AT&T 3B2-400 UNIX reinstall (96tpi)

Recently aquired a 3B2-400. After a little smoke, and a few trips of the circuit breakers, the machine is alive.

The primary hard drive does not appear to be readable, it tries, but it clearly needs a LLF and reinstall.

I have ~10 of the Programming Utility Disks, but not the idtools config/maintenance disk nor the UNIX System V install disks.
Online I have managed to find:

idtools v2.0 - binary copy
System V R3.2 - binary copies of the six main disks

The disk format required is DSDD 96tpi (250kbps, 300rpm, 80 tracks - 720KB) a.k.a. DSQD or DS2D

Does anyone have System V R2.0 disk images? (this would match my library of books)
Does anyone know how I can get my PC to write the images?
Is 300kbps @ 360rpm the same as 250kbps @ 300rpm? Is there a tool you can recommend?

I was just going to use ImageDisk on my 1.2Mb drive with DSDD media, set it to 300kbps, and write the images. But my image files aren't in IMD format. They're just binary copies with no file extension. If anyone can help me out, or point me in the right direction, that would be fantastic.

Ok, well this is what I did last night. I made the assumption my idtool file was generated using "dd" since that seems to be standard practice on UNIX/Linux. The file is 728,064 bytes.

I used BIN2IMD to convert the image to an IMD format - 250kbps 80 tracks, 9 sectors per track, sector order 1-9. This gave me a message stating the file ended at CHS 79/0/0 but generated the IMD file.

I then used IMD, and set 250kbps->300kbps and format/wrote the image to a DSDD floppy without error with a 1.2Mb drive.

The 3B2 failed to boot it. I went in to firmware, typed idtools and selected FD5. The drive just made a jittering noise for a while - then the machine tried the two hard drives - and resulted in BOOT FAILURE. I'm not sure what the floppy drive *should* sound like when attempting a boot, but I'm worried the drive needs maintenance (rails cleaned etc).

So I need to check the floppy drive, but what I did to create the disk - is it logical or did I miss something?
Does anyone have a set of these disks or one of these machines?

Hmm, did all of these use 96tpi (80 track) disks, or just some? There are images on Bitsavers for the At&t "Unix PC". I think that is the same thing, but at a glance those images appear to be for 48tpi (40 track) media.

728,064 doesn't sound right unless they actually only used 79 tracks.

They (the 3B2 series) all use 720Kb floppy drives.
Yeah I thought the file size was off as well, I'd have expected 737,280. But unfortunately it's the only disk image I could find (it configures/formats etc before UNIX is installed). Not sure if it was just a track short, or if I'm supposed to put something in to replace track 0, or what the deal is.

First few bytes of hex in the image are: 10 45 9C 4F 00 00 00 00 4C DC 01 7F A0 04 00 00 (in case anybody recognises a common pattern)

I have a set of disks for my 7300. They should be system V, but I don't know about R2.0. Don't know how good the disks are, either.

GottaLottaStuff said:

I have a set of disks for my 7300. They should be system V, but I don't know about R2.0. Don't know how good the disks are, either.

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I don't think that version would work on this, but thanks for the offer
I have found 3.2.x versions, and from what I found it seems that's what everyone ended up using on this platform - so that might do for now.

I've had a big stroke of success tonight, and now I'm certain I'll have this guy reinstalled. The floppy drive had a build up of dust/hair on the rails preventing seeks, and the heads were dirty. I've cleaned it up, and my idtool disk worked! I've just formatted Drive 0 30Mb and about to do Drive 1. I did a verify first to see if they could still be read - the original drive failed on sector 0, and the second drive made it to track 13 before the sector marker disappeared, so both needed a LLF. idtools was however able to read their bad track tables and disk types - which saved a lot of time.

Very happy right now. Only concern is the PSU fan does not spin (didn't notice this before) - I'm not sure if it's thermal controlled or faulty so for the meantime I have a desk fan blowing air through from the back.

I don't believe the 3b1 disks will install correctly on the 3b2. We have a 3b2 at the MARCH inventory we may have a few sets of spare disks. I have not personally worked witth this system you would have to ask Evan K.

Oops, the 3B1 is the "Unix PC", the 3B2 is something different (but "1" and "2" can look the same if you aren't squinting hard enough). Despite the similar name the "3B1 was essentially unrelated in hardware or software to the 3B2 line"

I was able to create a set of UNIX 3B2 System V R3.0 disks. These worked reliably however, despite multiple low level formats and verify passes, I get CRC errors after UNIX installs - causing kernel panics. I beleive this to be a hardware issue and I'll need to go through the usual hardware diagnostic stuff you'd do for any machine - check/clean cables, try one drive at a time, try another drive etc and see what happens.

After the clean and a bit of usage, it's floppy drive is very reliable now.

Cheers billdeg - I have found some images to use, once I finish this project I'll put together a little repository for others. I'm converting the binary images in to IMD format - so they can be quickly written on a 1.2Mb drive using a PC.

SpidersWeb said:

I was able to create a set of UNIX 3B2 System V R3.0 disks. These worked reliably however, despite multiple low level formats and verify passes, I get CRC errors after UNIX installs - causing kernel panics. I beleive this to be a hardware issue and I'll need to go through the usual hardware diagnostic stuff you'd do for any machine - check/clean cables, try one drive at a time, try another drive etc and see what happens.

After the clean and a bit of usage, it's floppy drive is very reliable now.

Cheers billdeg - I have found some images to use, once I finish this project I'll put together a little repository for others. I'm converting the binary images in to IMD format - so they can be quickly written on a 1.2Mb drive using a PC.

Click to expand...

I'm in the same boat. Once your done, I'd like to try and get my 400 running too. Install media on tape should work as well.

eeguru said:

I'm in the same boat. Once your done, I'd like to try and get my 400 running too. Install media on tape should work as well.

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I am being incredibly useless at finishing my machine. I had difficulty getting data written to the drives to pass CRC checks when being read back then got distracted by a 386DX/40 build, 286 build, I still haven't finished a 486 build, and one of my XT's just blew a cap.

If you need disk images, just let me know which ones. I've been given access to quite a few, but the ones I've converted to IMD and tested on the machine are System V R3.0 Base Disks 1-6 and the Setup disk (idtools/devtools etc etc). Work fine when written to DS-DD disks. DS-HD was a no go.

Edit: I'd have no idea how to get it on to a 23Mb Cipher but the machine will boot from tape if you ask nicely.