[rescue] Sun 3/50 DVMA memory error, and another 3/50 with parity error

[Curtis H. Wilbar Jr.]

So, I have 2 3/50 boards I'm trying to resurrect.

I thought one was good (passed diags with diag switch on).  The other I 
know has a
bad ram chip.

The one I thought was good... gets (as one example):

MEMORY ERROR! STATUS D4, DVMA-BIT 0, Context 0, Vaddr: FFE10C, Paddr: 
003FC10C,
Type 0 at 0FeF4C88

It gets several of D4, D2, and D1 when it attempts to boot, or if you 
interact with it
at the boot PROM.

I did try changing the large socketed (MMU + more) chips from the board 
with the bad
memory chip... same behavior.  I have not tried changing CPU, FPU, boot 
rom, or any
PALs.

As for the one with the bad ram chip, it fails quickly on power up with:

Memory Parity Data Test
 Err 2: Addr 0x00000400, Exp: 0x00000001, Obs: 0x0080001, Xor: 0x00080000

I've not found any memory map to help me determine which chip this is.
0x00000400 is the 1024th byte of RAM... so I'd suspect the first bank... 
but which
bank that is I don't know.

Anyone have a 3/50 memory map so I know which chip to replace ?  Or a good
technique for figuring that out ?

Thanks in advance,

-- Curt