[plt-scheme] integer->byte?

Hello all:

Part of the old code I'm updating depended on passing around lists of
char data.  What I was really doing was sending out lists of bytes and
receiving other lists of bytes from a variety of serial devices.  (I had
been using strings, but found that manipulating lists of bytes was less
ambiguous in important cases, and I didn't have to keep track of lengths
and terminating characters.)

I see all the byte string manipulation things, and those look ok to me.
But what I really want is to be able to manipulate a list of 8-bit
values, to send to and receive from a serial device.  For example, how
do I turn the literal value #x7f into an eight-bit value?  There is no
integer->byte command.

To be more specific, I used to have this:

  (define header (list (integer->char #x7e)))
  (define middle (list (integer->char #x05)
                       (integer->char #x47)))
  (define footer (list (integer->char #xff)))

But I can't see how to write this in the brave new byte world.  Can
anyone suggest how something like this should read?

The (list->byte) function doesn't really do what I want, since it
creates something comparable to a string and not something list-like. 

Many thanks (again),

 -tom

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