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A routine whose job is to set everything in
the computer -- registers, memory, flags, everything -- to zero,
including that portion of memory where it is running; its last act
is to stomp on its own "store zero" instruction. Death code
isn't very useful, but writing it is an interesting hacking
challenge on architectures where the instruction set makes it
possible, such as the PDP-8 (it has also been done on the DG Nova).
Perhaps the ultimate death code is on the TI 990 series, where all
registers are actually in RAM, and the instruction "store
immediate 0" has the opcode "0". The PC will immediately wrap
around core as many times as it can until a user hits HALT. Any
empty memory location is death code. Worse, the manufacturer
recommended use of this instruction in startup code (which would be
in ROM and therefore survive).
