I've found out the reason for the non-printing printf's. The code in prf.c only actually outputs to the console if the contents of the switch register are non-zero... the code in question is the function putchar() in /usr/sys/ken/prf.c Still can't get the second DL11 going though ;) -- ---------------------------------------------------------------------------- Robert Manners Osney Laboratory rjm(a)swift.eng.ox.ac.uk Dept of Engineering Science University of Oxford 01865 288762 Try: http://swift.eng.ox.ac.uk Linux - the only choice "There's more to life than books you know, but not much more" ----------------------------------------------------------------------------