> On Feb 18, 2022, at 3:18 PM, Gary Grebus <g...@grebus.com> wrote:
>
> On 2/18/22 09:46, Paul Koning wrote:
>> ...The 9000 also had its own I/O bus, XMI, different from BI. I don't know
>> how its performance compares, whether it was worth the effort.
>
> XMI already existed as the system bus for the VAX 6000 series machines. I/O
> on the VAX 6000's was via an XMI-to-BI bridge. I don't remember the exact
> performance specs on XMI, but it was wider and faster than BI.
>
> XMI was then also used as one of the possible I/O buses on the VAX 10000 and
> AlphaServer 7000 and 8000 series machines, via a system bus to XMI bridge.
> So the XMI I/O adapters were common across all these series of machines.
I didn't remember all those details, thanks.
There also was an effort at one point to adopt FutureBus in DEC systems. We
did a pile of design in the network architecture group to figure out how to
handle interrupts and bus cycles efficiently; I don't remember if anything
actually shipped with that stuff.
paul
