  The MacTerminal MINI-HOWTO
  Robert Kiesling
  v1.4, 9 November 1997

  This mini HOWTO describes the 1,002nd use for a dead Macintosh (grin):
  how to configure the Mac for use as a Linux terminal.  Configurations
  using getty and the terminal program kermit are described, as well as
  using kermit peer-to-peer networking between between Linux and a Mac­
  intosh.  This document may be reproduced freely, in whole or in part,
  provided that any usage conforms to the general copyright notice of
  the HOWTO series of the Linux Documentation Project.  See the file
  COPYRIGHT for details.  Send all complaints, suggestions, errata, and
  any miscellany to kiesling@terracom.net, so I can keep this document
  as complete and up to date as possible.

  1.  Introduction.

  This mini-HOWTO should give you some Insanely Great ideas for how to
  make your Macintosh work with Linux.  Unfortunately, I have been very
  busy, and so I haven't been able to include even half of what I wanted
  to include, like using MacTCP and Open Transport to connect to your
  Linux box via a PPP line.  That will need to wait for future versions.

  This mini-HOWTO doesn't cover networking with LocalTalk and AppleTalk,
  either.  I might explore these avenues if there's enough interest in,
  say, printing to a LaserWriter printer from Linux.  Otherwise, it
  seems to me that such applications, being more trouble than they're
  worth (not to mention pricey), are beyond the scope of this document.

  I don't plan to cover MkLinux in this document, either.  It's more
  than adequately documented elsewhere.

  So if you have ideas for this document, drop me a line at the e-mail
  above.  Both systems embody a lot of the beginner's mindset as well as
  technical prowess, and in my opinion they don't talk to each other
  nearly enough.

  2.  Setting up a serial link.

  To set up a serial link between a Mac and a Linux machine, you will
  need, on the Linux side, either a DB9 Female-to-DB25 Male serial cable
  or a DB25 Female-to-DB25 Male serial cable, depending on your serial
  port.  On the Macintosh side, you will need a DIN9-to-DB25 Male high-
  speed modem cable.

  Make sure that the cable is labeled a "high speed" cable, because some
  older Macintosh cables are configured with their handshaking lines
  tied high, which makes them useless for high-speed serial connections.

  You will also need a null modem adapter, available at Comp USA, Radio
  Shack, and similar outlets, and a DB25 Female-to-DB25 Female serial
  gender changer to connect the two serial cables.

  I have heard that Mac printer cables are really null modem cables in
  disguise, but I can't confirm this.  Some of them are DIN9-to-DIN9
  anyway, and wiring one into a serial link would be more trouble than
  it's worth.

  If this sounds like Greek to you, read the Serial-HOWTO for details of
  RS-232 cable configurations and data transmission protocols.

  Before connecting the Mac and the Linux machines, you should determine
  that you have a working serial port on both machines, either by
  connecting a modem and dialing out to another computer with minicom
  (Linux), ZTerm (Mac), kermit (either), or the communications program
  of your choice.

  The latest version of minicom is available from
  sunsite.unc.edu/pub/Linux/apps/serialcomm/dialout and mirror sites.

  ZTerm is a complete, easy to use comm program.  Unfortunately, it's
  shareware.  A current version is available from mac.archive.umich.edu
  and outlets like it.

  The kermit program has been ported to every computer and operating
  system in existence.  The archives are located at
  ftp.columbia.edu/kermit.

  You should strongly consider using kermit on both machines at this
  stage at least, because 1) it's free (although it's not covered by the
  Free Software Foundation's General Public License); and 2) it's a lot
  less confusing to have kermit on both machines than two completely
  different communications programs.

  If you have another way to determine that the serial ports of the two
  machines are operational, feel free to use that.  The point is to
  ensure that both machines have working serial ports.

  Making the actual serial connection should be easy, given the
  directions above.  In case it isn't, the connection looks like this:

   Linux PC    DB9- or DB25-  Null     Gender   DIN9-to-       MacBox
   ---------   to-DB25 male   Modem    Changer  DB25 Mac      --------
   |       |   serial cable. |     |  |     |   Serial Cable  |      |
   |       |-----------------|     |--|     |-----------------|      |
   |       |                 |     |  |     |                 |      |
   ---------                  Adapter                         --------

  3.  Client-server connection with kermit.

  This is the most transient of all the configurations described here.
  It requires the least amount of system configuration, although in
  operation, it is the more difficult to use of the systems described
  here.

  In brief, you start kermit on both the Linux machine and the Mac, and
  place one of them in server mode.  It doesn't matter which machine is
  the client ant which is the server, because this is a peer-to-peer
  connection.  However, the Linux kermit can take advantage of Linux's
  superior scripting abilities, so it seems logical (to me at least) to
  designate the Linux-side kermit as the server, because this is the
  more readily automated task.

  You should ensure that kermit is installed correctly on both the Mac
  and the Linux PC.  Follow the instructions in the respective kermit
  distributions.  On the Linux machine type kermit at the shell prompt
  to start it.  You may need root permissions in order to set the port
  and baud rate.

  kermit, the recent POSIX versions for Unices, supports baud rates up
  to 115 Kbps.  The more recent Macintosh versions support serial port
  speeds up to 57.6 Kbps.  This should be more than sufficient for any
  dumb tty-type application, but if you need a higher-speed connection,
  you're s.o.l, as far as kermit and serial lines are concerned.
  However, kermit provides facilities for communication over a TCP/IP
  link, but I haven't been able to test it.  See the alternative in the
  following sections.  Just remember, especially on the Mac side, to use
  a different port for kermit serial connections than your TCP/IP
  connections, because Mac kermit will rudely hose a serial port that is
  already in use.

