Thanks ripsaw8080: The settings above work as you suggest. The preplot program runs very fast (core=dynamic, cycles=max ) with no perceptible difference from windows xp dos. The tecplot with core=auto, cycles=auto works acceptably fast albeit slower than windows xp dos. I have not yet investigated …

Yes, it works by e.g. SET DOS16M=:50M, memsize=50 and provided I set also ems=true and xms=true (not =false). This is again excellent news and thank you very much. I suppose the main remaining issue is the speed. The "preplot" program still takes ages to complete. Since there are so many variables …

Great news , thanks to ripsaw8080: The tecplot program loads the *.plt file successfully, with the settings suggested. Also it works with ems=true and xms=true. It also works with memsize=64 provided always the command SET DOS16M=:16M is executed (e.g. in the autoexec.bat). This is all nice, …