public void handler(int offset, int data) {
            if (offset == 0 || offset == 0x700) {
                if ((cpuB_latch & SNK_NMI_PENDING) != 0) {
                    cpu_cause_interrupt(1, Z80_NMI_INT);
                    cpuB_latch = 0;
                } else {
                    cpuB_latch |= SNK_NMI_ENABLE;
                }
                return;
            }
            io_ram.write(offset, data);
        }