VAX9000 unearthed

[Paul Koning]

> On Feb 18, 2022, at 3:18 PM, Gary Grebus <glg at 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