mode_setup;
def row(expr x) =
 cc:=(x-1)div 8; rr:=7-((x-1)mod 8);
 if rr=7: beginchar(cc,width/pt,8/pt,0); fi enddef;
def cols(text t) =
 for n:=t: addto currentpicture also unitpixel shifted (n,rr); endfor
 if rr=0: endchar; fi enddef;