> Paul Thompson wrote:
> > 
> > I seem to recall the 6000 line officially supported 512MB max.  Are you
> > hitting that in your memory board configuration?
> 
> yes, I'm hitting this :-), this is a flaw in the design IMO.
> I will have unsused slots and unused cards in the end :-(.
>  
``flaw in the design'' may be something to discuss :-) The maximum amount
of memory a VAX can have is 512MB, due to the hardware design.
512MB was an awful lot of memory in the mid-70's when the 11/780 was 
designed, it could only have 64K memory cards. The I/O space in the 
machine always starts at 512MB. (*)

There came an address extension bit in newer machines that allowed a VAX
to have up to 3.5GB of memory, but I don't know anything about it.
I think it was NVAX only.

-- Ragge

(*) The 11/750 is an exception when it has its I/O at 14MB instead.
Therefore it can only handle 14MB of memory.