Expects: AH    25H
          AL    interrupt number
          DS:DX interrupt vector: address of code to handle an interrupt
          ------------------------------------------------------------------
 Returns: none
          ------------------------------------------------------------------
    Info: Sets the interrupt vector table entry for interrupt number AL to
          DS:DX.

          Same as storing a 4-byte address into 0000:(AL*4), but lets DOS
          know what you're doing, and ensures that no hardware interrupt
          occurs while the vector change is taking place.