>I've been working on a good bus protocol for potentially-busy CPU's.  The
>best I've come up with so far for connecting precisely two CPU's which may
>be arbitrarily busy and do not have any "special" hardware useable for such
>a task is described below.  Note that I2C does not meet this criterion since,
>without hardware assistance, a busy slave device could miss bits coming from
>the master.

cut........

>What does everyone think of this as a protocol?
>
Clumsy and unnecessary. Consider this protocol.

Two pics or any other devices, with one input and one output each. they
don't ever change (great for the PC printer port). To communicate one drops
its output the other then provides an ack etc.......  and then provides the
clock for the sender. Work out the details yourself  but I've given you the
idea.

You have with just two fixed lines bidirectional tranfer with handshaking
built in!

This is how the parallax programmer comunicates the the PC with just two
fixed direction lines. Its  brilliant!

Regards,

Jim Robertson

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