General > General Technical Chat
LOL! My Calculator Crashed!
SiliconWizard:
--- Quote from: rsjsouza on December 31, 2020, 03:42:20 pm ---
--- Quote from: george.b on December 31, 2020, 03:19:54 pm ---Interesting - those calculators use a NEC V30 processor, says Wikipedia. 8088-compatible. Cool!
--- End quote ---
Wow... That is cool indeed, although I wonder if battery life sucks. The NEC V30 was not famous for low power... ::)
--- End quote ---
This 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.
george.b:
--- Quote from: DiTBho on December 31, 2020, 04:04:06 pm ---
--- Quote from: Ed.Kloonk on December 31, 2020, 04:01:30 pm ---Wonder if it runs Doom.
--- End quote ---
No, it doesn't. It's not hackable, there is no SDK, and it only has 64Kbyte of ram :D
--- End quote ---
Wikipedia 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.
DiTBho:
--- Quote from: SiliconWizard on December 31, 2020, 07:47:06 pm ---Are 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?
--- End quote ---
Yesterday 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".
DiTBho:
--- Quote from: george.b on December 31, 2020, 08:44:30 pm ---
--- Quote from: DiTBho on December 31, 2020, 04:04:06 pm ---
--- Quote from: Ed.Kloonk on December 31, 2020, 04:01:30 pm ---Wonder if it runs Doom.
--- End quote ---
No, it doesn't. It's not hackable, there is no SDK, and it only has 64Kbyte of ram :D
--- End quote ---
Wikipedia 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.
--- End quote ---
And what did I say? "not hackable" :D
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 :D
SiliconWizard:
--- Quote from: DiTBho on December 31, 2020, 09:34:41 pm ---
--- Quote from: SiliconWizard on December 31, 2020, 07:47:06 pm ---Are 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?
--- End quote ---
Yesterday 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".
--- End quote ---
OK, 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/fx2.0
And 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.
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