Interrupt Priority

The interrupt priority feature is enabled by setting the IPEN bit. When interrupt priority is enabled the GIE/GIEH and PEIE/GIEL Global Interrupt Enable bits of Compatibility mode are replaced by the GIEH high priority, and GIEL low priority, global interrupt enables. When the IPEN bit is set, the GIEH bit enables all interrupts which have their associated bit in the IPRx register set. When the GIEH bit is cleared, then all interrupt sources including those selected as low priority in the IPRx register are disabled.

When both GIEH and GIEL bits are set, all interrupts selected as low priority sources are enabled.

A high priority interrupt will vector immediately to address 00 0008h and a low priority interrupt will vector to address 00 0018h.