Multi-CPU Qbus VAXen

From: Eric Smith <>
Date: Fri Oct 10 15:35:33 2003

"emanuel stiebler" <> wrote:
> If you're thinking about you own box (doing your own backplane), try to
> use four ka655 with 64 mbyte memory each and 4 mbyte shared memory on
> the qbus.

AFAIK, the KA650 and KA655 do not have the support for multiple
processors on Qbus that was present in the KA630. The KA630 (MicroVAX II)
had two features for this:

1) The bus interface could be configured to be a bus requester rather
    than the system bus arbiter. This has to be done on all CPUs other
    than the first. (Note that the VAX 11/780 was also capable of this,
    as discovered and exploited by George Goble).

2) Each processor has a "doorbell" register to allow other processors
    to interrupt it.
Received on Fri Oct 10 2003 - 15:35:33 BST

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