added details about .tyerr

book.tex

@@ -4009,19 +4009,20 @@ environment.
 \end{figure}
 
 \begin{exercise}\normalfont
-Complete the implementation of \code{type-check-R2} and test it on 10
-new example programs in $R_2$ that you choose based on how thoroughly
-they test the type checking function. Half of the example programs
-should have a type error to make sure that your type checker properly
-rejects them. The other half of the example programs should not have
-type errors. Your testing should check that the result of the type
-checker agrees with the value returned by the interpreter, that is, if
-the type checker returns \key{Integer}, then the interpreter should
-return an integer. Likewise, if the type checker returns
-\key{Boolean}, then the interpreter should return \code{\#t} or
-\code{\#f}. Note that if your type checker does not signal an error
-for a program, then interpreting that program should not encounter an
-error.  If it does, there is something wrong with your type checker.
+Complete the implementation of \code{type-check}.  Test your type
+checker using \code{interp-tests} and \code{compiler-tests} by passing
+the \code{type-check} function as the second argument.  Create 10 new
+example programs in $R_2$ that you choose based on how thoroughly they
+test you type checking function. Half of the example programs should
+have a type error to make sure that your type checker properly rejects
+them. For those programs, to signal that a type error is expected,
+create an empty file with the same base name but with file extension
+\code{.tyerr}. For example, if the test \code{r2\_14.rkt} is expected
+to error, then create an empty file named \code{r2\_14.tyerr}.  The
+other half of the example programs should not have type errors. Note
+that if your type checker does not signal an error for a program, then
+interpreting that program should not encounter an error.  If it does,
+there is something wrong with your type checker.
 \end{exercise}
 
 
@@ -4178,10 +4179,11 @@ on whether the comparison came out according to the condition code
 \itm{cc} (\key{e} for equal, \key{l} for less, \key{le} for
 less-or-equal, \key{g} for greater, \key{ge} for greater-or-equal).
 The \key{set} instruction has an annoying quirk in that its
-destination argument must be single byte register, such as \code{al},
-which is part of the \code{rax} register.  Thankfully, the
-\key{movzbq} instruction can then be used to move from a single byte
-register to a normal 64-bit register.
+destination argument must be single byte register, such as \code{al}
+(L for lower bits) or \code{ah} (H for higher bits), which are part of
+the \code{rax} register.  Thankfully, the \key{movzbq} instruction can
+then be used to move from a single byte register to a normal 64-bit
+register.
 
 The x86 instruction for conditional jump are relevant to the
 compilation of \key{if} expressions.  The \key{JmpIf} instruction