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Created page with 'The ''Endian''-ism of a processor refers to the order in which multi-byte values are stored in memory. == Little-Endian == Little-endian systems store the least-significant byt…'
The ''Endian''-ism of a processor refers to the order in which multi-byte values are stored in memory.
== Little-Endian ==
Little-endian systems store the least-significant byte of a multi-byte value at the lowest address.
For example, on 6502 systems (with a 8 bit/1 byte word size), the 16-bit value $FFEE stored at address $1000 would be stored like this:
$1000 $EE
$1001 $FF
Likewise, on an x86_64 system, the 64-bit value 0xFFEEDDCCBBAA9988 would be stored at memory location 0x1000 like this:
0x1000 0x88
0x1001 0x99
0x1002 0xAA
0x1003 0xBB
0x1004 0xCC
0x1005 0xDD
0x1006 0xEE
0x1007 0xFF
== Big-Endian ==
Big-endian systems store multi-byte values with the most significant byte at the lowest address.
For example, on a Motorola 68030 CPU, the value 0xFFEEDDCC would be written at memory location 0x1000 as:
0x1000 0xFF
0x1001 0xEE
0x1002 0xDD
0x1003 0xCC
== Bi-endian ==
Bi-endian CPUs can store data in either format (though sometimes not instructions). ARM [[Aarch32]] and [[Aarch64]] systems, PowerPC, Alpha, recent SPARC, MIPS, and Itanium systems are bi-endian.
== Other Memory Sequences ==
There are a few, rare architectures which store values in a sequence other than strict little-endian or big-endian format.
== Little-Endian ==
Little-endian systems store the least-significant byte of a multi-byte value at the lowest address.
For example, on 6502 systems (with a 8 bit/1 byte word size), the 16-bit value $FFEE stored at address $1000 would be stored like this:
$1000 $EE
$1001 $FF
Likewise, on an x86_64 system, the 64-bit value 0xFFEEDDCCBBAA9988 would be stored at memory location 0x1000 like this:
0x1000 0x88
0x1001 0x99
0x1002 0xAA
0x1003 0xBB
0x1004 0xCC
0x1005 0xDD
0x1006 0xEE
0x1007 0xFF
== Big-Endian ==
Big-endian systems store multi-byte values with the most significant byte at the lowest address.
For example, on a Motorola 68030 CPU, the value 0xFFEEDDCC would be written at memory location 0x1000 as:
0x1000 0xFF
0x1001 0xEE
0x1002 0xDD
0x1003 0xCC
== Bi-endian ==
Bi-endian CPUs can store data in either format (though sometimes not instructions). ARM [[Aarch32]] and [[Aarch64]] systems, PowerPC, Alpha, recent SPARC, MIPS, and Itanium systems are bi-endian.
== Other Memory Sequences ==
There are a few, rare architectures which store values in a sequence other than strict little-endian or big-endian format.