December 31, 2020, 03:42:20 pmThis actually had a V30MX.According to the manual, which you can find here:www.buchty.net/casio/files/v30-core.pdf, the V30MX had low power modes (standby and stop) which when properly used allowed much lower power consumption than the vanilla V30.

author: george.b
author_rank: Frequent Contributor
timestamp: December 31, 2020, 08:44:30 pm
content: Quote from: DiTBho on December 31, 2020, 04:04:06 pmWikipedia seems to suggest otherwise. It says the OS is sitting on a Mask ROM. I'd imagine it wouldn't be impossible to substitute it for an EEPROM and make it run something else.

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 09:34:41 pm
content: Quote from: SiliconWizard on December 31, 2020, 07:47:06 pmYesterday my calculator crashed and I had to force a an hard reset to resume. This flushed all the basic programs out of the storage area in RAM and restored the calculator to the factory conditions. There is a menu in the calculator, which lists resources, and, with zero programs and variables used, it explicitly reports 64Kbyte as usable free ram.But! It also tells about free space for programs, vars, lists, matrices, and screenshots.So I think the ~300Kbyte of ram refers to "physical amount" of ram, which is however partitioned in "ram to store Casio-Basic programs" and "ram usable by applications".

author: DiTBho
author_rank: Super Contributor
timestamp: December 31, 2020, 09:57:45 pm
content: Quote from: george.b on December 31, 2020, 08:44:30 pmAnd what did I say? "not hackable"Well umm ... let me think more about that .. years ago someone reported some partially successful attempts to overflow the return-address of some function on the stack by putting some crazy stuff on the input shell.What the dude typed looked like typed by a drunk, it made no sense, but it somehow exploited some bugs or vulnerabilities (does the firmware checks all the parameters? Probably no). This usually crashes the calculator, but potentially could also open doors to some nice hack.Who knows? Maybe we will see something someday on Youtube

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 31, 2020, 09:58:03 pm
content: Quote from: DiTBho on December 31, 2020, 09:34:41 pmOK, yes the total amount of RAM is likely partly used by the system to store built-in programs. Depending on the source, they mention 146 KB or 144 KB, not sure where you got the 300 KB figure from.https://www.rskey.org/fx2.0And from what I got, there would actually be a 256 KB RAM chip inside. And then 768 KB of Flash. Not sure how all of that is mapped in the address space.There is little documentation out there (I haven't found a documented teardown or schematic), but that would be fun to see. I'm not sure how much you are attached to it, but if you felt like it, a teardown would certainly be interesting to see.

author: tom66
author_rank: Super Contributor
timestamp: December 31, 2020, 10:05:11 pm
content: The original Casio FX-83GT (and related versions) had a firmware bug where if you nested too many fractions you would cause the calculator to draw garbage on the screen and corrupt the system memory. Skilled 'hackers' use these bugs to overwrite memory and enable features not shipped on the default variants.

author: mag_therm
author_rank: Frequent Contributor
timestamp: December 31, 2020, 10:37:53 pm
content: I have owned HP calculators for 37 years.I think I went through about 5 in that time and most were HP35scientific.and the reason is.....?Reverse Polish entry. I got used to it and can't stand the algebraic.

author: george.b
author_rank: Frequent Contributor
timestamp: December 31, 2020, 10:39:37 pm
content: Quote from: DiTBho on December 31, 2020, 09:57:45 pmYes, and I'm saying it might be

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 31, 2020, 11:55:03 pm
content: Opening it would help determining how hackable it is.If it uses conventional SMD parts and a 2-layer PCB, as I suspect, reverse-engineering it should be doable. And if the ROM itself is in an indentifiable package, one could probably read it, disassemble the content and from that try and figure out memory mapping, keyboard access, LCD... etc. I'd be curious to see the innards!

author: GlennSprigg
author_rank: Super Contributor
timestamp: January 02, 2021, 11:04:24 am
content: Use a Slide-Rule... No batteries required !!!