I think you guys know I have a working PC164, runs like a champ,
and one that I am playing with to get running.

Tonight I upgraded the memory in the owrking machine, full up memory
slots, the proper memory, real 36 bit, 60NS, and all that.

I had the machine going beep beep beep, with the memory error
indication.
I removed the memory, retested the new four that I was installing
by putting them in the front four slots, worked like a champ.

Reinstalled those same simms in the back slots, installed the
previously working 4, got the same beep beep beep.

This time I ONLY REMOVED THE 128/256 jumper - so that the 256 bit
data path is emabled vice 128.  That was the only change.  I did not
move the machine in any way other than removing the jumper.
Powered back up, and BINGO, runs with full mem (AND APPEARS to be 
noticably faster but that is subjective).

Reading the Docs, I see the 256 bit path as an OPTION, not a 
requirement.  I had planned to do this anyhow, to squeak a couple
more cycles out of it....
Did I miss something?  Is this required with fullup slots on the 
PC164?

Oh, it is running more than 800K keys/sec doing RC5 cracks.
thanks
bob