extflash - Flash interface via expansion port.

Copyright (c) 2003 Marcus R. Brown <mrbrown@0xd6.org>
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The PS2 50000 series BIOS introduced a new expansion (Dev9) device driver for
NAND (serial) flash and a method for booting off of this device - the "External
Flash ROM".  This flash is the same type as the 64Mbit flash found in the PS2
memory card.  As far as I know, these chips come from either Samsung or Toshiba
(datasheets can be found on their semiconductor websites).  Toshiba part numbers
are listed below.

	Part No.           Size
	TC48V64BFT         64Mbit (8MB)
	TC58128AFT         128Mbit (16MB)
	TC58256AFT         256Mbit (32MB)
	TC58512FT          512Mbit (64MB)
	TH58100FT          1024Mbit (128MB)

These devices are accessed via SmartMedia commands.

Apparently these devices are formatted using MCFS, the filesystem used on
normal PS2 memory cards. The OSD can boot from these devices the same way it
can boot from the HDD.

Why SCEI would include this driver within the 50k BIOS remains a mystery.  It's
possible that this is the "firmware update" inside the PSX.  I wrote the
extflash driver to get a better understanding of the hardware interface to
these devices.
