Yes, I should have been more specific. The CF card is what I prefer, since the SD's 4-channel (high-speed) mode requires quite a bit of external hardware (CRC generator, etc.) if you want speed. The CF's are just as fast, but with much less hardware (Just the MCU, and whatever else you will need for your task anyway).

There are, in fact, removable modules that use CF to emulate IDE drives, but you can't easily plug those into a PC. Unfortunately, the USB host task carries with it so much overhead, I'd be discouraged if I had to use it, at least for a simple data logging task that had to be read by a PC.

If the requirement is for a file system, well, it's available, but I'd hope one could get by without it. It's tempting to use a FAT file system, since PC's can trivially read 'em at the PC. Unless the task requires multiple files, there's really no need.

A simple utility to read from and write to the CF or SD would probably work out OK. In that case the same code could be ported to the PC with a shell to deal with Windows, and the rest is easy.

RE