\setuppapersize     [A5][A4]
\setuplayout        [location=middle,marking=on] 
\setuppagenumbering [alternative=doublesided]
\setupbodyfont      [lbr,6pt]
\setupheadertexts   [alfa][beta]

\setuplayout        [headspace=1cm,lines=56,header=1cm,footer=0cm,
                     backspace=1cm,width=middle,grid=yes]

\showframe \showgrid

\starttext 
  \startcolumns[n=3]
  \dorecurse{10}{\input tufte \par \input knuth \par} 
  \stopcolumns
\stoptext
