From: greg@gagme.chi.il.us (Gregory Gulik)
Subject: AT&T 3B2 (and related) Frequently Asked Questions and Answers 2/2
Followup-To: comp.sys.att
Originator: greg@gagme
Organization: GAGME Public Access UNIX, Chicago, Illinois, USA
Date: Wed, 20 Jan 1993 23:43:18 GMT

Archive-name: 3b2-faq/part2

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Subject: 17 What are the pinouts of those phone-like serial connectors?
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The connectors 3B2's use are called RJ-45.  They are 8 conductor
telephone like connectors, and lucky for us, are pretty standard.
You can either buy the cables and connectors from AT&T for an arm
and a leg, or elsewhere.  I don't know about the cables, since I've
never bought them from anyone but AT&T, but I have made my own
RS-232 connectors with excellent results.

The following is an excellent description of the RJ-45 port on the
3B2:

From: rthomas@hakatac.almanac.bc.ca (Robert N Thomas)

Looking into the 8 pin modular RJ-45 jack you'll see that pin 1
should be on the right.

	Diagram of what you should see when looking
	at an 8 PIN modular jack connector.

               +----------+
               | 87654321 | 
               |          |
               +--+    +--+
                  |    |
                  +----+

Ok, not all 3B2 8 pin modular jack connectors are created "EQUAL".
These beasties are used for running StarLan 1MBit, EPORTS cards,
PORTS cards, as well as for running ETHERNET 10MBits as well.

The pin outs for the two modular jack cables on the back of the
3B2, as well as for the PORTS card should be as follows:

     PIN     Lead           Direction             Explanation
    =====  ==========     =============         ========================
      1     PROT GRD                              Ground
      2     reserved                              Not Connected
      3     TXD0            Out                   Transmit Data
      4     DTR0            Out                   Data Terminal Ready
      5     RXD0            In                    Receive Data
      6     DCD0            In                    Data Carrier Detect
      7     SIG GRD                               Signal Ground
      8     reserved                              Not Connected

The 2 modular jacks on the back of your machine should be labeled
console and contty.  If your talking about a PORTS card, here is
what one looks like:

     Centronics connector
     for Parallel Printer
          |
         \|/
     +------------+     +----+    +----+    +----+   +----+
      \          /      |    |    |    |    |    |   |    |
       \________/       +-__-+    +-__-+    +-__-+   +-__-+

                           ^         ^        ^        ^
                          The above 4 RJ45 connectors are for
                        plugging serial terminals into your 3B2.

The EPORTS card is card that has 8 RJ45 connectors (8 pin modular
jacks) on it.  This card is where you would want to plug a high
speed modem onto your system, because the above connectors DO NOT
SUPPORT HARDWARE FLOW CONTROL.  The PIN OUTS for the EPORTS card
is as follows:
   
     PIN     Lead           Direction             Explanation
    =====  ==========     =============         ========================
      1     PROT GRD                              Ground
      2     CTS             Out                   Clear to Send
      3     TXD0            Out                   Transmit Data
      4     DTR0            Out                   Data Terminal Ready
      5     RXD0            In                    Receive Data
      6     DCD0            In                    Data Carrier Detect
      7     SIG GRD                               Signal Ground
      8     RTS             In                    Request to send

* NOTES:

CTS & RTS (if you have them).
	Most 3B2 systems need to do the following to enable hardware
	flow control.  Otherwise the 3B2 will ignore RTS & CTS.
	Also see the FAQ item about handing high speed modems on
	EPORTS cards for more detailed information.

	epstty hfc    <-- XON/XOFF flow control must be disabled
			  before you do this.  The stty command is
			  one way to disable XON/XOFF.  Line
			  DISCIPLINES are another way to do this.
			  See etc/gettydefs file.

DTR0 notes. {3B2 uses this to signal DISCONNECT}

	When the 3B2 is active on the port  (waiting for someone
	to logon to the port or whatever.), DTR is active.   When
	the 3B2 wishes to DISCONNECT (ie, too many wrong passwords,
	or the user logs off the port), it will lower DTR momentarily.
	If you are trying to get a modem to work, you might want
	the modem to DISCONNECT the user when DTR is dropped..

DCD0 notes. {Used to tell 3B2 that the user has DROPPED CARRIER}

	When the DCD is set inactive, the 3B2 will assume that the
	user has either turned off the terminal, or dropped carrier.
	If this occurs, the user is logged off the system, and
	background tasks are aborted.  If DCD is inactive, be
	aware that NONE of the standard AT&T provided utilities
	are capable of sending anything to the device.  There is
	a way to get around this in the more recent releases of
	the 3B2's OS.  See your admin documentation for details.

	Otherwise, in the case of a MODEM, when the user drops
	carrier, you want the modem to "momentarily" lower this
	DCD0 just long enough for the 3B2 to realize that the user
	has dropped carrier.  The modem should then Re-ENABLE DCD0,
	so that the 3B2 will be able to send data to the modem.
	{needed for cu, and outbound UUCP to work correctly in
	older releases of the OS}

	Most semi-decent modems are capable of handling DCD and
	DTR in a 3B2 friendly manner.  I have done this with PEP's,
	USR HST's, and MicroComm 9600 AX modems, without incident.

From: pen@cbnewsf.cb.att.com (paul.e.nepermann)

Here are the pinouts for the connectors from the 8 pin modular to
the 25 pin adapters.

	8 pin modular to 25 pin RS232C Terminal/Printer
	8 pin modular to 25 pin RS232C ACU Modem

	      |       Terminal/Printer        |	ACU Modem
8 pin side    |	25 pin/male   |	25 pin/female |	25 pin
	      |		      |		      |
1  FG	      |	FG	1     |	FG	1     | FG	1
2  CTS (in)   |	RTS	4     |	RTS	4     | CTS	5
3  TXD (out)  |	RXD	3     |	RXD	3     |	TXD	2
4  DTR (out)  |	DCD	8     |	DCD	8     | DTR	20
5  RXD (in)   |	TXD	2     |	RXD	2     | RXD	3
6  DCD (in)   |	DTR	20    |	DTR	20    | DCD	8
	      |	DSR	6     |		      |
7  SG	      |	SG	7     |	SG	7     | SG	7
8  RTS (out)  |	CTS	5     |	CTS	5     | RTS	4

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Subject: 18 What is the u3b. newsgroup heirarchy?
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Don't worry about it, you're not missing anything.  It's an almost
completely dead heirarchy that used to be about 3B2's and 3B1's.
Discussions about 3B2's have migrated to comp.sys.att, and discussions
about 3B1's have migrated to comp.sys.3b1.

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Subject: 19 What is the proper way to rebuild the kernel after tuning
	    kernel parameters?
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# cp /unix /oldunix
# cd /etc/master.d

Edit your kernel parameters

# cd /boot
# mkboot -k KERNEL
# cd /
# sysadm firmware

Once in firmware mode, have the 3B2 boot using /etc/system

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==============================================================================
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-- 
Gregory A. Gulik                                 Call Gagme, a public access
       greg@serveme.chi.il.us                    UNIX system at 312-282-8606
   ||  gulik@rtsg.mot.com                        For information, drop a note
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