RPN, postfix, HP calculators, FORTH, etc. -- everybody know about it?

%!
moveto, lineto
  distances measured in "points", orientation on page
stroke, showpage
fill
rmoveto, rlineto
findfont, scalefont, setfont, show
rotate, translate, scale
practicalities: 1/4" margin on page, unreliability of exact location on page,
   the problem with large black regions
syntax: spaces and cr and tabs all have the same effect: separating commands
   and items to be put on the stack