Hexspeak, like leetspeak, is a novelty form of variant English spelling using the hexadecimal numbers. Created by programmers who wanted a magic number, hexspeak words can serve as a clear and unique identifier with which to mark memory or data.
Using hexadecimal notation, which includes the digits 0123456789ABCDEF, it is possible to spell several words.
Notable magic numbers
Many computer processors, operating systems, and debuggers make use of magic numbers, especially as a magic debug value.
0x8BADF00D ("ate bad food") is used by Apple in iOS crash reports, when an application takes too long to launch, terminate, or respond to system events.
0x1BADB002 ("1 bad boot") Multiboot header magic number.
0xB16B00B5 ("big boobs") was required by Microsoft's Hyper-V hypervisor to be used by Linux guests as their "guest signature".[4] This offending code was later changed to 0x0DEFACED ("defaced").
0xBAADF00D ("bad food") is used by Microsoft's LocalAlloc(LMEM_FIXED) to indicate uninitialised allocated heap memory when the debug heap is used.
0xBADDCAFE ("bad cafe") is used by Libumem to indicate uninitialized memory area
0xCAFEBABE ("cafe babe") is used by Mach-O to identify Universal object files, and by the Java programming language to identify Java bytecode class files.
0xCAFED00D ("Cafe Dude") is used by Java as a magic number for their pack200 compression.
0xD15EA5E ("disease") is a flag that indicates regular boot on the Nintendo GameCube and Wii consoles.
0xDEADBABE ("Dead Babe") is used by IBM Jikes RVM as a sanity check of the stack of the primary thread
0xDEADBEEF ("dead beef") is frequently used to indicate a software crash or deadlock in embedded systems. DEADBEEF was originally used to mark newly allocated areas of memory that had not yet been initialized -- when scanning a memory dump, it is easy to see the DEADBEEF.
It is used by IBM RS/6000 systems, Mac OS on 32-bit PowerPC processors and the Commodore Amiga as a magic debug value. On Sun Microsystems' Solaris, it marks freed kernel memory. On OpenVMS running on Alpha processors, DEAD_BEEF can be seen by pressing CTRL-T. The DEC Alpha SRM console has a background process that traps memory errors, identified by PS as "BeefEater waiting on 0xdeadbeef".
0xDEADC0DE ("dead code") is used as a marker in OpenWRT firmware to signify the beginning of the to-be created jffs2 filesystem at the end of the static firmware.
0xDEADDEAD ("dead dead") is the bug check (STOP) code displayed when invoking a Blue Screen of Death either by telling the kernel via the attached debugger, or by using a special keystroke combination. This is usually seen by driver developers, as it is used to get a memory dump on Windows NT based systems. An alternative to 0xDEADDEAD is the bug check code 0x000000E2, as they are both called MANUALLY_INITIATED_CRASH as seen on the Microsoft Developer Network.
0xDEADFA11 ("dead fall") is used by Apple in iOS crash reports, when the user force quits an application.
0xDEAD10CC ("dead lock") is used by Apple in iOS crash reports, when application holds on to a system resource while running in the background.
0xDEFEC8ED ("defecated") is the magic number for OpenSolaris core dumps.
0xFACEFEED ("face feed") is used by Alpha servers running Windows NT. The Alpha Hardware Abstraction Layer (HAL) generates this error when it encounters a hardware failure.
0xFEE1DEAD ("feel dead") is used as a magic number in the Linux reboot system call.
0xE011CFD0 is used as magic number for Microsoft Office files. In little endian this reads D0CF11E0, "docfile0".
0x0000000FF1CE ("office") is used as the last part of product codes (guid) for Microsoft Office components (visible in registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall registry key).
0x00BAB10C ("oo-ba-block") is used as the magic number for the ZFS uberblock.
C15C:0D06:F00D ("cisco dog food") used in the IPv6 address of
http://www.cisco.com on World IPv6 Day. "Dog food" refers to Cisco eating its own dog food with IPv6.
face:b00c ("facebook") used in the IPv6 address of
http://www.v6.facebook.com
0xDEADD00D ("dead dude") is used by Android in the Dalvik virtual machine to indicate a VM abort.
0xCEFAEDFE ("face feed") is used by Apple in iOS as a header for binary files. In little endian this reads FACEFEED, "Face Feed".