CF cards on classic machines (was Re: Another disk imaging project)

On 8/4/05, Tony Duell <ard at p850ug1.demon.co.uk> wrote: In this vein, I'm fiddling with CF cards on a variety of machines (C-64 w/IDE-64, SBC-6120 w/IOB-6120 and with external CF interface, Elf 2000 w/ElfDisk board...) and am running into what might be compatibility issues with older CF cards. I've found a variety of web resources googling around, but does anyone have any information about when there might have been a sea change in CF features between the days of 4MB cards and "modern" 512MB cards? Specifically, I have a stack of HP 4MB CF cards that work with many devices. Those and some 8MB and 16MB cards (Kodak, SanDisk, etc, not brandless ones), don't seem to work reliably in some of my devices (IDENT failing, as one example) but in the same device, my Elf2K for example, the 1GB card came right up with the expected manufacturer string. So was there some change starting with, say, 32MB or 128MB cards, about timing or some other issue that might affect something as simple as reading the device registers from the embedded controller? In case it matters, AFAIK, the problems I'm having are only with using a CF card in a strictly 8-bit mode (something that CF cards do that "real" IDE drives do not). I'm not thinking this is something subtle - I'm thinking that someone might remember some warning somewhere about "oh, yeah... don't use 16MB cards in _that_ device... you have to use 32MB or newer". Any and all impressions accepted. I'm not the creator of any of these devices, so I have to kinda nibble around the problem from the edges before I try any sort of attempts at a fix. Of course, a pointer to a white paper on how to talk to CF cards in 8-bit mode would be most welcome. :-) Thanks, -ethan