modding IDE cable to write-protect compact flash?

hi all:

I am involved in a mini-project that is to build a solid state computer (mini-ITX based) that will feature read-only medium. we have chosen compact flash for its relatively cheap cost and larger compacity. and due to the phyiscal limitations of the setup, we cannot use the popular USB-flash sticks that come with a write-protect switch, we have to stick with a CompactFlash-to-IDE converter.

it would be really nice if we could somehow protect the data on the Compact Flash on a physical layer. we have thought about mounting the Compact Flash read-only, but that doesn't protect the data on the Compact Flash to be modified if someone gained super-user access to this machine.

i am wondering if it is feasible to short a few pins in the standard IDE cable, so that the write signal does not get passed onto the Compact Flash card. has anyone attempted similar solutions? i would really appreciate any pointers and suggestions.

Thanks in advance.

Reply to
Joshua Kuo
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A similar idea is on our drawing board. One of our client wants to be able to control both reading and writing to the CF. Our solution is to gate the addresses and read/write enable lines with a CPLD sequencer. Unfortunately, the added board space (more than 2.5" x

1.5") makes it unattractive for other clients. For now, this version is going to this one client only, as part of the agreement as well.

Most of them can't boot from USB, period.

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IDE-CF Compact Flash Drive

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Reply to
Sales for IDE-CF flash drive

indeed, we have a certain space to play with, and unfortunatly, someone in the group has already gone as far as getting a bunch of custom cases made, and because he has already spent all that money and time into it, we didn't want to throw those cases away. and due to the design and space of these custom cases, it's impossible for us to go with anything USB based... the CF card slot will be in the front of the case, looking muhc more like a floppy drive.

Reply to
Joshua Kuo

Back to the orginal issue, the USB CF write protection is implemented on the USB controller chip. You need some simple logic to map the data port and read/write signals, a simple CPLD would do it. We might end up with another small board with two IDE connectors and a mach211 (just because we have a whole bunch of them).

Reply to
Sales for IDE-CF flash drive

Ah! Now I see. You *want* a larger solution. Yes, CompactFlash will provide that.

BTW, at the Dayton Computerfest today I noticed an adapter that went from a USB header to four or six kinds of flash memory card slots mounted in a floppy disk-sized enclosure. It was only $10, but I couldn't come up with enough motivation to get it (while carrying out loads of rack-mount stuff).

--kyler

Reply to
Kyler Laird

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