VGA_GC_MISCELLANEOUS
reg[5] = vga_get_grc(VGA_REG_BASE, VGA_GC_MISCELLANEOUS);
vga_set_grc(VGA_REG_BASE, VGA_GC_MISCELLANEOUS, 0x00);
vga_set_grc(VGA_REG_BASE, VGA_GC_MISCELLANEOUS, (reg[5] & 0x03) | 0x0c);
REG_WRITE1(sc, VGA_GC_ADDRESS, VGA_GC_MISCELLANEOUS);