TBD_SIZE
tbdaddr = ether1_txalloc (dev, TBD_SIZE);
ether1_writebuffer (dev, &tbd, tbdaddr, TBD_SIZE);
tst = ether1_txalloc (dev, TX_SIZE + TBD_SIZE + NOP_SIZE + ETH_FRAME_LEN);
tst = ether1_txalloc (dev, TX_SIZE + TBD_SIZE + NOP_SIZE + ETH_FRAME_LEN);