Configuring an MS11-L for an 11/24

Chris Zach cz at
Sat Oct 17 22:12:27 CDT 2020

And one mistake already: Pulling the 11/24 box out shows the H777 supply 
in it does supply +15v, so the memory board jumper is configured back to 

Also I see slots 3-6 only need G727 knuckebusters as DMA is jumpered by 
default, as is slot 9. With the Rl11 controller in slot 7 and the RX02 
controller in slot 8 I should be good. Still will need to find a 9302 
terminator somewhere. I wonder if a 930 knucklebuster terminator will work.


On 10/17/2020 10:26 PM, Chris Zach via cctalk wrote:
> So I'm working on this old MS11-L board I have had sitting around 
> forever. M7891 DK. Goal is to use it in my 11/24 with KT24 MMU.
> I've switched the jumpers so it will run on a +12 supply instead of a 
> +15, and so it will run in an extended Unibus slot as opposed to a 
> normal unibus.
> However I'm stumped regarding the +5v and +5 BBU supply lines. The 
> problem is the manual says to set the jumper that is above C12 (bottom 
> of board, two capacitors next to each other, pretty easy to spot) so 
> that W3 is in and W7 is out if you just have +5v. On this board, W3 is 
> out, W7 is in, but there are two other jumpers right above them (nothing 
> is labelled on the board).
> So....
> Is it the bottom jumper that is +5 or the bottom and the one above that 
> need to be moved?
> This might be why this board never worked right, if the memory refresh 
> is expecting power on the BBU line and I don't have that then it's not 
> going to work very much :-) But which jumper is the right one to use?
> Thanks!
> Chris

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