[rescue] Sun 3/50 memory error

Curtis H. Wilbar Jr. rescue at hawkmountain.net
Fri Jan 31 14:35:24 CST 2003

>Date: Fri, 31 Jan 2003 11:06:13 -0800 (PST)
>From: James Lockwood <james at foonly.com>
>To: The Rescue List <rescue at sunhelp.org>
>Subject: Re: [rescue] Sun 3/50 memory error
>On Fri, 31 Jan 2003, Curtis H. Wilbar Jr. wrote:
>> Parity error at Addr 0x00001000, Data 0x00000001, Status Exp 0x00000040,
>> Obs 0x000000F0
>Take a look at that address.  This is an error on, basically, the first
>chip tested.  It's possible that this is a chip error, but I'd suspect a
>lot of other things first.

Before I even received this, I did some more playing... read on...

>> I suppose I could remove the parity systems board (as it plugs into the
>> MMU slot and the MMU plugs into this board)... I could try the MMU from
>> the working? board...
>Yes.  Pull the board completely and see what happens.  My bet is that if
>the problem doesn't go away, at least it will change in such a way that
>will help you track it down.

I pulled the board completely putting the MMU and PCHk chips onto
the mainboard.  Since I think the four PALs ? that the board also
drops into may be different, I borrowed those from the other 3/50 board
and restested... yay !  works 100% (and no DVMA errors when typing like
the other one).

When I pulled the memory expansion board, I noticed that it wasn't
firmly in the PCHK chip socket... so once I knew the board was good
I replaced the memory expansion board, doing the chip move again...
and at got past the initial parity check, but then hit a parity
error later in the full memory test...  <sigh>...

So, I tried swapping out the 4 SIMMS on the expansion board... still
a parity error during the memtest.....

So, I put all 8 in (there were only 4 when I got it, but I have more 30
pin 1 Meg SIMMS than I care to admit :-) ).... system saw 8 meg of
RAM, no parity error.....

So then I pulled the jumper from pins 1+2 like I saw documented on the
web for 12 meg operation, and it saw all 12 meg, and tests it fine...

The big problem I think was two fold... 

1. The expansion board includes nothing to retain it to the system board
   except the tension of the connectors within the sockets !  Due to
   transport and heat cycling creeped it loose in the socket...
2. I think the SIMMs were in the wrong sockets for 8 meg operation... I
   don't know if they should have been in the other 4 or some staggered
   arrangement, but I was planning on putting it to 12 meg anyway, so I'm
   not going to go back and figure that one out (especially since I've cracked
   (almost completely breaking) one of the damn plastic levers to hold one
   of the SIMMS in !).

So now I am the proud ? owner of a 12 Meg Sun 3/50 !  yay...

Now if only I knew how to deyellow the plastic :-(.  I hate how some
plastics do that... I have a nice old 17" Viewsonic monitor that is
yellowed on one side from sunlight... it's great monitor but a bit
unsightly :-(.

Now I have to figure out if I want to run SunOS 3.X (if I could find
that OS), SunOS 4.X (4.0.3 (again have to find that OS) or 4.1.1 (I
have that one)), NetBSD, or OpenBSD....

Anyone with experience on those OSes on a 3/50... what would people 
recommend for this old relic...

>rescue list - http://www.sunhelp.org/mailman/listinfo/rescue

-- Curt

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