10 Oct
2003
10 Oct
'03
12:47 p.m.
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).
It may be, as you say, that the KA65x cannot do this. The KA655 TM seems
to be silent here - or at least it is in the sections I quickly read
just
now. The bus interface is handled by the CQBIC, but I don't have that
particular manual handy right now. If the CQBIC can do this, then I
expect
that most of the CVAX MicroVAX 3000 Series machines can do it (and if it
cannot, then presumably none of them can).
2) Each processor has a "doorbell" register
to allow other processors
to interrupt it.
This I think it does have - at least it has a register called IPCR. I
don't
have the KA630 User Guide (*sniff* - someone must have one they can
scan!)
so I cannot compare terminology directly, but I think this is what the
doorbell register is. Since I don't know of anything that uses it,
finding
example code to verify this may be somewhat hard!
--
---------------
Antonio Carlini arcarlini(a)iee.org