The MAPCHR program translates text files into a form suitable for
transmission over normal dial-up lines using DIAL for example. If MAPCHR
is not used, funny characters such as αβελπ∀∃~∂ and so forth get
translated to not-so-funny characters such as ↑B↑C↑F↑H↑G↑T↑U↑Z↑O (where ↑
means CONTROL).  As an example, ↑C will kill most programs at the
receiving computer used to read text over the phone.  Similarly, ↑Z will
exit the MAIL program if you are trying to get things across that way.
Other losses include conversion of tab's to four spaces, the loss of page
marks, and the insertion of carriage returns (by the system) for long
lines.  MAPCHR gets around all these nuisances by converting all funny
characters to regular ASCII in a way that can be inverted, and lines
are broken up to reasonable size in a way which inverts.

After the "sanitized" output from MAPCHR is sent to the other site over
the telephone, you must run MAPCHR there also. Currently (29-JUL-82),
the only other place MAPCHR exists is CCRMA. (And when we get DIALNET
it won't be ANYWHERE else!) Thus to use MAPCHR, you need to install
a version on the other side. 

To run it, type R MAPCHR <RETURN>.  If you are converting to a file to be
sent over the phone, then you want to type Y after the prompt "Encode?".
Otherwise, for decoding a file back into regular (local) format, type N or
just <RETURN> to this prompt.  Next you will be asked for input and output
filenames, and you are on your way.

A handy feature of MAPCHR is the insertion of a check-sum character at the
beginning of every line in the remote-format file.  When the file is
decoded at the "other end", you are told if there are any errors, and a
list of page/line numbers pointing to all detected errors is printed.
Finally, if there were any errors, by typing CONTINUE after MAPCHR is
finished, you can swap to E with page-marks prepared at all lines
containing errors (like the CKSUM program does).  Since the decoded file
is reconstructed without zero-padding after the individual pages, E will
have to reformat the file.

If you are desparate to get a binary file across, First convert your data
to SIXBIT using, say, the CNVSIX program.