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| IM (Interrupt Mode) || 2-bit || Specifies the interrupt mode (0, 1, or 2) || Controls how interrupts are handled:
* IM 0: External devices provide interrupt vectors.* IM 1: Fixed vector at 0038h.* IM 2: Vector provided by I register and external data.
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| I (Interrupt Vector) || 8-bit || Holds base address for interrupt mode 2 || Combined with external data to form an interrupt vector