A number of 70s computing systems had nine-bit bytes, most prominently the PDP-10, but today11 Apparently, it was the System/360 that really set the standard here. all systems use 8-bit bytes and that now seems natural.22 Though you still see RFCs use "octet", and the C standard has a CHAR_BITS macro, to handle the possibility of a different-sized byte. As a power of two, eight is definitely nicer. But I think a series of historical coincidences would actually go our way with 9-bit bytes. IPv4: ...