Introduction

0xDECAFBAD is a hex oddity-- a coincidence of hexadecimal digits which just happens to hold some incidental semantic content to weird humans.

Chronicle yours here.

0xABADCAFE

• JanneJalkanen: Amiga Mungwall initialized all free memory at startup to this value to catch errant pointers.

0xBAADF00D

• Ole Eichhorn: "A colleague tells me Windows 2000 uses 0xBAADF00D for uninitialized memory"

0xBADCAB1E

• Blake Winton: "If you're debugging a PocketPC? program, and the debugger loses the connection to the device, you will get back an error code of 0xBADCAB1E"

0xBEEFCACE

• Used by Microsoft .NET as magic number in resource files System.Resources.ResourceManager.MagicNumber

0xCAFEBABE

• Why CAFEBABE?: "The Java class file's magic number"
• Doug Landauer: "I worked for Sun from about 1986 until 1995, mostly on debuggers and then C++ compilers..."
• Steve Zellers: "0xcafebabe is also the constant value at the start of mach-o files."

0xC0CAC01A 0xADD511FE

• Steve Zellers: "OK, my final say: 0xC0CAC01A 0xADD511FE"
• The Brunching Shuttlecocks rate Coke slogans

0xC0DEDBAD

• JanneJalkanen: Amiga Mungwall (a memory leak tracking tool) would change the MMU tables so that all references to address zero return this.

0xDEADBEEF

• Why CAFEBABE?: "Old IBM machines used 0xDEADBEEF to "initialize" uninitialized memory."
• Andrew Duncan: "0xDEADBEEF was used, IIRC, for null pointers in PowerPlant?, Metrowerks' app framework for Mac."
• JanneJalkanen: 0xDEADBEEF was also used by Amiga Mungwall to "mung" freed memory.

0xDEADF00D

• JanneJalkanen: Again, Amiga Mungwall used this to "mung" all newly allocated memory that was not explicitly cleared.

0xDE:AD:BE:EF:CA:FE

• Wes Felter: "Some home-brewed Ethernet addresses I've seen: 0xFE:ED:BA:BE:F0:0D (describing Calista Flockhart?) 0xDE:AD:BE:EF:CA:FE (time for a steak?) 0xDE:AD:CA:FE:BA:BE (must be a Java-hater)."

0xDE:AD:CA:FE:BA:BE

• Wes Felter: "Some home-brewed Ethernet addresses I've seen: 0xFE:ED:BA:BE:F0:0D (describing Calista Flockhart?) 0xDE:AD:BE:EF:CA:FE (time for a steak?) 0xDE:AD:CA:FE:BA:BE (must be a Java-hater)."

0xDEAC

• JerryKindall: The Apple II's ProDOS? operating system kept a table of device drivers for the various block devices attached to a computer. 0xDEAC (or $DEAC as we wrote it in those days) was the address pointed to if there was no block device installed in a particular slot. 0xDEAC happens to be one byte less than 0xDEAD, so obviously the intent was to use 0xDEAD -- but a re-assembly of the OS at some point probably shifted the address by one byte.

0xDECAFBAD

• LesOrchard: "Caffeine uber alles."

0xFADEDEAD

• Jon Pugh: "Every OSA script ends with 0xFADEDEAD."

0xFE:ED:BA:BE:F0:0D

• Wes Felter: "Some home-brewed Ethernet addresses I've seen: 0xFE:ED:BA:BE:F0:0D (describing Calista Flockhart?) 0xDE:AD:BE:EF:CA:FE (time for a steak?) 0xDE:AD:CA:FE:BA:BE (must be a Java-hater)."

0x00FEEDFACECOFFEE

• Seen used on a MUD by Luminesc.