At 12:09 PM 16/10/96 G, you wrote: many versions of Auto bauding have been used over the years.. in all cases a sequence is required that is unique enough to identify the bit durations quickly and effectively. The old saga of the 1.5 bit stop can cause a problem. As has been point out 'U' is in ASC hex format 0x55 and alternating this with the code hex 0xAA all the bits change state so the software problem is not as great. ---------------------------------------------------------------------------- ---------- Tony Grimer ---- cm1918@scitsc.wlv.ac.uk (Tony D. Grimer) School of Computing (SCIT) Room MU406 Tel - 0902-321810. ---------------------------------------------------------------------------- ----------