Re: Jeri board and extra things
Date: 2001-05-03 15:13:35

On Thu, 3 May 2001, Nate Dannenberg wrote:

> > The only problem is maybe the lengh of the busses. We cannot equip this slot
> > expander with buffers as we have no means to tell when the buffer should be
> > activated and, more important, in what direction.
> Use bus transceivers.  These are bi-directional buffers of a sort, with a
> Read/Write direction line, which could be tied to the computer's R//W
> line.  Cartridges use this line of course, to sense read/write operations,
> and so the transceivers should, too.  As I understand it, the propagation
> delay across these things is tiny enough to be of no real concern.  This
> type of buffer/transceiver has an Output Enable line as well if I remember
> right, which of course could just be tied active for most lines, such as
> the address and data busses, the clock lines, and so on.
> These little guys have a place in the Power SID project I'm trying to
> build (never seem to find the time), and are there to elimiate some of the
> noise the SID picks up from the rest of the bus when it's de-selected.
> David: what was the part number for those transceivers you suggested for
> PowerSID?  I don't have the plans handy.

It's the same setup as in the vic20. Two unidirectional buffers , and one
bidirectional for the data lines.  74ls244/74ls245.  My book isnt available
atm :(

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