Unibus disk controller with modern storage

Noel Chiappa jnc at mercury.lcs.mit.edu
Thu Oct 20 16:32:07 CDT 2016

    > From: Paul Koning

    > That's fine if your target is an OS for which you can write drivers. It
    > wouldn't help RSTS users.

Right, they're stuck with exact clones of DEC controllers. (For Unix, tweaking
the RP11 driver to handle the extended RP11 should take all of 12 minutes,
tops! :-)

    > Q22 disks .. RL02 also, if I remember right.

Oh, right, the RLV12 - forgot about that. Still, it would be nice to be able
to run RK11's and RP11's in 22-bit mode! :-) Especially since there will be
replicas of DEC's indicator panels for them, whereas an RL11 indicator panel
would definitely be... an anachronism! ;-)

    > A possible answer for a lot of this is to do the actual emulation
    > algorithms in software, in an embedded CPU inside the FPGA. For MSCP
    > that's obvious, but it would work for the others as well I suspect.

Dave B is a wizard with Verilog, so until it gets to the complexity level of
MSCP we'd probably do it all in Verilog.

    > From: Jon Elson

    > I did **ONE** board with some kind of gold flash that a PCB house 
    > recommended. ... it was a colossal disaster. You had to lift the pin
    > ... Since then, I have used pure tin HASL, and had little trouble.

I think gold came into the discussion in the context of the contact fingers
where the board plugs into the backplane. I've never seen a QBUS/UNIBUS board
with tin fingers, although they were common on SIMM memory cards; no idea
if tin would work for QBUS/UNIBUS - although now that I think about it,
SIMM cards didn't slide into position, but kind of rotated, so maybe tin
would work there.


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