Hey all-
I have been trying to figure out if write-protecting CF or PCMCIA flash
memory when mated to a CF/PCMCIA-to-IDE converter is possible and I have
found some interesting stuff, but I am not technically proficient enough
to decode it... So perhaps someone out there on the list could help me
with this?
This is from http://copper.he.net/~whiteedc/pdf/ATA10.pdf and it
describes the function of the "write protect" pin (33) for PCMCIA ATA
flash:
Write Protect, 16 bit I/O port: In memory mode, WP i s hel d low:
always writable). In I/O mode , IOIS16# is asserted low when Task
File Registers are accessed in 16 bit mode. In True IDE mOde this
signal i s asserted low when this device i s expecting a word data
transfer
cy cle.
From my understanding, the last mode, True IDE, is what we would want
to use for our LEAF boxes as it allows the card to look and act like an
IDE drive. So what I would like to know is if pin 33 is held high (and I
have a very weak idea of what that means) and the card is in True IDE
mode, what exactly will that do? i.e. what the heck is a word data
transfer cycle and what happens if we block it? I am thinking that if
pulling this pin high we can disable writes, then a modification can be
done to the CF/PCMCIA-2-IDE adapters to enable/disable writes via a
switch mounted on the front of the LEAF box.
Or another possibility is to use these cards in mode 1, memory mode,
which seems to fully support write-protect. But I don't know if there is
kernel/bootloader support for this mode of flash.
This company does make PCMCIA flash cards with *hardware* write protect
switches on them, but I haven't been able to get a hold of them to find
out who they resell these through.
http://copper.he.net/~whiteedc/pcmcia/pcmcia_flash.php (look under
Features section).
Would anyone else be interested in these flash cards with write-protect
switches on them? Or am I barking up the wrong tree here?
Searching for a boot medium greater than the sum of two floppies ;)
Zack
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