[A83] Re: calculator networking - good idea?
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[A83] Re: calculator networking - good idea?
Jeff wrote:
>Hello all.
>...
>My thoughts for the first, simplest calculator network hardware would be a
>hub with
>four or so 2.5mm jacks. The "red," "white," and "ground" conductors of each
>jack would be respectively connected to the "red," "white," and "ground"
>conductors of the all other jacks. Would one calculator's link port have
>enough output current to power the inputs of three other calculators in such
>an unpowered hub? A powered hub would have simple buffers to assert the
>outputs of each jack.
>
>
>
I have thought of another configuration. Where the calcs are kindof in a
ring.
white cable on calc1 is connected to red on calc 2. calc 2:s white
connects to red on calc3, and the white on calc3 connects back to calc 1.
In theory, it might even be possible to use the standard protocol for this.
the protocol works as far as I have understood like that to send a 0,
you pull one of the lines low, and the recieving calc ack:s this by
pulling the other line low. to send 1 you pull the other line first, and
the reciever ack:s with the first line.
This way all 0:s send will travel in a (counter)clockwise direction, and
all 1:s in the other direction.
the senders bit will be transfered around the ring, and ack it.
this has one drawback. collisions. You probably have to assign one calc
as master, telling the others when they can send, with sufficent delays.
collision is a problem in your design also though.
Mine has the advantage that each calc only have to drain one other calc
low, just as normal link, instead of having to drain many. (or if you
build some circutry in the hub to compensate for this)
It could also be a bit slow if you have many calcs connected.
--Olle
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