Throughout the rest of this discussion, assume the standard eight bit byte applies unless specifically stated otherwise. A nibble is half a byte, or four bits. A word is the default data size for a processor. The default size does not apply in all cases. The most common word sizes are 16 and 32, but words have ranged from 16 to 60 bits.
Some processors require that data be aligned .
Some processors allow data to be unaligned, but this usually results in a slow down in performance. Endian is the ordering of bytes in multibyte scalar data. The term comes from Jonathan Swift's Gulliver's Travels. While processors handle endian issues invisibly when making multibyte memory accesses, knowledge of endian is vital when directly manipulating individual bytes of multibyte scalar data and when moving data across hardware platforms. Examples of big endian processors are the IBM System 360 and 370, Motorola 680x0, Motorola 68300, and most RISC processors.