MC_BASE_32_KHz
mc146818_write(sc, MC_REGA, MC_BASE_32_KHz | MC_RATE_1024_Hz);
mc146818_write(NULL, MC_REGA, MC_BASE_32_KHz | MC_RATE_128_Hz);
MC_BASE_32_KHz | MC_RATE_128_Hz);
MC_BASE_32_KHz | MC_RATE_1024_Hz);
mc146818_write(NULL, MC_REGA, MC_BASE_32_KHz | MC_RATE_128_Hz);
MC_BASE_32_KHz | MC_RATE_128_Hz);
MC_BASE_32_KHz | MC_RATE_1024_Hz);
mc146818_write(sc, MC_REGA, MC_BASE_32_KHz | MC_RATE_NONE);