VAX9000 unearthed

[Gary Grebus]

On 2/18/22 15:35, Paul Koning wrote:
> 
> 
>> 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.
> 

There was a FutureBus I/O subsystem for the AlphaServer 8000 series.  It 
was a qualified, orderable option, but I can't imagine we sold very many 
(if any).  It was done supposedly because the US Navy was standardizing 
on FutureBus for some application.  I vaguely recall DEC made an 
Ethernet adapter that went on FutureBus, but you would have needed 
another I/O bus to have a usable system.

The native I/O interface on the AlphaServer 8000 (aka TurboLaser) was 
one or more system bus to "hose" modules, where a "hose" was a pair of 
cables that provided a 32 bit data path in each direction.  The hose 
connected to a bridge module on the target I/O bus.  There was support 
for XMI, PCI, and FutureBus.

	-- Gary