I looked the example of the work with at250x0 and has not understood one thing. Why when sensing from memory in she is written 0xff? This program possible to find on request SPI here. Here is this fragment: while (length--) { SPDR = 0xFF; while ((SPSR & 0x80) == 0); *buf++ = SPDR; } About this in documentation on at250x0 is not written. This is some particularity?