<which was the first UNIX port to a non-DEC machine? I seem to recall bot <UNIX and C were spawned around 1968 or so, but the first UNIX micro By 1978 it had been ported to Interdata 8/32, Honeywell 6000 and IBM System/370. This information was obtained from the preface of "The C programming language" Kernighan and Ritchie. There is no question in my mind that Unix (and flavors) is the most widely ported(to different platforms) OS of them all. CPM is likely a close second as most widely implemented on platforms with similar CPU but often radically different IO. The reason I added this is like unix, CPM ran on 8080 (z80, z180, z280, NSC800), 8086 (8088, 80186...) and 68000. UCSD Pascal P-system is the only other that was ported to non similar CPUs like 8080/z80, PDP-11, 6502 (Apple][), wd microengine. Allison