FAQ

I have a calculator cfx 9850G, how can I call routines you found in ROM ?

You cannot use them directly, there is a very difficult process how to do it. You must open your calculator, remove the ROM chip and read the data (512 KB).Then change some parts of it and write it back to ROM chip. You must use new rewriteable memory (EEPROM,...) which you must put back in your calculator. I am solving the software part of this problem, the hardware part has successfully solved my friend, who is working on some manual how to do it. I will add a link here to his page after he finish it. He stopped cfx hacking.

I have a cable and a PC<->Casio interface with software, can I read the ROM data this way ?

It's NOT possible. There is no hardware problem, but the calculator has NO such sending routine.

Can I download somewhere on your page the ROM data to study / hack it / write an emulator?

No, I cannot public this binary file, because Casio Ltd. has it copyrighted. I asked Casio for an agreement and some additional informations about assembler, CPU type, etc. but I only got automatically generated answer that my questions was successfully received ...

I have read at http://<somewhere> that they are salling the cable for $xx, should I buy one, or is it too expensive ?

I cannot help you with this problem, I have home-made cable and interface with my own software, which is NOT compatible with another products.

Where can I get the table of tokens ?

Here. But first run the executable, in MS-DOS fullscreen, it installs casio font. Without installing this font some tokens are unreadable.

Can you send me the manual for the calculator xx, diary yy, computer zz or other hardware / software ??

I have no manuals from the producer(s). This page is for advanced users, who have read the manual and know more than it is written in it.

Can you send me the price list of the calculators??

I am not salling calculators. This is not official CASIO page. It's my own page, I am not working for CASIO.

Can you send me any software (games, etc.) for the calculator (c) fx ...

I am not writting games. See section download, here is a few of games I have written for debugging my emulator.

I found hardware specification of one processor, which is very similar to the CPU, that is in cfx 9850 G.

Please, send me this manual !!!

How to upgrade RAM to 512 KB ?

I don't know yet. I only think, it's possible, because the address bus for RAM and ROM is the same (some wires are unused for RAM), ROM is 512 KB large, so here must be 19 lines. Theoretically you can remove the old small RAM chip and insert the new one with the same hardware properties (speed, power, etc). The additional address pins connect to ROM address bus. But I didn't test it !! Here is probably 1MB big ROM in the cfx9850 G+ calculator, so you can upgrade your RAM to 1MB in this case. But do not think, that the whole RAM will be available to the original CASIO routines (for matrix, list, files storage). The calculator will see only 64 KB (no change if you had it before upgrading, but if you had only 32 KB before upgrading, it's possible, that the calculator will not find the new RAM (software problem )). The additional RAM is available as a RAM disk for the data of the conventional RAM or for your application written in assembler. I think RESET will NOT delete this additional memory.:-))

Is it possible to connect a hard disk to the calculator ?

I think yes. Here are many ways how to do it. You can make an external device, which you connect using standard 2.5 jack. No hardware change required in the calculator, but the device must have some processor, which communicate with the calculator. My friend developed this device, but he used no disk, but large RAM. Other way is to connect drive directly to the calculator. I think it should be memory mapped device, here is a lot of unused address area (segments), but I don't now anybody, who developed this :-(((((((((.

Why here are no links in your page ?

I didn't find any page about CASIO calculator hardware (CPU, etc.), assembler programming, hacking. There exist some pages about hacking, but they contain only an information about communication protocol (probably not complete) and where to buy or how to make CASIO <-> PC interface. Sometimes I find page with some way, how to hack a calculator, but in most cases it only crashes calculator or it makes something really unusable or what can be done using simplier way. All the rest of the pages is about how to turn the calculator on, where is the [F1] button, or why somebody cannot convert a fraction to decimal - problems of BFUs. I found one page, which has good hacking information, but I cannot do section linkS with only one link.

I think I stop update my pages or I delete them at all, because nobody helped me in finding assembler support, so my pages are only additional work with NO effect. I only got a lot of stupid questions such as "Where can I find command Cseg ?".

Will be later...

Are there any bugs in ROM you found while analysing?

Yes, there are many misspelling, but not only in strings and datas. I have found (in routine which scrolls text to display new line) a bug,. if it is used in file editor mode (1st line is nom scrolled). The code contain instruction to put new cound of lines to move (not 6 - whole screen, but only 5), but this number is stored in ANOTHER register, which is few bytes later rewriten. But the only result is that scrolling in fileeditor mode (that should be faster, becaouse fewer lines) is not faster. ROM also contain interesting code such as:

1234: jmp 1237
1237:
I think it is a result of badly optimizing compiler.