NMI (INT 02h - Non-maskable interrupt)

        Generated by NMI signal in hardware. This signal has various uses:

        Parity error                    : all except Jr and CONV
        Coprocessor interrupt           : all except Jr and CONV
        Keyboard interrupt              : Jr, CONV
        I/O channel check               : CONV, PS50+
        Disk-controller power-on request: CONV
        System suspend                  : CONV
        Real-time clock                 : CONV
        System watch-dog timer,
        time-out interrupt              : PS50+
        DMA timer time-out interrupt    : PS50+