NeXTstation throws exception #29 on power on

Hi,

I'm thinking about buying a NeXTstation Color (non-Turbo) which is in very good visual condition.

The seller sent me the following photos which show an "Exception #29 (0x74) at 0x10002b4" after the "Testing system" panel.



Booting is not possible because of some more error messages:

.

What does exception #29 mean? Is it deadly or repairable?
What do the "bad version" messages mean?

TIA, bobo68

Through remote diagnostics I found out that the exception probably has to do with network booting which was enabled on the machine (see http://www.cilinder.be/docs/next/NeXTStep/3.3/nsa/ApE_Errors.htmld/index.html for the 0x74 code). After setting the boot command to "sd" the exception is gone.

The "bad version" errors are still there and I suspect there really is a non-compatible OS installed on the disk. Not sure though.

I've never actually seen an exception due to a missing network cable/connection. I suspect there may be something more going on here. Did you check the board for leaking caps? The bad label error can also indicate a dead SCSI drive in my experience, but as you said could also be a bad install. Do you hear the disk spin up?

--
Brian

I do not have the machine here, it is still with the seller. They say the HD spins up and makes no strange noises.

Re the exception: having a look at http://www.cilinder.be/docs/next/NeXTStep/3.3/nsa/ApE_Errors.htmld/index.html I found "Physical packet was garbled." for the 0x74 error code (if this is the right match). Seems plausible to me given that the machine wanted to net boot without a network attached.

What is the normal behaviour for net booting without a network & cable? Will it just sit there and wait?

I will let the seller send me some good pictures of the caps surroundings.

TIA, bob68

The "bad version" message is normal behavior, if there is no valid disk label on the boot disk. That might just mean, that the disk is unformatted or formatted for some other system. In worst case the disk is broken. But it would be easy to replace it with a working one.

"exception #29" is a level 5 interrupt. It is very strange, that it gets reported like this. It might point to a broken serial port (or is there something connected to it?).

Does the seller get the "system test passed" message before the exception occurs? Note that it might only be visible for the fraction of a second before the exception message shows up. If there is no "system test passed" message, i recommend to enable verbose test mode and see what it reports (for how to enable verbose test mode see http://www.cilinder.be/docs/next/NeXTStep/3.3/nsa/09_StartShut.htmld/index.html#9p --> Inspecting or Modifying Configuration Parameters).

Update: The magic number 0x45520200 seems to belong to the Apple Universal Disk Image Format (UDIF, .dmg file). I think the disk was maybe setup from such an image using dd or something similar. That image format does contain some metadata, that was obviously copied to the disk besides the raw data and made it unbootable. The disk is likely good on the hardware side, although there is no guarantee.

Update 2: If the result of the power-on test is not visible at the ROM monitor console, one can print it by typing "ec" to the NeXT> prompt. That might tell you, where the exception comes from.

Thanks for your help.

In the meantime I have the machine here with me. I did set the boot medium to sd. Now there is no Exception #29 any more. The machine boots to the NeXT> prompt and says "System test passed" (Extended Self Test). Also all other tests (FPU, SCC, ...) show no error.

I attached an external drive (SCSI2SD) with NS3.3. When I boot from that drive it first works well but then I get a repeating "ipl5: spurious interrupt" in a new window (similar to the ROM monitor window) titled "NeXT Mach Operating Sytem".



At this point I have to power down the system the hard way.  :(

This is quite strange stuff. At least i was right about the interrupt (ipl5 means interrupt priority level 5). From what i know the only devices connected to that interrupt line are the SCC (Serial Communications Controler), the NBIC (NextBus Interface Chip) and some remote interrupt.

I don't know how the remote interrupt is generated. Maybe someone else can help with this. That would be a potential cause for this error. In case it is no remote interrupt, i think it must be the serial controller.

The NBIC is unlikely to be the cause, because the NeXTstation has no NBIC socket.

You could check the area around the serial controller chip (it is an AMD AM8530H) for damages and check the serial ports for bad pins or dust.

Thanks, very helpful. I also found this hint http://www.nextcomputers.org/forums/viewtopic.php?t=705&highlight=ipl5+spurious and talked to diegel.

I will replace the caps, has to be done anyway.

BTW, does someone have schematics for the NeXTstation Color (non-Turbo)? I only found some for the Turbo.

Small update: the NeXTstation did boot up fine once yesterday. But it completely froze in the middle of using it (after 3 minutes or so). After that the spurious interrupt was back at boot time.