VAX-11/750 EMC Memory Board LEDs - test-drb@ccmp.vtda.org

8 Jul 2009

--- On Wed, 7/8/09, Ethan Dicks <ethan.dicks at gmail.com> wrote:

...
  One possibility is an ECC fault.? ISTR that since the
 boards fire up
 with zero or random contents, most/all of the locations
 don't have the
 right check bits.? The board sets the checkbits all at
 once at
 power-on, possibly with some sort of startup/refresh
 counter, so it
 might take a noticeable time to strobe through the array. 
Yes, that seems reasonable. The puzzling thing is that on all the boards, the light stays
on, just less brightly, after a few seconds. 

Is it the memory board or the memory controller that sets the checkbits ?

...

 Do the yellow lights seem to vary in brightness under
 different
 loading conditions during normal operation or are they
 essentially 
Can't tell yet; I have some other issues to resolve with the machine before I can get
to normal operation.

...
  dark?? Are your RAM chips socketed by chance 
No, they're soldered in.

Each one has a switch that I believe allows you to take the board offline. I can take any
board offline (which throws a red memory configuration error lamp on the memory
controller) except for the board in the left-most slot, no matter how few or many of these
things I put in there.

-Dave