I'm about to get a Casio Prizm FX-CG50 because I'm required to get a graphing calculator for calculus. This will be my first graphing calculator, and I have a few questions about it that I couldn't find easy answers to:

1. [s]How's the battery life on Alkaline batteries? Casio claims 140 hours, but the backlit screen makes me skeptical of that claim. 4 AAA batteries only store about 6 watt-hours of energy. If the battery life is bad, I'll get Ni-MH batteries.[/s]
I've heard that the battery life is good.
2. [s]If I install Ni-MH batteries, can I charge them by plugging the calculator into a 5V source, or will I need a separate charger?[/s]
I'll need a separate charger.
3. [s]If I plug it into a 5V source, will the calculator run off of that instead of the batteries, even if it doesn't charge them?[/s]
It will run off of the USB instead of the batteries, but the OS isn't smart enough to know that and will shut down thinking that it's out of power if I completely remove them.
4. Can I extend the battery life on Alkaline by setting the calculator to think I'm using Ni-MH? I've seen digital cameras that would only drain Alkalines to 1.2V but would drain Ni-MH batteries to 1V.
5. [s]Is it possible to completely disable the backlight?[/s]
The OS doesn't seem to support that and lowering the brightness to 1/250 (darker than allowed by default) using add-ins makes the screen hard to read, so it will likely be worse with it off.
6. If this calculator is overclockable, how much does overclocking impact the battery life?
I know it will, but I don't know by how much.
7. [s]Is it practical to mod the calculator to use LiPo batteries?[/s]
It's possible, but not really practical.

1. [s]Is https://www.cemetech.net/programs/prizm/ and this site in general where I go to get software for my calculator?[/s]
2. [s]Can I run software meant for the CG10/CG20 on a CG50?[/s]
Usually, but some software may be unstable or have weird-looking icons.
3. Can I run GNU/Linux on a CG50?
[s]Probably, but it likely won't be useable and nobody has put in the effort to do it.[/s]
4. Is it possible to brick the CG50 by messing with the OS too much, or does it have USB recovery in ROM?
I've heard that CG10/20s are brickable, but I'm not sure if Casio fixed that.
5. [s]Is it possible to install a CAS system on the calculator? I don't need CAS and I intentionally chose a calculator that doesn't come with it because it's banned on the ACT, but it may be fun to play with.[/s]
6. Am I required to use exam mode when taking AP tests or the SAT?

1. [s]https://www.cemetech.net/tools/prizm has some specifications listed, but they are for the CG10/CG20. Are they accurate for the CG50 too? If not, is there another page for the CG50? If there isn't, I'd like to at least know the CPU, clock speed, screen resolution, and the amounts of RAM and Flash.[/s]
Similar instruction set, faster CPU (118 MHz) 8 MB of RAM (64KB user accessible) and 32 MB of Flash (16 MB user-accessible filesystem), same resolution (396 by 224, 384 by 216 easily usable)
2. [s]There appears to be a serial port on the top that the manual said uses an SB-62 cable. I looked up that cable, and it looks like a normal 3.5mm audio cable. Can I use a normal 3.5mm cable? If not, what is preventing me from doing so?[/s]
It's a normal passive 2.5mm (not 3.5mm) cable, except with the "audio" channels crossed over so tx goes to rx and rx goes to tx.
Partial reply to the Software section:
1. Cemetech is one of the places to get programs for the fx-CG50 / Graph 90+E (French name), indeed. Plančte-Casio (French) probably has others.
2. I remember about quite a number of Prizm programs needing a bit of adjustment to work on the fx-CG50.
3. Nope.
4. I'll defer to the actual Prizm users Smile
5. Yes, Bernard Parisse's KhiCAS brings a subset of the power of giac to the fx-CG50. He had to cut down the functionality significantly in some areas to make the code fit in the 2 MB size limit for fx-CG50 applications, but it works. There's a topic on this board, others on e.g. TI-Planet.
Thanks for the information. Is there a technical reason why this calculator cannot run GNU/Linux, or is it simply because nobody has bothered to port it?
I'm not qualified about the fx-CG10/20/50 beyond general hardware specs, so maybe there's another technical reason I don't know... but well, even at such high level, 8 MB of RAM and 32 MB of Flash are on the really low end for running Linux + useful user-space Smile
Also, (very ?) few distros support the SH ISA. Buildroot does, though.
Yeah, that makes sense. I'm assuming that you *could* get it to run, but you'd probably have to reverse engineer the bootloader and some of the hardware interfaces as well. I'll edit my post to make it clear what I discovered on my own/found out on other forums since asking.
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