Running the PLUMBING GRAPHICS Subsystem under Microsoft Windows(tm) and Friends Try this: Install mred for Windows. Get the whole directory ~cslab/CS257/plt/collects/plumber/ and put it in the analogous place on your machine. (Be careful not to squish the filenames.) Invoke mred, then manually (load "plumbing-1.0.scm"), probably using (load "c:\\plt\\collects\\plumber\\plumbing-1.0.scm"), then plain (straight 100) should not get an error, but probably won't display anything in the graphic window. Go (display-graphic-object (straight 100)) and see if that works. If so (define d display-graphic-object) and then wrap all your manual interactions as in (d (tree 9)) and you should be okay. Some day we may find someone whose loathing for windows is weak enough and motivation strong enough to allow them solve the problem on that platform. --BAP. PS You'll want to get Emacs for Windows too, even though you cannot run Scheme with plumbing graphics under its control. PPS Yes, thanks, I now know that Microsoft Windows has no friends.