death code

A routine whose job is to set everything in the computer -

registers, memory, flags - 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 or the Data General 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

program counter 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).

[Jargon File]