The VTC has an active-High
interrupt output port named irq. This output is set
High when an interrupt occurs and set Low when the interrupt event has been cleared. The
VTC also contains three 32-bit
registers for configuring and reporting status of interrupts: Interrupt Status/Clear,
Interrupt Enable, and the Interrupt Clear Registers. A logical AND is performed on the
Interrupt Enable Register and the Interrupt Status Register to set the interrupt output
High. The Interrupt Clear Register clears the Interrupt Status Register. Writing a
1 to a bit in the Interrupt Status Register clears
the corresponding interrupt when set. Writing a 1 to a
bit that is cleared, has no effect.