Igorsk,
Well, I'd like to get a USB/or real serial interface hard/or not. ... so, following up on your idea(s)... (and assuming I'll be tackling this in 3 weeks...again.)
I don't have any access to check an actual sony for loaded modules, etc, so I can't answer even the simple which way is it *really* questions....
You mentioned a keyboard in the previous post; I see in the kernel for the 900 that the Freescale (ARM processor manufacturer) MXC keyboard port was modified for the ebook reader, strongly suggesting there is an active keyboard port. I can't check lsmod on the sony without control, so I don't know if it is module/compiled/active?
This isn't a USB keyboard .... do you know of how such a keyboard is connected?
On the memory:
The actual flash/nand rom is a single chip Samsung KLM2G1DEDD. That's a "moviNand/MCP NAND 2Gig nand1 kind, 1.65-1.95V, with a S3C49VDX02 controller" ... which I assume would make/emulate the MMC/SD interface;
no datasheet. But the chip itself is a dual in line ball grid array. Unfortunately, I don't have a steel mask to re-ball it with new solder, so although I can remove it -- I can't solder it back on; and buying a new one looks to be impossible...
So that leaves isolating an access point and extracting it that way, then decoding with linux software BUT....
I see in drivers/mtd/mtd_blkdevs.c that Sony modified all Linux mtd drivers for enhanced speed, then I noticed...
Sony fully wrote a driver/mtd/sbl , the abbr. "sbl" is unexplained, but it seems consistent with "serial block", eg: a serial access device like SD/MMC cards...? so, very similar to your idea of eMMC.
AND driver/mtd/sbl/mtdsbl.c links the sbl acronym to NAND/SBL memory which is the right kind of memory. The source code looks to be coding a proprietary format on the device, though I'm not sure. The Freescale MX31 processor has to have an interface already capable of booting the device, for it is the only rom -- or the ARM has to have an internal flash/mask rom to run a boot. sort of a LILO/GRUB type thing... last far stretch possibility --- otherwise --- there has to be another processor capable of loading RAM with Linux, and then resetting the ARM. hmmm... do you know which it is? or how to find out quickly?
There are driver mods in drivers/mtd/nand/nand_bbt.c, .../mtd/sdmparse.c, ../mtd/eMMC ../mtd/mtdpart which all muddy up
the issue.
Reading the nand memory isn't going to happen today, it's too complicated without a good clue ... but if there are any more suggestions on the software methods, I'll still try them before leaving tomorrow.
Ps: enlarge(able) photo below and note...
Sony mentioned discontinuing the 900, apparently they are changing the hardware...! so, this info is of limited value ... mostly good for people wishing to maintain and modify a defunct product... DMCA appropriate rvs. engineering. here's a good labeled photo of my board.
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