Author Topic: Casio Prizm documentation  (Read 166317 times)

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Offline jnesselr

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Re: Casio Prizm documentation
« Reply #525 on: April 16, 2011, 11:17:33 am »
So it's not RSA encrypted? That's good, as it means we could possibly change the OS, correct?

Offline JosJuice

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Re: Casio Prizm documentation
« Reply #526 on: April 16, 2011, 11:37:39 am »
So it's not RSA encrypted? That's good, as it means we could possibly change the OS, correct?
I don't think we can be sure yet... We know about one checksum that it has, but we don't know yet if it has more. If I recall correctly, Qwerty.55 (or was it z80man?) discovered that the OS sending program requires a valid MD5 hash.
« Last Edit: April 16, 2011, 11:38:01 am by JosJuice »

Offline fxdev

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Re: Casio Prizm documentation
« Reply #527 on: April 16, 2011, 01:23:55 pm »
Quote
I don't think we can be sure yet... We know about one checksum that it has, but we don't know yet if it has more.

Sure, but it's the same as seen in the diagnostics menu.
And 'ABS' seems to refer to the boot code checksum - so wherever you see 'ABS', then this means 'Simon only'. :D

Offline Munchor

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Re: Casio Prizm documentation
« Reply #528 on: April 17, 2011, 01:31:02 pm »
I was talking about this with alberthrock and would like to know if the SDK is ready for C with GCC Compiler and everything setup :D

Offline JosJuice

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Re: Casio Prizm documentation
« Reply #529 on: April 17, 2011, 01:45:02 pm »
I was talking about this with alberthrock and would like to know if the SDK is ready for C with GCC Compiler and everything setup :D
As far as I know: Everything isn't set up, but if you want to, you can gather the things that you need and put them together yourself.

Offline DJ Omnimaga

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Re: Casio Prizm documentation
« Reply #530 on: April 17, 2011, 08:47:13 pm »
I hope they didn't go the same way as TI and use a 1024 or even 2048 bit RSA private key...

At least we can still run ASM/C code easily, though.

Offline JonimusPrime

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Re: Casio Prizm documentation
« Reply #531 on: April 17, 2011, 10:03:04 pm »
I was able to build a correctly working GCC setup and was able to build something on windows no problem. I'll upload it to my web host asap The issue now is linking, the library that simon has packaged with his setup are not gcc friendly and I'll have to look into whether I can compile them sanely in a way that will work with GCC. I spent a few hours looking into it but the biggest hold up is that. We also need a g3awrapper program, but I though kristaba had one or at least a start on one.

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Offline z80man

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Re: Casio Prizm documentation
« Reply #532 on: April 18, 2011, 12:17:21 am »
I hope they didn't go the same way as TI and use a 1024 or even 2048 bit RSA private key...

At least we can still run ASM/C code easily, though.
Not really positive, but as a note the SH4 has a built-in hardware device that specializes in the fast calculation of RSA keys. It doesn't mean that Casio used an RSA key, but they could easily if they wanted to :P

List of stuff I need to do before September:
1. Finish the Emulator of the Casio Prizm (in active development)
2. Finish the the SH3 asm IDE/assembler/linker program (in active development)
3. Create a partial Java virtual machine  for the Prizm (not started)
4. Create Axe for the Prizm with an Axe legacy mode (in planning phase)
5. Develop a large set of C and asm libraries for the Prizm (some progress)
6. Create an emulator of the 83+ for the Prizm (not started)
7. Create a well polished game that showcases the ability of the Casio Prizm (not started)

Offline z80man

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Re: Casio Prizm documentation
« Reply #533 on: April 20, 2011, 01:30:07 am »
I've been trying to find a purpose for the SYNCO instruction that Casio used in the DirectDraw routine and I found something interesting. Now I haven't had enough time to fully disassemble the routine to find the true purpose, but what I found is that SYNCO is good for self modifying code. Reason being is the separate instruction and data caches meaning that if you modify some code that is close to the PC, the changes may not result when the instruction is executed. What SYNCO will do though is ensure that the pipeline is reorganized ensuring that the changes will take place. Now it does seem strange for Casio to use something as advanced as self-modifying code, but they just might of for this routine.

List of stuff I need to do before September:
1. Finish the Emulator of the Casio Prizm (in active development)
2. Finish the the SH3 asm IDE/assembler/linker program (in active development)
3. Create a partial Java virtual machine  for the Prizm (not started)
4. Create Axe for the Prizm with an Axe legacy mode (in planning phase)
5. Develop a large set of C and asm libraries for the Prizm (some progress)
6. Create an emulator of the 83+ for the Prizm (not started)
7. Create a well polished game that showcases the ability of the Casio Prizm (not started)

Offline DJ Omnimaga

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Re: Casio Prizm documentation
« Reply #534 on: April 21, 2011, 12:12:22 am »
Uhm I feel bad about your previous post. I seriously hope they won't eventually add a RSA key or something too...

Offline JosJuice

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Re: Casio Prizm documentation
« Reply #535 on: April 21, 2011, 04:51:16 am »
Since the prizmosdecomp.exe attachment in Goplat's post seems to be dead, here's a reupload...

Offline fxdev

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Re: Casio Prizm documentation
« Reply #536 on: April 21, 2011, 10:53:58 am »
Ah, thanks. I did not know there is such a program! :D
However, the OS image includes the fx-CG 20 boot code (which is not written) - I would be interested in the fx-CG 10 version.

So if you own an fx-CG 10, please do the following:
- start insight
- start the memory viewer
- go to offset 0x80000000
- press [F3]
- type 0x00020000 as file size
- upload the file memory.bkp somewhere

Offline SimonLothar

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Re: Casio Prizm documentation
« Reply #537 on: April 21, 2011, 11:04:58 am »
The differences between a fxCG10 and a fxCG20 (first 7 MB) are (apart from the calc-ID and the checksum)

fx-CG10: 0x303[1] : 0x41
fx-CG10: 0x305[1] : 0x5A

fx-CG20: 0x303[1] : 0x44
fx-CG20: 0x305[1] : 0xAA

Or have a look at "fx_calculators_SuperH_based.chm".
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Offline fxdev

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Re: Casio Prizm documentation
« Reply #538 on: April 21, 2011, 11:12:06 am »
And how is the .gp3 difference handled?
Btw, the time stamp must be different, too! ;)
« Last Edit: April 21, 2011, 11:16:55 am by cfxm »

Offline SimonLothar

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Re: Casio Prizm documentation
« Reply #539 on: April 21, 2011, 11:29:05 am »
And how is the .gp3 difference handled?
I'd say: calc-type dependent branches inside of the OS. The same procedure as every year...

Btw, the time stamp must be different, too! ;)
Yes, it is.
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