MicroVAX 3300/3400

[Zane Healy]

On May 25, 2021, at 11:54 AM, Glen Slick via cctalk <cctalk at classiccmp.org> wrote:
> 
> On Tue, May 25, 2021 at 10:54 AM Zane Healy via cctalk
> <cctalk at classiccmp.org> wrote:
>> 
>> One odd thing is that the KA640-A seems to plug into another board, before the DSSI drives. I’m getting ready to dig into that, and find out what that board is.
>> 
> 
> Is that an M9715 board plugged into the backplane between the CPU
> board slot and the power supply, or something else?
> 
> Or is there a cable plugged into the DSSI connector on the M7624 KA640
> adjacent to the memory bus connector that plugs into a some board and
> stops there, and then another cable from that board to the DSSI
> drives? Do the DSSI drives plug into the backplane, or do they have
> cables connecting to them?

It turns out that the oddness was the CPU Board, and a 16MB Clearpoint RAM board.   What I thought was the CPU, is really the header panel over the RAM and TK70 controller.  There is also a M9715 between the CPU and the powersupply that I’d missed seeing.  The cables to get to the DSSI connector by the Powersupply are hanging out the front.  Basically it’s a cable going from the KA640 to a ribbon cable to a cab kit, then DSSI cable from that to the connector next to the power supply.

I disconnected the DSSI cable from the KA640 (M7624), and got the same errors.  

The more I play with this, the more I like the chassis, and the more I want to get it going.  This chassis is definitely better than the 3rd party rack-mount chassis that my MicroVAX 3 lives in.  If it was working, it would simply need my RLV12 moved to it to be perfect.

At this point, I’m suspecting an issue with the KA640 board.

Zane