INT 8 THRU 0F - VECTORED HARDWARE LINES
   In IBM, these 8 interrupts are generated in response to IRQ 0 through
   IRQ 7 (if enabled via port 21h).
                                         [Tandy 1000]
        IRQ0  -  timer interrupt
        IRQ1  -  keyboard interrupt
        IRQ2  -  EGA vertical retrace    [fixed disk]
        IRQ3  -  serial port 2 (com2:)
        IRQ4  -  serial port 1 (com1:)
        IRQ5  -  fixed disk              [60 Hz ram refresh]
                 (LPT2 on PC/AT)
        IRQ6  -  diskette interrupt
        IRQ7  -  PPI interrupt (lpt1:, lpt2:)
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