What does IOT mean in regards to SIGIOT?

Question

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.

Solution

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

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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

Comments

[G-Man Says 'Reinstate Monica']

Also mentioned (very briefly, and not explained) in PDP-11 instruction reference (6-page PDF)