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fx-9750GA Plus ROM dumping?

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#1 TeamFX


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Posted 03 January 2017 - 01:45 PM

Anyone interested in dumping the fx-9750GA Plus ROM? (https://edu.casio.co...raphic/9750gap/)

French model name: GRAPH 35+ ("GRAPHIQUE") [white color] (http://casio.ledudu....type=308&lg=eng)
If it has USB ("GRAPHIQUE USB"), then this is an fx-9750GII. (http://casio.ledudu....ype=2735&lg=eng)
If it has green color, then this is an fx-9750G Plus. (http://casio.ledudu....type=236&lg=eng)

This model was manufactured in 2008 and is the last one with a classic CFX-9850-like firmware and hardware.
You can still get some on Ebay (disable Firefox tracking protection): http://www.geo-ship...._sellerType=All
Here is a short history of Casio calculators: http://www.spiderpix...ml/history.html
You would probably need this device programmer: http://www.mcumall.c...?idProduct=4282
And this TSOP adapter: http://www.mcumall.c...?idProduct=3102
The S29AL004D90TFI02 ROM appears to be supported: http://www.mcumall.c...msupportICs.asp
I also stumbled upon this: https://github.com/m...es/cpu/hcd62121
"The Hitachi hcd62121 is the custom cpu which was used in the Casio CFX-9850 (and maybe some other things too)."

IDA Pro 6.8 has support for:
- Hitachi HD63701/03 [6301]
- Hitachi HD63703/01 [6303]
- Hitachi HD64180 [64180]
- plus some other Hitachi or NEC processors
So it should be possible to disassemble that ROM data.
Contact: teamfx.casio@gmail.com


I took a photo of the fx-9750GA Plus hardware (type GY360).
The processor seems to be the same as on the CFX-9850GC Plus (type GY357).
The LCD interface seems to be a Toshiba T6K73 as on the fx-9860G. (http://pdf.datasheet...oshiba/1952.pdf)
The 512k ROM is a Spansion S29AL004D90TFI02 (http://www.cypress.c...216696/download)
The 32k RAM is a Cypress CY62256vnll-70SNXI (http://www.cypress.c.../43846/download)
RAM connectivity supports narrow SOIC (U103) and SOP (U104) chips.
The contact P101 invokes the test mode (a b/c + F6 + AC/on).

For the first time, Casio did not use a one-time programmable ROM!
Yet, the PCB pinout does not allow for write access...

Conclusion: You can still do some RAM backup hacking but no more.

GQ-4X Willem programmer with TSOP adapter:

Edited by TeamFX, 05 January 2017 - 02:48 PM.

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