DOSMAGIC
if (*(uint16_t *)&mboot.bootinst[DOSMAGICOFF] != DOSMAGIC) {
mbr->mbr_sig = htole16(DOSMAGIC);
if (mbr->mbr_sig != htole16(DOSMAGIC)) {
mbr->mbr_sig = htole16(DOSMAGIC);
mk2(img + MINBPS - 2, DOSMAGIC);
mk2(img + MINBPS - 2, DOSMAGIC);
if (cv2(buf + DOSMAGICOFF) != DOSMAGIC)