Was there ever a UNIX or even the thought of porting one to a PDP-10? 36-bit machine, 18-bit addresses (more on KL10 and KS10), and: *0 would return register 0 instead of a SIGSEGV ;) 8-bit bytes would have been a wasteful exercise, but you never know. (losing 4 bits of every 36-bit word) thanks! art k.