Текст заголовка сообщения полностью: Как ни странно, написано верно. Учим матчасть (цитата из даташита на M48/88/168) - Some of the Status Flags are cleared by writing a logical one to them. Note that, unlike most other AVRs, the CBI and SBI instructions will only operate on the specified bit, and can therefore be used on registers containing such Status Flags. The CBI and SBI instructions work with registers 0x00 to 0x1F only.