[SPAM] - Re: Simulated disk drive for RT-11? - Sending mail server found on relays.ordb.org

[Jerome H. Fine]

 >Allison wrote:

>>>On Jun 6 2005, 22:46, Allison wrote:
>>    
>>
>>>Note there were differenet backplanes used in the BA23 those
>>>that were compatable with uVAX-1, those that were uVAX-II
>>>and the microPDP-11. Use the wrong one with the desired CPU
>>>and bad results happen.
>>>
>>I've never seen more than one type of backplane in a BA23, and only one
>>is listed in my manuals: H9278-A.  It's compatible with all of
>>microPDP-11, uVAX-I and uVAX-II without so much as a jumper change.
>>Are you thinking of something else?
>>
>No, I have a few too.  I have this thing for aquiring odd systems.
>  
>
Jerome Fine replies:

As far as I understand, a 22 bit PDP-11/23 and all
PDP-11/73 systems use the same memory as the uVAX-I.
That would seem to indicate that the same backplane
can be used for either CPU in a BA23 box.  As for a
uVAX-II, I can remember using the SAME box for BOTH
a PDP-11/73 and a uVAX-II system at least 5 years ago.

So I am NOT saying that there are no backplanes which
can be used with only one of the microPDP-11, uVAX-I
and uVAX-II systems, only that as far as I understand
and based on my actual experience, all of the BA23 boxes
that I have (and I probably still have at least a dozen)
can run all three of the above CPUs.

If I am correct, can Tony please verify my statement
in the previous paragraph?  Or anyone else as well since
Allison may have additional information about special
backplanes which can run only one of the three CPUs.

So except for the 4 * 8 backplane from a BA23 with epoxy
in the last three slots (and it can still run all three
CPUs), I concur with what Tony has stated!

Sincerely yours,

Jerome Fine
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