\newcount\y \newcount\x \newcount\i \newcount\j
\def\alphabetshow{\y=`a \i=1
\vbox{\offinterlineskip%
\loop\ifnum\i<27
\x=\y \j=1
\hbox{\loop\ifnum\j<27
\ifnum\x>122 \advance\x by-26 \fi%
\hbox to.55em{\hss\char\x\hss}\advance\x by1 \advance\j by1%
\repeat\hss}
\advance\y by1 \advance\i by1
\repeat
}
}