AS/400 9404 and TWINAX questions...

From: Don Hills <>
Date: Sun Sep 26 20:21:55 2004

Wolfgang Eichberger <> wrote:
>It d be nice if you cold help me out a bit with these numbers. I could
>not really find out what these are. Could somebody please identify

Sorry, too many years have passed... I can't remember. <grin> Try here:

>I also got a 3197 terminal, twinax expansion boxes (2x 4 ports) and
>some cables with the machine. My first question: How do I connect the
>terminal correctly? I assume it plugs into port 0 for system console.
>Are the cables critical, could I use cat 5? I have not enough
>connectors I d be happy if anyone could supply some cheap connectors
>(male) and Infos about the twinax cabling sheme, especially how the
>pinout of the connectors and how I have to connect the console

Start with the 3197 terminal. It will either have 1 or 2 twinax ports.
If two, just connect a twinax cable between port 1 on the terminal and port
0 on the AS/400. If one, you will need a "t-cable" to connect to it to
provide the two ports. Twinax is somewhat like old 10base-2 (coax) Ethernet,
where the terminals are "daisy chained" and the end of the cable is
terminated. With 10base2 the terminator was a separate item, but with twinax
it is built into the device or T-cable - examine it carefully, you will see
a small plunger on port 2 which switches out the terminator when a cable is
screwed in to extend the chain.

You can use CAT 5 with special baluns and filters, but only for short runs.
The data rate is only 1 MB/sec but it is susceptible to reflections if the
wrong cable is used or it is not properly terminated, even in short runs.
Properly run and terminated twinax will work over runs up to 1 mile long.
The actual data stream is pure SDLC protocol in multi-point mode - each
terminal polled in turn by the controller in the system unit.

>I have no docs for the machine, but it should be loaded with an OS.
>When I turn it on it seems to IPL. Is there any Info available online?
>I think, I need some information about the OS too (at the back of the
>machine I can read Release Level 2 on a sticker. Somebody told me the
>OS-License is tied to the machine? If so, could someone provide me some
>backup copies of the system disks?

The OS license is tied to both the machine and the customer. I seem to
recall it is a monthly charge, no pay means no valid license. There is no
other OS than OS/400, IBM did publish full specs to allow anyone to write
their own OS but no-one ever did. The system software comes on tape (QIC-120
or 9-track, depending on the drive in your machine). Some microcode and
diagnostics come on 8 inch diskette.

Note: Don't just power it off while running after it has IPLed. You'll be in
for a very long (up to a full day in some cases) rebuild phase on next power
up. That's why many AS/400 systems had battery backup like yours, so they
could be shut down properly if there was a power failure. I think I remember

Good luck, the AS/400 and OS is different from just about any other
machine/OS you may have seen. It's actually quite simple and logical to use,
provided you are not familiar with operating other OSes. It is an object
oriented system, and with no concept of disks or files. Everything is an
object with attributes, and all objects are conceptually in main memory at
all times (64 bit address space, so plenty of room). Each sector on the hard
disks has its own 64-bit beginning address - each sector is formatted to 520
bytes instead of 512 to provide room for the address. The system maintains
tables of addresses versus disk location, and it is these tables that take a
long time to rebuild after a forced power off.

You really should try to get the manuals, there is online help but the
manuals will provide a lot of background information.

Don Hills    (dmhills at attglobaldotnet)     Wellington, New Zealand
It's ironic that people who are too smart to engage in politics
are governed by people who are not as smart.
Received on Sun Sep 26 2004 - 20:21:55 BST

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