<Teletype, so I'm pretty sure the Elf code is correct. I'm using 110 <bits per second, no parity, 8 data bits, one low (logic 0) start bit, <and one high (logic 1) stop bit. It seems to like the data TWO stop bits, tty did two. 8n2 <characters; I get consistent hex values for each character I send to the <Elf, but they seem to usually be either shifted left or right by one <bit, or they have the high bit set when it shouldn't be. It feels like It may be the one stop bit missing or there are too many transistions going on die to contact bounce (dirty commutator and poor signal conditioning on the other end). TTy reading 8 level tape is a continious stream of start, lsb...msb,stop stop and repeat. the COSMAC in this case is just sitting there playing catch. If the timing loop is off on the RX end you get garbage. Allison