\voffset -0.25in
\magnification =1440
\catcode`\@=11
\def\tracingall{\tracingonline\@ne\tracingcommands\tw@\tracingstats\tw@
  \tracingpages\@ne\tracingoutput\@ne\tracinglostchars\@ne
  \tracingmacros\tw@\tracingparagraphs\@ne\tracingrestores\@ne
  \showboxbreadth\maxdimen\showboxdepth\maxdimen\errorstopmode}
\def\tracingnone{\tracingonline=\z@\tracingcommands\z@\tracingstats\z@
  \tracingpages\z@\tracingoutput\z@\tracinglostchars\z@
  \tracingmacros\z@\tracingparagraphs\z@\tracingrestores\z@
  \showboxbreadth3\showboxdepth5\errorstopmode}
\catcode`\@=12
%
\def\boxit#1{\vbox{\hrule\hbox{\vrule\hskip3pt\vbox{\vskip3pt#1\vskip3pt}
\hskip 3pt\vrule}\hrule}}         % Note the scrunched format
\def\Blash{\tt\char'134}
\uchyph=0					       % Note this for below.
						       % What's wrong?
\font\bigrm = amr10 scaled \magstep 2 
\centerline{\bigrm Assignment 12a}\bigskip
The following is designed to provide some exercise in
thinking about the use of modes, a hyphenation problem, overfull
boxes which can be made to go away, and an indication of a use
of a specific penalty.  Thus it is designed to follow the 
review lecture you have just heard.


     What you may want to do
is to put {\tt\Blash tracingcommands=1} at some point in your file,
and to read, in the {\tt .lst} file, what \TeX\ thought it was doing
thereafter.  If you add {\tt\Blash tracingmacros=1}, then you can see
the expansions of the macros as they were processed, which is also
often informative.
%\tracingall
\bigskip
\hbox{Now this is in restricted horizontal mode.  Do you see why this might
be?}
\par But %\tracingnone
this is in horizontal mode proper.

\leavevmode \boxit{{And}} so is this in spite of the thing beginning the
line, which clearly must be a box and was not preceded by {\tt \Blash indent},
\indent and this is too(see p. 286).
\par\vskip 25pt
What would be nice is a little bit of math, say Euler's formula:
$$ e↑{i\pi}+1=0$$
which suggests the remarkable fact that $\sqrt{-1}$ is $e↑{i\pi/2}$.
Another well-known formula is the inequality which is sometimes called the ``Cauchy-Bunyakowski\u\i-Schwarz'' inequality, namely
\def\norm#1{\|#1\|}$$
|\langle A|B\rangle| \leq {\norm A}↑{1\over2}{\norm B}↑{1\over2}
$$.
It was rather unlucky that so many had to get in on the act, wasn't it,
for it led to a bad break.  And that period is wrongly placed.  Also
something is amiss here with this short list of mathematical variables 
$A, B \hbox{and }C$.
\medskip Now\par
\hbox{V}\hbox{M}\hbox{O}\hbox{D}\hbox{E}
Those last letters were dropped on the page in vertical mode.  Can you
think why that might be?



\bye