rex_vc1_read
rex_vc1_write(dc, rex_vc1_read(dc) & ~(VC1_SYSCTL_CURSOR |
rex_vc1_write(c,rex_vc1_read(c) & ~VC1_SYSCTL_VIDEO_ON);
rex_vc1_write(c, rex_vc1_read(c) | VC1_SYSCTL_VIDEO_ON);