Ok, can confirm j1b on P-DUO lives. But I couldn't figure out how to get DTR right on Windows w/ Putty, so in the end I uploaded the bit stream to flash, and reconnected to a Raspberry Pi. This link describes how to set it up to recognise the FTDI adapter for serial port use: http://www.element14.com/community/docs/DOC-76657/l/installing-and-running-xxicc-rev-00p Looks like each empty DO LOOP iteration takes 100 ns. Nice! -jcw Edit: it was not 10, but 100 nS. Still pretty good!