Plan 9 from Bell Labs’s /usr/web/sources/contrib/steve/root/sys/lib/texmf/metafont/misc/mode2dpi.mf
% Usage: mf '\mode=what_ever_mode; \input mode2dpi' let myexit = primitive_end_; mode_setup; string dpi; dpi := decimal round pixels_per_inch; message "DPI = " & dpi; fontmaking := 0; myexit;