SNDRV_GF1_GB_MEMORY_CONTROL
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01);
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, rom ? 0x03 : 0x01);
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01);
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01 | (invert ? 0x08 : 0x00));
snd_gf1_i_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01);
snd_gf1_i_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01);
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x01); /* DRAM I/O cycles selected */
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x03); /* select ROM */
snd_gf1_write8(gus, SNDRV_GF1_GB_MEMORY_CONTROL, 0x00); /* select RAM */