Henk Gooijen henk.gooijen at hotmail.com
Fri Jun 3 13:27:10 CDT 2016

-----Oorspronkelijk bericht----- 
From: jwsmobile 
Sent: Friday, June 03, 2016 7:51 PM 
To: General Discussion: On-Topic and Off-Topic Posts 
Subject: Re: PDP-11/94-E 

On 6/3/2016 9:11 AM, Jerome H. Fine wrote:
> >Rod Smallwood wrote:
>> >On 03/06/2016 16:43, Jerome H. Fine wrote:
>> Hi its a KDJ11-B all memory on CPU board
>> Rod
> I am very confused.  Is your mention of memory on the CPU board
> for the PDP-11/83 or the PDP-11/93?  I thought that the PDP-11/83
> never had memory on the CPU board (assuming that the cache is not
> regarded as memory).
> This aspect of the thread is probably no longer relevant, I just wanted
> to note that PMI memory can be used with what most individuals would
> consider to be a PDP-11/73 (naturally a quad) board and the PMI
> aspect of the memory will be activated when the PMI memory is
> installed ABOVE the CPU board.
> Also when PMI memory is installed BELOW the backplane, it is then
> used as normal Qbus memory in a Qbus system.  I can't see anyone
> doing that, but it is allowed.
> Jerome Fine
I suspect it is using this board.



I am guessing the 1.5mb isn't cache, but is system memory on this board.

There is also the KDJ11-BF which has no memory on board.  M8190-AE.


Nope, the M7554 is the PDP-11/53 CPU.
The 11/83 had its memory on the bus (either left or right of the module).
The 11/94 did NOT have memory on the bus, because *all* memory is
on the CPU module itself. Note that there are two versions of the 11/94.
One with 2 MB RAM and one with 4 MB RAM (all that can be addressed!).
The 2 MB version and the 4 MB version are identical, just half the RAM chip
population is not placed. However, all through-hole pins are soldered so
the upgrade from 2  MB to 4 MB would be a real PITA, *if* you'd try it at all!

- Henk

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