Subject: Re: ppp/ether/TCP/IP and serials
To: Allen Briggs <>
From: noud de brouwer <>
List: macbsd-general
Date: 07/24/1995 14:39:09
>At this point, I'm pretty sure that your problem is simply the flow

And that could be the end of a very bad dream. Hope so.

o You can configure the built-in serial ports for hardware handshaking
  (RTS & DTS) _or_ dialup security (DTR & CD) but not both, due to the
  lack of a sufficient number of modem control lines.

This is for hardware handshaking (not to use on serials only Hustler(?)):
        Mac          Modem
    Male Mini-Din-8  DB-25
    1 (HskO)  ---   4   (RTS)
    2 (HskI)  ---   5   (CTS)
    3 (TxD-)  ---   2   (TxD)
    4 (GDN)   ---   7   (SigGnd)
    5 (RxD-)  ---   3   (RxD)
    6 (TxD+)  ---   7   (SigGnd)or(NC)
    7 (GPi)   ---   8   (DCD)
    8 (RxD+)  ---   7   (SigGnd)
                    6 -- (DSR)
                   20 -- (DTR)

I picked the DTR & DCD flow control.
I made this cable (out of the A/UX FAQ) for dialin modem control:
    Mac       Modem
    1 (HskO)  20 (DTR)
              4  (RTS)  <- yep... it gets sent to Pin 20 & 4
    2 (HskI)  8  (DCD)
    3 (TxD-)  2  (TxD)
    4 (GDN)   7  (Sgnd)
    5 (RxD-)  3  (RxD)
    8 (RxD+)  7  (Sgnd)  <- this is right, it gets tied to Mac pin 4 too.

I did set:
&F2  a Supra running as a IBM error correction and data compression operation
E0   command echo disabled
Q1   result codes disabled
&D3  reset on DTR being dropped
&C1  raise DCD on connection
&W   save changes

S0=1 autoanswer
&W   save changes

I did put in gettytab:
     mb        bool              false      do flow control based on carrier

I did put mdmbuf in ttys

What misasumptions i made???
I'm trying &F and &F1
btw.: cc-ing to the list maybe someone else can give some extra input.
      (for me the list takes longer to reach so that's why it's done like that)

C.04)  How do I set up my Mac and A/UX to enable remote logins via a modem
       on tty0?

First of all, you must edit /etc/inittab to start getty on tty0 using mo_2400
(or whatever speed you want, such as mo_9600):

    00:2:respawn:/etc/getty -u -t 60 tty0 mo_2400

Make sure that your modem is set to be quiet, to not return result codes and
to not echo back. It must also reset on DTR being dropped ("atq1e0&d3" will
achieve this for most Hayes-compatible modems except certain (all) USR
modems). Your modem must also raise DCD on connection ("at&c1") in order to
have Dialup security (i.e. when the line is closed, HangUp the process.  This
means that MODEM flow control must be specified in gettydefs). You then save
these changes using the "at&w" sequence. Finally, to make it autoanswer, be
sure to add "ats0=1&w".

Make sure that the modem cable is correctly configured (NOTE: This is for
Dialup Security!):

    Mac       Modem
    1 (HskO)  20 (DTR)
              4  (RTS)  <- yep... it gets sent to Pin 20 & 4
    2 (HskI)  8  (DCD)
    3 (TxD-)  2  (TxD)
    4 (GDN)   7  (Sgnd)
    5 (RxD-)  3  (RxD)
    8 (RxD+)  7  (Sgnd)  <- this is right, it gets tied to Mac pin 4 too.

If you mess up pin 8 things can get so flaky that you'll never figure out
what's going on. You see, by grounding pin 8, you make the modem port truly
RS-232 compatible. If not grounded, the port will use the RS-422 standard,
which can cause lots of problems. For more info about pinouts and cable
pinouts, check out "/usr/lib/uucp/README".

Please note that getty is the bidirectional version of getty, which is
sometimes known as uugetty. Thus, you can have dial in and dial out at the
same time on the same port. You should be using at least version 1.16 of HDB
(see above: "known bugs" and Q&A #A.16)

As mentioned above, the cable described provides for Dialup Security and
prevents the use of hardware flow control... If, however, the exact same
baudrate is used throughout the phone link, the need for hardware flow
control is greatly reduced.