INT 0aH: IRQ 2 Cascade / Invalid Task State

  On ATs, INT 0aH is a hardware-generated interrupt (IRQ 2) forced by any
  occurrence of IRQ 7 through IRQ 15.  These are cascaded into the secondary
  interrupt controller.

  The actual handler for IRQ 2 is IRQ 9, handled by INT 71H.  Normally, no
  device uses IRQ 2, but an EGA or VGA may be programmed to use it to
  interrupt at the start of vertical retrace (see EGA I/O Ports).

Ř›CPU Exception InterruptřŘ
  286+ computer execute INT 0aH when the CPU is in protected mode and it
  detects an Invalid Task Segment State during a JMP, CALL, IRET, or INT

See Also: IRQs: Hardware Interrupts
          FDC I/O Ports
          BIOS Data Area
          ROM-BIOS Functions
          DOS Functions