Re: C64 cluster

From: David Wood (
Date: 2007-11-07 13:05:59

Ah, you're right.  I neglected to include the CLK line.  Let's change two
lines to 'two pair'. ;-)

For clock collissions, I'm unsure and will think about this today.


On Tue, 6 Nov 2007, Jim Brain wrote:

> David Wood wrote:
> > Network: Half-duplex packet-based bus network (think: Model railroad DCC
> > system).  Collision detection is done by using both serial ports linked
> > together: When you transmit a byte, you also recieve it.  Transmit, then
> > check to see if what yout ransmitted is what was seen on the line.  If not,
> > there was a collission with another node's data, and you need to retransmit
> > your data after a short/random delay.  This should be done after each byte
> > transmitted of course, so you dont flood the line with a packet full of
> > collissions.
> >
> >
> I believe the CIA serial ports are synchronous, so you need the SP1 and
> and CNT signal, which makes this harder, as CNT could get mangled if two
> machines try to transmit at the same time.   On the plus side, CNT and
> SP are open drain, so they wouldn't fight each other on the network.  It
> seems a token passing or some other collision avoidance scheme is
> needed.  The 64 PRG speaks of using the SP/CNT pins in a network, but
> master/slave.
> Maybe have a common ATN wire like the IEC protocol?  But, how to use it?
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