A/UX: How To Use With Apple Modem 2400


Article Change History
----------------------
08/31/92 - REVIEWED
o For technical accuracy.


While testing the new prerelease Apple Modem 2400 with A/UX, I was unable to
get it to function properly by using "getty" in the /etc/inittab. The modem
answered the phone but never produced a tone. The phone hung up.

When I changed /etc/inittab to use "apm_getty", the modem answered the phone
and presented a tone, but it would connect at 1200 only -- not at 2400.
Changing the apm_getty parm to "at_2400" did not solve the problem. This is
the /etc/inittab entry that I am using:

00:2:respawn:/etc/apm_getty tty0 at_2400

Can you suggest something that would work with our new Apple Modem 2400 and
allow it to operate at 300, 1200, or 2400 as determined by the speed of the
incoming modem?

We configured the Apple Modem 2400 for dial-in use with the standard getty. The
apm_getty operates only at 1200 baud. It is intended for use only with the
1200-baud Apple Personal Modem, which can't remember settings between resets.

Here are the steps we followed:

1) Connect the Apple Modem 2400 to the Macintosh modem port with cable
(M0197, 590-0552). Turn on the modem.

2) Edit the file /usr/lib/uucp/L-devices to add this line:

DIR tty0 tty0 2400

3) Open a connection to the modem using cu:

#cu -ltty0 -s2400 <- typed by you
Connected <- returned by cu

4) Recall factory settings, change for dial-in use, and save the new
settings:

AT&F <- typed by you
OK <- returned by modem
AT E0 Q1 &C0 &D2 S0=1 &W <- typed by you (0 is a zero)
<- nothing is returned because of our settings

5) Edit the file /etc/inittab to respawn a getty on tty0:

00:2:respawn:/etc/getty tty0 mo_2400

6) Edit /etc/gettydefs to limit rollover between 2400 and 300. Edit the
mo_2400 line to end with mo_2400 instead of mo_9600.

7) Start the getty process with INIT:

#INIT q

8) Dial in from another modem.

(NOTE: This configuration does not allow A/UX to sense a loss of the Carrier
Detect signal -- that is, an accidental disconnection can result in the next
caller getting the disconnected caller's login. Enabling this requires a
different cable that connects the GPi line (pin 7) from the modem to the HSKi
line (pin 2) of the Macintosh modem port. It also would require modifying the
modem setup string (in step 4) to set &C1 instead of &C0.)


Published Date: Feb 18, 2012