[Coco] hardware port mapping question
Mike Pepe
lamune at doki-doki.net
Tue Apr 24 11:53:54 EDT 2007
Mark McDougall wrote:
> Mike Pepe wrote:
>
>> Essentially what you're making here could be a 4x4 crossbar switch:
>>
>> ABCD
>> A++++
>> B++++
>> C++++
>> D++++
>>
>> It could be done with a bunch of latches and tri-state buffers.
>> Arbitration could be an issue, but it sounds like what you're looking
>> for is for each CoCo to have one "out" port that can be read by the
>> others. If that's the case, it becomes more possible. If you're
>> looking to write values into a common register, it becomes much more
>> complex.
>
> You could, of course, come up with a protocol that requires each
> computer to write to its own latch only.
>
> Regards,
>
Yes, it could be very simple- here's what I'm thinking.
Each CoCo has one "Out" port, which can be read by all machines, say at
a different address.
Each CoCo would poll the others for messages, reading twice to ensure
that the data wasn't captured in mid-write, and can respond via its own
write port.
There would need absolutely need to be some sort of protocol involved to
co-ordinate this operation.
Is Roger planning on making a multinode supercomputing cluster out of
CoCos?
-Mike
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