Unibus disk controller with modern storage

Noel Chiappa jnc at mercury.lcs.mit.edu
Sat Oct 22 12:43:50 CDT 2016

    > From: shadoooo

    > they can run linux for the software side

Maybe it's just me, but running Linux on an interface card strike me as
somewhat grotesque. It's bad enough running a far faster chip than the vintage
CPU, but... a majorly complex operating system to boot?

    > I'm trying to figure if an hybrid QBUS / UNIBUS solution is possible.
    > Of course one have to switch some jumper to avoid conflicts

Lots and lots and lots and lots of jumpers. The two buses are completely
unlike, pinout-wise.

And the UNIBUS board has to be a quad, and there are some QBUS chassis which
only take duals...

    > What kind of bus transceivers did you used for the QSIC

We used a mix of DS8641 quad transceivers (they're still available in
reasonably good numbers for a reasonable price) and AM2908 octal latching
transceivers with a tri-state output (to allow us to have a bidirectional
internal bus for BDAL00-BDAL21 - we were trying to minimize the number of pins
needed on the FPGA to interfaces to the QBUS). But we probably will use a
different FPGA on the production boards, and all DS8641's.

    > you have to go from 5V open-drain logic to 3.3V logic?

We do that with separate 74LVC7T245 level converter chips.


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