modding IDE cable to write-protect compact flash?

Question

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 chosencompact flash for its relatively cheap cost and larger compacity. and dueto the phyiscal limitations of the setup, we cannot use the popularUSB-flash sticks that come with a write-protect switch, we have to stickwith a CompactFlash-to-IDE converter.it would be really nice if we could somehow protect the data on theCompact Flash on a physical layer. we have thought about mounting theCompact Flash read-only, but that doesn't protect the data on the CompactFlash 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 IDEcable, so that the write signal does not get passed onto the Compact Flashcard. has anyone attempted similar solutions? i would really appreciateany pointers and suggestions.Thanks in advance.

Sales for IDE-CF flash drive · Accepted Answer

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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Joshua Kuo · Answer

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.

Sales for IDE-CF flash drive · Answer

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).

Kyler Laird · Answer

Ah!  Now I see.  You *want* a larger solution.  Yes, CompactFlash willprovide that.BTW, at the Dayton Computerfest today I noticed an adapter that went froma USB header to four or six kinds of flash memory card slots mounted in afloppy disk-sized enclosure.  It was only $10, but I couldn't come up withenough motivation to get it (while carrying out loads of rack-mount stuff).--kyler

modding IDE cable to write-protect compact flash?

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