CL_CRT1B
vga_wcrt(regbase, CL_CRT1B, tmp);
tmp = vga_rcrt(cinfo->regbase, CL_CRT1B) & 0xf2;
vga_wcrt(cinfo->regbase, CL_CRT1B, tmp);
vga_wcrt(cinfo->regbase, CL_CRT1B, 0x02);