On Tue, 12 Feb 2013 01:47:06 +0100, you wrote: What did you plan to run? Is DECnet even possible if you run TOPS-20? I seem to remember MRC mumbling at one time about him having hacked that, but I'm not sure if it ever became officially supported or distributed. Tops-10 might work with DECnet, but then I also wonder over which interface, and if it do Phase IV...? Both TOPS-10 and TOPS-20 have DECnet Phase IV in newer releases, but, if I'm not wrong, Ethernet support at large is a KL10 thing only, so the only KS10 option for DECnet would be DDCMP, but it should anyway run Phase IV (as long as there is enough memory, so maybe better stick to end node only). There is a problem with software: if I'm not wrong (again!), TOPS-20 on KS10 is limited to V4.1 (due to memory contraints?), instead I think that the same CPU would run TOPS-10 up to the final V7.x releases. Note that probably (?) TOPS-20 V4.1 had only Phase III, so Phase IV on 2020 seems to be available only with TOPS-10 and DDCMP. HTH, :) G.