Tony Duell wrote:
Well, I am not going to make the radio modules myself
(no way can I
meet
type approval, even if I meet the technical specs), but I would
certainly consider making something _round_ said modules.
I assumed that you'd start with a module for the RF stuff: but
that's essentially no different to plonking a 7474 on a board
(you could build it from discretes, but there's a nice
convenient package ...)
Now that's something that had not really struck me
(which is why this
sort
of discussion on the list is so useful) -- that the file sizes I am
going
to be transfering _are_ limited. 128Mbytes is larger than the
available
mass storage (let alone RAM memory) on most of my classics, so except
in
very unusual ciercumstances, the data I wish to transfer is going to
be a
lot smaller than that. Which means a buffer is certainly an option.
I mentioned 128MB simply because it is the *smallest* SDRAM I have
to hand in any reasonable quantity (I have a handful of 32MB and
64MB). 512MB is cheap too. I don't know at what point you go beyond
the likely capacity of any classic. There's not a lot of point in
going this route with anything that has an ethernet connection. In
my case that would leave machines like a PET, C=64, RML 380Z
and so on. 128MB would be overkill for any of those.
Of course, the other issue is speed. Assuming 19200 baud that's
~2KiB/s on a good day. It would take a chunk of time to fill
128MB.
Does it need to be idriectional?
I wasn't sure how you envisaged using this mechanism. If it's
always the case that machine A "prints" to machine B (i.e. A
sends, B collects) then the modules do not strictly need to be
bidirectional. But I suspect that it would be much more convenient
to have a single style of module that does both "send" and
"receive" and then just build enough of them to handle
your needs. Otherwise the sender and receiver will always be
at the wrong ends of a 30' walk :-)
Antonio
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