VGA_CRTC_V_DISP_END
wreg_crt(cirrus, VGA_CRTC_V_DISP_END, vdispend & 0xff);
outb_p(VGA_CRTC_V_DISP_END, vga_video_port_reg);
vga_wcrt(regbase, VGA_CRTC_V_DISP_END, vdispend & 0xff);
par->crtc[VGA_CRTC_V_DISP_END] = yres-1;
write3X4(par, VGA_CRTC_V_DISP_END, vdispend & 0xFF);
par->crtc[VGA_CRTC_V_DISP_END] = pos & 0xFF;