rdm2@nvuxr.UUCP (R McBurnett) (09/05/85)
The EMT instruction on a PDP-11 computer is an emulate trap instruction
intended to emulate a real hardware interrupt. At a guess it's original
purpose was to let software types tryout new software before the hardware was
ready. THEN someone had a good idea about how to use it ?intelligently? in
an operating system.. Both RSX11-M and RT11 used it extensively.
BTW the TRAP instruction works the same way as EMT but to a different vector,
and is useful for user programs that want to test hardware interrupts.
Roe McBurnett {ihnp4!packard,topaz}!nvuxr!rdm2
Bell Communications Research, Red Bank NJ