machine doesn't exit from open boot PROM mode

I have a sparcstation 20 sun machine.
when the machine boots it displays this:
<#0> ok
when I inserted a solaris 8 cd and  typed   boot cdrom
the system outputs this message:
      level 15 interrupt
and it again enters into the ok mode.
What can I do to make this machine work?
please help me.
AbebeAmareAsked:
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PsiCopCommented:
I haven't found anything helpful on SunSolve.

Questions: Whgat version of the OpenBoot PROM? What specific release date of Solaris v2.8?
liddlerCommented:
Is your devalias correct for cdrom?
shivsaCommented:
first i will load the latest OBP on this system.
i will check the CD device. since interrputs comes from hardware and it is coming when obp is trying to probe cdrom in.

so either obp is suspected or cdrom.

also as liddler suggested check also cdrom alias since if is not suspected cdrom it is suspected the hardware where cdrom alias is pointing.

was this cdrom was working well before. is this cdrom came from Sun hardware or u put something from your side, if yes then did u check if this cdrom is supported.
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AbebeAmareAuthor Commented:
I have the output of .version and devalias cdrom  commands on the OBP.
 .version
release 2.25 version 0 created 95/09/15
 devalias cdrom
cdrom    /iommu/sbus/espdma@f,400000/esp@f,800000/sd@6,0:d
The cdrom eas working well for other machines.it is solaris 8 software installation cd.
shivsaCommented:
obp looks quite old but should work here.
what were other machine, were they sun machines. what i am lloking at whether this cdrom is supprted on sun config or not.

could u run reset-all.
then run
test-all or something i really donot the full command but it should be something like this in obp.
or
test /iommu/sbus/espdma@f,400000/esp@f,800000/sd@6,0:d

if u see anything unusual post it
AbebeAmareAuthor Commented:
the "other" machines are sun sparcstation 5 and sun ultra 10 machine.
When I try test cdrom it simply returns to the ok prompt after a brief delay.
When I typed boot disk it says level 15 interrupt and returns to ok mode.
 I typed test-memory.
then I typed reset -all ( the environment variable diag-switch was set to true on the OBP)
The system responds with this:
 testing 64 Mbytes of memory ...
and  the system outputs a series of errors non stop (like the result of an infinite loop in any program)
Here is a single line from the error message:-
ERROR: physical address=0x1888 U-number=J0201
               Expected=0xa5a5a5a5  observed= 0xa5b5a5a5
And there are infinite number of errors of that type (with different physical address value)
 
shivsaCommented:
okie that what i suspectd, some hardware problem.
it means that RAM has gone bad, could u replace the memory on this system and try with some known good memory.

when u replace the memory just be sure to get the RAM which is compatible for this system.
PsiCopCommented:
Yep, bad RAM. The SS 20 takes 200-pin, 5v, ECC RAM. I think it supports 16 MB, 32MB and 64 MB modules. Low-end Ultras (5s and 10s) use the same RAM, as I recall.

Another possibility it that the RAM is not seated well.

If you pull off the cover, you'll see the RAM on the left-side of the motherboard, I think. The slots are numbered, J201, J301, etc. The error message you quoted above refers to J201, which is the first slot, as I recall. You may want to unplug the unit, pop out the module, check the contacts for corrosion, and then re-seat it. Plug everything back in and boot up and see what test-memory reports now.

If the error persists, replace the module.

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Hanno P.S.IT Consultant and Infrastructure ArchitectCommented:
No, Ultra 1, Ultra 2, Ultra 30 and Ultra 60 use the same type of RAM
AbebeAmareAuthor Commented:
Thank you all guys for your comment especially PsiCop.
I unplug the memory unit at slot J0201 and then I re-seat it.After that I did a test-memory but the same problem persists.
I removed the bad memory unit and I did boot -r then everything becomes ok except for the filesystem needing an fsck.
I did fsck and the machine is working good.
Here is my question though:- Is there any chance that I can correct the bad memory unit? I am just curious.
Thank u very much for your invaluable support.
liddlerCommented:
No :-(
Just throw it away
shivsaCommented:
Yes  AbebeAmare, throw it away. it will lots of efforts and all to correct that memory and it would not worth it.
it erquires hardware intervention.

glad it worked.
PsiCopCommented:
liddler is right - ram is cheap and the days when it was worth it for a manufacturer to map the memory defects, bypass bad cells and re-issue the RAM are long past. And in any case, that's only something that could be done in a production facility, its not an end-user operation. Chuck the RAM - or give it to a competitor. :-)
shivsaCommented:
any update on it.
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