Re: Need help to reanimate an AT&T AT&T 3B1/7300 UNIX-PC

On 26 Mrz., 03:50, "DoN. Nichols" <dnich...@xxxxxxxxxxx> wrote:
On 2008-03-25, Juergen Sievers <JSiev...@xxxxxxxxxxxxxxxxxx> wrote:

Hallo DoN.

Thank you very much for your big replay.
To give you more information about the system I added some more high
resolution pictures to the following location.

http://www.nadhh.hanse.de.com/eBay/AT&T.UNIX-PC/


Hmm ... that is an unfortunate location in that there were
several versions of the CPU board, and on some there were empty pin
layouts which have been used for such things as modifying the system to
Oh, you are right; there are some unused areas on this location. So I
have taken a detailed picture from it. But I believe too, there must
have been a capacitor on this location.

accept two hard disk drives of up to 160 MB formatted (190 MB
unformatted) -- drives which were made by both Maxtor and Piram (I have

It is a ST51 (64MByte MFM Drive) and the controller chip is an
WD1010A.

one of the latter, and have worked with a couple of the former.)
Obviously, only one of the drives could be internal. The drives were
all MFM drives, and to handle drives that large, it was necessary to
replace the hard disk controller IC with a later model. I would have to
rip a machine back apart to tell precisely what was there -- and it is
likely to be different on different versions of the system board.

1) 512 KB of RAM on board --7300 only.

2) 1 MB of RAM on board -- 7300 and 3B1 I believe.

3) 2 MB of RAM on board -- 3B1 only I believe.


On the main board are eight rows a (8+1) 256er RAM chips installed.

4) Export (Not sure whether there were three versions of this, but
the modem and telephone connectors were disabled in this, either
because of differing modem standards, or just because some of the
countries did not want their citizens to have access to modems.

Which you got will depend on where you got it, among other
things. If you got it from an eBay auction in the USA, it probably has
the modem jacks active.

Yes, the system was used in USA and I’m sure the modem line is active.
As you can see on the pictures I own a expansion box too, on which are
one more modem line is available. But I never tried this box yet.
Now -- the position of the component and the fact that it is
only two pins suggests that it is likely to have been a bypass
capacitor -- many were scattered around the system board to keep logic
OK, I decide it must be a capacitor. One like all the others in front
of each DIL-IC.

The missing battery should be a 3V coin cell. The original had
solder tabs, but I tended to replace them with sockets for the 2032
cells. The major problem without that is that you will have to reset
the time every time you boot, and will wind up with a few files with
very strange dates before the boot reaches the point to set the time.

OK, I saw this message already and I’m glad to hear that there is no
setup or configuration SRAM which I have to set up proper first.

Now -- from the rather oversized image of the system, what you
have seems to be a 3B1, as it has the raised area under the monitor stem
to clear the height of a full-height disk drive. The 7300 had only a
half-height drive. (Also, the file name for the missing part image was
a pain, with an '&' embedded, making it a pain to handle on a unix
command line.

I saw a file named “unix” on the root as also a link to it with a
uppercase name like “UNIX351a” or so. See pictures of screens.


As for your problem with booting -- the typical failure status
is for the inodes pointing to directories, or sectors making up part of
directories to be lost. resulting in the loss of quite a few files.
Many of them will be found and put in the lost+found directory by fsck,
but they will have names starting with a '#' and followed by the inode
number for the file, and you'll have to do a lot of detective work to
dig it out.

I’m willing to do all the work if the system would be get back to a
working state:)
But I can’t boot because I have no boot and installation disk now.
Some times after many retries the system has been booted from the HD.
But on that case many errors are appearing and I can not switch to the
graphical mode e.g.

So -- what you need is to boot from the first floppy of the
installation set, and progress from there, including booting first from

Oh yes, I would do that immediately if I would have a bootable floppy
disk?
I have some other old (MFM) systems which are able to write many
exotics disks formats on a 51/4” disk. But for that I need the images
of the AT&T’s boot and installation disks. Do you or somebody else can
send a dd image to me?

Now -- the installation set puts in most of what you need,
That would be wonderfully if some installation set would do that :)
But I haven’t any installation set available yet ?

except a good editor and no compiler. And there was one floppy pair
which was not to be included with exports -- it had the crypto software
and the programs which used it (like an encryption capable vi editor) --
so it could be left out of export systems.
OK, I will not use the system for real work anymore. It should only
become a very nice piece of my collection of running systems.


But you'll also want a set of floppys containing the
"Development Set", which supplies the compiler, the header files, and an
Yes, I really needing such floppies ?

encryption-free version of vi, among other things. Note that if you
*do* have the encryption floppies, you want to install the development
set first, then the encryption set, because it looks for the presence of
the plain vi and only installs the encrypted version if the plain is
already installed. It is possible to fool it into installing the
encrypted version if you put a file of the right name in the right
place, but I forget whether it was in /bin or /usr/bin .
Good hint, thanks a lot.

If you find a place to download the floppies, beware that the
Unix-PC used two non-standard floppy formats. The typical MS-DOS
I’m full of hope you are such a place for me, isn’t ?
machine of the period put nine sectors on a track. The boot floppy and
some others had eight sectors per track, and the rest had ten sectors
You are sure? I remember I was reading something about ten sectors???

per track -- making it difficult to build the floppies on anything other
than a 3B1. Some linux systems of the period had optional floppy
drivers which could generate and work with the odd sectored floppys, but
I never worked with that so this is only hearsay.
I use a old DOS machine with some tools from the good, old CP/ M era.
These tools can read and write many old disk formats. Hope it works
for my UNIX-PC too.

But given your museum focus, I suspect that you will want it as
close to factory supplied as possible, rather than as commonly modified
by the user community.
Yes, you are right. I prefer systems in their original state as like
as they were delivered.

Best of luck,
DoN.

Thanks and same return to you
Juergen

PS: Sorry about my bad English. My brain (if there is any) may be to
small to learn it much better. Abe rich kann etwas Deutsch, wenn das
helfen kann?
.

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