I've been looking around and I found that it was related to an abort call, Something to do with an IOT trap, but any resource I find seems to assume you already know what that is. Probably isn't important, but I saw it and was curious. I suppose it could even just be arbitrary letters.

1 Answer 1


What does IOT mean in regards to SIGIOT?

It stands for input/output trap.

Macro: int SIGABRT

This signal indicates an error detected by the program itself and reported by calling abort. See Aborting a Program.

Macro: int SIGIOT

Generated by the PDP-11 “iot” instruction. On most machines, this is just another name for SIGABRT.

Source Program Error Signals

PDP-11 Jump and subroutine instructions

Jump and subroutine instructions

  • JMP (jump)
  • JSR (jump to subroutine)
  • RTS (return from subroutine)
  • MARK (support of stack clean-up at return)
  • EMT (emulator trap)
  • TRAP, BPT (breakpoint trap)
  • IOT (input/output trap)
  • RTI & RTT (return from interrupt)

Source PDP-11 architecture


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