  With that in mind, your .kermrc file would contain something like
  this:

  echo Executing site initialization file /usr/local/bin/ckermit.local.ini....
  set prompt Chanel3 >
  set line /dev/ttyS0
  set baud 38400
  set send packet-length 2000
  set receive packet-length 2000
  set block 3
  set file type binary

  Then, in your ~/.kermrc file, you would have a line like

  take /usr/local/bin/ckermit.local.ini

  On the Macintosh side, set the same communication parameters for bps,
  stop bits, parity, and word length.  Some older versions of Mac Kermit
  do not support 2k packets, so you might need to set a smaller packet
  size.  Howerver, kermit sets the communication packet length based on
  the receive packet-length setting, so you need to set a shorter packet
  size on the Linux end, too.

  To actually communicate over the link, you need to enter server mode
  on either the Mac or Linux side.  It doesn't matter which.  See the
  kermit docs for details of server mode.

  3.1.  Macintosh resources.

  This is one of the very few kermit applications where setting a text
  file type for transfers is useful.  This is because Macintosh files
  have two parts: the data fork and the resource fork.  The data fork
  corresponds to what we in the Linux world think of as a file: it's the
  actual data.  The resource fork contains bitmaps for the icons,
  keymaps, font specifications, and the like.  If you transfer a file
  from Linux to the Mac, the file won't be recognized as a text file by
  the Mac, if you use binary mode.

  When transferring binary files between the two systems, you should use
  the Macintosh .hqx BinHex format, which is a 7-bit encoding of an
  8-bit data file.  Mac utilities like BinHexer or StuffIt will covert
  the file to its binary form.

  If you have a text file which inadvertently ends up as a data-only
  file on the Mac, it's likely that it won't even appear in an Open
  dialog list box.  What you need to do is open the file with ResEdit,
  which is available from mac.archive.umich.edu.  ResEdit will tell you
  that the file you're opening has no resource fork and then asks if you
  would like to add one.  You should answer "Yes" to this question.  You
  can then edit the file's Type and Creator by selecting the Open
  Special option of the File menu.  All Macintosh text files are type
  TEXT, so replace the question marks in the Text box with that.  The
  Creator code depends on your text editor or word processor.  Each one
  is unique, incidentally, and is how the Mac identifies different apps.
  The Creator code for GNU Emacs on the Mac is EMAC, for example.  If in
  doubt what the creator code of your text editor or word processor is,
  use ttxt, which is the creator code for TeachText (which is the Mac
  equivalent of EDLIN.EXE.)  Then your real word processor or text
  editor can translate the file from TeachText to its native type.
  There are many other neato things which TeachText can do, so it's
  worthwhile to keep it permanently on your Mac.  The book Voodoo Mac,
  by Kay Yarborough Nelson, is a good source of tried-and-true Macintosh
  tricks that use ResEdit, TeachText, the Finder, and other overlooked
  programs.

  4.  Logging in via kermit.

  Configuring Linux to use the Mac as a login: terminal is even easier.
  kermit is ideal for this purpose, because it is one of the few free
  communication programs which provides credible VT100/120/220
  emulation.

  Essentially, what you want to do is start kermit on the Macintosh side
  as in the previous section, but rather than issue server commands, you
  enter connect mode.  This is the normal terminal emulation mode that
  most people use, anyway.

  On the Linux side, the serial line must be configured with a getty on
  it to start a login: shell.  To do this, you need to tell init that
  the serial line has a terminal on it.  In your /etc/inittab file you
  will need a line something like this:

  T1:23:respawn:/sbin/getty -L ttyS0 9600 vt100

  Be sure to substitute the appropriate serial device for /dev/ttyS0 and
  the correct baud rate for 9600 in the command line above.

  This command tells getty to start login (the -L switch) on the
  terminal display, and, when the login times out, to re-start (respawn)
  the login program until someone logs in.  If no device is connected to
  the serial line, or if the connection is defective, you may see a
  message on the system console like: /dev/ttyS0 respawning too fast:
  disabling for 5 minutes.  If this happens, you can return things to
  normal by (as root) killing the getty process, or using the init q
  command.  Both of them have the effect of re-spawning the getty
  processe(s).  If everything is in order, you should see the Linux
  banner and login prompt on the Mac's kermit window.  That's all there
  is to it.

  Also, if you use something besides vanilla getty, like getty_ps, the
  command above will look somewhat different.  The important thing to
  remember is that everything to the right of /sbin/getty is an argument
  for getty itself; not init.  You should look at the manual pages for
  getty, init,and inittab if you have questions concerning the setup of
  init and getty.

  The Serial HOWTO provides helpful details on how to configure
  /etc/inittab for getty_ps, if that's what your system uses.

  To transfer files back and forth between the Macintosh and the Linux
  machine, you can (via the Mac's Kermit) issue the kermit -x command to
  start the Linux kermit in server mode.  You can then use the normal
  file transfer commands to send files across the serial line.  It's
  useful to set a prompt in your ~/.kermrc with a line like

  set prompt Linux-kermit >

  Otherwise, remembering which machine you're on can quickly become con­
  fusing.

  4.1.  Other Mac terminal programs.

  This method should work equally well for any other Mac terminal
  program.  If you have ZTerm, you can use rz and sz on the Linux
  machine to transfer files via the ZModem protocol.  If Microphone Lite
  came bundled with your fax modem, that works equally well, albeit
  without kermit's superior scripting and configuration facilities.

  5.  Conclusion.

  If you have questions about any of this material, or suggestions for
  future directions of Mac-Linux serial-line connectivity, don't
  hesitate to drop me a line at kiesling@terracom.net.

