CHAPTER 7
INTERRUPT LATCH ADDRESS

The interrupt vector is used to detect which of the four channels is creating the interrupt. A global interrupt (bit 7 of interrupt vector) is used to enable or disable all four channels by writing a logic 1 to enable, or 0 to disable the interrupt. After enable global interrupt (by software or hardware), each channel must be enabled or disabled separately by programming the OUT1 (0 for enable) signal in the 16450 chip. After the interrupt is enabled, you may read bit 0 to detect whether channel 1 is creating an interrupt or not? To read bit 1 to detect whether channel 2 is creating an interrupt or not? ...etc. When a data bit of the interrupt vector is set to 0, the corresponding channel is creating an interrupt. When the bit is set to 1, there is no interrupt.