So it's possible to write less than an entire page to flash? I recently got told via private email that I couldn't.

You can only erase whole pages. After that you can set bits (change 0s to 1s) by writing individual bytes. The only way to clear a bit (change 1 to 0) is by erasing and rewriting the entire page. The flash-persist erases the page the first time, then writes 128-byte lumps the next 63 times until it has to erase and start again. You can't change four bytes of flash without erasing and rewriting the page, unless by coincidence (or design!) your changes involve only changing 0 bits to 1.

Peter


PS. A voice in the back of my head is saying I've got the 1s and 0s the wrong way round. But you get the idea.