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Data Size & Arrangements

Data Organization and Endianism

• Numbering the bytes of a memory array

  • Bytes in memory are numbered from 0(first word) to 2n - 1(last word).

• Bit numbering can vary between processors.

  • Microprocessors (ARM, Intel) number the bits of a word from the least-significant bit (lsb) which is bit 0, to the most-significant bit (msb) which is bit m - 1, in the same way.

  • Some microprocessors (PowerPC) reverse this scheme.

• Byte numbering

  • Little endian - The least significant byte (LSB) is stored at the lowest (little-end) address.

  • Big endian - The least significant byte (LSB) is stored at the highest (big-end) address.